RU2634835C1 - Method of gold recovery from brown and stone coals - Google Patents

Abstract

FIELD: mining engineering.

SUBSTANCE: method includes crushing of coal to 6-10 mm, loading it onto a grid in metal airtight reservoir with a branch pipe, without water contact, heating up to 135-140°C and holding till complete evaporation of water, wherein heated steam passes through coal layer and through the branch pipe with its condensation in assembled cooled reservoir with sorbent suspension, collecting gold in volatile form transferred from coals.

EFFECT: selective extraction of gold from brown and stone coals without disturbance of their mineralogical and chemical composition.

1 dwg, 1 tbl

Description

The invention relates to mining, and in particular to methods of hydrometallurgical extraction of gold from brown and hard coal.

A known method of extracting gold from gold-containing natural lignite and coal, in which the flue gases and sublimates obtained by burning coal in a furnace, are mixed with water vapor, followed by cooling the resulting vapor-gas mixture in condensers (patent No. 2398033, priority 04 February 2009 )

A device is also known for extracting gold from flue gases (utility model patent No. 93803 of June 20, 2009). In this model, to extract gold from flue gases, a flue gas mixer with water vapor, obtained in a special steam generator, is used. A mixture of steam with flue gases is then processed in condensers to condense water vapor and produce water condensate. The condensers are cooled by a stream of cold water washing the walls of the condensers.

Both the method and the device have a significant drawback, namely, that industrial power plants for burning coal have a gigantic capacity in terms of the amount of smoke emitted into the pipe. Such volumes cannot be processed by the method of mixing with water vapor and cooling in condensers, since this requires additional useful floor spaces of production facilities, many times larger than the occupied areas and useful volumes of the boiler room itself. These factors are the reason for the significant appreciation of the entire process of extracting metal from flue gases.

In the process of research conducted with brown and black coal samples on the subject of gold content of coal deposits, a drop in the gold content in the samples was noted many times during storage of samples in a warehouse or laboratory. The fall in the gold content during storage of samples for several months to two to three years for various coals ranges from 30 to 95 percent of the initial gold content in freshly mined coal. A decrease in the gold content in coals was also noted when heating coal. This phenomenon, as we assume, is due to the conversion of metallic elemental gold into volatile organometallic forms under the influence of radicals formed in coals when exposed to atmospheric air and moisture after coal mining from the bowels of a coal seam.

The objective of the invention is the creation of a method that allows you to selectively extract gold from brown and hard coal without violating the mineralogical and chemical composition of coal, without losing coal its energy value and at the same time fully preserve the technological chain for burning coal in the furnaces of industrial furnaces, which corresponds to the tasks of associated extraction .

The essence of the invention lies in the fact that the method of extracting gold from lignite and bituminous coals involves crushing it up to 6-10 mm, loading it onto a grate in a metal sealed container with a nozzle, without contacting the water in it, heating the container to 135-140 ° C and maintaining until the water has completely evaporated, which passes through the coal layer in the form of heated steam and condenses through the pipe in a prefabricated cooled tank with a suspension of sorbent collecting gold transferred from coal.

The invention is illustrated in FIG. 1, which depicts a laboratory facility for the extraction of gold.

The laboratory setup consists of a steel cylinder 1 with a thread in the upper part of the outer wall and a blind bottom, a cover 2 with an internal thread screwed onto the cylinder, and a rubber gasket 3 in the cover. In the lid there is a hole with a welded pipe 4, on which a silicone tube 5 is put on. In the middle of the internal volume of the cylinder, a grid 6 with holes 1 mm is fixed. The lower end of the silicone tube is lowered into the flask 7 with a sorbent solution. The flask is placed in a basin 8 with running cold water, thermostat 9.

The experiment was carried out as follows.

200 ml of water was poured into the cylinder under the net, a suspension of coal with a grain size of 6-10 mm was poured onto the net. Close the lid tightly, squeezing the gasket. Then the cylinder was placed in a thermostat. The end of the silicone tube was brought out through the upper hole in the wall of the thermostat and lowered through a cork into a flask with a sorbent. Next, the thermostat was turned on to 135 ° C and held for a time until all the water had completely evaporated, steam would pass through the coal, and then it would not completely condense in the flask with the sorbent. It usually takes about 4 hours. Next, the installation is cooled, disassembled, the remaining coal and sorbent are analyzed for gold content.

Table 1 shows the averaged results of the experiments.

As a sorbent, a mixture of activated carbon and iron oxide was used. The data obtained indicate the presence of the transfer of the volatile form of gold by the flow of steam from coal to the sorbent. An increase in the percentage of extraction must be achieved by reducing losses during the transfer of volatile forms of gold and lowering the temperature of the solution with the sorbent.

The technical result of using the proposed method is the ability to extract gold directly from coal and further use of coal as energy raw materials without violating its structure, mineralogical and chemical composition, since its heating temperature for steam treatment is insufficient to initiate pyrolysis and sublimation reactions. Since there is practically no gold left in the coal, it is acceptable to assume that at the temperature of steam treatment during this treatment, reactions are completed when all gold is converted to volatile forms. Therefore, it becomes possible to extract all the gold from the coals in a completely proposed way, accordingly improving the design of the installation.

Claims (1)

A method of extracting gold from lignite and bituminous coals, including crushing lignite and bituminous coals up to 6-10 mm, loading them onto a grate in a metal sealed container with a nozzle without contacting the water in it, heating the tank to 135-140 ° C and holding to complete evaporation of water, while ensuring the passage of heated steam through a layer of coal and through a pipe with its condensation in a prefabricated cooled tank with a suspension of a sorbent collecting gold in a volatile form transferred from coal.

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