Experimental study on mineral processing of a primary gold deposit in Xinjiang

The op timal roughing conditionswere achieved by op timizing the influence factors of flotation index, they are grinding size of 85% - 74μm, pH is 9. 30, and dis2persant dosage of Na ₂ SiO ₃ is 200 g/t, and reagents dosage of CuSO ₄ is 100 g/t, collector dosage of amyl xanthate and BK901C is 50 g/t and 10 g/t and iol is 40 g/t. Laboratory test through a flotation flowsheet Of "one - stageroughing, two - stage cleaning and two - stage scaveng ing" at the op timal operating conditiona was performed. Thegold with the grade of 62. 41 g/ t and the recovery of 96. 83% can be obtained. It Show that this rimary gold orecan be enriched by flotation.

A primary gold mine in Xinjiang ore grade of 4.5g / t, gold-bearing ore industry type gold-bearing quartz veins and altered rocks are two types of composite rock. The main valuable metals that can be recycled are gold and silver . System identified by the rock, heavy sand identification, physical image of chemical analysis, X-ray analysis, spectral analysis, electron microprobe, SEM and image analysis means, a metal sulfide ores found mainly pyrite, arsenopyrite, followed by a small amount of yellow copper ore, tetrahedrite, galena, chalcocite, blue chalcocite, covellite, nickel glance, sphalerite and the like; a metal oxide minerals rutile, hematite; gangue The main minerals are quartz, feldspar , calcite , mica , and hornblende. Most of the natural gold in the ore is continually or occasionally associated with chalcopyrite and galena, and is embedded in fine or fine veins in the fissures and intergranular spaces of arsenopyrite or pyrite, or arsenopyrite or pyrite. At the interface with the gangue; a small part is immersed in gangue minerals (mainly quartz, calcite, dolomite); and a considerable part is granulated or irregularly wrapped in arsenopyrite and pyrite. This primary gold mine should not be used in the direct leaching process and needs to be first flotation to obtain high-grade gold concentrate and the best recovery rate ^{[1, 2]} .

Second, the nature of the ore

The results of multi-element chemical analysis of raw ore are shown in Table 1.

Table 1 Results of multi-element chemical analysis of ore

* The unit of Au and Ag is g/t.

XRD test results show that the primary gold ore is mainly composed of quartz, feldspar, calcite and dolomite, followed by mica, a small amount of chlorite, amphibole and tremolite , a very small amount of epidote, carbonaceous, mineral apatite and iron. Gold is mainly produced in the form of natural gold. The main carrier mineral of gold is arsenopyrite, followed by pyrite. The natural gold in the ore is mainly produced by fissure gold and intergranular gold, and secondly by sulfide-coated gold.

Third, the test plan

According to the research and analysis of process mineralogy, the natural gold particle size in the ore is mainly composed of fine-grained inlays, followed by unevenly embedded in the form of medium, fine and micro in the arsenopyrite, pyrite, sphalerite, chalcopyrite and Mineral cracks such as galena. For this type of ore, it is suitable to use a flotation process to concentrate the gold in the gold concentrate and then further process it. In this paper, the main factors affecting the flotation of gold concentrates were studied: grinding fineness, pH value of pulp, amount of activator, amount of dispersant, type and amount of collector , and the effect of backwater on flotation index. The weight of each sample in the test was 1 kg.

Fourth, the beneficiation test

(1) Grinding fineness test

The identification of the ore minerals indicates that the symbiotic relationship between the gold-bearing minerals and the gangue minerals is relatively close, so the grinding should reach a certain level in order to cleave the useful mineral monomers. The grinding fineness test and conditions are shown in Figure 1, and the test results are shown in Figure 2.

From the grinding fineness test analysis, the fineness of the ore grinding is too coarse and too fine, and its flotation index is not ideal. According to the observation of flotation phenomenon and the change of crude concentrate grade and recovery rate, when the fineness of the ore grinding is coarse, some gold minerals do not reach the cleavage of the monomer, and it is difficult to float. When the grinding fineness is -74μm and the content reaches 85%, the concentrate grade and recovery rate are both high, so the fineness of the grinding is reasonable.

(2) pH test

The pH value of the slurry is one of the important factors affecting the flotation effect. The sodium carbonate was used to adjust the pH value of the slurry to investigate the effect of different pulp pH values ​​on the flotation effect. The test procedure is shown in Figure 1 (the amount of sodium carbonate is a variable), and the test results are shown in Figure 3.

The results in Fig. 3 show that the crude concentrate has a grade of 33.75 g/t and a recovery rate of 93.32% at a slurry pH of 9.30 (the amount of sodium carbonate added is 1500 g/t). The pH value on the surface affects the collector's capture of useful minerals, which is essentially the electrode potential that affects the mineral surface, thus regulating the effective action of the collector ^[3] . Considering comprehensively, adding 1500g/t sodium carbonate and adjusting the pH value of 9.30 for flotation.

(3) Activator dosage test

The addition of copper sulphate to sulfide minerals can achieve the purpose of improving the recovery rate of useful minerals, especially pyrites such as pyrite, sphalerite, limonite, etc., which are significantly more volatile after activation ^[4] . In this experiment, copper sulfate was used as the activator, and the effect of its dosage on the flotation effect was investigated. The test procedure is shown in Figure 1 (the amount of copper sulfate used as a variable), and the test results are shown in Figure 4.

It can be seen from Fig. 4 that the addition of activator significantly increases the recovery of gold compared to the absence of copper sulphate, indicating that copper sulphate can interact with these gold-bearing minerals, indicating that it forms sulphuric acid, especially along its fissures. The copper film, the sulfide mineral covered with the copper sulfate film is greatly improved in floatability, but when the amount is too large, the recovery rate is lowered, so the amount of copper sulfate is determined to be 100 g/t.

(4) Dispersant type and dosage test

The dispersant disperses the slime and eliminates the harmful effects of the mud cover on the surface of other ore particles. Commonly used dispersants are water glass, sodium carbonate, sodium hexametaphosphate, and the like. The dispersant type test was carried out under the conditions of sodium hexametaphosphate and water glass of 200 g/t, and the results are shown in Table 2.

Table 2 Dispersant type test results

It can be seen from Table 2 that the dispersion effect of water glass is better than that of sodium hexametaphosphate. Although the grade of gold is reduced, the recovery rate of gold is improved, so water glass is used as a dispersant.

The water glass dosage test was carried out according to the flow and conditions shown in Fig. 1 (the amount of water glass used as a variable), and the results are shown in Fig. 5. It can be seen from Fig. 5 that when the amount of water glass is 200 g/t, the recovery obtained by the test is the highest.

(5) Test of type and dosage of collector

Under the condition of keeping the dosage of the collectors at 50g/t, the flotation effects of three collectors of Dinghuang, Y89 and Wuhuang were investigated respectively. The test results are shown in Table 3.

Table 3 Test results of collector types

It can be seen from Table 3 that the best effect is the levoperazine collector. After rough selection, the gold grade can reach 64.60g/t, and the recovery rate reaches 92120%, which is higher than the flotation index of other collectors. Therefore, the medicinal herb was selected as the collector, and the test was carried out according to the flow and conditions shown in Figure 1 (the amount of the collector was used as a variable, and 10 g/t of the collector BK901C was added). 6.

The test results show that with the gradual increase of the amount of valer yellow, the gold grade of the coarse concentrate gradually increases, and the recovery rate gradually decreases. When the dosage is (50+10) g/t, the gold grade in the coarse concentrate is 62.50g/t, the recovery rate is 96.53%, and the index is the best, so the dosage of the collector yellowin + BK901C is selected (50+). 10) g/t.

Table 4 Closed circuit test results

(6) Flotation closed circuit test

After the above process conditions are optimized, a rough selection, two selections, and two sweeps of closed circuit tests are performed under the determined optimal pharmaceutical system conditions. The test results are shown in Table 4, and the flow is shown in FIG.

The results show that under the optimal process conditions determined by the test, a good index of gold concentrate grade of 64.50g / t and recovery of 94.51% can be obtained. According to the return sequence of the middle mine shown in Figure 7, the middle mine returned to each flotation operation and was well sorted. The gold concentrate recovery rate increased significantly, indicating that most of the gold minerals in the middle mine are enriched. In the gold concentrate.

Fourth, the conclusion

The results of ore-bearing properties show that the main gold-bearing minerals are arsenopyrite and pyrite, and there is also some natural gold. It is suitable to use flotation method to obtain high-grade, high-recovery gold concentrate, and then further gold extraction. .

Through the rough selection test, the best operating conditions were obtained: grinding fineness -74μm 85%; activator copper sulfate 100g / t; combined collector: pentoxanthin 50g / t + BK901C10g / t; foaming agent 2 ^#油40g/t.

The use of the combined collector medicinal sulphate + BK901C has been shown to effectively capture gold and sulphide, increasing the gold concentrate grade and recovery. The laboratory closed-circuit test finally obtained a gold concentrate grade of 64.50g / t, the recovery rate of 94.51%, the test achieved a higher index.

references:

[1] Cheng Yaoxian, Zeng Maoqing. Research on gold extraction technology of primary gold deposits in a certain place[J]. China Mine Engineering, 2004, 33(5): 20-22.

[2] Dong Yingbo, Lin Hai, Shi Lei, Lian Fang, et al. Experimental study on the selectivity of a primary gold ore in Shandong[J]. Nonferrous Metals: Mineral Processing , 2008(5): 30-33.

[3] Tian Songhe, Luo Xinmin, Liu Zhongrong. Study on Flotation Process of a Gold Ore by High-efficiency Collector Y-89[J]. Nonferrous Metals: Mineral Processing, 2003, (6): 24-26.

[4] Wang Caixia, Zhang Lizheng, Yao Kai. Research and application of activation regulator to improve the recovery rate of gold selection[J]. Nonferrous Metals: Mineral Processing, 2003, (4): 32-34.

Author unit:

Zhou Dongqin, State Key Laboratory of Mineral Processing Science and Technology, Beijing Research Institute of Mining and Metallurgy

School of Resources and Environment, Hebei Polytechnic University, Dai Shujuan

Chengde Chenggang Tianbao Mining Co., Ltd. Li Hongwei

People's Inspection Institute of Heishan County, Liaoning Province

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