This invention relates to jigging machines used in the dressing and beneficiation of minerals(ores) such as coal, iron ore and others and more particularly to a wet jigging machine comprising a plurality of sets of settling beds such as to permit parallel, simultaneous processing of two or more mineral streams.

Jigging is a process of gravitational separation of the components of a solid mixture based on the differences in the specific gravities(SGs) of the constituents thereof. Jigging is carried out in a fluid wherein said components get stratified into layers in accordance with their SGs. To obtain said stratification, said mixture is laid out in the form of a bed mat is submerged in the jigging fluid which is then pulsated. Said bed loosens up during said pulsations allowing differential settling of the ore particles in the fluid to occur. Particles of the highest SG collect in a layer at die bottom of the bed while the others arrange themselves in layers of decreasing SGs going from the bottom of the bed to the top thereof. Said layers are also referred to as fractions in the further specification hereinbelow.

Jigging machines therefore essentially comprise a support member upon which the ore to be treated is placed. Said support member is referred to herein as the bedplate. The bed plate and the ore bed are housed in one part of a vessel(tank member) which holds the jigging fluid. Said bed with the bedplate remains submerged in the jigging fluid. In another part of vessel means are provided to pulsate the jigging fluid. The pulsations are cyclical and impart a reciprocating motion to the jigging fluid which alternately rises into said bed and men drains out therefrom, the bed however remaining fully submerged in the jigging fluid at all times during the said pulsing. Said upward movement of die jigging fluid into the bed is referred to as me pulsion(upward) stroke while the opposite part of die cycle wherein die fluid moves downwards in die bed is referred to as the suction(downward) stroke. Partial submergence of the bed is also practiced.

During the pulsion stroke, the ore bed dilates(expands) and loosens up, and during the reverse(suction) stroke contraction(compaction) of the bed takes place. Particle settling commences in die pulsion stage and continues during the suction stroke till a level of compaction of the bed is reached at which particle movement ceases. Classification occurs during said settling phase as different particles settle with differing velocities and accelerations depending on their SGs, sizes and shapes, the properties of the fluid, the parameters of the fluid flow, the properties of said bed, the instantaneous degree of said compaction and others. Said classification yields stratified layers of the ore material. The stratification becomes more refined successively with the progress of the pulsing operation.

The most commonly used jigging fluids are water and air. The process using the former is referred to as hydraulic jigging(or wet jigging) and the latter as pneumatic jigging(or dry jigging). Jigging beds may be of the fixed bed type or moving bed type. In the former, the bed remains stationery and the pulsing is generated by said pulsing means of the piston type or by compressed air or other means. In the latter systems, the bed is given a reciprocating motion causing the jigging fluid to move in and out said bed.

Prior art discloses a very large variety of jigging machine constructions such as rectangular plan vessels, circular plan vessels and vessels of other shapes and configurations. Said beds may be horizontal or inclined(sloping) and as mentioned, may be fixed or moving. The water space under a said bed is referred to herein as the hutch compartment or hutch for short A jig may comprise a plurality of said beds in series, with a common hutch or a series thereof, one for each said bed. The part of the jig tank member below said hutch is referred as the under-hopper. Under-hoppers generally have sloping sides and the material falling thereinto from the jig beds above collects therein from where it is withdrawn periodically or continuously by means such as bucket elevators or others. In some systems, the product(a fraction of value) also drops into said under-hoppers and is collected and withdrawn therefrom.

A wide variety of said pulsing means are disclosed such as piston systems that act on the hutch water in another part of said vessel, pulsing by compressed air, pulsing by air pressure pulses and others. Said piston systems may be downward acting from above or upward acting from below or acting along horizontal axes, being mounted in one or the other sides of said vessels(hutches). Piston pulsing systems may be actuated by compressed air or by mechanical means. A said bedplate together with the associated components such as the air chamber that supplies the pulsing air and the hutch thereof are referred to herein as a jigging cell.

Two different types of jigging procedures are followed in the prior art: through-the-screen jigging and over the-screen jigging. The former is also referred to as under the screen jigging. In through the screen jigging, arrangement is made for the bottom(lowermost) layer, which is the product material, to Ml into the hutch and therethrough to the under-hopper. The product material from said lowermost layer is of the ore constituent having the highest SG. After falling through, the product material collects in the hutch and is withdrawn therefrom through an outlet located thereon. The term 'hutch' is also used to refer to the under-hopper thereof at some places in this specification.

In an alternative arrangement, a discharge(sink) chamber is provided at the end of a said bedplate through which the said lowest layer, being a product layer or otherwise, is withdrawn. The discharge chamber comprises discharge gates at the bottom end
thereof.

The practice in through-the-screen jigging is to provide a ragging layer over the bedplate. The material of the ragging layer is selected to be of a somewhat higher SG than the desired product fraction and the particle size thereof is also selected to be higher man that of the product such that the ragging layer remains substantially stationery during pulsing and allows die product particles to trickle down therethrough and move into the hutch. In this arrangement, the bedplate is designed to be quite open.

Under-me-screen jigging systems without said ragging layer are also known in the art In these systems, the product particles fall through the bedplate into the hutch and no said intervening ragging layer is provided on the bed. In some systems, combinations of the two major jigging procedures are adopted.

The lowermost layer is usually the product in the case of metal ore jigging and is referred to as concentrates, sinks, sinks fraction and by other terms. The fraction that is discarded in the case of said metal ores is the top layer which is also referred to as the reject or refuse layer or fraction, or as floats and floats fraction. In the case of coal washing(jigging) it is the top layer that is the product while the said bottommost layer comprises gangue and other such waste matter. Said concentrates are also referred to as tailings. One or more middle layers of jig beds may also be of value and may be recovered. They are referred to as middlings. The jig of the invention can be adapted for recovery of any of said fractions.

The characteristics of the material mat comes through the ragging layer also depend'on the jigging operation if any conducted before the said jigging operation with a ragging layer. In some arrangements, the lowermost layer formed from one of die constituents of the ore serves as the ragging layer. Other systems are designed to allow an intermediate layer containing finer particles than the lowermost layer to fall through into the hutch as the hutch product.

In over-the-screen jigging, material is not allowed to pass into die hutch. The bedplate openings are merefore generally finer. Material withdrawal, whether of the product or tailings or middlings is carried out above the bed. Material is withdrawn at the end of a bed or at the feed end thereof. The lowermost layer drops down into a discharge system at die end of me bed while the upper layer(s) are skimmed off. Where a set of beds in series are used, lowermost layers may also be withdrawn at any intermediate point in the bed chain. Hybrids of over- and under-the-screen jigging are also adopted.

Jigs of prior art are operated in me batch mode or continuous mode or in a hybrid mode. In me continuous mode, the ore material to be treated is charged at one end of said bed. It moves along the bed and discharges at the far end. The feed rate, the bed length, the pulsing parameters and other system parameters are selected such as to give the desired separation and throughput. Separation occurs into a bottom product layer and a reject( waste) layer at the top. Through a system of gates, baffles or skimming arrangements bom said product and reject layers are discharged from the jig at me discharge end thereof. Said separation may be carried out in a single said bed or a plurality thereof may be provided for serial jigging. The propelling forward of the ore material along the bed is done by shaking, oscillation, or vibration of the bed or by other such mechanical means. Alternatively, or in addition, hydraulic means are employed. Sloping(inclined) beds are also used. Other arrangements for said discharge of various fractions, for example, at the feed end are also found in the art

In the hydraulic arrangement for propelling of the ore material mentioned above, water flows along said bed to the discharge end thereof. Said flow is constant and uni-directional unlike the flow of the pulsing water. This flow comes up through said bed and moves the ore material along the bed. In some installations, a certain amount of water enters the bed along with the ore feed.

In this specification, the said bottom layer is described as being the product layer. The other operational scenario where another said layer is the product is not described. This is in the interests of simplicity and conciseness. The jig of the invention can be easily adapted to treat a mineral such as, for example, coal where the top layer comprising washed coal would be the desired(product) layer. The lower layers in coal washing comprise gangue and other such waste matter of higher SG. It is easy and simple to adapt the jig of the invention for taking out middle fractions(middlings) if so desired. Thus, any of the said fractions can be the product or the reject It depends on the mineral being processed, the jig construction, the jigging procedure and the parameters of the jigging operation. To that extent the said terms may be considered interchangeable in the description and claims herein. The jig of the invention, it is stressed, is easily and simply adapted to any of the alternatives outlined hereinabove.

In many systems it is necessary to modify the intensity of said suction strokes. Said intensity is an important variable in the processing of ore by jigging. If said intensity is high over-compaction of the bed may occur. To adjust said intensity, a pre-determined flow of water into the hutch may be provided during the suction stroke. The opposite practice of withdrawing a certain amount of hutch water during said suction stroke is also adopted by some operators. There is an increased downward drag on the particles during said water withdrawal. This modifies the downward acceleration of the particles during said
settling. The profile of the flowrate of the jigging fluid in the bed with respect to time over the pulsion/suction cycle is a significant jigging parameter and is adjusted by means of said hutch flow mentioned above and by means of other factors. The appropriate said profile is determined by experimental tests on the ore in test jigs. The profile to be adopted depends on the parameters of the ore to be processed, the type and extent of separation desired and other factors and, as mentioned, is determined by a jig test

The wide variety of the jigging equipment constructions available in the art and die diversity of the jigging procedures/arrangements adopted in the art are described above. This is to emphasise mat the novel features of the jig of the invention disclosed herein are relevant to, and easily adapted to said constructions and procedures. This invention provides for an improved jig wherein are incorporated several improvements that are novel features not disclosed in the art. It may be noted that said improvements(novel features) are very versatile in so far as they are easily and simply adaptable to all known jigging equipment and specifically to each of the jigging equipment constructions covered in the survey presented hereinabove.

It is again observed that in the further specification hereinbelow, the description of the invention is limited to the context of hydraulic jigging wherein water is the jigging fluid. Jigging is of the fixed bed type with over the screen jigging. Jigging is on a continuous basis. The bed may be horizontal or sloping. There may be a plurality of said beds in series. The lowermost bed layer is supposed to be the desired(product) layer. In the embodiment of the jig of the invention described herein, the lowermost layer of the second bed thereof is the product layer. Said limitations in the description are in the interests of conciseness and without limitation to the scope of the invention.

The ore feed comes in at one end of the bed and moves down the major axis thereof. Suitable discharge arrangements are provided at the far end of the second bed for discharge of the product layer and at the end of the third and last bed for the discharge of the waste layers. Pulsing is by compressed air, means being provided for adjusting the parameters thereof to obtain the desired frequency and stroke for said reciprocating motion of the jigging water. Stroke intensity can be modified by suitable intervention with hutch water.

As mentioned, this narrowing(confining) of the description to a particular jigging configuration is in the interests of simplicity and conciseness and without limitation to the scope of the invention. It may be noted that the novel features of the jig of the invention are easily and simply adapted to each of said jig constructions and operating systems described herein and others. It is similarly adapted for hydraulic as well as pneumatic jigging; to both moving bed and fixed bed jigging systems and to over- and under-the-screen jigging. Fixed bed jigging systems are as described above while in moving bed systems, the bed is moved to obtain said relative reciprocating motion between the bed and the fluid. External pulsing means such as pistons or compressed air or other means are redundant in moving bed systems.

A jig is referred to in the art by several different terms such as jig, jig washer, washer box, washing deck, shaker, reciprocating screening device, ore box and others. In this specification, the term jig is uniformly used and is intended to be a generic term covering all the abovementioned and other names and constructions used in the art In the jigs described hereinabove, said separation takes place under the influence of gravity. There are jigs in prior art that carry out said separation partly or wholly under the influence of a centrifugal force. The novel features of this invention can be easily and simply adapted to jigs mat utilise centrifugal action. The term 'ore' is intended in this specification to cover any solid material or mixture that can be treated by the process of jigging and includes all metallic and non-metallic minerals and ores including coal and other such mineral fuels.

A clean and sharp separation strictly according to the constituent SGs is an ideal that is not always achieved in jigging practice. It is valid where the bed particles are small, strictly spherical and are all of the same size and where hindered settling is absent It further requires that the relative flow between the bed particles and the jigging water is laminar and low in velocity, and the Stoke's Law is applicable. Said clean stratification also requires that the said particles do reach their terminal velocities during the time intervals involved in said pulsing and that sufficient time is available during said pulsing for the particles moving at their terminal velocities to segregate and collect into said clean and sharply divided layers.

A bed containing particles that are of different constituents but that are all small, spherical and of the same diameters will generally speaking segregate and stratify along SG lines as in the ideal behavior indicated above. On the other hand, if the particles are all of the same material and are small and spherical but of different diameters, segregation will take place generally according to particle diameters.

In industrial contexts, the separation profile that can be achieved by the process of jigging lies somewhere between the said two ideal separation profiles described above. This is because industrial ore feeds are heterogeneous mixtures of different constituents wherein the particles are of different species, sizes, shapes, and specific gravities. In such a scenario, there are pairs of particles that are equal jigging, mat is, although they may be of different SGs, their size ratio is such the distance they travel in a particular time interval is substantially equal. Such particles tend to end up in the same said layer.

It will be observed from the above mat the sharpness of said separation(along SG lines) generally depends on the degree of uniformity of particle size in the feed. Prior art has therefore adopted the practice of dividing the ore feed into different size ranges before jigging. The ore is crushed and then screened(sieved) to give a plurality of fractions that are then jigged individually. The prevalent practice is to limit the classification of ore feed to two broad size ranges unless the product quality requirements necessitate division of the feed into further fractions. Said two broad size ranges are then subjected to the jigging process.

This invention is relevant to said practice of separate jigging, mat is, divided jigging. Said separate jigging is adopted in the art in many ore treatments. The different said streams are jigged on separate jigging equipment. Alternatively, where jigging is confined to a single jig then the two streams are processed at different times on the single jig. Said two streams generally speaking arise at a single point, that is, at a classifying system such as a screen system located after the crushing or grinding equipment The two streams are generated substantially simultaneously and at the same point

The diversion of the two streams to two separate jigs located apart from each other is wasteful in so far as it expends more labour and capital. Even if the two jigs were located side-by-side said cost disadvantage would remain although it would be somewhat lesser. Above all having two separate jigs with separate controls and perhaps separate operators is disadvantageous from the point of view of capital costs, manufacturing costs, processing time, ease of maintenance and others.

Thus, it is an object of the invention to provide a jig comprising two or more sets of beds that permit simultaneous and/or parallel processing of multiple fractions of an ore material, each said set comprising one or more said jigging beds in series.

It is a further object of the invention to provide a PLC-based control system for the jig, mat provides individualised control of the jigging parameters at each said bed and also, if desired, synchronised and co¬ordinated operation of a plurality of said beds.

A still further object of the invention is to provide an arrangement of jig internals and the securing and mounting system thereof such mat the flow path of the jigging water to an from said beds to the air chambers thereof is substantially free of obstructions and the said flow of jigging water is substantially free of turbulence and eddies.

A still further object of the invention is to provide a stack system for location, mounting and securing of said jig internals that is simple and easy to assemble and dis-assemble and that does not require to be fastened but is secured by means of a stack compression system.

A still further object of the invention is to provide a substantially obstruction-free access to the jig interior for maintenance personnel.

A still further object of the invention is to provide air chambers that are not integral with the said jig tank member but are discrete and separate and that are easy to access and remove for repair, replacement and maintenance.

A still further object of the invention is to provide a single integrated low-cost, low weight air control box for the jig that combines the two functions of air supply and air exhaust, that is, the functions of the conventional air surge boxes and exhaust boxes; that can service all the air chambers of the jig in a variety of operational combinations and that is substantially functionally-symmetrical.

A still further object of the invention is to provide a discharge gate system for the lowermost layers of a said jig bed comprising a plurality of discharge gates(openings), such mat during closure of the gates should one or more thereof be prevented from full closure by the lodging of material lumps therein, the closure of the remaining gates will minimise the unwanted discharge of material through the gate system.

A still further object of the invention is to provide an improved pneumatically-operated diaphragm-type control stop valve for air supply and air exhaust functions in the air box or system of air boxes through which the air going to said air chambers) and coming therefrom and going to exhaust is regulated.

A still further object of the invention is to provide an improved guidance system for the float stem of the bed density sensing device, of the jig, that provides more smoother and substantially stall-free and trouble-free operation of the said device. The terms 'bed density sensing device' and 'bed height sensing device' are used interchangeably herein.

A still further object of the invention is to provide a connection means for the connection of the air inlet and exhaust to an air chamber, suitable for said separate and discrete air chambers of the invention that are not attached to the jig bodies by either welding or other means.

According to the invention, therefore, mere is provided a mineral jig for carrying out jigging/separation operations on solid materials such as, for example, metallic ores, coal and other minerals comprising inter alia,

(i) a jig tank that houses the jigging cells, beds, bedplates, air chambers and other parts of the said jig;

(ii) a plurality of jigging cells, each said cell comprising one or more jigging bedplates,

(iii) one or more hutch compartmen(s) and under-hopper(s),

(iv) an air system for pulsing(pulsating) the jigging fluid(s), comprising one or more air chambers, air surge and exhaust box(es) with the necessary control valves for air supply and exhaust to/from said chambers,

(v) a control system for controlling/regulating the profile and/or parameters of the said pulsing operations by actuation of the said air supply and exhaust control valves, and for controlling/regulating the feed(s) and discharge of one or more of the mineral streams thereof, through one or more gate(s), baffle(s), or other feed and discharge devices), the said system comprising one or more bed height sensors for monitoring the height/thickness of one or more of the jigged layers on said bed(s), and generating the control signals for the operation of said gate(s), baffles, and feed and discharge devices,

said cells being arranged in a plurality of processing(jigging) lines, each said line containing one or more said cells, such as to allow parallel and/or simultaneous jigging of a plurality of streams of said solid materials in the jig.

The jig of the invention may additionally comprise one, more or all of the eight additional novel features listed hereinbelow.

The solution to the problem posed hereinabove is to provide a jig having multiple said processing lines as is provided by this invention. Within the scope of the invention, each said processing line may comprise one said jigging cell or a plurality thereof. Thus, within the scope of the invention each said processing line may consist of a single said jigging bed along with the associated hutch and air chamber, or a series of beds with individualised said air chambers and hutches or a series of beds with common air chambers and hutches or any combination of the said three constructions.

Multiple beds in prior art jigs are provided for successive processing of a single feed stream rather than parallel processing of multiple streams. In such prior art jigs the said single feed stream is treated in the first bed, subsequently in the second and so on.

Said multiple beds of prior art are located in a line on the jig structure for the purposes of said serial processing. The material flow is along their major axes which are all positioned in a substantially collinear configuration.

Prior art apparently does not disclose any jig construction wherein the multiple beds thereof mounted on a said single jig structure are in any configuration other than the said collinear arrangement. Prior art does not disclose a jig having multiple said bedlines mat permit a plurality of feed streams to be jigged simultaneously and/or in parallel.

The jig of the invention precisely permits such simultaneous or parallel processing or bom. In this specification, the term 'parallel' is used in the sense that processing along said multiple processing lines on a common jig structure need not necessarily be at the same time or simultaneously.

In the broadest aspect of the invention, the jig of the invention, therefore comprises multiple said bed lines(processing lines) disposed on a said single jig structure wherein each said bed line may comprise one said jigging cell or a plurality thereof that are operable in series. The provision of said multiple processing lines in a single jig assembly, gives it the capacity to process a plurality of feed streams.

Preferably, the two feed streams are of the same basic ore matter but within the scope of the invention the two streams can be of different materials. The jig of the invention can be easily and simply adapted for such applications involving different ore material streams. As far as the scope of application of the jig of the invention is concerned, the use of the terms 'ore' and 'mineral' may be considered to be interchangeable.

Within the scope of the invention, the jigging cells in a said processing line in the jig of the invention may be disposed with their major axes in a substantially collinear configuration or otherwise. Said collinear axes of the said processing lines in the jig of the invention may be disposed in a generally parallel orientation physically or otherwise.

Decked construction wherein said collinear axes are located one above the other and other such variants of construction are also within the scope of the invention. Within the scope of the invention, said hutch compartments of some of said jigging cells in the jig of the invention may be common or interconnected. This also applies to the said air chambers thereof.

In so far as multiple beds are involved in the jig of the invention it can be referred to as a multiple jig. Confusion can however occur with prior art jigs wherein a stream is serially processed in multiple beds. In the interests of clarity therefore the term 'multiple' is dropped. The jig of the invention is understood to mean a jig wherein the said jigging cells therein are disposed in a minimum of two independent processing(jigging) lines on a single jig structure. The jig of the invention is adapted to provide said parallel processing of multiple feed streams along with said serial processing of the individual streams if desired.
In the interest of simplicity and conciseness of description, the jig of the invention in the further description hereinbelow comprises only two said processing lines, each said line having three said jigging cells. This is also the construction of the embodiment described in detail herein wherein the three said cells in each of the two processing lines thereof are disposed in a said collinear configuration. This invention also offers novel integration of the construction, operation and functioning of the said two stream processing. The invention also offers several other optional novel features in the jig of the invention that translate into considerable cost and other benefits as elaborated hereinbelow.

The three jigging cells of the construction that is described hereinbelow have separate hutch compartments therefor but a common inter-communicating under-hopper. The hutches and under-hoppers of the two said processing lines are of course fully isolated from each other. Each bed of the jig of the invention is associated with its own hutch compartment and pulsing means. At least the bed wherefrom material is discharged is provided with sensing means comprising float bed sensors mat sense the height of the lowermost layer of the bed. Sensing the height of other layers is also within the scope of the invention. Each bed system and its pulsing air as also the hutch water flow and the water stream for said bed movement are individualised and adjusted/controlled independently through a novel common/unified PLC based control system. Other constructions are within the scope of the invention.

The jig of the invention offers several cost benefits such as saving in floor space, reduced weight and capital cost, easier operation and control and others. It would be appreciated that the greatest benefit is in capital costs but the other benefits are not inconsequential or insubstantial. The jig of the invention and the advantages thereof are further elaborated hereinbelow. Higher order jigs comprising more than two said processing lines are also feasible and are within the scope of the invention.

Said other advantages/benefits are reduction in operating costs, floor space savings, unitary control system, a more smoother and stable jig operation, ease of maintenance and others.

The concept of a a multiple(dual(twin) or a higher order) jig comprising said multiple processing lines has not been disclosed or suggested in the prior art nor such a problem posed or a solution visualised in the prior art. The need therefor and the advantages thereof have existed in the field for a long time but have apparently remained latent and unrecognized before the advent of this invention.

The jig of die invention may additionally and optionally comprise any one, more or all of the eight novel features mentioned hereinbelow:

i. improved said air chambers(stand-alone air chambers that are separate and not welded or fastened to the jig body) and an improved arrangement for mounting and securing thereof within said jig tank member(hutch) offering greater ease of assembly, dismantling and maintenance;

ii. improved system for mounting and securing arrangement for said bedplates within said tank member that offers greater ease of assembly, dis-assembly and maintenance and that provides a clear, obstruction-free flowpath for said pulsing water substantially across die full face of said bedplates;

iii. a stack system for the assembly of the jig internals such as the bedplate and the associated said air chamber and a stack compression system for mounting and securing thereof in the jig tank member, that offers greater ease of assembly, dismantling and maintenance and provides a said obstruction-free flowpath for the jigging water,

iv. an improved air inlet/exhaust connection for the air supply lines coming to the air chambers;

v. an improved float-type density based sensing system for sensing the density and/or height of me lowermost or other layer in a bed, that incorporates an improved guide system for the float stem thereof, which guide system provides smoother operation of the sensing device and a better response time thereof and which substantially eliminates immobilisation(stalling) of
said float stem movement during operation;

vi. an improved discharge gate system for the said bottom layer(concentrates) wherein the sinks chamber of the jig comprises a plurality of segmental outlets each provided with an independent closure means comprising a conical or square-based pyramidal poppet or other,

vii. an integrated dual-function air box that alternately connects the jig air chambers to the pulsing air supply and to exhaust mat combines the functions of the conventional air surge and exhaust boxes and that offers better response time and balanced operation of the pulsing system; and

viii. an improved pneumatic(air-operated) control valve for regulating air flow into, and exhaust from said air chambers.

In prior art jigs wherein the water is pulsated by compressed air, the said tank chamber holding the bedplate and hutch water is divided by a partition. The compressed air acts on the water surface on one side thereof while the said bedplate is located on the other side thereof. Several different configurations having this basic arrangement are found in the art

In an alternative prior art construction, an air chamber analogous to a diving bell is located within the hutch water, beneath said bedplate. The compressed air acts on the water surface within said chamber such that when air pressure is applied the air-water interface moves down therewithin. Water thus flows out of the said chamber, rises in the said tank chamber and flows into the jig bed during what has been called herein as the upward stroke.

Said first second, third and fourth additional novel improvements relate to the mounting and securing of said air chambers within the tank member, to the mounting and securing of the bedplate and the necessary sealing between the air inlet and the tank member and air chamber. Said four novel improvements are interconnected but each can be independently and separately adopted in conventional jigs if desired.

A said air chamber is a generally hollow member having a cross-section that is in the general shape of an inverted U. It extends laterally from one longitudinal sidewall of the jig to the opposite sidewall thereof. In one conventional construction, it is fully welded to said sidewalls along the U-shaped edges thereof.

Said securing of the U-shaped edges of the air chamber by full welding is disadvantageous because said chambers do require to be attended on a regular basis. This is because they are subjected to fairly severe erosion by the jigging water which during operation flows down therein round the U-arm edges and up over the outer surface thereof on way to the jig bedplate. The water men flows back along the same path during the suction stroke. Said erosion is accentuated by solids in suspension in the jigging water. Corrosion too can be fairly severe depending on the substances present in solution in the water. They are thus required to be periodically accessed for replacement and maintenance. Each said replacement or access to the chamber interior requires chipping away of the welds. It also requires an operators) to go into the tank member interior for the purpose.

In another conventional construction, the said U-shaped chamber is provided with end walls which abut said sidewalls in the assembled jig. The chamber is part-welded to the said tank member sidewalls or to bracket supports extending therefrom. Alternatively, it may be fastened to said supports. In this construction, maintenance will also involve an operator to enter the tank member to chip away the welds or undo the fasteners.

If air chambers with endwalls are adopted, the sealing between the air chamber and the air inlet thereto poses problems. It will be observed that sealing is required between said air inlet and the said sidewall and between it and the said endwall. Mutual isolation of the jig and air chamber spaces becomes necessary as also isolation of the said spaces from outside air. The difficulty is in providing such multiple sealing arrangements which have to be located in close proximity. Air leakage, particularly at the seal with the endwall tends to distort the said flow profile of the jigging water and adversely affect jig stability and the efficiency of separation. Good sealing at these points is therefore critical.

The abovementioned drawbacks have been removed in the air chamber securing and mounting system of the invention. According to the invention, the air chamber is mounted on short brackets(or a ledge or shoulder) extending inwards from said sidewalls and is held in position by a novel method that involves stack compression. In this system, bom said air chamber and the bedplate are located and held in position by application of pressure from the top. Said method does away entirely with said welding and does not require any fastening of either the air chamber or the bedplate. Said stack compression system comprises fastener means(screw means) by means of which the said holding pressure is generated. Said means are conveniently located at the top edges of said sidewalls. Alternative means of generating said stack compression pressure are within the scope of the invention.

Said stack comprises, going from the bottom to the top, the said air chamber, the said bedplate(s) and pressure plate members located one on each side mat extend upto, or near, the said top sidewall edges. Said plate members(thrust members) abut the bedplate edges(or lateral extensions thereon) and transmit the holding pressure thereto. Interposed between the bedplate and the said air chamber is a spacer plate that transmits the holding pressure from the former to the latter. A resilient member is provided between the former and the latter for distribution of the stack compressing pressure.

Said stack system is described in further detail hereinbelow. It will be observed mat by simple operation of said screw means from the exterior of said tank member, location pressure can be exerted on the said air chamber and bedplate or released to allow removal thereof for replacement or maintenance. Once the pressure is released, said members (air chamber and bedplate) can be easily lifted out of said tank member and serviced. The method does away with the need for workmen to enter the jig interior and offers considerable saving of labour and downtime over the prior art arrangements. Means other than screw means for the operation of the stack compression system are within the scope of the invention.

Said sealing problem is overcome in the jig of the invention by providing a novel compact dual seal mat provides simultaneous sealing between the air inlet pipe space, the jig tank member space, the air chamber space and the outside air. It is described in further detail hereinbelow and depicted in the accompanying drawings.

Conventionally, said bedplate is mounted on brackets or ledge supports that extend inwards from said jig sidewalk. The bedplate is secured thereto by fastener means. This is the arrangement found in compressed air pulsated jigs of prior art

Said mounting and securing arrangement for the bed plate is also not wholly satisfactory for two reasons. The first drawback in the prior art jigs, as mentioned, is the difficulty of accessing said fastening means that are located within the jig tank member and may even require an operator to enter the jig tank interior. The other is that said inwardly extending ledges and their fasteners constitute obstructions in the flow path of the jigging water to and from the face of said bedplate and also to operators during repair and maintenance work. Said projections and obstructions along said flowpath cause undesirable turbulence and eddies in the pulsing water stream. This invention does away with said projections associated with bedplate support arrangements of prior art.

Said bunch of problems of mounting and securing the said bedplate and air chamber and the associated drawbacks have been ingeniously overcome in the jig of the invention. The fastening of said bedplate and me welding of said chamber to said tank sidewalls or members attached thereto has been given up in the jig of the invention. In the jig of the invention, said two components are held down in position within the tank chamber by means of compressive force applied through screw means. Said two components are stacked one above the other.

This invention has constituted said bedplate and air chamber into a stack arrangement along with a spacer member that is interposed between said bedplate and chamber in the stack A thrust plate transmits the said compressive force from above the bedplate to the bedplate. Transmission from the bedplate to the air chambei/through said spacer plate. This discarding of welding, fastening and other such arrangements in the jig of the invention makes the assembling of said components into the jig; the accessing and dismantling thereof for maintenance and replacement and subsequent re-assembling easier than in prior art arrangements.

The jig of the invention in the broadest scope comprises two sidewalls extending longitudinally parallel to the major axis thereof and several partition walls within, that divide the tank chamber thereof into several longitudinal compartments that constitute said processing lines. One or more said beds are provided in each said compartment, said bed lines being generally parallel to said major axis. Said major axis is also the general direction of flow of the ore material during processing. When referring to said compartments, the terms 'partition wall' and 'sidewall' have sometimes been used interchangeably in the interests of simplicity. The appropriate meaning that is relevant to the context may be taken. Said longitudinal compartments are further divided by suitable laterally extending partitions to constitute separate individualised hutches for the beds in the processing line.

In the construction described in detail hereinbelow, the jig of the invention comprises two said compartments each having a line of three beds. The longitudinal sides of a said compartment comprise sheet metal members that are reinforced by suitable rolled members of the channel, angle or other types. Said criss-crossing reinforcing members form cavities(recesses) in said sidewalls. Some of said recesses are designed to constitute housings for the said stack support and compression arrangements. They extend from the tank member top edge down the sides of said sidewalls and form the guiding tracks/slots down which the stack compression assembly slides down during jig assembly. Said stacks are supported on inward extending ledges, brackets or shoulders located in said recesses.

Abrasion resistant tiles are mounted in the cavities(recesses) other than those which house said stack compression arrangements. Said pressure transmitting members of the stack compression system, namely the thrust and spacer plates also comprise recesses that are fitted out with said abrasion-resistant tiles therein and once located in said sidewall recesses provided for the purpose, their tiled surfaces are substantially flush with the tiled surfaces of the sidewalls and with the inner edges of said air chamber supporting arrangements. They are also generally flush with the inwardly extending flanges of the said sidewalls. This ensures an obstruction free path for the jigging fluid and an obstruction free access to the jig interior.

The approach spaces leading upto the faces of said beds, bom above and below the beds, are consequently substantially totally free of any obstructions such as projections from the sidewalls or cross-members extending between said sidewalls. This minimises turbulence and eddies in the pulsing water. Said approach spaces are substantially clear over the full face of the bedplates, that is, over the full cross-section of the jigging water flow. Thus, eddy-free and turbulence-free flow extends substantially right upto the edges of the said bedplates in the jig of the invention.

It will be observed that in the assembled jig, said stacked assembly held together under the compressive force of said screw means constitutes a cartridge. This construction offers the advantage of cartridge construction without the disadvantage of having to handle a heavy, voluminous and a long cartridge in and out of said vessel for replacement or repair to any component thereof This is because the holding pressure on the cartridge is easily turned off by operating said screw means leaving the individual stack members free to be easily lifted out one by one.

This invention has adopted a novel construction for connection of the air supply/exhaust pipe to the jig tank member. In conventional construction, the said tank member comprises an air inlet/exit port to which the air supply pipe is connected by flanged or other means, resilient sealing means being provided between the mating flanges as necessary.

When welding of the air chamber ends to said sidewalls is dispensed with as in the jig of the invention, the prior art arrangement becomes unworkable as it opens up a path between the air chamber space and the jig space and/or between the jig space and the outside atmosphere. Effective sealing in respect of said two paths is therefore essential if the non-welded construction is to work. Provision of two separate independent seals within the small space available at the region where the air supply pipe and the jig body meet is a tricky and difficult proposition.

This problem has been satisfactorily tackled in the air pipe connection provided by the invention wherein the mounting flange on the air supply pipe is in the general configuration of a raised-face flange that is located some distance behind the end thereof. The vertical face of the recessed part of the supply pipe flange with the bolt holes therein mates with, and is bolted to a corresponding flat ring weldably mounted on the jig sidewall. The air supply pipe end juts a small distance into said air chamber past the endwall thereof. Other constructions are within the scope of the invention.

Sealing between the outside atmosphere and the jig interior is provided by an O-ring seal which is provided on the shoulder extending between the said recessed and raised faces of the said air inlet/exit connection flange. The O-ring is located on said shoulder and engages with the inner cylindrical surface of the said corresponding flat ring weldably mounted on the jig sidewall. As will be noted air enters and leaves through the said air inlet connection.

Between the said raised face and me outer surface of said endwall(of the air chamber) is provided a resilient flat gasket member that provides sealing between the air chamber space and the outside air and between the air chamber and jig spaces.

The isolation of the jig space from the outside atmosphere is effected by said O-ring. Optionally, a sealing ring of resilient material may be provided between the said recessed face of the flange and the opposite mating surface thereof. Such a ring would provide additional sealing of the jig space from outside air.

Both said seals are positioned such that they are substantially clear of the abrasive environment that exists in the air chamber and the jig interior during operation.

The description above covers features (i), (ii), (iii) and (iv) of the abovementioned list of said additional novel features.

The fifth said additional novel feature relates to float-type bed density sensors such as are used in hydraulic jigs. Such sensors provide density(bed layer height) inputs to the jig controllers. In turn, said controllers generate control action to close or open one or more discharge gate means for the discharge of said concentrates or the tailings or both or control the feed rate and/or other functions. Said bed density sensor may also activate other control elements such as the baffle(s) if any located at the downstream ends of the beds.

The drawback of the known prior art bed density sensors is that the float movement thereof is not smooth and free which adversely affects their response time. Also they have a tendency to get stuck(stall) which disrupts the jig operation. This invention provides an improved guide system for said float movement.

Each element of said guide system of the invention comprises a set of three symmetrically located rollers that are disposed generally in a single plane round the float stem when assembled. The float stem moves between said rollers mere being at least two said elements provided along the length of said stem. Said rollers are of low-friction materials and their axle mountings are also substantially friction-free.

The system of the invention ensures a shorter response time for the sensor and trouble-free operation without hold-ups(stalling) of the stem movement. Said guide elements each comprising said three symmetrically located rollers are mounted in planes perpendicular to the said stem. Two such elements are placed along the stem for stem guidance. They are adjustably mounted on a generally vertical rod member provided by the side of said stem. More than two said elements may be provided if desired. Such a construction is within the scope of the invention.

The sixth said additional novel feature of the jig of the invention is the discharge gate system for the said product layer in the jig of the invention. In prior art jigs, it is conventional to have a single said opening for discharge. Said opening in prior art conventionally extends over the full cross-sectional area of the discharge chamber and is closed by a single flap member or other closure means extending over substantially the full cross-sectional area. Said flaps often fail to close fully when a lump of material gets caught between the flap and the discharge chamber frame or body. It will be observed that when the said flap is prevented from closing due to the lodging of a lump of material, material may continue to discharge from the sink chamber out through the partially closed jammed gate thereof. Such material may not meet the desired specifications which will affect the product specification and quality. As would be observed, the said unwanted discharge of material will occur across the full width of the discharge opening. Discharge chambers are also referred to as sink chambers herein.

This invention observes that having a plurality of said flaps(or gate systems) is advantageous because in the event of said jamming by a lump of material or for any other reason, the adverse effects thereof will be confined to the affected gate. The other gates would close fully. There will be a lesser effect on the product stream specification and quality. The closure means on said gates are square-based pyramidal closure members(poppets) in the preferred embodiment but can be of conical or other orientations. Such an arrangement of multiple(segmentised) gates is novel and not apparently disclosed in the prior art

Thus, in the discharge system of die jig of the invention, vertical operating rods extend from above the said sink chamber to said poppets. Said rods are linked and are actuated by the jig controller. The action of said gates is in unison, that is, said linkage simultaneously pushes down all said rods when the jig controller generates the control signal for the opening of the gates. Each said rod is spring-loaded such that said poppets move upwards under spring action to close the gates upon the cessation of the said gate opening control signal.

The advantage offered by the system of the invention over the prior art is that in the event of gate jamming the effect on the product specification(concentrate layer) is lesser. It will be observed that die unwanted discharge of material will be confined to the gate that has been prevented from closing by a material lump. Within the scope of die invention, said discharge chamber(sink) may comprise separate compartments each associated wim a said discharge gate located at me bottom thereof. Other constructions/variants are within the scope of the invention.

Discharge of the concentrate layer is initiated by the jig controller when the sensing inputs from the float density sensor indicate that the density and height of control layer match the set(desired) values. The discharge initiating means comprise a hydraulically operated baffle gate that is moved upwards by said control action. The concentrates men go over the edge of the bed and drop into the sink chamber. In the dual jig embodiment described and illustrated herein the said discharge gate arrangement wim a plurality of discharge gates is provided for the second of me three beds in bom the processing lines. Within the scope of the invention such gates may be provided for other said beds of the jig if required.

The seventh said additional novel feature of me invention relates to the supply and control of air to said cells. In prior art jigs, the air line coming from the air chamber branches into two. The ends of me two branches each terminate in a box. The two boxes are referred to as the air surge and air exhaust boxes respectively. They are also referred to as the inbox and outbox respectively. Control valves are provided at the mouths of said ends located within said boxes. Said surge box communicates with the source of compressed air used for jigging. The exhaust box connects to the outside air. Said combination of surge and exhaust boxes is also referred to as a Y-surge box arrangement because the two said pipe branches are configured in the general shape of the letter Y. Said boxes are located at only a short distance from the branching point of me 'Y' and are positioned substantially side by side.

Opening and closing of said control valves is initiated by the jig controller. During operation, compressed air is let into the air chamber by the opening of die appropriate control valve. The function of the surge box is to prevent surges and to act as an accumulator. With the opening of the control valve in the surge box the pulsion stroke commences. At the end of said pulsion stroke, the surge box control valve shuts and the exhaust control valve opens. This commences the said suction stroke. Air moves out of the air chamber to exhaust during this stroke.

The integrated air box of the invention combines and integrates the functions of the separate in- and outboxes of prior art. It integrates the supply of pulsing air to and the exhaust from all the six jigging cells in the jig of the invention. Three said cells are located on the left hand side and the other three on the right hand side of the jig of the invention. It replaces both said surge boxes and exhaust boxes of prior art jigs-

The air box of the invention is in the general configuration of a flat elongated generally rectangular-section box that symmetrically extends above the jig over the centerline thereof. A similar elongated rectangular-section box that is of smaller proportions is mounted(embedded) within the main air box and the two constitute the compressed air and exhaust air spaces(manifolds) respectively in the air control box of the invention. The former is connected to the compressed air supply and die latter with the atmosphere or to other exhaust arrangements. In effect, they constitute air supply and exhaust manifolds respectively.

Each of the six air lines coming from die six said cells of the jig ends in a rectangular-section box that is referred to herein as the end box. The six endboxes are small boxes that are embedded in said integrated airbox. Each end box comprises two said control valves one of which communicates with said compressed air space(manifold) and the other with said exhaust space(manifold). Operation of the control valves alternately lets compressed air into said end boxes or connects them to exhaust. Accordingly air flows into or out from the respective said air chambers. Said control valves are novel pneumatically-operated disc type air control valves and are described further hereinbelow. Said end boxes are generally L-shaped in configuration and of generally rectangular cross-section. Other configurations and constructions are within the scope of the invention.

It will be observed mat the construction of the integrated air box of the invention minimises the pipe lengths involved in the air system. It is a more compact arrangement than in the prior art and offers saving in weight, material costs and space. Above all, it offers a highly symmetric air supply system for the jig in so far as the pipe segment lengths on the two sides of the jig can be substantially equalised. The shorter pipe lengths ensure that the response times of the pulsing system are shorter(quicker) and the said symmetry ensures equalised and balanced response times and control responses to the individual jigging cells. Further the end boxes and the said compressed air and exhaust spaces provide a greater volume and capacity for said accumulator and surge prevention functions.

It will be observed that twelve box members of the conventional Y-arrangement of prior art would be required to service the six jigging cells in the jig of the invention. The single integrated air box of the invention is therefore able to replace twelve said Y-type air boxes of prior art. It will be noted that the superior response time and symmetry obtained in the integrated air box of the invention are just not possible with the conventional Y-arrangement. A Y-arrangement layout of the air system for a six cell twin processing line system would be a maze of pipes and would not be symmetric and balanced as is the system of the invention. Said functional symmetry provides greater stability in jig operation. Saving in material and manufacturing costs, ease in assembly and maintenance and better control and stability are some of the other advantages offered by the construction of the invention.

Based on the novel concept of the integrated air box of the invention described hereinabove numerous variants, configurations and cross-sections are possible. Such variants and embodiments are within the scope of the invention.

As mentioned hereinabove, the jig of the invention comprises a plurality of bed lines, each said line comprising one or more beds. Each said bed may be associated with an individual air chamber and hutch or otherwise. The jig controller of the invention is a PLC based controller system that allows setting up of individualised pulsing operations for said cells. It is possible to organise common pulsing operations for groups of two or more beds if required. The system of the invention offers the advantage that pulsing operation, discharge gate operation, feed rate, hutch water flow and other parameters may be controlled either individually for each bed or co-ordinated for groups of beds. It will be seen that numerous control configurations and control protocols are possible with the control system of the invention. Combined with the provision of said multiple bed lines the jig of the invention offers a great amount of flexibility in jigging operations.

The eighth said additional novel feature relates to the control valves used in jig installations to supply air to and exhaust air from said air chambers. The novel air control valve of the invention may be adopted in the integrated air box of the invention or may be used in the conventional said Y-type arrangements of prior art

The air control valves used in the said Y-arrangement air surge and exhaust boxes of the prior art are usually solenoid actuated disc type stop valves. Their function is to stop and start air flow into and out of said air boxes upon receiving control impulses from the jig controller such as to provide said pulsing. The chief drawback of the conventional said control valves is the poor response times thereof. Good response times are very critical in maintaining smooth operation and operational stability in j igs. Poor response times of conventional control valves are the result of the long stems adopted therein and the multiple cylinder type bearing arrangements thereof.

Conventional air control valves in jig systems, as mentioned, comprise a solenoid actuator linked to a disc type closure element The linkage between the two parts is a piston type member extending from within said solenoid to the said disc. The poor response times of said conventional valves arise from the friction between the said piston and the packing and locational components/members provided around said piston. As mentioned, low response times can distort pulsing water flow profile and upset the jig operational stability.

The air control valve of the invention comprises a pneumatic-actuator of the diaphragm type and a conventional disc type stop(closure) element attached thereto. Said discs sit on seatings that are mounted on said end boxes while the actuator ends of said valves extend outside said integrated air box.

Reduction in the response time is achieved by piston length reduction and by the simplification, and reduction in the number, of guidance/location arrangements(bearings) provided in prior art valves. The actuator of the invention comprises just a single said guidance/location point located at the back end of said piston thereof. Said piston is further held in the diaphragm. As will be observed substantially no friction arises in the piston-diaphragm joint.

Both the forward and return movements of the diaphragm are initiated by compressed air there being no spring action return. For this, compressed air supply is arranged to bom the above-diaphragm and below-diaphragm spaces. One end of said piston is connected to the valve disc and the back end thereof moves within a cylindrical guide member that is threadably mounted in the actuator body. Within said cylindrical cavity is provided a resilient end stop for the piston end. A central air passage in said back end that extends some way down the piston length connects the air space above said back end in the cylinder with the air space above the said diaphragm. By operation of said threaded means said end stop can be axially advanced or moved back. The piston stroke can be adjusted by moving the said end stop. Said air passage allows air into said air space above said back end when the piston moves down and allows escape of air therefrom during the return movement of the piston. The air control valve of the invention is described in further detail hereinbelow. Other means for said piston stroke adjustment are within the scope of the invention.

As mentioned, the jig of the invention may comprise any one, more or all of the said eight novel improvements of the invention. For those improvements not adopted in the jig of the invention the corresponding conventional constructions are incorporated in the jig of the invention. Thus, it will be observed that several embodiments of the invention are feasible depending on the number of said novel additional features incorporated. This invention includes embodiments wherein one or more of said eight novel features are adopted in conventional single-processing-line jigs.

The embodiment described in detail hereinbelow is a jig comprising said multiple processing lines and incorporating all die said eight additional novel features described herein. Thus, mis embodiment represents nine major embodiments corresponding to said main feature and the eight subsidiary features. Other embodiments/variants arise out of associating one or more of the said novel features/improvements with either the twin jig of the invention or any of the conventional jigs of the prior art

In order to provide a clearer understanding of the invention, and without limitation to the scope thereof, a few embodiments thereof are described hereinbelow with reference to the accompanying drawings wherein like numerals refer to like parts and wherein:

Fig. I shows an isometric view of the jig tank member of the invention including the under-hopper thereof;

Fig. 2 shows the GA(general arrangement) of the jig of the invention and the novel air control unit of the invention in longitudinal cross-section AA' which also shows the GA of the mounting and securing system of the invention for the air chambers and bedplates of the jig of the invention;

Fig. 3 shows the GA of the jig of the invention and the air control unit of the invention of Fig. 2 in lateral cross-section BB';

Fig. 4 shows the mounting and securing arrangement according to the invention for the air chambers and bedplates of the invention;

Fig. 5 shows the mounting and securing system of the invention of Fig. 4 for the air chambers and bedplates of the invention, in lateral cross section;

Fig. 6 shows the bedplate of the invention in cross-section depicting the reinforcement and the laterally-extending wing members thereof;

Fig. 7 shows a plan view of the jig of the invention depicting the twin processing lines of the jig of the invention;

Fig. 8 shows in cross-section the novel detachable connection of the air inlet/exit nozzle to the air chamber in the jig of the invention;

Fig. 9 shows the GA of the novel bed height sensor of the invention in the jig of the invention;

Fig. 10 shows the novel three-roller guide element according to the invention for the bed height sensor of the invention depicted in Fig. 9;

Fig. 11 shows the GA of the novel discharge gate system of the invention in the jig of the invention;

Fig. 12 shows novel segmental closure system in the discharge gate system of the invention depicted in Fig. 11;

Fig. 13 shows an isometric view of the unitary integrated air control unit(air box) of the invention which combines the air inlet, air exhaust and surge functions in the jig of the invention and depicts the novel adjustable pneumatically-operated, diaphragm air control valves of the invention;

Fig. 14 shows the air control unit of the invention of Fig 13 in longitudinal cross-section AA';

Fig. 15 shows air control unit of the invention of Fig. 13 in lateral cross-section BB'; including the adjustable diaphragm type pneumatic actuator part of the air control valves according to the invention.

Fig. 16 shows in plan and in elevation the stroke-adjustable, pneumatic actuator portion of the air control valves of the invention;

Fig. 17 shows in cross-section the stroke-adjustable, pneumatic actuator portion of the air control valve of the invention depicted in Fig. 16; and

Fig. 18 shows in plan view the unitary air control unit of Figs. 13-13.

It may be noted that the abovementioned Figs. 1 to 18 are presented as part of the provisional specification. Said figures of the provisional specification together with the text thereof are incorporated herein by reference. The incorporation of said drawings of the provisional specification herein by reference and not being repeated herein is in the interests of the conciseness of this specification and is without any limitation to the scope of the invention.

Reference numeral 1 in Figs. 1 to 3 denotes the jig tank assembly of the invention as a whole. As shown therein, it comprises a rectangular plan vessel which is referred to herein as the tank member 2. A longitudinal partition 5 divides the said vessel 2 into two parts which constitute the two jigging lines(processing linesX3,4) of the jig of the invention. Partition 5 extends over the full height of the vessel 2 from the vessel bottom to above the bed level and upto the vessel rim. Jigging line 3 is located on the left hand side(LHS) of the said partition and line 4 on the right hand side(RHS).

Locational and directional references in this specification, generally speaking are with reference to the direction of movement of the ore material on the jig, that is, the major axis thereof, unless otherwise required by the context. Similarly, other directional and locational references are also in relation to relevant axes. The reference is clear from the context thereof.

This novel construction of dual jigging lines in the jig of the invention permits parallel and/or simultaneous treatment of two separate streams of ore/mineral material which is not possible in prior art jigs.

The further description hereinbelow is with reference to and confined only to the LHS jigging line 3. This is in the interests of conciseness and simplicity as the description of jigging line 3 is equally applicable to jigging line 4. Again in the interests of conciseness reference is only made to part numbers associated with jigging line 3. Corresponding parts in the jigging line 4 are however numbered and depicted on the accompanying drawings. Same numbers are used for corresponding parts in the two lines, the ones with reference to the jigging line 4 being identified by the use of suffix letter 'A'. Thus, for example, part numbers 6 and 6A refer to identical parts, the former being on the LHS jigging line 3 and the latter on the RHSjiggingline4.

The LH side jigging line 3 extends from the feed end wall(14) to the discharge end wall (IS) between the longitudinal LH sidewall(16) and the partition wall (5) of the vessel 2. The entering ore material drops on the bedplate and forms a bed thereupon, which, during jigging, moves along the length of the jig. The bed is supported on bedplates mat are laid out in a line along the length of the jig. There are three bedplates (6,7,8) in the jigging line 3. Each of the first two bedplates(6,7) comprises a perforated plate (9,10) having reinforcements welded thereto. Said reinforcements form a skirt (ll)therearound. From the two lateral sides of said skirt extend short plate pieces(wing piecesX12,13). These ledge-like extensions(wing members) are the means whereby the bedplate is mounted and supported in the vessel sidewall(16) on the LH side and in the partition wall(S) on the RH side. Said mounting and support arrangement is novel and is an important part of this invention. As mentioned, the bedplate is supported and anchored by means of a stack arrangement which comprises compression means for applying locational pressure on the stack. Said arrangement is described further hereinbelow.

The construction of the third and last bed plate (8) is different from that of plates (6,7). It is a ragging bed and designed to be used with a ragging layer. The openings therein are therefore larger in size. It also comprises said reinforcements, said skirting and said wing pieces and is similarly mounted and supported in the jig. Bed plates (6 and 7) are inclined sloping down in the direction of material flow and bedplate (8) which is the plate with the ragging layer is flat and horizontal. The slope of bed plates (6 and 7) is adjustable from about 0 to 4 degrees. Other variants of construction are within the scope of the invention.

At the end of bedplate (7) is located the discharge chamber (19) for withdrawing the lowermost layer of the bed. There are two hydraulically adjustable baffle weir members( 17,18) which are operated by the j ig controller. Weir (18) is located at the downstream end of chamber (19) and weir (17) is located at the end of bed (8). By synchronized operation of the two weirs the layer thickness(es) are maintained at the desired level. It also determines the cut-off level of the bed. Material in the bed below that level falls into the discharge chamber (19) while the material above skims over the weir to proceed to bed (8).

Said discharge chamber is also called the sinks chamber. Baffle gate (18) is operated by control signal from the jig controller.

The numerals used to refer to said bedplates, namely (6,7 and 8) are also used to identify the bed of material thereon. After the ragging bed treatment the ore material exits the jig at the far end of bed (8).

The fine material in the bed that passes through said ragging bed, falls into the hutch and is withdrawn from the under-hopper continuously or intermittently.

Bed plates (6,7) are disposed at a slight inclination to the horizontal. Said inclination is adjustable between about 0 to 4 degrees. The inclination assists material flow in the axial direction. Ragging bed (8) is substantially horizontal.

The hutch compartments (23,24,25) below each said bed (6,7,8) are independent of each other. Partition walls extending laterally between the sidewalls (5,16) define said independent compartments. Thus, each jigging bed is part of an independent jigging cell. The air chamber (20,21,22) of each cell is located in the hutch compartment underneath the bed plate thereof. The air chambers are of generally inverted U-shaped configuration and as mentioned, they house the interface (28) between the hutch water(jigging water) and the air space 29. Said air space communicates with the source of compressed air used for pulsing the jigging water. Compressed air for pulsing comes in through inlet/exit 26 provided one for each cell. Port (27) is the outlet for hutch material from the under-hopper. It may be noted that the air chambers are of a generally streamlined configuration to minimise turbulence and eddies in the pulsing water, unlike as in prior art constructions. The outer surface of the air chambers are lined with abrasion resistant tiles as also several other surfaces on the stack compression components and the tank member interior that are in contact with the jigging water.

At the bottom of the discharge chamber (19), are a series of openings (30) wherefrom the said bottommost layer material exits the jig. Said openings (30) are rectangular in configuration and are closed by closure members (31). The opening and closing of said openings is simultaneous. For this purpose, each said member (31) is linked to the operating rod (32) through cross-bar (33). When the operating rod (32) is pushed down it moves said closure members (31) downwards. This permits material discharge from said openings (30). Raising the rod (32) stops said discharge. Cross-bar (33) extends horizontally and laterally above said openings. Said closure members (31) are provided with resilient means(spring means) that urge them into their closed positions.

Reference numeral (34) denotes the said stack compression system as a whole(see Figs. 4 and 5). Said stack compressing pressure is provided by screw compression means (35) located at, or in the region of the vessel rim (36). It is transmitted by the upper thrust member (37), mat sits on, and acts upon said ledge extensions(wing members) (12) provided on the lateral sides of said bedplates (6). Said stack includes another thrust member (38) that is interposed between the bedplate (6) and air chamber (20). It comprises a generally U-shaped slot that engages with the inverted U-profile of the air chamber (20). It transmits the stack compressing pressure onto the air chamber and thus secures it in position. It is also referred to herein as the spacer member.

As mentioned above, the air chamber is not attached to any part of the jig and it is located and secured solely by said compressing pressure. Air chamber (20), as indeed the entire said stack, sits on support pieces (39) mat extend from the left side vessel sidewall (16) and the said partition wall (5). Said compressing pressure is transmitted to said support pieces (39) and therethrough to the said tank member body. Between said ledge extensions (12) and the lower thrust member (38) is interposed a resilient member (40) which in this embodiment is a rubber piece the purpose of which is to distribute the stack compressing pressure uniformly. Two square section bars (73,74) welded on the sidewall (16) form a track for guiding the airchamber when it is lowered in the tank member and for holding it in position. Similar arrangements are provided on the other sidewall (5).

Both the upper and lower thrust members (37,38) are of plate/sheet construction. They are generally rectangular in shape, the lower member (38) having said U-shaped cutout in the lower side thereof. The edges of both thrust members are in-turned and extend inwards into the jig. They constitute flanges that provide the area over which the stack compressing pressure is transmitted down. Both said thrust members are in the form of shallow open boxes. The box construction allows for laying abrasion resistant tiles therein. The inside faces(facing the jig interior) of both said thrust members are fully faced with said abrasion resistant tiles.

Each said cell comprises a said stack compression system on the left side thereof and a similar one on the right Recesses (41) are provided in the vessel side walls and in the partition wall. The recesses are about 25 mm in depth but can be other sizes. This is also the width of said wing pieces(wing members) and the thrust member (37). Said depths are so arranged that in the assembled jig the tiled surfaces in the stack compression system are substantially flush with the other tiled surfaces located on the sidewalls.

Unlike as in conventional jigs, the air chambers in the jig of the invention are not welded to the vessel sidewall or the partition wall. As mentioned, this novel construction has been adopted in the jig of the invention for ease of maintenance, dismantling and assembling and to reduce downtime. Having dispensed with said welded construction, die jig of the invention needs to tackle the problem of air-sealing so mat no pulsing air escapes therefrom into the jig interior or to the outside atmosphere. Sealing between the jig space and the outside atmosphere is also necessary. Any escape of air from airspace (29) will affect the jigging flow profile adversely, disturb the steady-stage conditions of the bed and reduce jigging efficiency.

This invention has adopted a novel construction of the air inlet pipe (26) mat supplies compressed air to me air chamber and exhausts air therefrom during the said suction stroke. The said novel air inlet connection in the jig of the invention(see Fig. 8) is denoted generally by the numeral (42).

In conventional constructions, the air inlet pipe is welded to the jig sidewall. The air inlet connection (42) of me invention is provided with two sealing means, (43,44). The former (43) is an O-ring seal and is located on the cylindrical surface of the raised portion of the inlet pipe flange (45) and seals the vessel interior space from the outside atmosphere. Said cylindrical surface is also referred to herein as the shoulder. The second seal (44) which is a flat rubber ring is located on the inlet pipe mourn (46) between the raised face of flange (45) and the air chamber endwall (47). Inlet pipe mouth (46) extends past the air chamber endwall (47) into the air chamber interior. Second seal (44) isolates the air space of the air chamber from both the outside air and the tank member space. The mating between the recessed face of the inlet flange and the corresponding opposite surface on the jig may be optionally provided with resilient sealing means therebetween.

Another novel construction adopted in the jig of the invention is the guide means for the float bulb stem of the bed height sensor(bed density sensorXFigs. 9 and 10). Said guide means is represented generally by numeral (48). Bed height sensors are analogous to float-type densitometers and comprise a bulb provided with an extended stem that rises and falls in the bed. Guide means are provided along said stem to ensure smooth movement and thereby fast response thereof. The second bed of the jig of the invention(in both the processing lines) is provided with such a float bed height sensor which is generally indicated by numeral (49). It is set to the SG value of the bottommost layer or to any other desired SG. Said sensor generates a signal that is proportional to the height of said bottommost layer of the bed or an on/off signal corresponding to the preset cut-off height The jig controller in turn generates control action such as to close or open the discharge system for the said bottommost layer. It may additionally activate other control actions as desired.

The problem in prior art jigs is that the said guide system thereof is not satisfactory as it is based on a two-roller system in the guide means thereof. There is considerable friction in the guide means construction of prior art which reduces the response time thereof. An even more serious drawback is that the stem movement in conventional systems stalls frequently. Any such immobilisation of a said sensor can upset jig operation and stability.

In the jig of the invention, guide means comprising three-roller systems are provided and this is novel. They are substantially totally failure-free and provide a much smoother movement of the said stem. This results in a better response time and better jig operation.

The stem guide means of the invention comprises a triangular assembly (48) of three roller support members (51). The attachment between pairs of said members (51) at the apices of the triangular configuration is rigid but can be swivellable. Said members (51) are mounted on a base plate (50). Three anti-friction rollers (52) are mounted on said three members (51) and together they define the central space and axis for the movement of said stem (53). Two said guide elements are provided along stem (53). More can be provided if desired. Guide means (48) are mounted on the support column (54) of the bed height sensor as shown.

A still further novel feature incorporated in the jig of the invention is the air control unit(or air box) thereof. The air control unit(air surge box)of the invention is generally represented by numeral (55) in the accompanying drawings(Figs. 1 to 3 and 13 to 15).

In the arrangement adopted in conventional jigs, the airline coming from the air chamber thereof divides into two, the two ends terminating in a box each. Control valves are provided within said boxes at the mouths of said ends. One said box communicates with the source of compressed air used for jigging. The other communicates with the outside air. The former is referred to as the surge box and the latter as the exhaust box. Said boxes are located side by side and as the said two pipe branches are in the general configuration of a 'Y', they are sometimes referred to as Y-surge boxes.

Opening and closing of said control valves is initiated by the jig controller. During operation, compressed air is let into the air chamber by the opening of the appropriate control valve by the jig controller. The function of the surge box is to act as an accumulator and prevent surges. The release of compressed air from the air control box to the air chambers commences said pulsion stroke. At the end of said stroke, the exhaust control valve opens allowing the air to exhaust from the air chamber.

The air control box (55) of the invention is an integrated unit that connects to all the six jigging cells in the jig of the invention, three being on the left hand side and the other three on the right hand side. It replaces both said surge boxes and exhaust boxes of prior art jigs. Thus, the twelve box members that would be required to service the jig of the invention if the said conventional Y-arrangement is adopted are replaced by a single box unit in the arrangement of the invention.

Apart from this novel feature, another novel feature in the air box of the invention is that said airlines coming from the air chambers each end in a box member (36) that is located inside, that is, embedded in the said air control unit of the invention. Said boxes at the said line ends are referred to herein as the end boxes and are designed to serve the function of born said surge and exhaust boxes. Each said end box (56) is provided with two disc-type control valves (57, 58) respectively for compressed air and for air exhaust.

Briefly, the air box of the invention comprises a large box (75) that functions as the inlet manifold and surge box. Embedded therein is another elongated box (59) that functions as the exhaust manifold. The six end boxes (56) that are also embedded in the said inlet manifold box (75) and exhaust manifold (59) communicate with the two manifolds through air control valves (57, 58) that are operated by the jig control system.

Valves (57) for compressed air communicate with the space in the air box (75) which functions both as a surge chamber and as a compressed air manifold supplying the end boxes (56). Valves (58) communicate with manifold (59) that is referred to herein as the exhaust manifold. The entire assembly (55) is a unitary construction comprising box (75), box (59), the six boxes (56) and valves (57,58). The configuration of said boxes are as shown. They are all of generally rectangular cross-section, the end boxes (56), however, having a generally L-shaped configuration as shown. As shown, said adjustable stroke, pneumatically-operated diaphragm type disc control valves (57,58) of the invention are mounted on the respective end boxes (56) and extend such that the pneumatic actuators (60,61) thereof are located on the outer faces of boxes (59) and (75) respectively. Air control box (55) can be seen in plan view wherein the positioning and layout of said end boxes (56) is shown(Fig. 18).

Said unitary construction of the air box of the invention and the highly symmetrical configuration thereof is very compact and lightweight and provides several cost benefits and operational benefits. The most important advantage of the air box of the invention is that the functional symmetry of the box and the pipes thereof, provides very short response times and substantially equalised response times that greatly enhance jig stability.

Clearly the air box system of the invention imparts a very symmetrical configuration to the entire compressed air jigging system. It can be seen that this would not be possible by the adoption of the conventional Y-system. It will also be observed mat symmetry in die arrangement of the air lines to and from die air chambers, in the sizes and lengths of said lines on both sides and to each of the six cells has an important bearing on jig stability and control, on the response time of the control system and on the symmetry and uniformity of response of the six jigging cell systems. An unsymmetrical system is likely to give unbalanced and unstable operation. Lesser pipe lengths are required and the shorter air lines ensure better response of the control system.

The invention also provides an improved valve actuator for the disc valves (57) and (58)(Figs. 16 and 17). The actuator of the invention which is generally represented by numeral (60,61) is air-operated diaphragm type. The chief advantage of the actuator of the invention is that the response time thereof is superior to conventional actuators. This results from the reduction in friction achieved in the actuator of the invention. Conventional solenoid-operated valves involve a piston member moving in one or more cylindrical bearing and guidance members. Such an arrangement has considerable friction leading to low response times. Operational Mures also occur in such systems. Bom these drawbacks are removed in the actuator of the invention. Actuator (60,61) has further advantages that are covered hereinbelow.

Actuator (60,61) comprises diaphragm (62) mounted at the periphery thereof between actuator body parts (63,64). Compressed air is introduced above or below the diaphragm as necessary during operation through ports (65,66). Diaphragm (62) is attached to the actuator shaft (67) which is connected to the valve disc (68) of the control valve (57,58). Shaft (67) backs into a threaded member (69) which provides bearing and guidance for movement of shaft (67). Threaded member (69) houses stop means cum shock absorber means (70) for the shaft (67). Stop (70) is of resilient material. By operation of the threaded member (70) which is threadabry mounted on the actuator body part (63), stop (70) can be moved further down along the actuator axis to adjust me actuator stroke. Resilient stop (70) also prevents damage to the actuator by the impacts of the actuator shaft (67) when it moves upwards during operation. As mentioned, the actuators of the invention are mounted on the inlet and exhaust manifold boxes (75,59) and their respective disc closure means on the end boxes (56) of the air control box unit.

Bearing support and location for shaft (67) is limited to said threaded housing member (69) and the attachment between the shaft and the diaphragm. Part number (71) is the shaft seal. Part numbered (72), represents the holding plates by means of which shaft (67) is attached to the diaphragm. The reduced friction results in a better response time of the valve. The arrangement of the invention also results in lower shaft length over the prior art designs. The air control valve of the invention is therefore more compact and lesser in weight than prior art designs.

Embodiments and variations other than described hereinabove are feasible by persons skilled in the art and the same are within the scope and spirit of this invention.

We claim:
1. A mineral jig for carrying out jigging/separation operations on solid materials such as, for example, metallic ores, coal and other minerals comprising inter alia,

(i) a jig tank that houses the jigging cells, beds, bedplates, air chambers and other parts of the said jig;

(ii) a plurality of jigging cells, each said cell comprising one or more jigging bedplates,

(iii) one or more hutch compartment(s) and under-hopper(s),

(iv) an air system for pulsing(pulsating) the jigging fluid(s), comprising one or more air chambers, air surge and exhaust box(es) with the necessary control valves for air supply and exhaust to/from said chambers,

(v) a control system for controlling/regulating the profile and/or parameters of the said pulsing operations by actuation of the said air supply and exhaust control valves, and for controlling/regulating the feed(s) and discharge of one or more of the mineral streams thereof, through one or more gate(s), baffle(s), or other feed and discharge devices), the said system comprising one or more bed height sensors for monitoring the height/thickness of one or more of the jigged layers on said bed(s), and generating the control signals for the operation of said gate(s), baffles, and feed and discharge devices,

said cells being arranged in a plurality of processing(jigging) lines, each said line containing one or more said cells, such as to allow parallel and/or simultaneous jigging of a plurality of streams of said solid materials.

2. The jig as claimed in the preceding claim 1 and comprising two said processing(jigging) lines.

3. The jig as claimed in the preceding claim 2, wherein die said two jigging lines are disposed substantially parallel and side-by-side.

4. The jig as claimed in any of the preceding claims 1 to 3, wherein each said processing line comprises three said jigging cells having their major axes disposed in a substantially collinear configuration.

5. The jig as claimed in any of the preceding claims 1 to 4, wherein said cells comprise individualised said hutches and air chambers.

6. The jig as claimed in any of the preceding claims 1 to S, wherein at least one of the said air chamber(s) thereof is not attached to the walls of said tank but is supported on support members provided on the said walls and held in position by compressive force(s) applied thereto.

7. The jig as claimed in any of the preceding claims 1 to 6, wherein at least one of the said bedplates thereof is not attached to the walls of said tank and is supported on support members provided on the walls of said tank and held in position by compressive force(s) applied thereto.

8. The jig as claimed in any of the preceding claims 1 to 7, wherein at least one said bedplate and the associated said air chamber thereof are part of a stack system that is supported on said support members and held in position by a common system(s) of compressive force application, said stack system further comprising the necessary thrust transmitting elements between the said force application system and the bedplate and between the latter and the said air chamber and also optionally comprising one or more resilient members therein for distribution of said compressive force(s).

9. The jig as claimed in the preceding claim 8, wherein the said stack system and the compressive force application system thereof, is housed within suitable recesses in the said jig walls such as to provide a substantially obstruction-free access to the jig interior for maintenance and a substantially obstruction-free passage above and below the said bedplate for the movement of the jigging fluid into and out of the said bed.

10. The jig as claimed in the preceding claim 9, wherein said compressive-force-application system(s) is located at, or close to, the tank rim.

11. The jig as claimed in the preceding claim 10, wherein said compressive-force-application system(s) comprises screw means.

12. The jig as claimed in the preceding claim 11 wherein the said thrust transmitting elements and the jig walls are lined with abrasion-resistant material, the said recesses being dimensioned such as to provide a substantially flush, obstruction-free jig interior for said access and for said jigging fluid movement

13. The jig as claimed in any of the preceding claims 1 to 12, wherein at least one connection of the jigging air lines to the jigging cells thereof comprises a flanged connection wherein the flange thereof is in the general configuration of a raised-face flange, the said raised face thereof engaging with a corresponding face located/mounted on an endwall of the air chamber of a said cell, a resilient member being provided between said engaging faces, the recessed part of said raised-face flange being attached either to a sidewall of the jig, or to an opposing member attached thereto, said connection further comprising an O-ring seal engaging the cylindrical surface extending between said raised and recessed faces of the said flange and a corresponding cylindrical surface on said opposing member or the said sidewall such as to isolate the outside air, the jig space and the air chamber interior space from each other.

14. The jig as claimed in any of the preceding claims 1 to 13, wherein the air surge and air exhaust functions for a plurality of, preferably for all of the said cells thereof are performed by a single integrated substantially functionally symmetrical air control box comprising first and second elongated air boxes, and end boxes one for each said cell, said second box being embedded in said first and each said end box being embedded in both said first and second boxes, said first and second boxes constituting manifolds for the incoming jigging air and the outgoing exhaust air respectively, each said end box communicating with the air chamber of the associated said cell thereof and comprising a first control valve and a second control valve communicating respectively with said incoming and outgoing air manifolds and, said control valves being actuatable by a PLC-type(Programmable Logic Controller) or other control means to alternately let in, and let out said jigging air.

15. The jig as claimed in any of the preceding claims 1 to 14, wherein at least one said control valve is diaphragm-actuated by means of air pressure acting alternately above and below the said diaphragm, the valve stem comprising a first and second stem portions, said first being above the diaphragm and being guided in a closed-end cylindrical guide and said second being below the said diaphragm and being connected to the valve poppet/disc that engages with a seating surface provided on the surface of the associated said end box, said cylindrical guide comprising a resilient stop therein for said first stem portion and means for advancing/retracting said guide such as to permit adjustment of the valve stem stroke and, said first stem portion comprising an air bleed passage therein for releasing/letting in air from/to within said guide during operation of the said valve.

16. The jig as claimed in the preceding claim 15, wherein said means for said guide retraction comprise screw means.

17. The jig as claimed in any of the preceding claims 1 to 16, wherein at least one said discharge device for the discharge of a jigged material fraction from a said bedplate thereof comprises a discharge chamber having a plurality of discharge gates that are located at, or near the bottom of said chamber and comprising a linkage system therefor that allows simultaneous operation thereof.

18. The jig as claimed in any of the preceding claims 1 to 17, wherein the guide system for movement of the stem of at least one said bed height sensor thereof comprises a plurality of three-roller guiding elements that together define an axis and an elongated path for said movement, each said element comprising three guide rollers and the axles thereof, said axles being joined/at their ends to form a generally triangular-shaped frame.

19. A mineral jig for carrying out jigging/classifying operations on solid materials such as, for example, metallic ores, coal and other minerals comprising at least one air chamber as recited in the preceding claim 6.

20. A mineral jig for carrying out jigging/classifying operations on solid materials such as, for example, metallic ores, coal and other minerals comprising at least one said bedplate as recited in the preceding claim 7.

21. A mineral jig for carrying out jigging/classifying operations on solid materials such as, for example, metallic ores, coal and other minerals comprising at least one said bedplate and the associated airchamber thereof, as recited in any of the preceding claims 8 to 12.

22. A mineral jig for carrying out jigging/classifying operations on solid materials such as, for example, metallic ores, coal and other minerals wherein one said connection of the jigging air lines to the jigging cells is as recited in the preceding claim 13.

23. A mineral jig for carrying out jigging/classifying operations on solid materials such as, for example, metallic ores, coal and other minerals comprising at least one single integrated substantially functionally symmetrical air control box as recited in the preceding claim 14.

24. A mineral jig for carrying out jigging/classifying operations on solid materials such as, for example, metallic ores, coal and other minerals comprising at least one said control valve as recited in any of the preceding claims 15 and 16.

25. A mineral jig for carrying out jigging/classifying operations on solid materials such as, for example, metallic ores, coal and other minerals comprising at least one said discharge device as recited in the preceding claim 17.

26. A mineral jig for carrying out jigging/classifying operations on solid materials such as, for example, metallic ores, coal and other minerals comprising at least one said guide system, for the stem of a bed height sensor thereof, as recited in the preceding claim 18.

27. A mineral jig for carrying out jigging/classifying operations on solid materials such as, for example, metallic ores, coal and other minerals substantially as hereindescribed and illustrated with reference to the accompanying drawings.

28. A mounting and securing system for a bedplate and/or an air chamber for a mineral jig for carrying out jigging/classifying operations on solid materials such as, for example, metallic ores, coal and other minerals substantially as hereindescribed and illustrated with reference to the accompanying drawings.

29. A means for connecting a jigging air line to a jigging cell for a mineral jig for carrying out jigging/classifying operations on solid materials such as, for example, metallic ores, coal and other minerals substantially as hereindescribed and illustrated with reference to the accompanying drawings.

30. A stack system comprising a bedplate and an associated air chamber thereof, together with the mounting/holding stack compression thereof, for a mineral jig for carrying out jigging/classifying operations on solid materials such as, for example, metallic ores, coal and other minerals substantially as hereindescribed and illustrated with reference to the accompanying drawings.

31. A unitary, integrated air box for pulsing(pulsating) the jigging air for a jigging cell of a mineral jig for carrying out jigging/classifying operations on solid materials such as, for example, metallic ores, coal and other minerals substantially as hereindescribed and illustrated with reference to the accompanying drawings.

32. A control valve for jigging air supply and exhaust from/to surge and exhaust airboxes of a mineral jig for carrying out jigging/classifying operations on solid materials such as, for example, metallic ores, coal and other minerals substantially as herein described and illustrated with reference to the accompanying drawings.

33. A discharge gate device for the discharge of material from a bed of a mineral jig for carrying out jigging/classifying operations on solid materials such as, for example, metallic ores, coal and other minerals substantially as hereindescribed and illustrated with reference to the accompanying drawings.

34. A guidance system for the stem(s) of bed height sensor device(s) of a mineral jig for carrying out jigging/classifying operations on solid materials such as, for example, metallic ores, coal and other minerals substantially as hereindescribed and illustrated with reference to the accompanying drawings.