National University of Sciences and Technology “MISiS”, Moscow, Russia:

D. O. Ignatov, Graduate student, Department of Non-Ferrous Metals and Gold
A. A. Kayumov, Post-graduate student, Department of Benefication and Processing of Minerals and Technogenic Raw Materials
V. A. Ignatkina, Professor, Department of Benefication and Processing of Minerals and Technogenic Raw Materials, e-mail: woda@mail.ru

The tendency of increasing the content of arsenic in the form of sulfides as copper — tennantite (Cu₁₂As₄S₁₃), enargite (Cu₃AsS₄), tetrahedrite (Cu₁₂Sb₄S₁₃), and gold arsenopyrite (FeAsS), pyrite (FeS₂) in copper and gold ores reduces the quality of product concentrates, increases the technogenic burden on the ecology of metallurgical regions. The search for reagent regimes that increase the contrast of the technological properties of the separated sulphides is an urgent task. The flotation of monomineralic fractions of tennantite, arsenopyrite, and pyrite was investigated with the aim of separating them using the combinations of sulfhydryl collectors — butyl xanthate (ButKx), diisobutyl dithiophosphate (DTF) with isopropyl-O-methyl-N-thionocarbamate (ITC) in the pH range from 4 to 12.5 and controlled AFP. The concentration of sulfhydryl collectors in the experiments was 10^–4 mol/l. The acidity of the medium was created by H₂SO₄ and Ca(OH)₂. The increased flotation activity of arsenic-containing DTF minerals is experimentally shown both individually and in mixture with ITC in a weakly acid medium (pH 4–6). The recovery of FeAsS and Cu₁₂As₄S₁₃ with DTF is higher than with ButKh. Individually, the ITC practically does not flotate iron sulphides. The recovery of tennantite is four times higher than that of iron sulfides. The recovery of arsenopyrite DTF and ButKx in combination with ITC is lower than when they are used individually. The highest recovery was established with a ITC fraction in a mixture of 50% in the pH range of 4–7.5, which corresponds to Eh of 90–80 mV. The flotation activity of tennantite is maximal at an ITC fraction of 70–80% in combination with DTF at a pH of 6–9. Low flotation activity of pyrite is observed with a ITC fraction of 60–70% in a mixture with DTF in the pH range 4–12. The greatest recovery was obtained with the ratio of ITC: DTP = 75:25 and pH in the range 4–10, Eh fluctuated from 130 to 115 mV. The flotation activity of the investigated sulfides is reduced in the region of pH 12 or more (negative range of Eh values is 10–70 mV) at any ratio of collectors. The obtained experimental results are of practical value in the selection of the collector composition for increasing the contrast of the flotation activity of pyrite, arsenopyrite and tennantite.

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