DESC:FORM 2
THE PATENT ACT 1970
(39 OF 1970)
&
The Patent Rules, 2003
COMPLETE SPECIFICATION
(See Section 10 and Rule 13)

1 TITLE OF THE INVENTION :
MOLTEN SLAG-METAL HANDLING SYSTEM FOR SAFE AND EASY SEPARATION/RECOVERY OF METAL FROM MOLTEN SLAG-METAL MIX.



2 APPLICANT (S)

Name : PRIYAMVAD;

Nationality : Indian;

Address : Door No. 1779, G T Nagar, Ward No. 3, Opposite Ashok Leyland Showroom, NH 63 Main Road, Kurekuppa, Bellary, Karnataka - 583123,India.



3 PREAMBLE TO THE DESCRIPTION

COMPLETE

The following specification particularly describes the invention and the manner in which it is to be performed.

FIELD OF THE INVENTION
The present invention relates to a molten slag-metal handling system for safe and easy separation and recovery of metal from molten slag-metal mix involving an innovative structural configuration of slag container/thimble having the inner surface/lining with differentiated slope/inclination of side wall with respect to vertical axis at lower and upper portion of thimble which is used for collecting and handling slag drained out from a furnace/converter and a method of handling hot slag received from a furnace/converter in a selective manner to obtain metal free slag from a mixture of molten slag and molten metal by decantation process taking advantage of density difference of liquid slag and metal. This invention also facilitates efficient recovery of the metal settled down at bottom of thimble on cooling and solidification with thin layer of slag adhering on top that can be removed easily with any standard known procedure.

BACKGROUND OF THE INVENTION
In Steel making process, there are various by-products which are formed during the various reactions that are being carried out in the Steel Making operation. In this process, Slag is one of the major by-products which is formed due to the impurities present in the hot metal that is obtained from iron making.

It is well known that the hot metal is charged with a few percent of scrap as coolant, the process starting by blowing/arcing the hot metal and then the slag formation takes place, after many chemical reactions, the steel is made either with the help of L D Converter or with the help of Arc Furnace by complete removal of impurities to make steel. After the steel is produced with slag floating over the steel due to the density difference, the steel is tapped through a hole called Tap Hole. After the completion of Tapping (means metal is collected in a Steel Ladle), some product is leftover in the furnace which is called Slag. Then the leftover slag is completely dumped in the slag thimble provided. There will be metallic remains/particles that also flow with slag into slag thimble due to the slag metal mixture. This loss of metallic content directly affects the yield of the steel making because it is a processed steel and recovering this metal from that slag adds up to the cost of the steel making and also makes the slag handling difficult due to oxidation of the metal. The presence of metal content in slag makes it very hard to break or disintegrate. Also the metal content in the slag means loss in money and recovering it makes the process complicated. Various processes have been developed to recover the iron that inevitably goes with the slag. These processes typically recover the iron after the mixture of slag and metal has been cooled and solidified. For example, the separated slag from steel making process is poured in the slag pit and is subsequently allowed to solidify naturally or by spraying the cold water on the dumped slag. As a result, boulders are formed by entrapment of the iron particles within slag due to the development of mechanical and chemical bonds between them. The entrapped iron is recovered from the solidified slag by first crushing the boulders to suitable size and magnetic separation of the iron particles from the non-magnetic slag. However it is not possible to liberate all the iron particles from the slag. A part of iron is attached to the bulk of solidified slag. Further, during cooling and solidification of the slag, some part of iron is lost due to oxidation.

PRESENT PROCESS OF SLAG HANDLING
Generally two major processes of steel making are used for making the steel on large scale, where both slag and refined steel are produced in clear molten state, namely Basic Oxygen Furnace (BOF) and Electric Arc Furnace (EAF). In BOF at the end of the steel making process the refined molten steel is tapped through tap hole while leaving the slag inside the furnace along with a small amount of molten steel. The molten slag along with the left over steel is poured in to the slag thimble for its eventual disposal. The small amount of molten steel so sacrificed during tapping goes with the slag. The small amount of steel sacrificed to go with the slag is recovered by employing crushing and magnetic separation of the Slag/Metal mix after cooling and solidification of the slag.

In EAF process the slag is allowed to flush out of furnace during the refining process itself. However, small amount of the molten steel gets mechanically entrapped and drained with the flushing slag. The small amount of the molten steel thus ends up with the slag that is collected. Additionally, the small amount of iron entrapped during slag flushing is recovered by the process described above.

In both the processes, the molten steel and the slag are not clearly obtained as two physically distinct products. The slag along with the small amount of molten iron in the form of the molten steel, is collected in the slag thimble and transported to the slag handling yard for subsequent solidification and separation of the iron from the slag. The slag thimble is tilted to pour the slag iron mixtures in to the slag pit prescribed for slag dumping. It is tilted on one side on its axis in the vertical plane upside down such that the slag and metal mixture flows in to the slag pit.

Hence poured slag and iron mixture is allowed to solidify either naturally or by spraying cold water. Subsequently, once the slag is solidified the slag and iron mixture bonds up chemically and mechanically forming a boulder mass. This boulder is broken in to smaller size by using the excavators/heavy earth movers in to the manageable size. This process of breaking is so called the loosening. During loosening some amount of metal that is visible by naked eye is recovered using excavators itself.

Once the loosening of the slag is complete the solidified and the loosened slag is taken out of the slag pit and whatever iron particles are present in the slag are separated magnetically as per the capacity of the magnet.

Usually the metal is recovered from the secondary steel making by allowing the metal and the slag to cool and solidify naturally and mechanically liberate the steel that is visible to the naked eye and the remaining steel left over which is present under the slag is eventually disposed-off because there is no other method present for the separation of the steel.

In conventional process of slag handling, slag from the steel furnace is bought to the yard and dumped in allocated area called PIT. After dumping of few numbers of slag thimbles of some prescribed quantity as per the capacity of the slag pit that is how much it can hold, up to that much amount of slag is dumped then that slag is cooled with the help of water. (Ferric oxide is formed by the oxidation reaction of Steel with atmospheric moisture and oxygen which is very difficult to process in order to recover iron from it. It makes the processing even harder and lengthy which is avoided since it is an expensive process). Then the slag is loosened after the cooling with the help of heavy earth movers but with much difficulties. This adds up the cost of processing of slag and steel making because even disposal of gangue material is very important, and even if the metal present comes in contact with the cooling water there are possibilities for oxidation of the metal which is uneconomical to reuse.

DEFECIENCIES/DISADVANTAGES OF THE CONVENTIONAL SLAG HANDLING PROCESS
In the conventional process, there are many flaws which not only make the process difficult but also increases the cost of steel making and makes the process too much unsafe. Some of them are listed below:
1. Since the slag is dumped and cooled in a very vast area, the molten slag which comes in contact with entrapped metal, bonds up and forms a hard cake of mass/bolder. Before its disposal it must be broken into small pieces. This is very difficult to loosen/break in to small pieces because of the hardness.
2. Due to the metal entrapped in molten slag, the metal gets mixed with molten slag. After cooling this mixture, the process of loosening becomes very much difficult.
3. Due to the metal entrapped in molten slag, the metallic losses will be more and as a result, the Yield is decreased.
4. Due to the hardness of slag & metal mixture, the use of heavy earth mover is required for longer periods of time which results in greater pollution, noise and dust. Besides, fuel consumption is also more in this process. Since more cooling is required, there will be more dust formation which results in equipment and machines requiring more maintenance.
5. As the slag is loosened, it is disposed/sent to MRP (metal recovery plant) to recover any metallic content that is present in the slag. In order to minimize the metallic losses, the cost of processing slag adds up to the overall Cost of Steel Making. In MRP, first the steel mix slag is charged in a hopper and passed through crushers, screens and number of conveyers. Then the crushed particles are passed over the magnetic separator where magnetic particles are recovered. The recovered metal will be in the form of coarse particles and also contains some particles of slag. This slag has some amounts of impurities like sulphur (S), phosphor (P), silica (SiO2), alumina (Al2O3) etc. which is uneconomical for reuse. If used it adds up to the cost of steel making.
6. This conventional Metal Recovery Plant (MRP) is a very lengthy process. It takes more time and requires more area. There is too much dust generation in this process which is not environment friendly and also uses more electricity, water, land, fuel, manpower and other heavy equipment and earth movers.
7. Safety parameter wise, conventional slag handling/process is very much unsafe.
8. The main problem in metal recovery is that while cooling, the metal that is to be recovered, comes in contact with atmospheric air/moisture or water resulting in the formation ferrous oxides of FeO and Fe2O3. Recovering back the metal from this mixture is extremely difficult.

Various processes have been developed to recover the iron that inevitably goes with the slag. These processes typically recover the iron after the mixture of slag and metal has been cooled and solidified. For example, the separated slag from steel making process is poured in the slag pit and is subsequently allowed to solidify naturally or by spraying the cold water on the dumped slag. As a result, boulders are formed by entrapping of iron particles within the slag due to the development of mechanical and chemical bonds between them. The entrapped iron is recovered from the solidified slag by first crushing the boulders to a suitable size and magnetic separation of the iron particles from the non-magnetic slag. However it is not possible to liberate all the iron particles from the slag. A part of iron is attached to the bulk of solidified slag. Further, during cooling and solidification of the slag, some part of iron is lost due to oxidation.

Applicant’s co-pending application in related field disclosed a method of slag handling to control metallic loses in slag generated in steel making. The invention deals with recovery of metal lost due to oxidation during molten Slag Handling and Scrap Metal Recovery in the Steel Making Industry. The present invention thus provide a simple process wherein controlled pouring of the slag from said container/thimble for slag dumping such that only the top slag initially flows out and when the slag containing left over molten metal/steel surface during pouring, stopping said pouring such that substantial portion of only the top slag is dumped and the leftover molten metal/steel with slag layer floating on top is retained and thus eliminate metallic losses that otherwise occur due to oxidation of the metal that comes in contact of atmospheric moisture and water when slag handling is done by conventional method.

However, the slag pot/thimble used for the purpose of the above invention was of conventional configuration which could not efficiently separate slag from liquid residual metal during pouring just by arbitrarily controlling the angle of tilt of the thimble and hence there was the possibility that some metal might flow along with slag lost during pouring of slag layer, as metal lying below slag could not be clearly detected by manual inspection during such pouring.

In the previous invention it was not so clear as to what point the dumping/pouring of molten mixture from the Slag container/thimble (1) should be stopped so as to recover the complete metal. The new innovative design of the Slag container/thimble in the present work gives an easy, efficient and well defined approach as to when and at what point the dumping/pouring of molten mixture from the Slag container/thimble (1) should be stopped.

There has been thus a need in the field of iron and steel production to develop a slag pot and method of slag handling which would not only reduce metal loss during slag dumping by separating slag from residual metal in thimble in more efficient manner but also avoid metal loss due to oxidation. The slag thimble and the method of slag handling would ensure separating metal free slag and residual metal in thimble in an easy and environment friendly manner without needing use of electricity, water, land, fuel, manpower and other heavy equipment /earth movers. This invention thus aims at eliminating loss of metal that is inevitably lost presently being retained in slag and because of oxidation. Although the system and method of present invention has been described in relation to steel production, the same principle of slag and metal separation can be applicable for other metal manufacturing industries such as copper, aluminium or the like.

OBJECTS OF THE INVENTION

The basic object of the present invention is directed to provide molten slag-metal handling system for safe and easy separation and recovery of metal from molten slag-metal mix involving a slag container/thimble configured to separate metal free slag and the residual liquid metal contained in the slag and a method of slag handling to separate metal free slag by decantation process, from mixture of liquid slag and metal collected in said thimble from furnace/converter, for dumping the slag in yard/pit so that residual metal is efficiently recovered thereby reducing metal loss significantly including loss due to oxidation.

A further object of the present invention is directed to said method of handling hot slag received from a furnace/converter using said innovatively designed slag container/thimble whereby liquid metal entrapped in slag is forced to be contained in the bottom portion of the said slag container/thimble due to the new/innovative design of the slag container/thimble and prevents the metal from coming into contact with a large surface area of the inner lining/surface of the slag container/thimble thus making it easier to remove later on.

A further object of the present invention is directed to said method of handling hot slag received from a furnace/converter using said innovatively designed slag container/thimble whereby complete metal content in the mixture of molten slag and molten metal can be recovered without the use of other complicated or expensive technologies/procedures/devices/constructions/apparatus.

A still further object of the present invention is directed to said method of slag handling in specially configured slag container/thimble which would facilitate dumping slag minimising the possibility of residual liquid metal flowing along with slag during pouring.

A still further object of the present invention is directed to said method of slag handling in specially configured slag container/thimble whereby existing method of breaking solidified slag using heavy earth movers in order to recover the metal content from the slag that is dumped from a slag container/thimble is eliminated.

A still further object of the present invention is directed to said method of slag handling in specially configured slag container/thimble which would help in obtaining metal free molten slag which will make the process of treating molten slag in other apparatus extremely easy thus multiplying the percentage of slag reusability all around the world.

A still further object of the present invention is directed to said method of slag handling in specially configured slag container/thimble which would help in improve steel productivity by efficiently recovering entrapped metal in slag reducing metal loss and thus would favour reduced cost of production of steel.

A still further object of the present invention is directed to said method of slag handling in specially configured slag container/thimble which would be simple, safe and operator friendly.

SUMMARY OF THE INVENTION
The basic aspect of the present invention is directed to a molten slag-metal handling system for safe and easy separation and recovery of metal from molten slag-metal mix comprising:
a container/thimble having an open top lip/mouth and a closed bottom inner surface and surrounding inner side wall ;

said surrounding inner side wall having differentiated inclination along height of thimble including atleast an upper portion of the inner side wall having an inclined outwards disposition from the vertical axis which together with an lower portion contiguous to said upper portion but inclined at lesser inclination outwardly compared to said upper portion, define a controlled molten slag disposal mechanism from said molten metal-slag with said upper portion of the inner side wall having an inclined outwards disposition from the vertical axis assumes a substantially horizontal disposition upon placing the thimble at a tilted disposition for controlled slag disposal and the said relatively less outwardly inclined lower portion contiguous to said upper portion enabling arresting the flow out of the molten metal from the container even in such tilted slag disposal state.

A further aspect of the present invention is directed to said molten slag-metal handling system wherein the slag container/thimble having differentiated inclination on upper portion and lower portion of side wall with said upper portion having relatively higher outward inclination in the range of 6 to 35 degrees from vertical axis and said lower portion having relatively less outward inclination in the range of 0 to 30 degrees from vertical axis of slag vessel/thimble, wherein upper part is at least 5 degrees more inclined from the vertical axis, than the lower part.

A still further aspect of the present invention is directed to said molten slag-metal handling system comprising said differentiated inclinations of side wall including curved, multi-linear or spout like profile said upper portion of the inner side wall having peripheral inclined outwards disposition from the vertical axis upon assuming an inclined disposition for slag disposal assumes a substantially horizontal disposition for controlled slag disposal and creates a pocket for arresting the molten metal flow out in combination with the contiguous substantially vertical and less inclined periphery of the lower portion of the container and the closed bottom, wherein the progressively incremental inclination ranges from lower most part – 0 to 6 degrees, middle part – 6 to 15 degrees and upper part – 11 to 25 degrees with respect to vertical axis, and wherein there exist at least 5 degrees difference in inclination angle between each part.

A still further aspect of the present invention is directed to said molten slag-metal handling system comprising said upper portion having peripheral inclined outwards disposition from the vertical axis is having an outward inclination with respect to the vertical axis more than said lower portion having said less inclined peripheral wall with respect to the vertical, wherein said inclinations vary for different requirements of the slag container/thimble specifications and sizes.

A still further aspect of the present invention is directed to said molten slag-metal handling system wherein said container/thimble for handling molten slag-metal mix having substantially inverted bell shape of its inner surface/lining wherein said open top lip/mouth portion having diameter more than the closed bottom portion.

A still further aspect of the present invention is directed to said molten slag-metal handling system wherein said container/thimble for handling molten slag-metal mix having the thickness of the lower portion of the said container/thimble is more than the thickness of the upper portion.

Another aspect of the present invention is directed to said molten slag-metal handling system wherein non linear side wall configuration of said container/thimble for handling molten slag-metal mix having a characteristic property that it tends to keep/force the molten metal away from the open top lip/mouth of the Slag container/thimble during slag dumping process and forces the metal to be contained at the bottom of the Slag container/thimble during the entire dumping process.

Yet another aspect of the present invention is directed to said method for safe and easy separation and recovery of metal from molten slag-metal mix involving the molten metal-slag handling system as described above comprising:

i) Initially allowing the molten mixture of metal-slag to settle for a period of 4 to 5 minutes in the slag container/thimble;
ii) and slowly dumping the molten mixture from the Slag container/thimble by tilting the slag container/thimble up to a point at which a atleast a part of the upper portion of the upper inner side wall having an inclined outwards disposition from the vertical axis assumes a substantially horizontal disposition for safe and easy disposition of molten slag separated from the heavier molten metal arrested within the contiguous less outwardly inclined lower inner wall and the contiguous closed bottom of the container adapted to force the molten metal away from the open top/lip region of slag container/thimble; and
iii) bringing the container/thimble in usual vertical disposition after said disposal of the molten slag for cooling the retained volume at lower portion and recovering molten metal therefrom.

A further aspect of the present invention is directed to said method wherein the said molten metal left over for said cooling and recovery is subjected to natural cooling to be obtained as a single solid lump of metal with some slag adhered on top, which can be released by inverting the container/thimble.

A still further aspect of the present invention is directed to said method wherein the slag that is adhered to the solid metal lump is removed by hitting/hammering using any heavy earth mover.

Another aspect of the present invention is directed to said method wherein before dumping process, the volume of the molten metal present in the total molten slag- metal mixture in the Slag container/thimble is less than a prescribed volume and wherein said prescribed volume in relation to said slag container/thimble is given by a position where the Slag container/thimble is tilted from the vertical axis to a point when a part of the upper portion of the side wall of the Slag container/thimble becomes horizontal so that the prescribed volume of the given Slag container/thimble is the volume enclosed between a horizontal surface coinciding with the horizontal upper portion of the side wall and the bottom inner surface of the Slag container/thimble and said prescribed volume is in a range of 2% to 10% of total volume of slag thimble that is retained in the bottom after removing slag.

Yet another aspect of the present invention is directed to said method wherein remaining metal on cooling and solidification is easily removed since it sticks to very less surface area of the inner lining/surface of the slag container/thimble and when inverted in order to remove it, there being no obstruction due to the open shape of mouth of the slag container/thimble.

A further aspect of the present invention is directed to said method wherein when molten slag comes in contact with the said slag container/thimble, a thin layer of slag sticks to the inner surface of the slag container/thimble that acts as an anti sticking material and prevents the metal to stick to the inner surface of the slag container/thimble.

A still further aspect of the present invention is directed to said method wherein a layer of molten slag floating on top of molten metal is maintained to avoid the oxidation of metal by atmospheric oxygen.

A still further aspect of the present invention is directed to said method wherein leftover molten mixture left in the slag container/thimble after the dumping process, can also be transferred to another container/apparatus for further processing/cooling.

The above and other objects and advantages of the present invention are described hereunder in greater details with reference to following accompanying non limiting illustrative drawings.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Fig. 1: illustrates the inner surface/lining of a conventional slag container/thimble used for collecting and dumping hot molten slag received from the furnace/converter.
Fig. 2a: illustrates a conventional slag container/thimble in a vertical position.
Fig. 2b: illustrates a conventional slag container/thimble in a position where it is slightly tilted to one side.
Fig. 2c: illustrates a conventional slag container/thimble in a position where it is tilted to an angle larger than that shown in Fig. 2b.
Fig. 3: illustrates the inner surface lining of the newly designed slag container/thimble. This is a bi-linear configuration.
Fig. 4a: illustrates the newly designed slag container/thimble of Fig. 3, in a vertical position.
Fig. 4b: illustrates the newly designed slag container/thimble of Fig. 3, in a position where it is slightly tilted to one side.
Fig. 4c: illustrates the newly designed slag container/thimble of Fig. 3, in a position where it is tilted to an angle larger than that shown in Fig. 4b, such that a part of the upper portion of the side wall has become horizontal.
Fig. 4d: illustrates the newly designed slag container/thimble of Fig. 3, tilted back to upright position after dumping metal free slag.
Fig. 5: illustrates an alternative configuration of the inner surface lining of the newly designed slag container/thimble having a curved profile of side wall instead of a bi-linear profile as shown in Fig. 3.
Fig. 6a: illustrates the newly designed slag container/thimble (having a curved profile) in a vertical position.
Fig. 6b: illustrates the newly designed slag container/thimble (having a curved profile) in a position where it is slightly tilted to one side.
Fig. 6c: illustrates the newly designed slag container/thimble (having a curved profile) in a position where it is tilted to an angle larger than that shown in Fig. 6b, such that Point A and Point B have come at the same horizontal level.
Fig. 6d: illustrates the newly designed slag container/thimble (having a curved profile) tilted back to upright position after dumping metal free slag.
Fig. 7 illustrates another alternative configuration of the inner surface lining of the newly designed slag container/thimble having multiple inclinations of the side wall.
Fig. 8 illustrates yet another alternative configuration of the inner surface lining of the newly designed slag container/thimble having side wall similar to a normal slag container/thimble and an outward curved/inclined portion on the upper portion of the wall on one side forming a pouring spout like profile.
Fig. 9 illustrates another alternative configuration of the inner surface lining of the newly designed slag container/thimble similar to that shown in Fig. 8 but having the spout like configuration on both the sides.

DETAILED DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE ACCOMPANYING DRAWINGS

The present invention is related to molten slag-metal handling system for safe and easy separation and recovery of metal from molten slag-metal mix involving a specifically designed inner lining/surface of the slag container/thimble which can be used for dumping metal free slag by separating it from a mixture of molten slag and molten metal favouring residual metal recovery in a very easy and efficient manner.

It is well known that if a mixture of molten slag and molten metal is left for some time in a container/thimble, it can be seen that metal being heavier settles down and slag floats on top of the metal. When the mixture of molten metal and molten slag is allowed to settle for sometime in this newly designed slag container/thimble and then slowly poured out, only the top molten slag floating above the molten metal falls out of the slag container/thimble and the molten metal settles down in the container and does not fall down during pouring because it is forced to be contained in the bottom portion of the said slag container/thimble due to the new/innovative design of the slag container/thimble. The innovative design also prevents the metal from coming into contact with a large surface area of the inner lining/surface of the slag container/thimble thus making it easier to remove later on.

This newly designed slag container/thimble gives the user a tool for hot slag handling such that the metal content in a mixture of molten slag and molten metal can be separated from the slag content without the use of any sophisticated or expensive technology/construction/ device/process. As a result, metal free slag can easily be dumped from the slag container/thimble.

The new method described herein for handling hot slag received from a furnace/converter will eliminate the oxidation loss of metal that occurs in the conventional process when the mixture of molten slag and molten metal is cooled using water.

The inventive constructional feature of the slag container/thimble according to present invention and the selective method of separating metal free slag and residual metal settled at bottom while handling slag and metal mixture using this thimble are described hereunder with reference to the accompanying figures wherein,

Accompanying Fig. 1 illustrates the inner surface/lining of a conventional slag container/thimble (20) used for collecting and dumping hot molten slag received from the furnace/converter. It has an open top lip/mouth (10), a closed bottom surface (11) and a side wall (14) which is inclined outwards at some angle from the vertical axis of the slag container/thimble (20).

Fig. 2a illustrates a conventional slag container/thimble (20) in a vertical position, containing molten slag layer (15) floating on top of a molten metal layer (16).

Fig. 2b illustrates a conventional slag container/thimble (20) in a position where it is slightly tilted to one side, containing molten slag layer (15) and molten metal layer (16) such that the top surface of the molten slag layer (15) is at a height equal to the height of the lower most portion of the open top lip/mouth (10) of the slag container/thimble (20) and the molten metal layer (16) is settled down in the bottom right portion of the slag container/thimble (20).

Fig. 2c illustrates a conventional slag container/thimble (20) in a position where it is tilted to an angle larger than that shown in Fig. 2b, containing molten slag layer (15) and molten metal layer (16) such that the top surface of the molten slag layer (15) is at a height equal to the height of the lower most portion of the open top lip/mouth (10) of the slag container/thimble (20) and the top surface of the molten metal layer (16) is almost near the lower most point of the open top lip/mouth (10) of the slag container/thimble (20).

Fig. 3 shows the front and top view of the inner surface lining of a bi-linear configuration of the newly designed slag container/thimble (1). It has an open top lip/mouth (10), a curved and closed bottom surface (11). The side wall of the slag container/thimble (1) is inclined outwards from the vertical axis and is constituted of a lower portion and an upper portion in such a way that the upper portion of the side wall (12) is more inclined from the vertical axis than the lower portion of the side wall (13), with said upper portion having relatively higher outward inclination in the range of 6 to 35 degrees from vertical axis and said lower portion having relatively less outward inclination in the range of 0 to 30 degrees from vertical axis of slag vessel/thimble, wherein upper part is at least 5 degrees more inclined from the vertical axis, than the lower part.

Fig. 4a illustrates the newly designed slag container/thimble (1) in a vertical position, containing a molten slag layer (15) floating on top of a molten metal layer (16).

Fig. 4b illustrates the newly designed slag container/thimble (1) in a position where it is slightly tilted to one side, containing molten slag layer (15) and molten metal layer (16) such that the top surface of the molten slag layer (15) is at a height equal to the height of the lower most portion of the open top lip/mouth (10) of the slag container/thimble (1) and the molten metal layer (16) is settled down in the bottom right portion of the slag container/thimble (1).

Fig. 4c illustrates the newly designed slag container/thimble (1) in a position where it is tilted to an angle larger than that shown in Fig. 4b, such that a part of the upper portion of the side wall (12) has become horizontal. The slag container/thimble (1) is containing molten slag layer (15) and molten metal layer (16) such that the top surface of the molten slag layer (15) is at a height equal to the height of the lower most portion of the open top lip/mouth (10) of the slag container/thimble (1) and the top surface of the molten metal layer (16) is at a height below the lower most point of the upper portion of the side wall (12) of the slag container/thimble (1).

Fig. 4d illustrates the newly designed slag container/thimble (1) tilted back to upright position after dumping metal free slag. The slag container/thimble (1) contains the entire molten metal layer (16) settled at the bottom and a small layer of molten slag (15) floating on top of the molten metal layer (16).

Fig. 5 shows the front and top view of the newly designed slag container/thimble (1) having a curved configuration. The said slag container/thimble (1) has a curved and closed bottom surface and is surrounded by side wall. The side wall of the slag container/thimble (1) is curved and inclined outwards from the vertical axis. It also shows Point A (24) and Point B (25).

Figures 6a, 6b and 6c show the newly designed slag container/thimble(1) with a curved profile, which is tilted at different angles from the vertical. The slag container/thimble (1) is vertical in Fig. 6a and slightly tilted in Fig. 6b. In Fig. 6c, the slag container/thimble (1) is further inclined from the vertical such that Point A (24) and Point B (25) are at the same horizontal level.

Point A (24) and Point B (25) are two points marked at the corresponding outer surface of the Slag Container/thimble (1) such that they are externally visible. These are used along with the slag container/thimble (1) configurations that have a curved, multi-linear or spout like profile as shown in Figures 5,7,8 & 9, wherein the progressively incremental inclination ranges from lower most part – 0 to 6 degrees, middle part – 6 to 15 degrees and upper part – 11 to 25 degrees with respect to vertical axis, and wherein there exist at least 5 degrees difference in inclination angle between each part depending on design configuration and shape.

Point A (24) and Point B (25) are used to stop the dumping process at a point where they both come at the same horizontal level. At this position, the volume of the mixture that is left in the slag container/thimble (1) is equal to Specified Volume (4).

The innovative design of the Slag container/thimble (1) has a characteristic property (2) that it tends to keep/force the molten metal (16) away from the open top lip/mouth (10) of the Slag container/thimble (1) during dumping process (17) or alternate dumping process (18) and forces it to be contained at the bottom of the Slag container/thimble (1) during the entire Dumping process (17) and Alternate Dumping Process (18).

Dumping process (17) involves allowing the molten mixture to settle for five minutes in the slag container/thimble (1) and then slowly dumping the molten mixture from the Slag container/thimble (1) by tilting the slag container/thimble (1) up to a point at which a part of the upper portion of the side wall (12) of the Slag container/thimble (1) becomes horizontal as shown in Fig. 4c.

Alternate dumping process (18) involves allowing the molten mixture to settle for five minutes in the slag container/thimble (1) and then slowly dumping the molten mixture from the slag container/thimble (1) by tilting the slag container/thimble (1) up to a point at which Point A (24) and Point B (25) come at the same horizontal level.

After alternate dumping process (18), some molten mixture is leftover in the Slag container/thimble (1) due to the innovative design of the Slag container/thimble (1) and a substantial portion of metal free slag is dumped/poured out of the slag container/thimble (1). After the alternate dumping process (18), the volume of the leftover molten mixture in the slag container/thimble (1) is equal to the specified volume (4) of the slag container/thimble (1). Then the Slag container/thimble (1) is again tilted to an upright position.

The leftover molten mixture left in the slag container/thimble (1) after the dumping process (17) or alternate dumping process (18), is left to naturally air cool in the Slag container/thimble (1) itself. If required, this leftover molten mixture left in the slag container/thimble (1) can also be transferred to another container/apparatus for further processing/cooling.

Upon solidification of this leftover molten material after natural/air cooling, a single solid lump of metal is formed with some slag adhered on top of it. This solid lump of metal and slag can be removed from the Slag container/thimble (1) by simply inverting it upside down. The slag that is adhered to the solid metal lump can simply be removed by hitting/hammering using any heavy earth mover. Slag free metal can thus be obtained in a single solid lump which can be used as required.

The characteristic property (2) of this invention is easily achieved by utilising the shape/geometric construction/design of the inner lining/surface of the side wall of the slag container thimble (1) and due to natural properties of the molten slag and molten metal such as density, specific gravity, viscosity, stickiness, etc, without the use of other complicated or expensive technologies/procedures /devices/constructions/apparatus (6). These complicated technologies /procedures/devices/constructions/apparatus (6) may make the whole process complicated, expensive, unsafe, tough and lengthy.

For the characteristic property (2) of this invention to be held true, it is required that before Dumping process (17), the volume of the molten metal present in the total molten mixture in the Slag container/thimble (1), is less than the prescribed volume (3).

The prescribed volume (3) of a given Slag container/thimble (1) can be described as follows:

The Slag container/thimble (1) is tilted from the vertical axis to a point when a part of the Upper portion of the side wall (12) of the Slag container/thimble (1) becomes horizontal. At this point, the prescribed volume (3) of the given Slag container/thimble (1) is the volume enclosed between a horizontal surface coinciding with the horizontal Upper portion of the side wall (12) and the inner surface of the Slag container/thimble (1). The specified/prescribed volume ranges between 2-10% of volumetric capacity of slag thimble depending on its designed geometric shape and size.

In case of curved, multi-linear and spout profiles, i.e. profiles other than the linear profile of Fig. 1, For the characteristic property (2) of this invention to be held true, it is required that before Alternate Dumping process (18), the volume of the molten metal present in the total molten mixture in the Slag container/thimble (1), is less than the Specified Volume (4).

The specified volume (4) of a given Slag container/thimble (1) can be described as follows:
The Slag container/thimble (1) is tilted from the vertical axis to a point when Point A (24) and Point B (25) come at the same horizontal level as shown in Fig. 6c. At this point, the specified volume (4) of the given Slag container/thimble (1) is the volume of molten slag-metal mixture left over in the slag container/thimble (1).

Point A (24) and Point (B) are marked in such a way that specified volume (4) as shown in Fig. 6c is approximately 3 to 5% of the total volumetric capacity of the slag container/thimble (1).

WORKING OF THE INVENTION
A newly designed slag container/thimble (1) as described above is taken which is nearly at room temperature. The mixture of molten slag and metal from a furnace/converter is collected in the newly designed slag container/thimble (1). As the molten slag comes in contact with the said slag container/thimble (1), a thin layer of slag solidifies and sticks to the inner surface of the slag container/thimble (1). This thin layer of slag itself acts as an anti sticking material and prevents the metal to stick to the inner surface of the slag container/thimble (1).

The molten mixture collected in the said slag container/thimble (1) is then allowed to settle for 4 to 5 minutes. After 4 to 5 minutes, metal layer is settled down at the bottom of the container and a layer of molten slag is formed that floats on top of the molten metal layer. It can be seen that the floating top slag layer is completely metal free. Then, the molten mixture is slowly poured out from the slag container/thimble.

Molten mixture is poured down by slowly tilting the slag container. Initially, the top slag layer starts pouring out of the slag container.
Metal remains settled down and is contained at the bottom right portion of the slag container/ thimble (1) during pouring because of the design/geometric construction of the slag container/thimble (1).

Since the top slag layer is metal free, the slag that is initially being dumped is metal free slag. For this, the slag container is tilted up to a point when a part of the upper portion of the side wall (12) becomes horizontal as shown in Fig. 4c. Alternately, in slag container/thimble with curved, multi-linear and spout configurations, the slag container is tilted up to a point when Point A (24) and Point B (25) come at the same horizontal level as shown in Fig. 6c.

Then the slag container is tilted back to upright position as shown in Fig. 4d and Fig. 6d. The remaining molten mixture is left for natural/air cooling in the same container. If required, it can also be transferred to another container and left to cool naturally. When the leftover mixture cools and solidifies, a single solid lump of metal is formed along with a solid layer of slag adhered on top of it. This layer of slag that sticks to the metal lump can easily be removed by hitting it lightly by a heavy earth mover. Thus, metal can be easily obtained which is completely free from slag.

Also, the metal free slag which is obtained can be either dumped or be treated by any other method as required.

It is thus possible by way of the present invention to achieve the following advantages and functional benefits in slag handling in steel plant:
a. Oxidation loss of metal is completely eliminated since the need for water cooling of slag and molten metal is completely ruled out.
b. The presence of metal in slag makes it very difficult to process it further in order to remove free lime, disintegrate etc. This invention provides a tool and a mechanism to obtain completely metal free slag which is very easy to process in any apparatus/method since there is no metal present in it. This can multiply the slag reusability percentage and save the world from the hazard of dumping slag.
c. The complete metal is recovered in a pure and single solid form.
d. This new design of slag container/thimble and the corresponding method for dumping slag is very safe since water is not used for cooling the molten slag/metal and therefore, there is no chance of blasting.
e. This innovation will provide better control on metal chemistry.
f. In the previous invention it was not so clear as to what point the dumping/pouring of molten mixture from the Slag container/thimble (1) should be stopped so as to recover the complete metal. This new innovative design of the Slag container/thimble (1) gives an easy, efficient and well defined approach as to when and at what point the dumping/pouring of molten mixture from the Slag container/thimble (1) should be stopped.
g. This innovative design and corresponding dumping method guarantees that after the dumping process (17) or alternate dumping process (18), complete molten metal can be contained in the slag container/thimble (1) and only metal free slag is dumped from the slag container/thimble (1).
h. The molten metal (16) is contained in the bottom of the slag container/thimble (1) and after Dumping process (17) or alternate dumping process (18), it does not come into contact with a large surface area of the inner lining/surface (2) of the slag container/thimble (1). So, after cooling, if the molten metal (16) solidifies and sticks to the inner lining/surface (2) of the slag container/thimble (1), it is easy to remove it from the slag container/thimble (1) since it sticks to very less surface area of the inner lining/surface (2) of the slag container/thimble (1). If the slag container/thimble (1) is inverted in this situation in order to remove it, then there is no obstruction due to the open shape of the slag container/thimble (1) and no damage will occur to the Dumping/pouring apparatus if/when the solidified molten metal/slag will fall down upon inverting.
i. This innovative design is very simple in construction.
j. This innovative design of slag container/thimble eliminates the requirement of a Metal Recovery Plant for recovering metal from the molten mixture of slag and metal received from a furnace/converter.
k. This innovative design provides an extremely cost effective and environment friendly method for separating metal from a mixture of molten metal and molten slag received from a furnace/converter. This method is also very safe and energy efficient since the requirement of heavy earth movers will be drastically reduced/eliminated.
,CLAIMS:I Claim:

1. A molten slag-metal handling system for safe and easy separation and recovery of metal from molten slag-metal mix comprising:
a container/thimble having an open top lip/mouth and a closed bottom inner surface and surrounding inner side wall ;

said surrounding inner side wall having differentiated inclination along height of thimble including atleast an upper portion of the inner side wall having an inclined outwards disposition from the vertical axis which together with an lower portion contiguous to said upper portion but inclined at lesser inclination outwardly compared to said upper portion, define a controlled molten slag disposal mechanism from said molten metal-slag with said upper portion of the inner side wall having an inclined outwards disposition from the vertical axis assumes a substantially horizontal disposition upon placing the thimble at a tilted disposition for controlled slag disposal and the said relatively less outwardly inclined lower portion contiguous to said upper portion enabling arresting the flow out of the molten metal from the container even in such tilted slag disposal state.

2. The molten slag-metal handling system as claimed in claim 1 wherein the slag container/thimble having differentiated inclination on upper portion and lower portion of side wall with said upper portion having relatively higher outward inclination in the range of 6 to 35 degrees from vertical axis and said lower portion having relatively less outward inclination in the range of 0 to 30 degrees from vertical axis of slag vessel/thimble, wherein upper part is at least 5 degrees more inclined from the vertical axis, than the lower part.

3. The molten slag-metal handling system as claimed in anyone of claims 1 or 2 comprising said differentiated inclinations of side wall including curved, multi-linear or spout like profile said upper portion of the inner side wall having peripheral inclined outwards disposition from the vertical axis upon assuming an inclined disposition for slag disposal assumes a substantially horizontal disposition for controlled slag disposal and creates a pocket for arresting the molten metal flow out in combination with the contiguous substantially vertical and less inclined periphery of the lower portion of the container and the closed bottom, wherein the progressively incremental inclination ranges from lower most part – 0 to 6 degrees, middle part – 6 to 15 degrees and upper part – 11 to 25 degrees with respect to vertical axis, wherein there exist at least 5 degrees difference in inclination angle between each part.

4. The molten slag-metal handling system as claimed in anyone of claims 1 to 3 comprising said upper portion having peripheral inclined outwards disposition from the vertical axis is having an outward inclination with respect to the vertical axis more than said lower portion having said less inclined peripheral wall with respect to the vertical, wherein said inclinations vary for different requirements of the slag container/thimble specifications and sizes.

5. The molten slag-metal handling system as claimed in anyone of claims 1 to 4 wherein said container/thimble for handling molten slag-metal mix having substantially inverted bell shape of its inner surface/lining wherein said open top lip/mouth portion having diameter more than the closed bottom portion.

6. The molten slag-metal handling system as claimed in anyone of claims 1 to 5 wherein said container/thimble for handling molten slag-metal mix having the thickness of the lower portion of the said container/thimble is more than the thickness of the upper portion.

7. The molten slag-metal handling system as claimed in anyone of claims 1 to 6 wherein non linear side wall configuration of said container/thimble for handling molten slag-metal mix having a characteristic property that it tends to keep/force the molten metal away from the open top lip/mouth of the Slag container/thimble during slag dumping process and forces the metal to be contained at the bottom of the Slag container/thimble during the entire dumping process.

8. A method for safe and easy separation and recovery of metal from molten slag-metal mix involving the molten metal-slag handling system as claimed in anyone of claims 1 to 7 comprising:

i) Initially allowing the molten mixture of metal-slag to settle for a period of 4 to 5 minutes in the slag container/thimble;
ii) and slowly dumping the molten mixture from the Slag container/thimble by tilting the slag container/thimble up to a point at which a atleast a part of the upper portion of the upper inner side wall having an inclined outwards disposition from the vertical axis assumes a substantially horizontal disposition for safe and easy disposition of molten slag separated from the heavier molten metal arrested within the contiguous less outwardly inclined lower inner wall and the contiguous closed bottom of the container adapted to force the molten metal away from the open top/lip region of slag container/thimble; and
iii) bringing the container/thimble in usual vertical disposition after said disposal of the molten slag for cooling the retained volume at lower portion and recovering molten metal therefrom.

9. The method as claimed in claim 8 wherein the said molten metal left over for said cooling and recovery is subjected to natural cooling to be obtained as a single solid lump of metal with some slag adhered on top, which can be released by inverting the container/thimble.

10. The method as claimed in anyone of claims 8 or 9 wherein the slag that is adhered to the solid metal lump is removed by hitting/hammering using any heavy earth mover.

11. The method as claimed in anyone of claims 8 to 10 wherein before dumping process, the volume of the molten metal present in the total molten slag- metal mixture in the Slag container/thimble is less than a prescribed volume and wherein said prescribed volume in relation to said slag container/thimble is given by a position where the Slag container/thimble is tilted from the vertical axis to a point when a part of the upper portion of the side wall of the Slag container/thimble becomes horizontal so that the prescribed volume of the given Slag container/thimble is the volume enclosed between a horizontal surface coinciding with the horizontal upper portion of the side wall and the bottom inner surface of the Slag container/thimble and said prescribed volume is in a range of 2% to 10% of total volume of slag thimble that is retained in the bottom after removing slag.

12. The method as claimed in anyone of claims 8 to 11 wherein remaining metal on cooling and solidification is easily removed since it sticks to very less surface area of the inner lining/surface of the slag container/thimble and when inverted in order to remove it, there being no obstruction due to the open shape of mouth of the slag container/thimble.

13. The method as claimed in anyone of claims 8 to 12 wherein when molten slag comes in contact with the said slag container/thimble, a thin layer of slag sticks to the inner surface of the slag container/thimble that acts as an anti sticking material and prevents the metal to stick to the inner surface of the slag container/thimble.

14. The method as claimed in anyone of claims 8 to 13 wherein a layer of molten slag floating on top of molten metal is maintained to avoid the oxidation of metal by atmospheric oxygen.

15. The method as claimed in anyone of claims 8 to 14 wherein leftover molten mixture left in the slag container/thimble after the dumping process, can also be transferred to another container/apparatus for further processing/cooling.

Dated this the 10th day of February, 2021
Anjan Sen
Of Anjan Sen & Associates
(Applicant’s Agent)
IN/PA-199