Treatment process of arsenic-bearing gold ore

With the development of gold ore resources deepening, easy to handle gold ore reserves are gradually reduced, and the structure of complex, low-grade and disseminated fine grain size of refractory gold ores proportion gradually increased. According to statistics, gold produced by refractory gold resources accounts for more than 1/3 of the world's gold production. It can be seen that such gold resources have become the main source of gold production. Dealing with such gold ore has become the most important topic in current mineral processing research. .

Gold ore containing arsenic is recognized as one of the world type of refractory gold ores, but also deal with the largest amount of recoverable highest economic value of gold ore. China's arsenic-bearing gold resources are mainly distributed in the southwest, northwest and northeast regions. Difficulties arsenic gold ore processing is that arsenic minerals and gold minerals (mainly arsenopyrite) and is intimately associated pyrite, gold distributed in a fine particulate, often wrapped in pyrite and arsenopyrite, or present in its single Between the crystals, the difficulty in selecting gold is increased. At the same time, the gold concentrate contains high arsenic and the gold recovery rate is low, which is not conducive to subsequent metallurgical work. At present, flotation is one of the effective methods for pretreatment of arsenic-bearing gold ore. The purpose of flotation of arsenic-bearing gold ore is to separate arsenic from gold to achieve gold recovery. It is necessary to study and improve the beneficiation process of arsenic-bearing gold ore, which can not only improve the economic benefits of the technology, but also contribute to environmental protection and has the significance of sustainable development. At present, many scholars at home and abroad have conducted a lot of research on the separation of arsenopyrite and gold-bearing sulfide ore. The flotation separation of arsenic-bearing gold ore is the main embodiment of flotation separation of gold-bearing sulfide ore and arsenic minerals. The research focus on the separation of arsenopyrite and gold-containing sulfide minerals focuses on the selection of flotation reagents and the flotation process.

1 Research progress on flotation reagents for arsenic-bearing gold ore

The focus of research on flotation reagents is the development of low-cost, high-efficiency and small-toxic mixed agents. So far, the research work on flotation reagents has achieved more results.

1.1 Highly selective collector

The gold collectors generally include ethyl xanthate, butyl xanthate, isoamyl xanthate, cresol black medicine, sodium hydroxy citrate and oleic acid. Zhu Shenhong and Qian Xin, Tong Xiong and Qian Xin] When studying an arsenic-containing gold ore, it was found that butyl xanthate, sec- octyl xanthate and glucosinolate could selectively float golden iron in alkaline medium. Mines, and the combined use of these agents is more effective for the separation of gold-bearing iron ore and arsenopyrite, and can enhance the flotation of gold-bearing iron ore. With the reduction of single nature and easy flotation of gold ore, refractory gold ore with complex mineral composition has become the main gold resource. For the flotation of such ores, it is difficult to achieve an ideal indicator for a single pharmaceutical system. For this reason, more and more mineral processing workers are focusing on the compatibility of existing pharmaceutical agents, focusing on mixed drugs and developing new agents to solve existing problems. Zhang Dazhu and Jia Zhenwu pointed out that the gold recovery rate of arsenic-containing fine-grained gold ore in Wujiatun was low. It was proposed to replace the original single-butyl yellow drug as a collector with a mixture of black and butyl xanthate. Through the small closed circuit test, the gold recovery rate increased by 26.11%. BA Qianturia is based on butyl xanthate and excess acrylol. The new ПРОКС agent made by combining propylene trithiocarbonate with propoxylated sulfide is fixed on the surface of a toxic sand. By preventing the adsorption of xanthate, the surface of the arsenopyrite mineral is hydrophilic, thereby inhibiting the arsenopyrite. When the yellow drug is used as a collector to float the pyrite and the arsenopyrite, the first addition of the ПРОКС agent can effectively inhibit the arsenopyrite, and can also improve the yellow iron. The floatability of the mine. Liu Siqing and Zhang Wenlin combined the baking gum with sodium sulfate to inhibit the arsenopyrite, and obtained gold concentrates with ideal indexes. Huang Wanfu and Li Xindong used a combination of No. 38 collector and butylamine black in a 3:2 ratio to study an arsenic-bearing gold deposit in Jiangxi. The gold recovery rate was over 93.48%.

1.2 Arsenic inhibitors

In arsenic-bearing gold ore flotation, inhibitors are often used to increase the hydrophilicity of minerals or to prevent the action of minerals and collectors,

The floatability is suppressed, thereby achieving flotation separation of arsenic and gold, thereby realizing gold recovery. The inhibitors of arsenic mainly include five types: lime combination type, oxidant type, carbonate type, sulfur oxide type and organic inhibitor.

(1) Lime combined inhibitors. Because the arsenopyrite and sulfide minerals have different critical pH of flotation, in the flotation of arsenic-containing gold ore, lime is usually used as a pH adjuster to promote the dissolution or oxidation of the mineral surface, thereby achieving the purpose of inhibiting arsenic. However, the use of a single lime method to suppress arsenopyrite or pyrite is not ideal. In order to obtain the desired test index, it is often mixed with other chemicals, mainly lime-ammonium salt method (NH4NO3 and NH4Cl), lime-sodium sulfite method. and lime - copper sulfate method. In alkaline pulp, the surface of pyrite will oxidize to form hydrophilic substance Fe(OH)3, and the surface of poisonous sand will oxidize to form hydrophilic substances FeAsO4, Fe3(AsO4)2 and Fe(OH)3. These hydrophilic substances Covering the surface of the mineral to form a hydrophilic film, which inhibits pyrite and arsenopyrite. A gold mine in Henan is a high-arsenic refractory gold mine. By using lime to control the alkaline conditions required to inhibit arsenic minerals, and adding a protective agent LA, the surface of the gold-bearing mineral pyrite is destroyed under alkaline conditions. The oxidized hydrophilic membrane, the gold grade in the gold concentrate obtained by the closed circuit experiment reached 68.00×10-6, the recovery rate was 78.43%, and the arsenic content was only 0.37%. The gold arsenic flotation separation was successfully realized.

(2) oxidant type inhibitors. In view of the characteristics of easy oxidation of poisonous sand in the flotation process, the effect of effectively suppressing the floatability of the arsenopyrite can be achieved by aerating or stirring the slurry or adding an oxidant. In the study of arsone inhibitors, Beattie found that using NaOH as a pH adjuster and H2O2 or NaClO as an oxidant can oxidize the iron oxide hydrophilic film on the surface of the arsenopyrite to inhibit the arsenopyrite. The sulfur and arsenic separation process of high-arsenic and high-sulfur refractory gold ore in Tianma Mountain was found. The use of NaClO as an oxidant can selectively oxidize and inhibit arsenopyrite. The separation effect of sulfur and arsenic is very significant, and the arsenic removal rate is 90%. The amount of arsenic is <0.3%. Yuan Laimin et al. Separated a arsenic-containing refractory gold deposit, using a stage selection and stage inhibition process, and selecting a variety of inhibitors for combined testing, finally screening out a combination of lime, NaHSO3 and a small amount of cyanide, which can effectively inhibit The poisonous sand finally obtained the gold concentrate of gold concentrate of 82.50×10-6, the gold recovery rate was 87.01%, and the arsenic contained 0.27%. The separation effect of gold and arsenic was very significant.

(3) A carbonate type inhibitor. Principle of the method: carbonates (mainly Na2CO3 and ZnCO3) have a certain cleaning effect on the oxides on the surface of sulfide minerals such as pyrite, thereby activating the sulfide minerals such as pyrite, and making the difference in floatability between sulfide minerals and arsenic minerals. Increase and improve the separation effect. It has been found that the ratio of Na2CO3 and ZnCO3 has no effect on the flotation effect; when Na2CO3 and bleaching powder are used in combination, the inhibition of the arsenopyrite can be enhanced by appropriate control of the addition of the agent.

The order of entry can improve the flotation effect of pyrite.

(4) Sulfur oxide inhibitors. Sulfur oxides have long been used as arsenic inhibitors, mainly Na2SO3, thiosulfate, Na2S and K2S2O8. Among them, Na2SO3 is a commonly used inorganic modifier, which is cheap and effective; K2S2O8 inhibitor has strong selectivity, and separation flotation is not affected by oxidation time.

(5) Organic inhibitors. Due to the low cost and no harm to the environment, research on organic inhibitors has received increasing attention. Among them, organic inhibitors with good inhibitory effects are mainly dextrin, sodium humate (ammonium), tannin, polyacrylamide, lignosulfonate and mixtures thereof. The combination of organic inhibitors and inorganic inhibitors to improve the selectivity of gold flotation process is the focus of current organic inhibitor research. When Tong Xiong and Qian Xin conducted research on the separation of golden iron ore and arsenopyrite, the use of organic and inorganic combination inhibitor sodium humate was effective in inhibiting arsenopyrite and achieved good separation of gold and arsenic. Zhang Jianfeng and Hu Yuehua synthesized a class of nitrogen-containing small molecule non-sulfurized ore organic inhibitors that can effectively inhibit pyrite. They have good selectivity in the flotation of pure minerals and artificial mixed ore of pyrite and arsenopyrite. Completely inhibit the arsenopyrite. Yang et al. separated the pyrite and arsenopyrite from a magnetic separation tailings in Yunnan. The organic inhibitor MF was used as an inhibitor of arsenic and good experimental indexes were obtained. Mu Wei et al. recovered pyrite from a high-arsenic pyrite tailings in Mengzi area of ​​Yunnan Province, and used the new organic inhibitor SN to achieve effective suppression of arsenopyrite without affecting the recovery rate of pyrite.

2 Research progress on flotation process of arsenic-bearing gold ore

The conventional flotation process does not have an ideal inhibitory effect on arsenic. However, the application of new technologies and new processes has effectively improved the flotation efficiency of arsenic-containing refractory gold ore. China has achieved outstanding performance in flotation technology and process innovation: controlling the flotation of gold-containing arsenic sulfide ore by potential, accurately controlling the slurry potential with N2 instead of air, and effectively suppressing arsenic; filling air in Na2CO3 medium Can effectively improve the floatability of arsenic pyrite.

3 Prospects for research on flotation technology of arsenic-bearing gold ore

In the mining of rare metal resources, there are fewer and fewer single mineral sources. Most of the mineral resources are complex composite mineral sources. However, the demand for rare metal resources in China is increasing. Therefore, the mining of complex gold mines has become the current situation. Inevitable requirements. In view of the large proportion of gold-bearing resources in arsenic-bearing gold mines, the development of flotation technology will surely be paid attention to by all parties, and flotation reagents and flotation processes are important factors affecting the development of flotation technology. Selection and process research will become an important topic in future flotation technology, and flotation research on arsenic-bearing gold ore is moving to a higher level.

At present, the recovery rate of gold is not high in the flotation of arsenic-bearing gold ore, so the flotation technology needs to be further improved. Flotation technology is getting more and more widely used. In this process, the use of pharmaceuticals is the key. Collectors and inhibitors have become the focus of research on difficult gold mining in China. With the emergence of more advanced pharmaceuticals, The recovery rate of gold in arsenic-bearing gold ore will be improved. The innovative development of flotation process and combined process can make the process of arsenic-bearing gold mine more efficient, combined with advanced science and technology, the innovation of flotation technology will bring new changes.

4 Conclusion

The mining and recycling of rare metals still faces many problems, and the mining of arsenic-bearing gold is a typical example. Compared with a single gold mine, the treatment of arsenic-bearing gold ore is more complicated. It is necessary to carry out flotation separation in non-single gold mines. The unique chemical properties of arsenic and gold determine the unique existence of the two. The choice of the agent during the selection process is the key to the realization of arsenic gold separation. The use of new flotation processes and combined processes will inevitably lead to wider application of flotation technology.

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