Dry enrichment method for placer gold ore

Abstract

FIELD: precious metals mining industry; gold mining industry.SUBSTANCE: technique for separating dry bulk materials by density (specific gravity) in an air flow of a separator. The method of dry enrichment of placer gold-bearing ore includes crushing the ore, drying it to a relative humidity of 10-15% and pouring the ore into a bin with a nozzle installed in it. A cylinder of filter material is inserted into the nozzle with a gap to the inner walls of the hopper. In the nozzle, a fan creates a rotating flow of compressed air, which, together with particles of placer gold-bearing ore, is directed through the channels of a cylinder made of filter material and a separation is carried out, in which heavy particles of placer gold-bearing ore get stuck in the channels of the cylinder made of filter material, and lighter particles with a specific gravity lower than the specific gravity of gold, with a flow of compressed air are directed along the axis of the cylinder to the exit from the nozzle into the dump. After the channels become clogged with heavy particles of gold-bearing ore, the cylinder of filter material is removed from the hopper nozzle, ground, and the resulting mixture is sent for the final gold extraction operation.EFFECT: increase in the efficiency of gold extraction from low-grade placer gold ore and the provision of year-round gold mining in the northern regions of the country.1 cl, 1 dwg

Description

[0001] The invention relates to a technique for separating dry bulk materials by density (specific gravity) in a separator airflow and can be used in the precious metals mining industry, particularly in gold mining. These methods provide the greatest economic benefits in gold mining, especially in regions with harsh climates. Dry enrichment offers advantages over other technologies that use water, other solvents, and chemical reagents, as it eliminates the need for subsequent drying and purification of the finished product and sludge storage. The main disadvantage of existing precious metals mining methods is the mandatory use of a liquid medium in the process. This feature makes precious metals mining impossible in winter conditions (in northern latitudes) and in summer, when water resources are absent or scarce.

[0002] A method for extracting precious metals is known, wherein the separation of processed rock from waste rock is achieved by a rotating air flow in a hopper. (Patent 2117538. Gravity-assisted aerodynamic method for extracting precious metals from crushed dry placer rock. Published August 20, 1998)

[0003] The presence of an auger with a mechanism for feeding loose crushed dry rock into the separator chamber (bunker) reduces the reliability of the method.

[0004] Dry enrichment of crushed gold-bearing ore is known using filter material, a receiving tank, separation of waste gold-bearing ore, and channels. (Patent 2699287. Device for dry enrichment of gold ores. Published 04.09.2019. Bulletin No. 25)

[0005] The disadvantages of this device are the significant energy consumption for the formation of the air-dust mixture flow, the distortion of the particle flight trajectories by a large air flow and the loss of a small fraction of raw material particles.

[0006] The closest analogue is the method of dry enrichment of placer gold-bearing ore, which includes crushing the ore, drying to a relative humidity of 10-15% and pouring the ore into a bin with a nozzle installed in it (Patent No. 2309804. Method of dry enrichment of placer gold-bearing ore. Published 10.11.2007. Bulletin No. 31).

[0007] This patent uses the windage of the upper and lower flows.

[0008] The technical result of the present invention is that a more efficient dry method for extracting gold from low-grade placer gold ore is proposed, which makes it possible to ensure year-round gold mining in the northern regions of the country.

[0009] The technical result is achieved by the fact that in the method of dry enrichment of placer gold-bearing ore, including crushing the ore, drying to a relative humidity of 10-15% and pouring the ore into a hopper with a nozzle installed in it, a cylinder of filter material is inserted into the nozzle with a gap to the inner walls of the hopper, in the nozzle a fan creates a rotating flow of compressed air which, together with particles of placer gold-bearing ore, is directed through the channels of the cylinder of filter material and separation is carried out, in which heavy particles of placer gold-bearing ore get stuck in the channels of the cylinder of filter material, and lighter particles with a specific gravity lower than the specific gravity of gold with a flow of compressed air are directed along the axis of the cylinder to the exit from the nozzle into the dump, after clogging the channels with heavy particles of gold-bearing ore, the cylinder of filter material is removed from the nozzle of the hopper,it is ground and the resulting mixture is sent for the final gold extraction operation.

[0010] Figure 1 shows a device that provides a method for dry enrichment of placer gold-bearing ore.

[0011] In the proposed method of dry enrichment of placer gold-bearing ore, the gold-bearing ore is crushed, dried to a relative humidity of 10-15% and poured into bin 2. From bin 2, the crushed gold-bearing ore is fed into nozzle 1. A powerful fan 7 is turned on, which creates a swirling main flow 6 of compressed air. Under the action of the swirling main flow 6, streams 8 of compressed air are directed together with heavy particles of placer gold-bearing ore through the channels of the filter material of the cylinder 3. Heavy particles of placer gold-bearing ore (gold, platinum metals) get stuck in the channels of the filter material, and the air streams pass further along the gap 4 to the outlet 11 from the nozzle 1. The second stream 9 of the empty, lighter part of the gold-bearing ore with a specific gravity significantly lower than the specific gravity of gold passes along the axis of the cylinder.After the channels become clogged with adhered gold-bearing ore particles, filter cylinder 3 is removed from nozzle 1 of bin 2, burned, and then ground. The resulting mixture is sent for the final gold extraction process. The remaining, lighter portion of the gold-bearing ore is sent to the waste heap.

[0012] The device for the method of dry enrichment of placer gold-bearing ore comprises a nozzle 1 inserted into a hopper 2. A cylinder 3 made of filter material is inserted into the nozzle 1 with a gap 4 to the inner wall 5 of the hopper 2. A powerful fan 7 is used to create a swirling main flow 6 of compressed air. The air flow 8 of compressed air together with particles of placer gold-bearing ore passes through the channels of the filter material of the cylinder 3. The second flow 9 of empty, lighter part of the crushed gold-bearing ore passes along the axis of the cylinder 3. A loading opening 10 is provided to feed the crushed gold-bearing ore from the hopper 2 into the nozzle 1.

[0013] The gold contained in the ore is found mainly in the form of small grains, ranging in size from fractions to several millimeters, or in the form of intergrowths with ore minerals.

[0014] The average density of crushed gold-bearing ore is about 3000 kg / m3 3 , while the density of gold particles is 19320 kg / m3 3 , which makes it easy to separate gold from waste rock or rock with a low gold content in the flow.

[0015] The sequence of operations includes: - creation of a rotating air flow in the nozzle and uniform introduction of a metered portion of pre-processed rock into it; - separation of rock and precious metal in a rotating air flow; - nozzle purge.

[0016] The lightest particles are blown out, thereby enriching the rock. The optimal airflow structure in the nozzle is determined by the nature and condition of the rock or, in the case of crushed feedstock, by varying the airflow speed by adjusting the amount of air supplied by the fan.

[0017] The proposed method can be used for gold ores of any mineral and chemical composition. However, preliminary calibration is required, which involves determining the initial particle detachment velocity.

[0018] The important tasks solved by the proposed method are: - ensuring year-round precious metal extraction in any region, including northern latitudes, in winter, under extremely low temperatures (down to -60°C) from permafrost rock, and in summer, in the absence or shortage of water resources. The proposed method features a compact unit.

Claims

A method for dry enrichment of placer gold-bearing ore, including grinding the ore, drying it to a relative humidity of 10-15% and pouring the ore into a bin with a nozzle installed therein, characterized in that a cylinder of filter material is inserted into the nozzle with a gap to the inner walls of the bin, a rotating stream of compressed air is created in the nozzle by a fan, which, together with particles of placer gold-bearing ore, is directed through the channels of the cylinder of filter material and a separation is carried out, in which heavy particles of placer gold-bearing ore get stuck in the channels of the cylinder of filter material, and lighter particles with a specific gravity lower than the specific gravity of gold, with a stream of compressed air are directed along the axis of the cylinder to the outlet from the nozzle into a dump, after the channels are clogged with heavy particles of gold-bearing ore, the cylinder of filter material is removed from the nozzle of the bin, it is ground and the resulting mixture is sent for the final operation of gold extraction.

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