Tomasz Chmielewski

The oxidation of Fe(II) in aqueous sulphuric acid under oxygen pressure

Abstract An experimental investigation is presented on the oxidation of Fe(II) in aqueous sulphuric acid under oxygen pressure. The effects of partial oxygen pressure, pO2, temperature and initial concentrations of H2SO4 and Cu(II) on the oxidation process rate have been determined within the ranges applied in a new hydrometallurgical process for copper recovery from its sulphide concentrates [13–16]. The Fe(II) oxidation reaction rate was found to be described by a second-order kinetic equation at a ferrous iron concentration exceeding 3–8 g/l: d[Fe(III)] d t =− d[Fe(II)] d t =κ[ Fe(II)] 2 p O 2 exp − 56.9 RT

Pressure leaching of a sulphide copper concentrate with simultaneous regeneration of the leaching agent

Abstract An experimental study is presented of leaching of a sulphide copper concentrate with aqueous ferric sulphate under oxygen pressure. The effects of oxygen pressure, sulphuric acid concentration and ferrous iron additions on the copper leaching rate have been determined. Partial pressure of oxygen has been found to govern the rate of copper leaching while the concentration of sulphuric acid only slightly influences this rate. Oxygen enhances the leaching rate mainly by oxidizing ferrous iron to ferric iron — the major leaching agent — and not by direct action on the minerals. Leaching of a sulphide copper concentrate under oxygen pressure with aqueous ferric sulphate leads to a three-fold reduction of both the necessary leaching time and ferric sulphate concentration in the leaching solution over those for conventional leaching with concentrated aqueous ferric sulphate.

Hydrometallurgy in Kghm Polska Miedz SA - Circumstances, Needs and Perspectives of Application

Systematically shrinking copper resources and remarkably declining copper ores grade leads to the growing role of hydrometallurgical processes in manufacturing copper and accompanying metals. Technical, economical, and ecological aspects of application of hydrometallurgy were discussed with regard to dominating smelting methods. Specific conditions of in the Polish copper industry were evaluated and important aspects of necessary application of hydrometallurgy at KGHM for more effective processing of copper ores and concentrates were indicated. The hydrometallurgical unit operations compulsory in unique conditions of Polish copper industry: high content of carbonates, decreasing content of Cu, and increasing content of Pb, As, and organic carbon were analyzed. Hydrometallurgy was recognized as the only real chance for more rational utilization of metal resources from the Polish copper deposits. The advantageous chemical and mineralogical composition of Polish copper ores and concentrates and easy access to sulphuric acid additionally substantiate the need for comprehensive research work.

The effect of contact of copper sulphide grains on the initial rate of leaching in oxygenated sulphuric acid solution

Abstract The initial stage of leaching of chalcocite, bornite, and chalcopyrite as well as chalcocite-chalcopyrite and bornite-chalcopyrite mixtures in oxygenated aqueous sulphuric acid was investigated at 368 K. It was determined that chalcopyrite accelerates the rate of copper leaching from chalcocite due to grain contact between chalcocite and chalcopyrite. In contrast, chalcopyrite decreases the rate of dissolution of bornite.

Electrochemical investigation on adsorption of potassium ethyl xanthane on galena

Abstract The voltammetric measurements on galena is potassium ethyl xanthate (KEtX) aqueous solutions have been conducted to establish the conditions od appearance of a peak responsible for the surface reaction between glena and EtX − ions. This peak was recorded at potentials much lower than equilibrium potential (E R ) calculated for the Pb(EtX) 2 formation in a bulk process (PbS + 2EtX − = Pb(EtX) 2 + S o + 2e − ). The adsorption potential E a and the value of its shift ( Δ E=0.12V) in relation to the equilibrium potential of Pb(EtX) 2 formation have been determined from positions of both anodic and cathodic peaks observed for the surface process. The value of ΔE corresponds to a free energy change which is equal to 2.77 kcal/mole (11.59 kJ/mol).

Pressure leaching of sulfide concentrate produced by Lubin Concentrator (KGHM “Polska Miedz” SA, Poland)

The rapidly declining quality of ores and concentrates produced by Lubin Concentrator (KGHM) makes the flotation concentrates exceptionally difficult-to-process by flash smelting. Currently, a hydrometallurgical process, using sulfuric acid with the presence of oxidants as a leaching medium, seems to be either a reasonable alternative or a complementary option to pyrometallurgy. The unique lithological, mineralogical and chemical properties of the concentrate were considered in a selection of the process route. Results of a pressure leaching of the copper sulfide concentrate from Lubin Concentrator (ZWR Lubin) with oxygenated aqueous H2SO4 solutions are presented. The effect of temperature from 120 to 200 °C, initial concentration of H2SO4 from 60 to 100 g/dm3, and oxygen partial pressure ranging from 0.5 to 2.0 MPa were investigated. The pressure leaching appeared to be an efficient process for recovering copper from the Lubin concentrate. At optimal leaching conditions (140 °C, 100 g/dm3 H2SO4, 1.0 MPa O2) 96% of Cu was extracted after 4 h.