CLIAMS:We Claim:

1. A specific gravity liquid suitable for float-sink separation of run-off mines coal or ore comprising mill scale fines including iron oxide magnetic particles/powder having a size of less than 45 microns and in selective concentration mixed and suspended in water to provide a specific gravity liquid with a specific gravity of at least 1.2 and up to 2.1 for separation of run-off mill coal or high specific gravity liquid having a specific gravity of 1.4 to 2.5 for separation of ores depending upon the desired use.

2. A specific gravity liquid as claimed in claim 1 wherein said mill scale fines comprise
True specific gravity: 4.1 to 5.2 ;
Particle size: +325 mesh 10% (Max) -325 mesh 90% (Min);
Surface property: The surfaces have films of iron oxide thereon so that no red rust occurs in water.

3. A specific gravity liquid as claimed in anyone of claims 1 or 2 wherein said mill scale fines have desired Magnetic property involving
Content of non-magnetic substances 2-3%
Content of magnetic substances 97-98%; and
Desired settling property: The height of the clear water produced in 5 minutes is 15% or less of the height of a specific gravity liquid and the settling speed of the iron powder in water is not so high.

4. A specific gravity liquid as claimed in anyone of claims 1 to 3 involving a desired variable end use related specific gravity based on variable inclusion of mill scale as hereunder:

Content of mill scale fines (w/v %) Media solution (Sp.gravity)
17 1.10
33 1.20
50 1.30
67 1.40
83 1.50
100 1.60
117 1.70
133 1.80
150 1.90
168 2.00
183 2.10

and liquid viscosity in the range of 15 centipoises to 150 centipoises

5. A specific gravity liquid as claimed in anyone of claims 1 to 4 optionally comprising fine particles (slime) of some clay minerals for the purpose of maintaining the stability of the specific gravity liquid of iron powder.
6. A gravity separation method involving the specific gravity liquid as claimed in anyone of claims 1 to 5 comprising providing said specific gravity liquid involving mill scale fines with or without addition of fine particles (slime) for the purpose of maintaining the stability of the above-described specific gravity liquid of iron powder. comprising iron oxide magnetic particles/powder having a size of less than 45 microns and in selective concentration mixed and suspended in water to provide a specific gravity solution with a specific gravity of at least 1.2 and up to 2.1 for separation of run-off-mines coal or high specific gravity of 1.4 to 3.5 for separation of ores depending upon the desired use, and
pouring various run-off-mines coal/ores into the specific gravity liquid formed so as to subject said raw coal or ores to float-sink separation for desired beneficiation.
7. A gravity separation method as claimed in claim 6, wherein said mill scale fines used are composed of iron oxides having physical properties, as the medium for forming a liquid having a high specific gravity and low viscosity comprising:
True specific gravity: 4.1 to 5.2;
Particle size: +325 mesh 10% (Max) -325 mesh 90% (Min);
Surface property: surfaces having films of iron oxide thereon so that no red rust occurs in water (for example, Fe3 O4 film);
Magnetic property: iron powder having strong magnetism so as to be suitable for recovering them from the water wherein
Content of non-magnetic substances 2-3%;
Content of magnetic substances 97-98%;
Settling property: height of the clear water produced in 5 minutes is 15% or less of the height of a specific gravity liquid with moderately low settling speed of the iron powder in water.
8. A gravity separation method as claimed in anyone of claims 6 or 7, carrying out precise float-sink separation of run-off-mines coal using a specific gravity liquid having specific gravity in the range of 1.4 to 1.6.
9. A gravity separation method as claimed in anyone of claims 6 to 8, wherein mill scale fine particles used have a size of less than 45 microns is mixed and are suspended in water contained in a water bath for the purpose of separating and recovering washed coal of low ash content from run-off-mines(ROM) coals to form a specific gravity liquid with a specific gravity of 1.5 is used for washing ROM coal (-100 mm +25 mm) to bring down ash content in raw coal (31%) to 20% ash content in washed Coal.
10. A gravity separation method as claimed in anyone of claims 6 to 9, wherein raw coals is poured into the specific gravity liquid formed so that the washed coal with a specific gravity of about 1.5 value can be separated and recovered as floated product.
11. A gravity separation method as claimed in anyone of claims 6 to 10, wherein since the content of magnetic substances in mill scale fines used is in the range of 97-98%, the mill scale powder are recovered involving a wet-type magnetic separator with substantially no loss if the product obtained by float-sink separation is washed with fresh makeup water.
12. A gravity separation method as claimed in anyone of claims 6 to 11, comprising subjecting sink product obtained from coal beneficiation to gravity separation using the liquid with a high specific gravity of 1.6, to obtain thermal coal and rejects.

Dated this the 30th day of April, 2015
Anjan Sen
Of Anjan Sen & Associates
(Applicants Agent)

,TagSPECI:FIELD OF THE INVENTION

The present invention relates to providing a specific gravity liquid suitable for float-sink separation of run-off mines coal or ores comprising mill scale fines suspended in water and a gravity separation method involving said specific gravity liquid for performing float-sink separation of raw coals or ores. More particularly, the present invention is directed to a method for coal beneficiation using blast furnace flue dust, sludge and mill scale fines as magnetic media for float-sink separation of raw coals by involving a specific gravity liquid in which the above fines are mixed and suspended in water. This gravity separation method comprises mixing and suspending the blast furnace flue dust, sludge and mill scale composed of fine particles having a size of less than 45 microns to form a specific gravity liquid having specific gravity within the range of 1.2 to 2.1, depending upon the intended use, and pouring various raw materials such as Run-off-Mines coals or ores into the specific gravity liquid so as to subject the raw materials to float-sink separation.

BACKGROUND OF THE INVENTION

In conventional methods of separating various raw materials by using a given specific gravity liquid, the chemicals used in laboratories generally include Zinc chloride (ZnCl2), Carbon tetrachloride (CCl4), Benzene (C6H6),Toluene (C7 H8), Bromoform(CHBr3), Tetrabromoethane (C2H2Br4), Methyl iodide (CH3I), Acetylene tetrabromide (CHBr2) etc. However, all these chemicals are expensive, and some of them have high degrees of toxicity and are thus not usable in industry.

Gravity separation methods have been industrially used in which suspensions of fine particles of solids in water, such as fine particles of Barytes (BaSO4), Pyrite (FeSO4), Magnetite sand (Fe3O4) and Ferrosilicon (Fe+Si), which are relatively inexpensive, easily available and have substantially no toxicity are formed. These are adjusted to have a given specific gravity so as to be used in gravity separation, solids as ores being placed in these liquids and used for float- sink separation therein.

However, although the upper limit of the specific gravity of a liquid which can be formed by this method depends upon the specific gravity of the fine solid particles serving as a medium and the ratio of water mixed therewith, any increase in the ratio of the fine particles mixed with the water causes the viscosity of the liquid to be increased. Thus, precise float-sink separation even of particles having sizes of 5 to 6 mm is difficult, and in practice the upper limit of the ratio of the fine particles mixed with the water is 40% by volume. Therefore, the upper limit for the specific gravity of a gravity liquid which can be formed by a medium of the type that generally used is 1.3 to 1.6 at most, and it is difficult to form a liquid having a specific gravity higher than this limit and yet having a low viscosity.

Beneficiation of coal refers to the removal of non-coal material from raw coal to produce a relatively clean coal product. Raw coal is composed of high purity coal material and non-coal material. Non-coal material in coal, commonly referred to as ash, normally includes pyrite, clays, and other alumina-silicate materials. The presence of large amounts of these ash materials can create problems during combustion, such as slugging and fouling. Sulphur is present in raw coal in two forms, organic sulphur and inorganic sulphur. Organic sulphur is chemically bound as part of the coal matrix. Inorganic sulphur is all sulphur not chemically bound in the coal matrix. Pyrite sulphur is the predominate form of inorganic sulphur. Sulphate sulphur is another form of inorganic sulphur associated with ash forming materials. Physical beneficiation effectively removes only inorganic sulphur. Processes for beneficiating coal are varied, but commonly utilize dense medium separation, jigs, or froth flotation to separate clean coal from non-coal material. Because of its versatility, high efficiency and ease of operation, heavy/dense medium separation is perhaps the preferred separation technique.

In heavy/dense medium separation, raw coal is introduced into a medium having a specific gravity intermediate between that of coal and non-coal material. The dense medium may be a homogeneous, liquid, but is more often composed of water and magnetic particles, such as ferromagnetic particles. Magnetite is a commonly used magnetic particle. Separation can be carried out in a dense media bath or tank, or in a cyclone. When bath is used, float product is clean coal and sink product is refuse. When a cyclone is used, coal is generally removed as the overflow product while refuse becomes the underflow product. After separation of coal and refuse, it is advantageous to recover the magnetic particles from the coal and from the refuse for reuse.

Raw coal feed, typically known as run-of-mine coal, is a mixture of three components, namely organic material, rock and pyrite. In raw coal, some particles are liberated, meaning that they constitute relatively pure components. Other particles are locked, meaning that these particles contain two or more of the three components locked together. Such locked particles are referred to as middling.

Indian coal has drift origin, resulted in intimate mixing of mineral matter with coal, giving rise to the ash content. The coal-ash distribution in the coal matrix in Indian coal is so interwoven that coal is essentially required to be crushed to small sizes for affecting liberation of coal and ash particles. Coal beneficiation largely depends on gravity difference of coal and ash particles. The Near Gravity Material (NGM) at any specific gravity of cut is high, which means at any specific gravity of cut there is quite good amount of misplacement of coal towards sink and vice versa. It further put hurdle to achieve sharp separation during coal washing. Clean coal technology being practiced in coal washeries, as pre-combustion clean coal technology, mainly focus on cleaning of coal by removing ash from coal. Earlier only coking coal was being washed because steel making needs coking coal of ash of 17 to 18%. The raw coal ash in Indian coking coal varies from 25 to 30%. Now-a-days, Ministry of Environment & Forests has put restriction on the use of high ash coal in power sectors, which necessitated priority to wash non-coking coal also. The choice of process equipment involved in coal washing depends on factors such as the type of coal being treated, the market requirement and the economics. Indian coals thus need to be prepared/ beneficiated to meet the desired parameter in terms of Quality, Size etc. for the Industries like, Steel, Power, Cement, Sponge Iron, Paper etc.

OBJECTS OF THE INVENTION

The basic object of the present invention is directed to provide a specific gravity liquid suitable for float-sink separation of raw coal or ore comprising mill scale fines and a gravity separation method involving a specific gravity liquid in which mill scale fines is mixed and suspended, for performing float-sink separation of raw coals or ores.

A further object of the present invention is directed to provide a gravity separation method which uses mill scale fines and which is capable of precise float-sink separation of run-off-mines coal using a specific gravity liquid having specific gravity in the range of 1.4 to 1.6.

A still further object of the present invention is directed to a gravity separation method, wherein mill scale powder produced by integrated steel plant composed of fine particles having a size of less than 45 microns is mixed and suspended in water to form a specific gravity liquid for the purpose of separating and recovering washed coal of low ash content from ROM coals to bring down ash content in raw coal (31%) to 20% ash content in washed Coal. Clean coal with a specific gravity of about 1.5 value can be separated and recovered as floated product.
A still further object of the present invention is directed to a gravity separation method using mill scale fines for performing float-sink separation of raw coals, wherein mill scale fines is used in forming a specific gravity liquid with low viscosity enables separation of particles having sizes -10 mm to + 3 mm which is smaller than that which is feasible with conventional methods favoring float-sink separation precisely.

A still further object of the present invention is directed to a gravity separation method using mill scale fines for performing float-sink separation of raw coals, wherein the content of magnetic substances is in the range of 97- 98%, so that the mill scale powder can be recovered by means of a wet-type magnetic separator with substantially no loss if the product obtained by float-sink separation is washed with fresh makeup water.

SUMMARY OF THE INVENTION

The basic aspect of the present invention is directed to provide a specific gravity liquid suitable for float-sink separation of run-off mines coal or ore comprising mill scale fines including iron oxide magnetic particles/powder having a size of less than 45 microns and in selective concentration mixed and suspended in water to provide a specific gravity liquid with a specific gravity of at least 1.2 and up to 2.1 for separation of raw coal or high specific gravity liquid having a specific gravity of 1.4 to 3.5 for separation of ores depending upon the desired use.

A further aspect of the present invention is directed to provide said specific gravity liquid wherein said mill scale fines comprise
True specific gravity: 4.1 to 5.2 ;
Particle size: +325 mesh 10% (Max) -325 mesh 90% (Min);
Surface property: The surfaces have films of iron oxide thereon so that no red rust occurs in water.

A still further aspect of the present invention is directed to provide said specific gravity liquid wherein said mill scale fines have desired Magnetic property involving
Content of non-magnetic substances 2-3%
Content of magnetic substances 97-98%; and
Desired settling property: The height of the clear water produced in 5 minutes is 15% or less of the height of a specific gravity liquid and the settling speed of the iron powder in water are not so high.

Yet another aspect of the present invention is directed to provide said specific gravity liquid involving a desired variable end use related specific gravity based on variable inclusion of mill scale as hereunder:

Content of mill scale fines (w/v %) Media solution (Sp.gravity)
17 1.10
33 1.20
50 1.30
67 1.40
83 1.50
100 1.60
117 1.70
133 1.80
150 1.90
168 2.00
183 2.10

and liquid viscosity in the range of 15 centipoises to 150 centipoises

A further aspect of the present invention is directed to provide a specific gravity liquid optionally comprising fine particles (slime) of some clay minerals for the purpose of maintaining the stability of the specific gravity liquid of iron powder.

A still further aspect of the present invention is directed to provide a gravity separation method involving the specific gravity liquid as described above comprising
Providing said specific gravity liquid involving mill scale fines with or without addition of fine particles (slime) for the purpose of maintaining the stability of the above-described specific gravity liquid of iron powder. comprising iron oxide magnetic particles/powder having a size of less than 45 microns and in selective concentration mixed and suspended in water to provide a specific gravity solution with a specific gravity of at least 1.2 and up to 2.1 for separation of run-off-mines coal or high specific gravity of 1.4 to 3.5 for separation of ores depending upon the desired use, and pouring various run-off-mines coal/ores into the specific gravity liquid formed so as to subject said raw coal or ores to float-sink separation for desired beneficiation.
Yet another aspect of the present invention is directed to said gravity separation method, wherein said mill scale fines used are composed of iron oxides having physical properties, as the medium for forming a liquid having a high specific gravity and low viscosity comprising:
True specific gravity: 4.1 to 5.2;
Particle size: +325 mesh 10% (Max) -325 mesh 90% (Min);
Surface property: surfaces having films of iron oxide thereon so that no red rust occurs in water (for example, Fe3 O4 film);
Magnetic property: iron powder having strong magnetism so as to be suitable for recovering them from the water wherein
Content of non-magnetic substances 2-3%;
Content of magnetic substances 97-98%;
Settling property: height of the clear water produced in 5 minutes is 15% or less of the height of a specific gravity liquid with moderately low settling speed of the iron powder in water.
A further aspect of the present invention is directed to a gravity separation method, carrying out precise float-sink separation of run-off-mines coal using a specific gravity liquid having specific gravity in the range of 1.4 to 1.6.
A still further aspect of the present invention is directed to a gravity separation method, wherein mill scale fine particles used have a size of less than 45 microns is mixed and are suspended in water contained in a water bath for the purpose of separating and recovering washed coal of low ash content from run-off-mines(ROM) coals to form a specific gravity liquid with a specific gravity of 1.5 is used for washing ROM coal (-100 mm +25 mm) to bring down ash content in raw coal (31%) to 20% ash content in washed Coal.
Another aspect of the present invention is directed to a gravity separation method, wherein raw coals is poured into the specific gravity liquid formed so that the washed coal with a specific gravity of about 1.5 value can be separated and recovered as floated product.
Yet another aspect of the present invention is directed to a gravity separation method, wherein since the content of magnetic substances in mill scale fines used is in the range of 97-98%, the mill scale powder are recovered involving a wet-type magnetic separator with substantially no loss if the product obtained by float-sink separation is washed with fresh makeup water.
A further aspect of the present invention is directed to a gravity separation method, comprising subjecting sink product obtained from coal beneficiation to gravity separation using the liquid with a high specific gravity of 1.6, to obtain thermal coal and rejects.
The above and other objects and advantages of the present invention are described hereunder in greater details with reference to the following non limiting illustrative example.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to provide a gravity separation method which uses mill scale fines and which is capable of precise float-sink separation of run-off-mines coal using a specific gravity liquid having specific gravity in the range of 1.4 to 1.6. The method of producing the specific gravity liquid using mill scale fines and the float-sink separation of runoff mines coals or ores are illustrated with the following example:

Example:

To achieve the above-described object, a gravity separation method using mill scale fines of the present invention is characterized by mixing and suspending the powder composed of fine particles having a size of less than 45 microns in water to form a specific gravity liquid with a specific gravity of at least 1.2 up to 2.1 depending upon the desired use, and by pouring the various raw coal into the specific gravity liquid formed so that the raw materials are subjected to float- sink separation.

In the aforesaid gravity separation method, mill scale powder which is produced by integrated steel plant and which is composed of fine particles having a size of less than 45 microns is mixed and suspended in water contained in a water bath for the purpose of separating and recovering washed coal of low ash content from ROM coals to form a specific gravity liquid with, for example, a specific gravity of 1.5 to be used for washing ROM coal (-100 mm +25 mm) to bring down ash content in raw coal (31%) to 20% ash content in washed Coal.

The raw coals is poured into the specific gravity liquid formed so that the washed coal with a specific gravity of about 1.5 value can be separated and recovered as floated product.

As described above, in the present invention, iron powder composed of fine particles having a size of less than 45 microns is used to form a specific gravity liquid with a specific gravity of 1.2 or more, depending upon the intended use, and various raw materials such as coking coal or thermal coal are poured into the specific gravity liquid formed so as to subject these raw materials to float-sink separation. Therefore, it is possible to highly precisely separate low ash coal or high ash coal thereof which has a higher specific gravity from the raw coal, and to separate out substances which cannot be generally separated by conventional methods. In addition, since the use of mill scale fines in forming a specific gravity liquid with low viscosity enables separation of particles having sizes -10 mm to + 3 mm which is smaller than that which is feasible with conventional methods, the invention offers the remarkable effect that float-sink separation can be effected precisely.

The present invention uses a mill scale fines, which is composed of iron oxides and which has the following physical properties, as the medium for forming a liquid having a high specific gravity and low viscosity:

True specific gravity: 4.1 to 5.1
Particle size: +325 mesh 10% (Max) -325 mesh 90% (Min)
Surface property: The surfaces have films of iron oxide thereon so that no red rust occurs in water (for example, Fe3 O4 film).
Magnetic property: The iron powder has strong magnetism so as to be suitable for recovering them in the water.
Content of non-magnetic substances 2-3%
Content of magnetic substances 97-98%
Settling property: The height of the clear water produced in 5 minutes is 15% or less of the height of a specific gravity liquid and the settling speed of the iron powder in water is not so high.

A liquid with a specific gravity of 1.1 or more is formed by using mill scale fines having such physical properties, depending upon the intended use. The formation of a liquid having a specific gravity of 2.1 is described below. In this case, the percentage of the mill scale fines/powder solution with water is as follows:

Addition of mill scale fines (w/v %) Media solution (Sp.gravity)
17 1.10
33 1.20
50 1.30
67 1.40
83 1.50
100 1.60
117 1.70
133 1.80
150 1.90
168 2.00
183 2.10

This specific gravity liquid has a concentration by volume of 17% and a sufficiently low viscosity, while a specific gravity as high as 2.1 can be obtained. Thus, the low ash contained in ROM coal can be easily recovered by using a float-sink separation method. In addition, since the content of magnetic substances is in the range of 97- 98%, the mill scale powder can be recovered by means of a wet-type magnetic separator with substantially no loss if the product obtained by float-sink separation is washed with fresh makeup water.

As described above, the mill scale fines liquid with high specific gravity has low viscosity and thus enables raw materials to rapidly settle or float and gravity separation can be achieved with little error occurring due to undesired movement of the materials.

When sink product obtained from coal beneficiation were subjected to gravity separation using the liquid with a high specific gravity of 1.6, the results obtained were thermal coal and rejects.

The precision of this separation is same as compared with conventional separation methods using magnetite and water with desired specific gravities. The above-described coking coal recovery efficiency and the results of proximate analysis are same as magnate solution.

In addition, in the float-sink separation of the above-mentioned experiment using the high-specific gravity liquid composed of mill scale fines, the specific gravity liquid has low viscosity and thus enables gravity separation of fine particles and separation of particles having a size down to 3 mm with high precision. In contrast, the high-specific gravity liquid obtained from a medium (the above-described mill scale fine solid particles) which is generally used has high viscosity and thus makes precise float-sink separation even of particles having a size of 5 to 6 mm difficult.

Therefore, the separation method using the high-specific gravity liquid obtained from the above-described medium can be applied to almost all float-sink separators such as Heavy media bath, rotary drum-type, vertical wheel-type and screw sweeping-type separators regardless of the classes thereof. Although this example concerns a liquid with a specific gravity of 1.5, the use of mill scale powder having a true specific gravity of up to 5.2 is feasible and liquids having specific gravities within the range of 1.2 to 2.1 can be formed by changing the ratio of iron powder mixed in water. ROM coal as well as certain types of ore can be subjected to float-sink separation using a high-specific gravity liquid having a specific gravity of 1.4-3.5.

It is also effective to add fine particles (slime) of some clay minerals for the purpose of maintaining the stability of the above-described specific gravity liquid of iron powder.

Since there is no industrial example in which various raw materials are subjected to float-sink separation using the above-described specific gravity liquid obtained by using mill scale fines/powder as a medium, this invention will allow the development of a new industrial field in which mill scale fines/powder is used as a new heavy media material.

We Claim:

1. A specific gravity liquid suitable for float-sink separation of run-off mines coal or ore comprising mill scale fines including iron oxide magnetic particles/powder having a size of less than 45 microns and in selective concentration mixed and suspended in water to provide a specific gravity liquid with a specific gravity of at least 1.2 and up to 2.1 for separation of run-off mill coal or high specific gravity liquid having a specific gravity of 1.4 to 2.5 for separation of ores depending upon the desired use.

2. A specific gravity liquid as claimed in claim 1 wherein said mill scale fines comprise
True specific gravity: 4.1 to 5.2 ;
Particle size: +325 mesh 10% (Max) -325 mesh 90% (Min);
Surface property: The surfaces have films of iron oxide thereon so that no red rust occurs in water.

3. A specific gravity liquid as claimed in anyone of claims 1 or 2 wherein said mill scale fines have desired Magnetic property involving
Content of non-magnetic substances 2-3%
Content of magnetic substances 97-98%; and
Desired settling property: The height of the clear water produced in 5 minutes is 15% or less of the height of a specific gravity liquid and the settling speed of the iron powder in water is not so high.

4. A specific gravity liquid as claimed in anyone of claims 1 to 3 involving a desired variable end use related specific gravity based on variable inclusion of mill scale as hereunder:

Content of mill scale fines (w/v %) Media solution (Sp.gravity)
17 1.10
33 1.20
50 1.30
67 1.40
83 1.50
100 1.60
117 1.70
133 1.80
150 1.90
168 2.00
183 2.10

and liquid viscosity in the range of 15 centipoises to 150 centipoises

5. A specific gravity liquid as claimed in anyone of claims 1 to 4 optionally comprising fine particles (slime) of some clay minerals for the purpose of maintaining the stability of the specific gravity liquid of iron powder.
6. A gravity separation method involving the specific gravity liquid as claimed in anyone of claims 1 to 5 comprising providing said specific gravity liquid involving mill scale fines with or without addition of fine particles (slime) for the purpose of maintaining the stability of the above-described specific gravity liquid of iron powder. comprising iron oxide magnetic particles/powder having a size of less than 45 microns and in selective concentration mixed and suspended in water to provide a specific gravity solution with a specific gravity of at least 1.2 and up to 2.1 for separation of run-off-mines coal or high specific gravity of 1.4 to 3.5 for separation of ores depending upon the desired use, and
pouring various run-off-mines coal/ores into the specific gravity liquid formed so as to subject said raw coal or ores to float-sink separation for desired beneficiation.
7. A gravity separation method as claimed in claim 6, wherein said mill scale fines used are composed of iron oxides having physical properties, as the medium for forming a liquid having a high specific gravity and low viscosity comprising:
True specific gravity: 4.1 to 5.2;
Particle size: +325 mesh 10% (Max) -325 mesh 90% (Min);
Surface property: surfaces having films of iron oxide thereon so that no red rust occurs in water (for example, Fe3 O4 film);
Magnetic property: iron powder having strong magnetism so as to be suitable for recovering them from the water wherein
Content of non-magnetic substances 2-3%;
Content of magnetic substances 97-98%;
Settling property: height of the clear water produced in 5 minutes is 15% or less of the height of a specific gravity liquid with moderately low settling speed of the iron powder in water.
8. A gravity separation method as claimed in anyone of claims 6 or 7, carrying out precise float-sink separation of run-off-mines coal using a specific gravity liquid having specific gravity in the range of 1.4 to 1.6.
9. A gravity separation method as claimed in anyone of claims 6 to 8, wherein mill scale fine particles used have a size of less than 45 microns is mixed and are suspended in water contained in a water bath for the purpose of separating and recovering washed coal of low ash content from run-off-mines(ROM) coals to form a specific gravity liquid with a specific gravity of 1.5 is used for washing ROM coal (-100 mm +25 mm) to bring down ash content in raw coal (31%) to 20% ash content in washed Coal.
10. A gravity separation method as claimed in anyone of claims 6 to 9, wherein raw coals is poured into the specific gravity liquid formed so that the washed coal with a specific gravity of about 1.5 value can be separated and recovered as floated product.
11. A gravity separation method as claimed in anyone of claims 6 to 10, wherein since the content of magnetic substances in mill scale fines used is in the range of 97-98%, the mill scale powder are recovered involving a wet-type magnetic separator with substantially no loss if the product obtained by float-sink separation is washed with fresh makeup water.
12. A gravity separation method as claimed in anyone of claims 6 to 11, comprising subjecting sink product obtained from coal beneficiation to gravity separation using the liquid with a high specific gravity of 1.6, to obtain thermal coal and rejects.

Dated this the 30th day of April, 2015
Anjan Sen
Of Anjan Sen & Associates
(Applicants Agent)

ABSTRACT

TITLE: A SPECIFIC GRAVITY LIQUID SUITABLE FOR FLOAT-SINK SEPARATION OF RUN-OFF MINES COAL OR ORE COMPRISING WASTE MAGNETIC MATERIAL FINES GENERATED IN INTEGRATED STEEL PLANT AND GRAVITY SEPARATION METHOD USING THE SAME.

The present invention relates to a specific gravity liquid suitable for float-sink separation of raw coal or ore comprising blast furnace flue dust, sludge and mill scale fines suspended in water and a gravity separation method involving said specific gravity liquid for performing float-sink separation of raw coals or ore. More particularly, the present invention is directed to a method for coal beneficiation using blast furnace flue dust, sludge and mill scale fines as magnetic media for float-sink separation of raw coal including imported coal by involving a specific gravity liquid in which blast furnace flue dust, sludge and mill scale fines is mixed and suspended in water. This gravity separation method comprises mixing and suspending the blast furnace flue dust, sludge and mill scale composed of fine particles having a size of less than 45 microns to form a specific gravity liquid having specific gravity within the range of 1.2 to 2.1, depending upon the intended use, and pouring various raw materials such as Run-off-Mines coals or ores into the specific gravity liquid so as to subject the raw materials to float-sink separation.