Study on Beneficiation Process of a Refractory Gold Deposit in Heilongjiang Province

Heilongjiang a gold mine ore is a siliceous rocks TINY, disseminated type refractory gold ore. Mainly in the form of microscopic gold gold gold micro-fine microstructure times enriched in arsenic-containing pyrite and arsenopyrite minerals and the like. In addition, the content of organic carbon in the ore is relatively high, and it is easy to over-grind during the grinding process. It floats easily during the sorting process, affects the gold grade of the concentrate, and consumes a large amount of chemicals. Aiming at the more complex ore properties of the gold mine, a large number of mineral processing techniques have been carried out to provide a method for industrial production of the gold mine.

First, the nature of the ore

(I) Multi-element analysis of raw ore chemistry and gold phase analysis The results of multi-element analysis of ore-bearing chemistry are shown in Table 1. The results of gold phase analysis are shown in Table 2.

Table 1 Analysis results of main chemical components of ore

(II) Analysis of main mineral composition of ore

The metal minerals in the ore mainly include natural gold, pyrite, arsenic-containing pyrite, pyrite, and arsenopyrite. Gangue minerals are quartz, chalcedony, sericite, organic carbon.

(III) Analysis of main embedding characteristics of gold in raw ore

The gold in the ore mainly exists in the state of natural gold. The gold is closely associated with sulfides such as pyrite and arsenopyrite, and is in the form of fine particles, diffuse microscopic gold and submicroscopic gold in the presence of pyrite and arsenic. Among the sulfide minerals such as pyrite and arsenopyrite, gold encapsulated in pyrite (including a small amount of other sulfide minerals) accounted for 73.01%, gold encapsulated in arsenopyrite accounted for 15.49%, and gold encapsulated in gangue mineral accounted for 11.50%. . Gold is closely related to arsenic. Gold is mainly enriched in minerals such as arsenic pyrite and arsenopyrite.

2. Experimental study on cyanide leaching gold of ore

Cyanidation has been the main method for extracting gold and silver, more mature technology, the operation is relatively easy [1-2].

(1) Cyanide leaching grinding fineness test

Cyanide leaching tests under different grinding fineness were carried out. Add lime 5k to adjust the pH value of the slurry to 11.0, liquid solid lzE=2:1, sodium cyanide dosage 2k, mechanical agitation leaching, leaching time 24h. The test results are shown in Figure 1. The test results show that with the increase of grinding fineness, the leaching rate of gold has not changed significantly, and the leaching rate of gold is very low.

Figure 1 Cyanide leaching grinding fineness test results

(2) Sodium cyanide dosage test

Cyanide leaching tests were carried out under different amounts of sodium cyanide. Grinding fineness -74μm accounted for 90%, adding lime 5k to adjust the pulp pH to 11.0, liquid-solid ratio 2:1, mechanical agitation leaching, leaching time 24h. The test results are shown in Figure 2. The test results show that with the increase of the amount of sodium cyanide, the leaching rate of gold has not changed significantly, and the leaching rate of gold is very low.

Figure 2 Results of sodium cyanide dosage test

Subsequent experiments on liquid-solid ratio, stirring time, bottom carbon density, and immersion after oxidation pretreatment showed that the leaching rate of gold was not significantly improved. Therefore, direct cyanide leaching of raw ore is not economically or technically feasible.

Third, the ore mining flotation test research

In view of the fact that the leaching rate of direct cyanide in raw ore is too low, and the ore gold minerals are mainly embedded in sulfide minerals such as pyrite and arsenopyrite, it is proposed to achieve gold enrichment and obtain qualified gold concentrate by flotation. purpose.

(1) Tester type and dosage test

In the grinding fineness of 90% -74m, copper sulfate in an amount of 100g / t, collector under conditions butyl xanthate using 100g / t, the control agent selected from the group of the rough type and amount test. The adjuster used sodium carbonate and lime commonly used in the ore dressing process. The test results are shown in Figure 3.

Figure 3 Test results of regulator types and dosages

1-grade gold grade as lime adjuster; gold grade when sodium 2-carbonate is used as adjuster; 3-carbonate

Gold recovery rate when sodium is used as a modifier; gold recovery rate when 4-limine is used as a modifier

The test results show that the recovery rate of gold in coarse concentrates increases first and then decreases with the increase of the amount of adjusting agent. Under the condition of 1000g/t, the recovery rate of using lime as the adjusting agent is higher than that of using sodium carbonate. Nearly 10%; but when the amount of lime continues to increase, the recovery rate of gold is significantly reduced, indicating that higher pH has a strong inhibitory effect on sulfide minerals. Therefore, it is determined that the adjusting agent is lime, and the amount is preferably 1000 g/t.

(2) Copper sulfate dosage test

According to the nature of the ore, gold is mainly distributed in sulfide minerals such as pyrite and arsenopyrite. Therefore, increasing the surface activity of these sulfide minerals is the key to improving the gold recovery rate. Under the condition that the fineness of grinding is -74m, 90%, the amount of lime is 1000gt, and the collector is 100gt of butyl xanthate, the crude copper sulfate dosage test is carried out. The test results are shown in Figure 4. The test results show that the grade and recovery of gold in the coarse concentrate increase with the increase of the amount of copper sulfate. Comprehensive consideration, the amount of copper sulfate can be used 200g / t.

Figure 4 results of copper sulfate dosage test

(3) Test of collector type

The collector type test (the amount of which is 100 g/t) was carried out under the conditions of grinding fineness of -74 μm of 90%, lime dosage of 1000 gt, and copper sulfate dosage of 200 g/t. The test results are shown in Table 3. The test results show that compared with other collectors, the collector BK912 not only has a high recovery rate of gold, but also has a relatively high gold grade of coarse concentrate. Therefore, BK912 is selected as a gold collector.

Table 3 % of collector test results

(4) BK912 dosage test

In order to determine the appropriate dosage of collector BK912, the amount of collector BK912 was tested under the conditions of grinding fineness of -74μm 90%, lime dosage of 1000g/t and copper sulfate dosage of 200g/t. See Figure 5. The test results show that with the increase of BK912 dosage, the gold grade of coarse concentrate is reduced, and the gold recovery rate is greatly improved. When the dosage of BK912 is 250g/t, the recovery rate of crude concentrate is the highest; continue to increase the amount of BK912, coarse concentrate The rate increases, the gold grade decreases, and the gold recovery rate no longer increases. Therefore, the amount of BK912 should be 250g / t.

Figure 5 BK912 dosage test results

(5) Rough grinding grinding fineness test

Grinding fineness is one of the important factors in beneficiation. Reasonable grinding fineness is very important for the whole beneficiation process. Under the condition that the amount of lime is 1000g/t, the amount of copper sulfate is 200g/t, and the collector is BK912250g/t, the coarseness grinding condition test is carried out. The test results are shown in Figure 6. The test results show that with the improvement of grinding fineness, the gold grade of coarse concentrate is reduced and the gold recovery rate is improved. When the fineness of grinding -74μm accounts for 90%, the recovery rate of crude concentrate is relatively high. Therefore, the rough grinding fineness is preferably -74 μm in 90%.

Figure 6 rough grinding grinding fineness test results

(6) Flotation time test

Flotation time [3] refers to the time that the slurry stays in the flotation tank. It is an important parameter for selecting flotation equipment . The flotation time is not enough, which directly affects the metal recovery rate. In order to determine the appropriate flotation time, a flotation time test was carried out, and the test results are shown in Fig. 7. The test results show that the recovery rate of gold in gold concentrates increases with the extension of flotation time, and the growth rate is slower. Due to the long flotation time, it is advisable to use two rough selection processes.

Figure 7 Flotation time test results

(7) Selected water glass dosage test

In order to further improve the grade of gold in gold concentrates, a selection of water glass dosage tests was conducted ^[4] . Two rough selection and three selection processes were used, and the test results are shown in Fig. 8. The test results show that the gold grade and gold recovery rate of gold concentrates increase first and then decrease with the increase of water glass dosage. Considering that the amount of water glass is 500g/t, it is suitable.

Figure 8 Selected water glass dosage test results

(7) Refining fineness test of coarse concentrate

It can be seen from the analysis of the main inlaid characteristics of gold that the gold in the ore mainly exists in the state of natural gold, and the gold is closely associated with sulfides such as pyrite and arsenopyrite, and is microscopic and diffuse microscopic gold ^{[5 ]} and submicroscopic gold state forming pyrite, arsenopyrite and arsenic-containing pyrite and other sulfide minerals. Therefore, in order to further improve the grade of gold in gold concentrate, it is necessary to re-grind the coarse concentrate. In order to determine the appropriate regrind fineness, a regrind grinding fineness test was conducted. Two rough selections, coarse concentrate regrind, and three selective test procedures were used. The test results are shown in Figure 9. The test results show that no matter whether the coarse concentrate is reground or not, the qualified gold concentrate can be obtained, and the recovery rate of gold is basically the same, but if the grinding can further improve the gold grade of gold concentrate and reduce the gold concentrate. Yield, thereby reducing the cost of gold extraction from gold concentrates. The test results show that the regrind fineness of coarse concentrate should be -39μm and 75%.

Figure 9 results of regrind test

L-gold grade; 2-gold leaching rate

(6) Closed circuit test process and results

The closed circuit test process is shown in Figure 10, and the test results are shown in Table 4. From the closed-circuit test results, it can be seen that the fine ore is finely ground to -74μm, accounting for 90%. After two rough selections and two sweeps, the coarse concentrate is re-ground to -39μm, accounting for 75%, three selected closed-circuit processes. A qualified gold concentrate with a yield of 4.28%, a gold grade of 50.60, and a gold recovery of 87.27% was obtained.

Figure 10 closed circuit test process

Table 4 Closed circuit test results

Fourth, the conclusion

1. The test ore is a siliceous rock type fine particle and a dip dyed type refractory gold ore. The gold mineral has a fine particle size, and the gold is mainly concentrated in the form of fine-grained microscopic gold and sub-microscopic gold in minerals such as fine-grained arsenic-containing pyrite and arsenopyrite.

2. The gold leaching rate of direct cyanidation of raw ore is very low, and the highest leaching rate is only 13.36%, which is technically unfeasible and economically unreasonable.

3. Adopting a new type of gold collector BK912 with strong harvesting ability and good selectivity, not only the recovery rate of gold is greatly improved, but also the gold grade of gold coarse concentrate is relatively high.

4, using coarse concentrate re-grinding, in the case of ensuring the same rate of recovery, can further improve the grade of gold concentrate.

5. Applying a closed-circuit test procedure of fine grinding, coarse concentrate re-grinding, two rough selection, three selections and two sweeps, a qualified gold concentrate with a gold grade of 50.60 and a gold recovery of 87.27% can be obtained.

references

[1] Editorial Board of "G-Production T-Art Guide". Gold Production Process Guide [M]. Beijing: Chinese Academy of Sciences Press, 2000.74-75.

[2] Yang Jinlin, Zhang Hongmei, et al. Experimental study on the selectivity of a gold ore in Cambodia [J]. China Mining Engineering. 2005, (5): 19-21.

[3] Xu Shi. Research on ore selectivity (2nd edition) [M]. Beijing: Metallurgical Industry Press, 2006.133-140.

[4] Peng Binbing. Exploratory experiment on gold extraction from refractory gold deposits[J].Xinjiang Nonferrous Metals.2006,(4):34-36.

[5] Zhou Leguang. T-Art Mineralogy (3rd Edition) [M]. Beijing: Metallurgical Industry Press, 2007-03-205.

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