Rapid Atmospheric Leaching of Chalcopyrite Using a Novel Reagent of Trichloroisocyanuric Acid

With the decrease in high-grade chalcopyrite resources, the copper extraction from low-grade chalcopyrite has attracted more and more attention. However, the kinetic rates of chalcopyrite leaching with traditional oxidants are usually very slow due to the formation of the passivation layer. In this study, a novel reagent of chlorinated oxidant, trichloroisocyanuric acid (TCCA), was used to leach chalcopyrite for the first time. The experimental results showed that when the initial oxidant concentration for TCCA was 0.054 mol·L−1, the leaching temperature was kept at 55 °C, and the pH of the pulp was controlled at 1, the oxidation efficiency of Cu can reach above 90% in less than 30 min. Various analyses of chalcopyrite mineral ore and its oxidized residues, such as chemical composition analysis, X-ray diffraction analysis, scanning electron microscopy analysis and X-ray photoelectron spectroscopy, were conducted, respectively. No obvious passivation layer was found on the chalcopyrite surface, though the sulfur product can also be generated during the leaching. Reaction kinetic analysis results showed that the different influence of surface reaction and diffusion process on the dissolution of chalcopyrite is little due to the fast leaching speed. After calculation, the activation energy of the whole leaching reaction is 9.06 kJ·mol−1, much lower than that in other reports. The mechanism was also proposed that TCCA was hydrolyzed in the solution to form hypochlorous acid, which is the strong oxidant, and cyanuric acid, which prevents the formation of a passivation layer. The processing in this study is expected to be applied as a novel method for atmospheric leaching of chalcopyrite.

Processing of gold-antimony concentrates

This paper describes the results of a study that looked at processing of goldantimony concentrates with selective extraction of antimony and gold as commodities. The common global practice of processing antimony sulphide concentrates (20–30% Sb) is based on alkaline sulphide leaching followed by precipitation of metallic antimony by electrowinning. However, application of this technique to process sulphide concentrates that, apart from antimony, also contain gold, can be difficult as, together with antimony, up to 10–15% of gold can leach to the solution. It takes a special process during final refining of cathode antimony to recover that gold. This paper describes a process that involves two stages of atmospheric leaching of antimony. The gold that leached to the solution is precipitated with zinc after the first stage of antimony leaching. Together with atmospheric leach tailings, it then goes to the pressure oxidation unit. This process helps oxidize the rest of the sulphides and release refractory gold. The resultant cake is processed following a standard sorption cyanidation technique. The paper looks at the antimony leaching rate and the rate at which gold leaches to the solution during this process. The paper describes the results of selective precipitation of gold from gold-antimony solutions and highlights certain features of this process. A series of tests was conducted to test the techniques of pressure oxidation of atmospheric leach tailings and cyanidation of the residue. The paper also describes a process that was developed for processing of goldantimony concentrates and precipitation of antimony and gold. An antimony recovery exceeding 90–95% can be achieved when using this process. At the same time, the percent of dissolved gold can be reduced from 10–15 tо 1–3%.

Processing technology for carbonate ore from the Argun deposit

Priargun Mining and Chemical Association has been producing uranium in the Streltsov ore field for more than 50 years. The main ore bodies with high content of uranium have been mined out during this period of time, and the uranium content has dropped in ore which is currently extracted. In connection with this, appraisal of the mineral resources and mineral reserves of Priargun MCA has been accomplished. The Argun ore is composed of a few process types—iron silicate and uranium, silicate–uranium–molybdenum, carbonate and uranium, carbonate and molybdenum, carbonate–uranium–molybdenum and rebellious ore (contains zirconium and brannerite). It is required to undertake technology-based rating and certification of the Argun ore. The autoclave leaching technology is found to be higher economically efficient as against the atmospheric leaching technology due to lower operating expenses. From the preliminary studies, four samples of anion-exchange resins are recommended for further testing: A500Y, BM77-14, D299 and Ambersep 920UXL SO4. These ion-exchangers were used to analyze their influence on sorption–desorption of uranium and molybdenum. All these ion exchangers had preserved their sorption capacity in 10 sorption–desorption cycles. Based on the studies into adsorption of uranium and molybdenum from leached slurry at the Argun deposit, the optimal sorbent for extraction and separation of uranium and molybdenum is Ambersep 920UXL SO4. Producibility of natural uranium to meet ASTM C 967-13 standards is analyzed on a laboratory scale. The produced uranium concentrate contains much less impurities than it is stipulated by International Standard Specification ASTM С 967-13. The action chart of processing of carbonate ore from the Argun and Zherlovoe deposits is developed and economically justified.

Review of the past, present, and future of the hydrometallurgical production of nickel and cobalt from lateritic ores

Laterite ores are becoming the most important global source of nickel and cobalt. Pyrometallurgical processing of the laterites is still a dominant technology, but the share of nickel and cobalt produced by the application of various hydrometallurgical technologies is increasing. Hydrometallurgy is a less energy-demanding process, resulting in lower operational costs and environmental impacts. This review covers past technologies for hydrometallurgical processing of nickel and cobalt (Caron), current technologies (high-pressure acid leaching, atmospheric leaching, heap leaching), developing technologies (Direct nickel, Neomet) as well as prospective biotechnologies (Ferredox process).