Experimental study on fine ore gold ore beneficiation

I. Introduction

Sulfur fine disseminated gold ore is an important gold resources, such as gold or gold ore fines submicroscopic gold was present in the package or disseminated pyrite, arsenopyrite and other sulfides, also finely ground Difficult to separate. The encapsulation of these minerals prevents the gold particles from effectively contacting the gold immersion agent, hinders the gold leaching, and is directly cyanated by conventional cyanidation. The gold extraction rate is less than 40%, which is extremely difficult to handle gold mines. Such gold mines are widely distributed in China. It is a common and effective method to treat the minerals by enriching the gold-bearing sulfide ore by chemical dressing and then immersing the gold by cyanidation. Therefore, the recovery of gold-bearing minerals from ore dressing is an important part of the treatment of this type of ore and an important guarantee for improving the total recovery rate of gold ^{[1 , 2]} .

The ore studied in this paper is a fine-grained gold ore in Guizhou. The gold in the ore is mainly embedded in the pyrite-based sulfide minerals by fine-grained gold. Because the pyrite has good floatability, it can be floated. The method recovers pyrite to enrich gold ^{[3 , 4]} . According to the characteristics of high silicate content in ore, detailed experiments were carried out, and Na ₂ CO _{3 was used} as pH adjuster, Na ₂ SiO _{3 was used} as gangue inhibitor, CuSO was used as sulfide mineral activator, and butyl ammonium black. The flotation process of small flotation experiments was carried out by the conventional flotation process of the drug and Dinghuang as collectors , and also provided the basis for the development of the mine ^{[5 , 6]} .

Second, samples and methods

(a) sample

A fine-grained gold deposit in Guizhou mainly contains metal minerals such as pyrite, arsenopyrite and hematite, and gangue minerals such as quartz , dolomite, calcite , water (绢) mica and kaolinite, and also contains some organic matter. The chemical composition analysis results of the samples are shown in Table 1. According to the chemical composition analysis results of the sample, in addition to Au, the Cu, Pb, Zn and other elements have no comprehensive recycling value. The gold minerals in the ore are mainly produced in the form of natural gold, embedded in minerals such as pyrite and arsenopyrite, and pyrite is the main carrier mineral of gold.

Table 1 Results of chemical composition analysis of samples

(2) Test chemicals and equipment

The test uses a cone ball mill to grind, a series of single tanks and a series of hanging tank flotation machines for flotation. The water in the test is tap water, the 2 ^# oil is industrially pure, and the other test chemicals are chemically pure.

Third, the research results and discussion

(1) Grinding fineness test

The pre-flotation grinding operation aims to dissociate the minerals in the ore and grind the ore to a particle size suitable for flotation. The optimum particle size of the grinding should not only maximize the dissociation of the fine-grained sulfide minerals, but also minimize the interference of the gangue slime to improve the flotation efficiency of the fine-grained sulfide ore. In order to determine the best grinding fineness and obtain a better index for flotation, the flotation test will be carried out according to the flow and process conditions of Figure 1. The test results are shown in Table 2.

Figure 1 Flow chart of grinding fineness condition test

Table 2 Grinding fineness test results

It can be seen from Fig. 2 that as the fineness of the grinding increases, the gold recovery rate increases. However, when the grinding fineness exceeds -0.074 mm 90%, the gold recovery rate is rather reduced. Therefore, it is preferable to determine the grinding fineness to be -0.074 mm 90%.

(2) Testing conditions for drug selection

In the flotation operation, the main factors affecting the sorting effect are pH adjusters, dispersants, activators and collectors. In order to obtain the best operating parameters, the above four factors were orthogonally tested when the grinding fineness was -0.074 mm 90%. The orthogonal test was designed using L ₉ (3 ⁴ ) orthogonal table. The test factors and levels are shown in Table 3. The design of the test plan is shown in Table 4.

Table 3 Test factors and levels (g/t)

Table 4 Gold rough selection orthogonal test head design and test arrangement

As can be seen from Table 4, for the pH adjuster A, the optimum level corresponding to the sorting efficiency is 2; for the dispersant water glass amount B, the optimal level corresponding to the sorting efficiency is 2, that is, water glass The optimum amount is 500g / t; activator for copper sulfate, the optimum amount is 200g / t; collector combination, the optimum amount of butyl xanthate 80g / t, tetrabutylammonium aerofloat 40g / t.

Whether the optimal level of each factor selected above is reasonable, and the verification test should be carried out under the optimal conditions selected. The test flow is shown in Figure 1. The test results showed that the crude gold concentrate yield was 10.34%, the gold grade was 52.63g/t, the gold recovery rate was 82.47%, and the sorting efficiency was 0.364%. The results of the nine test points in Table 4 are all worse than this result, indicating that the selection of the optimal conditions is reliable.

(3) Flotation closed circuit test

On the basis of the optimal conditions of rough selection, a laboratory closed-circuit test of coarse and fine three sweeps was carried out. The test procedure is shown in Fig. 2. Test conditions: rough selection conditions of grinding fineness -0.074mm accounted for 90%, sodium carbonate dosage 6000g / t, water glass dosage 500g / t, copper sulfate dosage 200g / t, butyl yellow dosage 80g / t, D Ammonium black medicinal amount 40g / t, No. 2 oil 30g / t. The conditions of the sweeping selection were: butyl yellow medicinal amount 40 g/t, butyl ammonium black medicinal amount 20 g/t, and No. 2 oil 10 g/t. Sweeping II: butyl yellow medicinal amount 30g / t, butyl ammonium black medicinal amount 15g / t, No. 2 oil l0g / t. Sweeping III: butyl yellow medicinal amount 20g / t, butyl ammonium black medicinal amount 10g / t, No. 2 oil 10g / t. The test results are shown in Table 5.

Table 5 Closed-circuit test results

Figure 2 Flotation closed circuit test process

Fourth, the conclusion

1. Through the grinding fineness test of the mine and the orthogonal test of the crude selection conditions, it is determined that the optimal operating conditions for the rough selection of the ore are: grinding fineness of 0.074mm accounting for 90%, sodium carbonate dosage of 6000g /t, water glass dosage 500g / t, copper sulfate dosage 200g / t, butyl yellow pharmaceutical dosage 80g / t, butyl ammonium black pharmaceutical dosage 40g / t.

2. In the laboratory closed-circuit test based on the optimal conditions of rough selection, a gold concentrate with a gold grade of 48.04 g/t and a recovery rate of 85.63 can be obtained. This result indicates that the gold in the ore can be floated by flotation. Carry out recycling and enrichment.

references

[1] Xia Guangxiang, Fang Zhaozhen, Shi Wei. Gold extraction technology and prospect of refractory gold deposits [J]. Nonferrous Metals Smelting, 2001 (4): 31-34.

[2] Alias. Metal Minerals/Non-ferrous Metals. China Mineral Resources Network, 2004.

[3] Hu Weibai. Flotation [M]. Beijing: Metallurgical Industry Press, 1986.

[4] Xie Guangyuan. Mineral Processing [M]. Xuzhou: China University of Mining and Technology Press, 2001.

[5] Xu Shi. Research on ore selectivity [M]. Beijing: Metallurgical Industry Press, 1 989.

[6] Zhu Yushuang, Zhu Jianguang. The chemical principle of flotation reagents [M3. Changsha: Central South University of Technology Press, 1987.

Author unit

Guizhou University School of Mines (Nie Guanghua)

Zijin Mining and Metallurgy Design and Research Institute (Liu Chunlong)

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