Papers by Keyword: Pressure Leaching

Abstract: Autoclave oxidative leaching is one of the most promising hydrometallurgical approaches for copper suplhide materials processing. In previous studies [2–4], the possibility of an efficient autoclave treatment of chalcopyrite concentrate was confirmed. The concentrate has the following chemical composition, %: 21.5 Cu, 0.1 Zn, 26.5 S, 24.5 Fe, 0.05 Pb, 0.04 Ni, 16.2 SiO₂ [1]. At high temperature conditions (190–200 °C; 4–6 bar) in sulfuric-acid media during 100–120 min about 98% Cu was extracted. A leaching residue after POX (POX-cake) contained the following compounds, %: 55 Fe₂O₃, 40 SiO₂, 4 MeS₂/MeS. Current paper presents the results on purification of POX-cakes from iron by autoclave treatment. Futher ways for by-products (SiO₂-cake and FeSO₄-solution) processing are sugested.

Abstract: Ural enrichment plants processing copper-porphyry deposits are produced chalcopyrite concentrates of the following chemical composition, %: 21.5 Cu, 0.1 Zn, 26.59 S, 24.52 Fe, 0.05 Pb, 0.04 Ni, 16.28 SiO₂ [1]. According to previous studies [2, 3, 21], such concentrates can be effectively treated using pressure oxidative leaching (POX). At temperature of 190–200 °C, partial oxygen pressure 4–6 bar and [H₂SO₄] = 15–30 g / L during 100-120 min about 98 % Cu was extracted. In this paper, an inluence of chalcopyrite concentrate preliminary grinding on efficiency of the POX stage was studied. It was found that even the finest grinding of the particle size class P₈₀ = 13 μm does not lead to significant intensification of process kinetics.

Abstract: This paper is describing an investigation of sodium lingo-sulfonate and sodium dodecyl-sulfate mixtures influence on zinc concentrates high temperature oxidative pressure leaching and zinc electro-winning. For this purpose, surfactants concentration at leaching tests was varied from 200 to 800 mg∙l^-1. It was established that the maximum zinc extraction (99 %) at leaching was achieved in the presence of mixture containing 800 mg∙l^-1 lignosulfonate and 200 mg∙l^-1 sodium dodecyl-sulfate. Therefore, this mixture can be recommended for high temperature oxidative pressure leaching of zinc concentrates. Sulfur-sulfide pellets formation also was observed at a low lingo-sulfonate concentration (200 mg∙l^-1) in a mixture with sodium dodecyl-sulfate. This phenomenon can lead to emergency shut down of autoclave. It was observed that the mixture usage of 800 mg∙l^-1 lignosulfonate and 200 mg∙l^-1 sodium dodecyl-sulfate had no significant impact on zinc current efficiency, it was in the rage of 92-93 %. The mixture usage of 200 mg∙l^-1 lignosulfonate and 600 mg∙l^-1 sodium dodecyl-sulfate allowed to increase current efficiency up to 95 %. Increasing sodium dodecyl-sulfate concentration in mixtures with lignosulfonates leads to decrease of current efficiency, to formation of deep pores and defects on cathode zinc surface.

Abstract: This article presents a study of Tomtor rare earth ore decomposition. This material contains a lot of valuable components such as REE and niobium (mas., %: 12,8 ΣREO (rare earth oxides), 0.039 Sc, 18.4 P₂O₅, 9.9 Fe, 9.0 Al, 0.24 ThO₂, 8.2 Nb₂O₅). The study aims to find efficient ways of processing this deposit. Technologies using the sulfuric acid as the main reagent to leach are described in this article. Investigation has three trends. The first trend is agitation leaching at low sulfuric acid concentrations, temperatures up to 95 °C and atmospheric pressure. The second trend is pressure leaching at low sulfuric acid concentrations, high temperatures (up to 180 °C) and high pressure. The third trend is high temperature sulfatization with concentrated sulfuric acid at elevated temperature (up to 180 °C) and atmospheric pressure followed by aqueous leaching. The dependence of target components (rare earth elements, scandium, phosphorus) and the impurity (iron, aluminum, thorium) extractions into solution from major factors was studied.

Abstract: This paper is describing an investigation of surfactants influence on zinc sulfide wetting by non-polar liquids and sphalerite concentrates pressure leaching parameters. Zinc sulfide preferential wettability by oil was tested in presence anionic surfactants with different chemical structures. Interfacial tension was determinated by the maximum liquid drop volume method. It allows to determine surfactant potential effectivity on pressure leaching of sphalerite concentrate. It is found that SDBS decreases zinc sulfide wettability by non-polar liquids in a greater degree than SDS and Ls. Combined addition of Ls and SDBS allowed to receive residues with optimal coarseness, eliminate pellet formation and increase zinc extraction.

Abstract: This paper describes an investigation of the surfactant influence on zinc sulfide wetting and the pressure leaching of zinc concentrates. For this, a variety of anionic and cationic surfactants with different chemical structures were tested. The methodology for mineral preferential wettability determination via establishing correlation between the spreading coefficients was proposed. It allows determining the surfactant potential efficiency. The influence of contrastively functional reagents on zinc concentrate pressure leaching was reviewed. It is found that simultaneous usage of stabilizers and dispersing agents allows enhancing zinc extraction, eliminating pellet formation at lower reagent consumptions. The beneficial effect of surfactant mixture was seen through the increased zinc sulfide wetting by solution and colloid protection of sulfur particles via solvate-adsorption and structural factor of stabilization. The optimal composition of surfactant mixture was proposed and allowed to extract 95 % of zinc along with pellet formation elimination.

Abstract: A limonitic laterite ore from Indonesea was treated by pressure leaching in H₂SO₄-Mg(NO₃)₂ medium, using Mg(NO₃)₂ as an oxidant. Experiments were conducted in order to determine the optimum conditions by studying various parameters, including Mg(NO₃)₂/ore mass ratio, initial acidity, reaction temperature, holding time and liquid/solid ratio. Pressure leaching experiments showed that nickel, cobalt and iron extractions were 90.8 %, 91.9 % and 2.1 % after 60 min of leaching at 493 K with 0.06 g/g Mg(NO₃)₂/ore mass ratio, 140 g/L initial acidity and 2 mL/g liquid/solid ratio.The total decrement of acid consumption was 72 g H₂SO₄/kg ore in the presence of Mg(NO₃)₂.

Abstract: A laboratory-scale method for treating bulk concentrate for reclaiming lead and silver was developed utilizing new hydrometallurgical technology as an alternative to the traditional pyrometallurgical processing. The condition experiments of every chief segment in the whole flowsheet have been systematically investigated, and then the whole hydrometallurgical processing flowsheet was determined. The main contents are followed as: Bulk concentrate was treated using pressure leaching in autoclave, the optimal leaching conditions were determined. The elemental sulphur was deprived from the pressure leaching residue using flotation-distillation. Carbonate conversion -silicofluoric acid leaching on flotation gangue containing lead sulfate using hydrometallurgy was carried. And Leaching silver using thiourea from the residue was carried after extracting lead. Through the whole hydrometallurgy flowsheet, the reclaiming of lead and silver was actualized.

Abstract: In this paper, removal of iron from metallurgical grade silicon with pressure leaching is carried out. We investigated the factors such as the concentration of hydrochloric, particle size of raw material ground, temperature, pressure and reaction time, which influenced on the removal of iron. The results show that the optimum operating conditions for pressure leaching in hydrochloride are: acid concentration 4 mol/L, diameter for raw material less than 50 μm, leaching temperature 160 0C，leaching pressure 2.0 MPa, leaching time 2.0 h. The content of iron residual in MG-Si powder was reduced to about 200 ppmw. The removal efficiency of iron is up to 90.90 %.