Description

Title of Invention: A METHOD OF BENEFICIATING AND TRANSPORTING MINERALS

Technical Field Technical Field

[1] The invention is related to mining and can be applied to underground and open-pit development of mineral deposits of various kinds. Background Art Background Art

[2] Known are gravitational methods of beneficiating minerals based on the use of the difference in densities of mineral components of the rock mass for their separation from one another. For this purpose, the produced rock mass, for instance, coal diluted with waste rock, is delivered by mine transport to mine hoists, lifted to the ground surface, crushed and submerged into a heavy water/salt medium representing calcium chloride or ferric chloride solution in water, whose density is intermediate between those of separated components. After the stratification of such mechanical mixture of minerals in a heavy medium into light and heavy, the dressing products are discharged out of the separator, and the heavy water-salt medium is fed to the regeneration unit and then returned to the starting point of the process. Thus product beneficiated in this manner is delivered to customers, and final tailings are stored on the territory adjacent to the dressing plant in the form of dumps (see, e.g., Washing coal: Patent 1724 Great Britain, Cl. 82).

[3] The described conventional organization of mining industry with ground-based processing of minerals results in unpractical energy consumption for delivering huge volumes of waste rock belonging to the rock mass to the ground surface from great depths of mining, as well as an important environmental damage due to storing the final dumped tailings on the ground surface.

[4] On the other hand, as a result of in-depth underground mining, big volumes of worked-out space are formed in the place of mineral deposits. In the course of time this leads to an intense development of geo-mechanical processes of rock shifting starts in the overlying rock mass. It causes a corresponding damage to all ground-based constructions, buildings and land on the whole because of the ground surface subsidence consequences.

[5] The method of beneficiating minerals, in particular, coal, which is the closest to the method according to the present invention from the technological standpoint, consists in crushing the initial rock mass delivered to the surface and submerging it into some

mineral salt solution in water, whose density is intermediate between those of the target component and waste rock (see 'Heavy liquid based on Cs and Rd salts for gravity separation of coals, minerals, and/or ores. WO 2000/036185. 22 June 2000'; USA Patent 4,376,700 'Method for beneficiating coal ore', 1983).

[6] The coal, which is lighter than the waste rock, floats in this heavy water-salt medium, whereas the remaining incombustible minerals, being heavier, sink in it.

[7] After the discharge from the separator, beneficiation products are filtered from the heavy working liquid, which is returned to the beneficiation process. However, after such hydro-mechanical separation the surface of thus obtained beneficiation products still carries mineral salt solution, which makes this material unusable. Besides, coal concentrate and final tailings impregnated with water-salt solution result in irreversible removal of the expensive heavy working liquid out of this open technological cycle, which makes this production process economically unacceptable.

[8] By this reason, beneficiation products are washed with water for final removal of the remains of water-salt heavy medium from their surface. However, waste drain water released in this case represents a strongly diluted water-salt solution, which is inapplicable for reuse as a heavy working liquid due to its low density. Therefore, for final regeneration and restoring the initial density of the heavy working liquid, drainage wastes remaining after washing the beneficiation products should be concentrated by evaporation. However, this method of concentrating dilute solutions of mineral salts is rather energy-consuming, since the removal of excessive water by evaporation state is associated with the consumption of large volumes of power-generating steam or other kinds of commercial energy supply.

[9] It is an object of the present invention to decrease the energy consumption of mining industry and ensure environment protection. Disclosure of Invention Technical Problem

[10]

Technical Solution

[11] This object is achieved according to the present invention by the proposed method of beneficiating and transporting minerals, which includes crushing of the initial mineral and stratification of mineral components of the rock mass in a heavy liquid, whose density is intermediate between those of the target and waste components, into light and heavy fractions with the subsequent regeneration of its residues, which are returned later to the starting point of the process, and the delivery of beneficiation products to their destination places, wherein the surface of mineral components of the rock mass after crushing and before their submersion into the heavy liquid is coated

with an easily solidifying low-melting-point slippery coating made of a substance chemically inert to the heavy liquid and immiscible with the latter, with a subsequent (after their stratification in the heavy liquid) drainage of its residues from the bene- ficiation products, performed concurrently with its melting, wherein the loading of the initial mineral mixture covered with the solidified slippery coating into the heavy liquid is performed at a temperature lower than that of the hydro-mechanical removal of liquid residues from the beneficiation products, with the subsequent stratification of the two-phase effluents into the heavy liquid and molten substance covered the surface of the minerals to be separated, which are returned afterwards to the starting point of the technological process with their simultaneous cooling, wherein the delivery of the light fraction to its destination place is performed in the heaviest liquid itself.

[12] Water solutions of pure mineral salts and their various mixtures may be used as heavy medium for the beneficiation and transportation of minerals.

[13] For applying protection layers inert with respect to mineral salt solutions and encapsulating the surfaces of separated minerals prior to submerging the rock mass into a heavy water-salt medium, various organic easily- solidifying (and, respectfully, low- melting-point) water- immiscible substances, first of all, various oil treatment products, may be used. Such compositions may include bitumen, oil tar, various paraffin, heavy gas oil, black oil, and various industrial and hydraulic oils and greases. Preferably, waste and secondary products and various discharged and low- value oil products should be utilized. To the same purpose, organic synthesis products, e.g., glycols and synthetic fats, may be used, as well as various compositions of natural plant, animal, and mineral origin substances like colophony, sealing wax, wood tar oil, peat wax, nature paraffin, stearin, etc.

[14] Covering the surface of separated minerals with low-melting-point low-density slippery coatings exhibiting a given set of chemical, rheological, thermo-dynamical, and sanitary properties, together with the use of a definite temperature difference between the separation and heavy liquid regeneration operations, thus controlling the beneficiated material surface phase state, and applying high separation factor inertial and centrifugal fields to the beneficiation products at the stage of hydro-mechanical removal of heavy liquid residues from the beneficiation products, allows not only to release the rock mass from the waste rock directly in the working area, while completely eliminating carry-over of water-salt heavy liquid residues with beneficiation products from this beneficiation cycle, but to use heavy liquids of lower density for the technological process proposed which gives additional advantages of reducing the produced mineral stock treatment and transportation cost.

[15] Thus, all distinctive features of the invention are naturally interconnected, and the objective put by the invention can be reached only by the totality of these features.

[16] Patent search and literature review have not revealed any features similar to the engineering solution of the present invention in its technical concept, which allows us to conclude that its distinctions are essential. Advantageous Effects

[17]

Description of Drawings

[18] The method is implemented by consecutive performance of the following basic operations:

[19] 1. - crushing the initial rock mass; D

[20] 1. - screening dusty fractions from the ground material; D

[21] 1. - applying low-melting-point slippery covering to the surface of materials to be separated; D

[22] 1. - separating minerals from waste rock in a heavy water-salt medium with a density intermediate between those of the target and waste components followed with continuous transportation of encapsulated target product to the destination point within the heavy water-salt medium; D [23] 1. - hydro-mechanical removal of heavy water-salt medium residues from the surface of beneficiation products concurrently with melting the recycled cover material from the surface; D

[24] 1. - stratification of two-phase wastes separated from the beneficiation products into a light (molten covering substance) and heavy (heavy water-salt medium) fractions; D [25] 1. - return of molten covering substance and regenerated heavy water-salt medium to the starting point of the technological process. D [26] Figure 1 shows the flow sheet of coal mine preparation according to the present invention.

[27] Rock mass fed from the mining face by belt conveyor 1 is crushed in crusher 2 and then fed to vibrating screen 3. Undersize product of the screen including dusty fractions is processed by conventional methods. Oversize product of screen 3 is processed by molten easily solidifying compound in order to produce a screening coating on its surface, which prevents moistening of the material to be beneficiated with a heavy water-salt liquid. For this purpose, the material is loaded into drum mixer 4 and mixed with a mixture of waste engine oil with bitumen and fuel oil, i.e. with a sufficiently viscous and easily solidifying hydrocarbon non-aqueous medium. This is accompanied with blowing cold air into mixer 4, which favors to the solidification of hydrocarbon mixture on the surface of minerals being separated. [28] The material encapsulated by this solidified hydrocarbon coating is loaded into

heavy-media separator 5 filled with heavy liquid with the density of 1.45 g/cm 3 representing a four-component water-salt solution obtained by simultaneous dissolution of calcium chloride, zinc chloride, calcium bromide and monobasic calcium phosphate in water.

[29] To avoid heat influx to the surface of minerals to be separated, heavy-medium separator 5 is covered with thermal insulation.

[30] Being lighter than waste rock, coal floats in the bath of heavy-medium separator 5, and, remaining in floated state, comes via trough 7 into free-flow pipeline 9 and further to the shaft station or other destination (in the case, e.g., of open mining).

[31] The product delivered to the destination point with heavy medium comes into drum screen K), which performs the initial hydro-mechanical separation of said system into solid and liquid phases. At the same time, hot air is blown into drum screen K) which initiates melting of the coal surface coating. As a result, the melt of non-water substance appears on the coal surface increasing the slipperiness of the surface and greatly facilitating the separation of heavy water-containing liquid.

[32] The final removal of the last residues of heavy water-containing liquid and molten hydrocarbon coating that covered the coal surface during separation and transportation is realized in centrifugal filter H. This operation is also performed with a simultaneous heating of the deposit on the centrifuge drum by blowing hot compressed air through the coal layer.

[33] Due to a high separation factor, the last layers of covering oil-and-mazut mixture adjacent to the solid surface of coal are removed in centrifuge H. As a result, the coal surface covered with low-melting-point coating becomes totally exposed, and the finished product of such technological process becomes visually indistinguishable from dry coal extracted from the initial rock mass without any wet technological processes.

[34] Two-phase drainage outlets of drum screen K) and centrifuge H are pumped with vertical pump 13 into hydrostatic separator 15., where they are separated into pure initial water-salt solution and liquid oil-mazut mixture.

[35] Further, the beneficiated coal is loaded by belt conveyor 12 to corresponding storage reservoirs and then delivered to the ground surface by a rope-skip lift or other mine transport means, as in open coal mining.

[36] Regeneration of the heavy working liquid residues and molten protective coating covering the surface of waste rock separated from coal is performed in a similar manner.

[37] For this purpose, waste rock sunk in the heavy liquid is discharged from heavy- medium separator 5 by an elevator wheel with perforated shelves 6 performing the initial drain of working water-salt medium running back into the separator bath. At the

same time, the elevator wheel shelves are blown over with hot air in the zone of the rock discharge.

[38] The waste rock flow comes via trough & to drum screen JO and then loaded into centrifuge 11.

[39] These devices perform the final removal of all kinds of the liquid phase residues from the waste

[40] rock, exactly as in the case of coal.

[41] Two-phase discharges of these stages of hydro-mechanical removal of liquid from the rock surface are pumped over into hydrostatic separator 15 by vertical pump 13. The waste rock removed in this way from the technological process is immediately directed via belt conveyor 14 to the waste area packing, thus releasing the mine lift from unpractical expenditure of power for the delivery of the ballast together with rock mass to the surface and, at the same time, preventing the earth's surface subsidence.

[42] Hydrostatic separator 15_ performs the stratification of two immiscible liquids - water-salt solution and oil-mazut mixture - into two fractions. Being lighter, the oil- mazut mixture floats in such aqueous medium forming an upper layer, which is discharged from through an overflow lip, while the heavy liquid cleared from this non- water phase is collected in the conical part of separator 15..

[43] Then oil-mazut mixture is fed by vertical pump 13 into mixer 4 for treating the dust- free broken rock, whereas the heavy water-salt mixture cleared from the former is returned by centrifugal pump 16 into heavy-media separator 5 for reuse. Both technological flows are cooled down by pumping through refrigerators J/7.

[44] To replenish the system with fresh oil-mazut mixture and water-salt working medium, containers 1£ and 19 are used. Container 19 with oil-mazut mixture is equipped with a steam heated coil pipe in order to prevent the fluidity loss in such viscous and easily solidifying medium under unfavorable weather conditions.

[45] In a similar way, beneficiation and transportation of shale oil, fossil potassium and magnesium salts such as sylvinite and carnallite, as well as certain types of other ores, and not only coal, can be implemented.

[46] Example

[47] Excavated mass with ash percentage of 34% delivered from the mining face of a coal mine is crushed down to the size of 50 mm and then fed to a screen in order to separate fractions below 0.5 mm, which are discharged for further processing by conventional beneficiation methods.

[48] Oversize fraction of the screen is treated with fuel oil, thickened bitumen and waste engine oil cooled down to (15 o C) and concurrently blown with cold (-2 o C) air.

[49] The material encapsulated with such hydrocarbon solidified coating is loaded into a cold (0 o C) water solution of calcium chloride with zinc chloride and admixtures of

calcium bromide and monobasic calcium phosphate (density 1.48 g/cm 3 ), where coal is separated from waste rock.

[50] Beneficiated coal with ash percentage of 7% in the same water-salt solution is fed by a non-pressure pipeline to the shaft station, where it is dewatered in a drum screen blasted with hot (50 ° C) air. Then, the liquid phase residues are finally removed by deep squeezing in a centrifuge filter blasted with hot (50 o C) air, after which the coal is delivered to the surface and shipped to customers.

[51] Drainage discharges of the coal are accumulated in a hydrostatic separator. Waste rock sunk in water solution of mineral salts is discharged from the heavy media separator by an elevator wheel with perforated shelves heated with hot (50 o C) air. Further, the residuals of liquid phase and traces of oil-mazut mixture are removed, first by draining in the drum screen, and then by final squeezing in the centrifuge filter both blasted with hot (50 o C) air.

[52] The waste rock removed in this way from the rock mass is placed in the exhausted space, while the released liquid phase together with drains discharged from beneficiated coal is stratified by a

[53] hydrostatic separator into light (fuel-oil mixture with bitumen and waste motor oil) and heavy (water-salt solution) fractions.

[54] Liquid mixture of mazut, bitumen, and waste engine oil is passed through a cooler and returned to the mixing drum, where it is used for treating the oversize product of initial rock mass screening, while thus completely recovered water-salt solution, being also passed through the cooler, is returned to the starting point of the process where it is used for the separation by density in heavy medium.

[55] Said technical features of the method of the present invention in comparison with known engineering solutions in the field of gravitational beneficiation and transportation of minerals stipulate for a number of technological, economic and ecological advantages consisting in a practically closed cycle of heavy fluid regeneration, significant reduction in vertical mine transport electric energy consumption owing to the fact that waste rock is not delivered to the ground surface within the rock mass, and efficient prevention of the detrimental effect of mining industry on the environment. Best Mode

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Mode for Invention

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Industrial Applicability

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Sequence List Text

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