The separation of copper and arsenic is mainly to solve the separation problem of copper minerals and arsenopyrite, which can be summarized as follows:
(1) Highly selective collector. It is very important to enlarge the separation of the two minerals by using selective collectors. For example, the combination of xanthate and black medicine of butylammonium, the mixture of xanthate and sulfur and nitrogen, osn-43, aminoalcohol xanthate and phosphoaminophenol have good selectivity to a specific ore under certain conditions. Auxiliary collectors such as DPG or 8-hydroxyquinoline can be added to the ball mill together with inhibitors to improve separation efficiency and recovery of precious metals.
(2) Combined inhibitor mainly composed of lime: lime is a commonly used alkaline pH regulator, which can not only improve the pH value of pulp, but also promote the dissolution or oxidation of mineral surface. However, the amount of lime should be carefully controlled. If it is excessive, it will also have a certain inhibition on copper sulfide minerals. Therefore, when the inhibition effect of single lime is not good, other inhibitors such as sodium cyanide, zinc sulfate and SO2 can be used. The results show that the combination of lime-so2-zn (CN) 2-complex is the most effective for the inhibition of arsenopyrite. When there are a large number of secondary copper minerals in the raw ore, when arsenopyrite is activated by Cu2 + with high floatability, lime and sodium sulfide can be used for sharing; at this time, S2 – and Cu2 + generate insoluble precipitates, thus eliminating the activation of Cu2 +.
(3) Oxidation method: arsenopyrite is easy to be oxidized. The floatability of arsenopyrite can be strongly inhibited by aeration oxidation (ph5.7-6.5), long-time stirring or adding various oxidants. The commonly used oxidants are bleaching powder, potassium permanganate, potassium dichromate and manganese dioxide. The order of the action of these oxidants is: bleaching powder > potassium permanganate > potassium dichromate > manganese dioxide.
The oxidation process can be accelerated by increasing pulp temperature. A large number of experiments show that the order of oxidation strength of some sulfide minerals is arsenopyrite, pyrrhotite and chalcopyrite when the pulp temperature is increased. The control temperature of 40-50 ℃ can strengthen the inhibition of arsenopyrite.
(4) Inorganic inhibitors such as thioxyacid: thioxyacid or thiosulfate is used to inhibit arsenopyrite. The experimental results show that the inhibition order of arsenopyrite is: Knox Liu > sodium thiosulfate > sodium sulfite.
(5) Organic inhibitors: in addition to inorganic inhibitors, people are increasingly interested in finding new, cheap and effective organic inhibitors for environmental protection. The organic inhibitors of arsenopyrite include dextrin, tannin, lignosulfonate, polyacrylamide, etc. at the same time, it is found that the combination of organic inhibitors and inorganic reagents has obvious effect.
II. Separation practice of copper arsenite sulfide
The research results at home and abroad show that the separation of arsenopyrite and copper sulfide can be realized completely by using the existing beneficiation technology.
It has been reported in Japan that chalcopyrite and arsenopyrite are easy to float. Lime and sodium cyanide can be added to the mixed concentrate and stirred in the pH range of 10.5-11.5. Then sulfuric acid or SO2 can be used to adjust the pH value to weak acid pH value of 5-7. Only the flotation of chalcopyrite can be carried out without collector to separate the two minerals. The results show that when the copper arsenic mixed concentrate contains 3.81% copper and 15.28% arsenic, the copper concentrate grade is 19.4%, arsenic content is 0.24%, copper recovery rate is 92.4%, arsenic concentrate grade is 18.6%, copper content is 0.35%, and arsenic recovery rate is 92%.
Great progress has also been made in the separation process of copper and arsenic in China. For example, in the weak acid medium of pH = 5-7.0, the sulfite lime method is used to suppress arsenopyrite and pyrite, and the selective methyl thiamine and ethyl xanthate are used to flotation copper minerals. When the original ore contains 0.7% arsenic, the arsenic content of copper concentrate is reduced by less than 0.3%, and the copper recovery rate and concentrate quality are improved. In Leiping mine, Chenzhou, Hunan Province, the arsenopyrite was restrained by lime method, which reduced the arsenic content of copper concentrate from more than 2% to less than 0.5%.