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A gold mine was completed and put into operation in 1980. After three phases of overall engineering and technological transformation, the daily production capacity of 500t was developed to become 2800t of daily processing capacity and 3400kg of gold was produced in 2007. The comprehensive utilization of tailings is a subject that the mine has been very important for many years. Especially in recent years, the gold mine attaches great importance to technological innovation and scientific and technological progress, and attaches great importance to the comprehensive utilization of tailings and the full recovery of useful components. Through engineering efforts, engineers and technicians carried out a series of experimental studies on the comprehensive utilization of tailings, and finally determined the tailings comprehensive recovery process of tailings classification coarse-grained re-grinding and tailings classification and fine-grained re-election. Through the production practice, it has obtained considerable economic benefits, made full use of limited resources, reduced environmental protection pressure, and achieved good economic and social benefits.
1 Experimental study on re-election of the gold mine tailings
1.1 The tailings coarse-grain re-election test The gold grade of the gold ore flotation tailings is 0.25g/t. After mineralogical research, the tailings loss gold mainly exists in the tailings with inclusions and continuum, if not fine. Grinding, it is difficult for gold to dissociate and thus cannot be recycled.
In 2004, the gold mine cooperated with a research institute to replace the quartz sand in the production of aerated bricks with tailings, and successfully developed aerated bricks. According to the need to make aerated bricks by using tailings, the quartz sand in the production of aerated bricks is replaced by tailings, and the quartz material in the tailings needs to be separated and used. The gangue materials such as quartz are hard-to-grind materials, which are coarse-grained particles in the tailings, which need to be graded out and then ground to meet the utilization requirements. To this end, the flotation tailings are first classified by a cyclone to control the coarse fraction, that is, the amount of graded grit is about 15%, and a coarse-grain grade product with a content of about 200 mesh of about 200% can be obtained. As a material to be ground for brick making. According to the requirements, the ball mill is used to grind this part of the material to -200 mesh and account for more than 60%. In the case where the gold grade of the tailings is maintained at 0.25 g/t, the gold grade of this fractionated grit is 0.50-0.60 g/t. Considering that this part of the product has a high grade, and after regrind, the particle size is finer and meets the flotation requirements, so a flotation test is carried out. Through experiments, it was found that after one rough selection and two selections, a concentrate product with a gold grade of 40.00 g/t can be obtained. The grade of tailings after flotation is 0.25 g/t, which is basically equivalent to the original tailings grade. According to the tailings volume of 2800t / d, after the classification, the amount of sand sinking is about 400t / d. Under the premise of maintaining the gold grade of concentrate of 40.00g / t, a considerable amount of concentrate products can be selected.
1.2 Experimental study on fine-grained re-election of tailings Flotation tailings are classified by cyclone, coarse-grained grit is re-grinded, and some metals are recovered by flotation, and then used for brick materials of building materials company. The cyclone overflows the fine fraction for filling or direct discharge. The gold mine tissue engineering technician conducted a systematic optional test study on fine-grained tailings. The research focuses on the flotation collector dosage of the fine-grained tailings after the cyclone classification, the influence of the dispersant on the selection index and the flotation time required for the concentrate grade that can be enriched. The experimental results show that: for the flotation overflow tailings flotation, it can still recover about 20% of the gold in the tailings; when the gold grade of the fine-grained tailings remains 0.22g/t, after a rough selection, Once selected, the concentrate grade can reach 5g / t, the yield is 1%. It can be seen that the refinement of the classified product fine-grained tailings can obtain a concentrate equivalent to the original ore grade.
2 Process transformation of the gold mine tailings re-election
According to the results of the experimental research, the tailings re-election was carefully studied and demonstrated, and finally the technological transformation was carried out.
2.1 Condition of tailings treatment before transformation The process of tailings treatment before transformation is shown in Figure 1. 
Before the transformation, the tailings were classified by a cyclone, and the bottom stream was given to a filling station. The graded overflow was given to a 24m thickener. After concentration, the tailings slurry was pumped to the tailings dam with a Mars pump, and the thickener overflowed. Mineral processing production use.
2.2 Modified tailings treatment process The modified tailings treatment process is shown in Figure 2.
2.2.1 Reconstruction of coarse-grained tailings treatment process The gold ore processing of raw ore is 2800t per day, producing about 130t of concentrate and about 2670t/d of tailings. After the tailings are classified by the cyclone, the coarse-grained grade (sinking) is about 400t/d, and the output overflow is about 2270t/d. After the grit is returned to the ball mill and after grinding, the grinding product is re-classified, the fine-grained product of the graded overflow product is given to the flotation operation, and the graded grit product is returned to the ball mill for re-grinding. The flotation concentrate is sold after pressure filtration. The flotation tailings are supplied to the brick factory to make brick raw materials.
2.2.2 Process of fine-grained tailings treatment after transformation The fine-grained grade of the first classification of tailings is fed to the flotation operation for flotation again. The flotation tailings are graded into the filling operation, and the grit sand coarse-grain grade products are filled into the wells and supplied to the underground for filling. The overflow fine-grain grade product is concentrated to a 24m thickener, and the concentrated product is delivered to the tailings dam by the final tailings with a Mars pump. The overflow water of the thickener is returned to the beneficiation process. Fine-grained flotation concentrates are deposited after sedimentation.
The added fine-grained tailings re-election process is a rough selection and a selection. Three 16m3 flotation machines are used for rough selection, and one 8m3 flotation machine is selected.
3 Production practice of re-election of the gold mine tailings
3.1 Production practice of coarse-grained tailings re-grinding and re-election The process of re-grinding the re-grinding of coarse-grained tailings is 400t per day, and can produce about 2.5t of concentrate products with a grade of 40g/t or more per day. The amount of metal recovered is more than 100g.
According to the gold content of the concentrate is 110 yuan / g, the daily concentrate value is 11,000 yuan.
The daily cost of the steel ball is 2,800 yuan, the electricity cost is 1,500 yuan, and other expenses such as pharmacy, labor, materials, etc. are 1,000 yuan, and the total cost of running the daily is 5,300 yuan.
The coarse-grained tailings re-grinding process results in a profit of 5,700 yuan / d, calculated by the annual operation of 350d, the annual benefit of 1.95 million yuan.
Without removing the grinding cost of the brick factory (that is, the grinding cost is calculated in the tailings recovery), the annual economic benefit is about 1.95 million yuan.
3.2 Production Practice of Fine-Grained Tailings Re-election Increased fine-grained tailings re-election process The daily processing of tailings is 2270t, according to the concentrate yield of 1%, the grade of 5g/t, and the concentrate price of 100 yuan/ g calculation, the daily concentrate value is 11,350 yuan.
According to the daily electricity bill is 2100 yuan, labor costs 400 yuan, pharmacy, materials and other expenses are 1,500 yuan, the total cost per day is 4,000 yuan. The fine-grained tailings re-election process has a daily benefit of 7,350 yuan, calculated by the annual operation of 350d, and the annual benefit is 2,572,500 yuan.
4 Conclusion
(1) Under the premise of not affecting the original production, the gold mine can reasonably carry out research and application of coarse and fine-grained flotation according to the loss of tailings-grade metal amount and the needs of brickworks materials. Further recovering gold from tailings, increasing the recovery rate of ore dressing by 2%, making full use of mineral resources and improving the economic benefits of enterprises.
(2) After the death of the project, it can reduce the tailings by 8250t per year, which is conducive to the protection of the ecological environment. At the same time, the annual disposal cost of one-off tailings is 247,500 yuan.