Metro is one of the major gold mine gold mine, a mining design scale of 500t / d, two design mining scale of 1250t / d, has now reached the production capacity of 2100t / d of ore mined by the middle of a 70m Extend down to a mid-section of 530m. As the ore mining extends deeper, the ore properties have undergone major changes, mainly due to the decreasing grade of gold, the closer relationship between gold minerals and quartz , the finer grain size of gold, and the increase of gold content in fine-grained quartz. These factors all make the ore's selectivity worse, and the original beneficiation process and process conditions are not fully adapted. To this end, the Xincheng Gold Mine Concentrator has carried out a series of technical transformations in recent years, maintaining a good mineral processing technical index and achieving significant economic and environmental benefits.

I. Introduction to the original process of the mineral processing plant

The crushing adopts the three-stage and one-closed process, the coarse crushing is set in the well, the medium crushing and fine crushing are respectively adopted the standard type and short-head type 1750 cone crusher, and the pre-screening adopts the 2YA1548 type double-layer vibrating screen, and the screening is performed by the YA1548 type single layer. The vibrating screen has a mesh size of 20 mm x 30 mm and a final product size of -20 mm.

The grinding process adopts a closed-circuit process, which is divided into 4 series. The 1~3 series consists of one MQG2100×2200 lattice ball mill and one FLG-1500 spiral classifier, and the 4 series is a new series of the second phase. It adopts one MQG2700×3600 lattice ball mill and one 2FLG-2000 double spiral classifier to form a closed circuit.

Flotation is a series of two, using a rough, one sweep, two fine process structure. The flotation concentrate is re-grinded and graded and then enters the cyanidation operation. A part of the flotation tailings is filled into the well and a part of the pump is tailed.

The cyanidation operation adopts a typical CCD process, and the replaced gold mud is smelted by fire method to produce finished gold and finished silver .

Second, the problems in the original mineral processing

(1) Two cone crushers of the crushing system are in service for an extended period of time, and cannot be renewed for various reasons. The failure rate is high in production; the efficiency of pre-screening and inspection of screening and screening is low; medium and fine crusher crushers 2 ^# , 5 ^# feed belt running speed, difficulty manual cleaning, easy to plug the crusher. These factors lead to low production efficiency and large product size.

(2) There are many grinding and grading series, and the operation and management are difficult, and the process conditions are not easy to control. The concentrate regrind system MQG1500×3000 ball mill has long service life, serious aging and high accident rate; the cyclone works unstable, the classification efficiency is low, and the fineness of the regrind product is coarse, which directly affects the cyanide index.

(3) The selection time of the second selection operation of the flotation system is too long, and the concentrate enrichment ratio is low, only 1.1. From the results of the process mineralogical research, it is known that the sulfide content in the lower middle ore is reduced, and the natural gold content is increased. If the selection time is too long, the natural gold is easily contaminated and lost.

(4) The single consumption of sodium cyanide in the cyanidation leaching operation is high, sometimes reaching 10kg/t or more, and the cost of the medicament is too high.

(5) Problems such as tight production water and poor water quality restrict the smooth progress of production.

Third, mineral processing technology transformation and effect

(1) Equipment transformation

1. Replace the broken vibrating screen frame tube with thick-walled seamless steel tube, and change all the ribs into groove form, improve the overall strength of the screen body, and change the rib board from the original 7 to 3, increasing Nearly 30% of the screening area. Through the transformation, the screening efficiency is greatly improved, the driving time is shortened, and the annual electricity saving is 127,000 kW·h, with a value of 63,000 yuan.

2. Combine the original 8 ^# and 11 ^# crushing product transportation belts of the crushing system, use the long drive screw as the traction device, and transform the tensioning device to solve the problem of the deviation and slip of the original 11 belt, simplifying the operation, each year. It can save about 52,000 yuan in spare parts and power consumption. The belt speed of the 2 ^# and 5 ^# cone crusher feeding belts is reduced from 1.25m/s to 1.0m/s, and the belt width is widened from 650mm to 800mm, which reduces the difficulty of hand selection and the failure rate of the cone crusher. , improve the crushing efficiency of the cone crusher.

3. Use one MQG2700×3600 ball mill to replace the original three MQG2100×2200 ball mills, and cooperate with one 2FLG-2000 spiral classifier to simplify the grinding operation, save the spare parts inventory cost, and stabilize the concentration of the selected slurry. And fineness.

4. The concentrate regrind system uses one MQY2100×3000 ball mill instead of the original two MQY1500×3000 ball mills; the grading equipment is changed to a polyurethane cyclone set with pressure display device, which is easy to install and maintain, and has high classification efficiency. About 5 percentage points of the original cyclone. After installation and use, the pass rate of grinding fineness increased by 12 percentage points, the content of -0.043mm increased by 4 percentage points, and the recovery rate of cyanidation increased by 0.28 percentage points.

5. The φ12m single-layer thickener for cyanidation operation and the 12m thick three-layer thickener for washing operation were efficiently modified, and the thickener was installed with the ore buffer degassing tank, and the feeding vertical was installed at the center feeding station. Barrels, diffuser plates are installed under the barrels. After the transformation, the thickener runs stably, the running phenomenon of the precious liquid disappears, and the quality of the return water has been greatly improved.

(II) Optimization of mineral processing process structure

1. Through detailed examination of the flotation process, the selection of the flotation operation is changed to 1 selection, which reduces the secondary pollution of the gold surface, making the flotation process more suitable for the change of the nature of the lower middle ore. In the case of ensuring flotation recovery rate and concentrate grade, the operation is simplified, and the annual electricity consumption and spare parts cost are reduced by 141,000 yuan.

2. Increase the pressure filtration operation before leaching, remove the water from the concentrate and return to the main plant for reuse. In the leaching operation, the replacement of the poor liquid is used to adjust the slurry, so that the cyanide-containing sewage is not discharged, and the water is returned more than 120m per day. The annual cost of saving new water is 147,000 yuan.

3. The original effluent tailings overflow water will be recycled and returned to the production system for recycling. The daily return water will increase by 1100m, and the annual new water cost will be 1.348 million yuan, and the zero discharge of the whole plant production wastewater will be realized. Benefits and environmental benefits are considerable.

(III) Optimization of mineral processing conditions

1. The original fine crusher cone crusher is updated to the Nordberg HP300 cone crusher, and the mesh size of the crushing section is changed from 20mm×30mm to 14mm×14mm, so that the crushed product particle size can be reduced from -20mm to -12mm. The length of a closed-circuit grinding is increased from -0.074mm to 50% to 55% to -0.074mm, which is 60% to 65%, and the regrindness of the second-stage concentrate is increased from -0.043mm to 90% to -0.043mm. More than 95%, to ensure the full separation of gold minerals.

2. The flotation collector is changed from the original use of butyl sodium xanthate to 85% of butyl sodium xanthate and 15% of isoamyl xanthate to exert synergistic effects of the agent and improve the useful minerals. Hydrophobic.

3, as much as possible to replace solid sodium cyanide with liquid sodium cyanide, so that the cost of concentrates is reduced by 21 yuan / t, annual economic benefits increased by 750,000 yuan, and the use of liquid sodium cyanide is easy to operate, high security.

4. On the one hand, in the winter, the heat preservation measures are taken for the leaching operation, so that the temperature of the winter pulp is increased by 5-6 °C, which promotes the dissolution of gold minerals; on the other hand, the cyanide operation area is isolated, and the flow of foreign water is strictly prohibited, ensuring The balance of water volume. After the implementation of the above measures, the leaching rate of gold increased by 0.2 percentage points, and 4178g of gold was recovered annually, creating an economic benefit of 668,000 yuan.

5. In the flotation and leaching operations, four electromagnetic program-controlled dosing machines were used instead of the original manual dosing. The accuracy of dosing was fundamentally improved, and the cost of pharmaceuticals also decreased. The automatic concentrating device is installed on the west φ12m single-layer thickener for concentrate concentration and the west φ12m single-layer thickener for washing operation, so that the concentration of the thickener discharge is stably controlled, ensuring the continuous, balanced and stable cyanide process. , created a good condition for the successful completion of the cyanidation index.

Fourth, the conclusion

The Xincheng Gold Mine Concentrator has carried out extensive analysis, research and optimization of the ore dressing equipment, process and process conditions, and maintained a high selection in the unfavorable situation that the grade of ore gold decreased year by year and the ore selectivity deteriorated. Technical indicators, the annual cumulative economic benefits of more than 3.17 million yuan. At the same time, the entire beneficiation process has realized the complete recycling of production water, making full use of valuable water resources, completely solving the environmental pollution caused by the beneficiation production wastewater, and has produced significant environmental benefits.

references

[1] Hu Chunrong, Yang Feng. Review on the development of gold smelting technology [J]. Gold, 2001, 21 (1); 29-37.

[2] Zhang Guogang, Zheng Jiguo, Li Hui, et al. Practice of mineral processing technology reformation in Xincheng Gold Mine[J]. Gold, 2002, 21(6); 33-35.

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