Search

The use of a strongly acidic Dowex G-26 cation-exchange resin for the recovery of copper from synthetic sulphate solutions of low copper concentration (0.5-0.7 g/l) which is similar to the chemical and mechanical polishing waste effluent of the electronics industry is described. Copper adsorption from the solution was complete (99.6%) in a 14-min contact time for an aqueous:resin ratio of 100 ml/g and at an equilibrium pH value of 2.5. Copper adsorption data were found to follow a Langmuir isotherm with kinetic studies demonstrating a second-order reaction rate. Changes in the resin after adsorption of copper were identified by comparison of the Fourier transform infrared spectra of activated and copper-loaded resins. Copper (99.7%) could be eluted from the copper-loaded resin using 10% sulphuric acid at an aqueous:resin ratio of 25 and a contact time of 20 min to furnish a copper-enriched solution. A process flowsheet for the recovery of copper from waste solutions is proposed., The use of a strongly acidic Dowex G-26 cation-exchange resin for the recovery of copper from synthetic sulphate solutions of low copper concentration (0.5-0.7 g/l) which is similar to the chemical and mechanical polishing waste effluent of the electronics industry is described. Copper adsorption from the solution was complete (99.6%) in a 14-min contact time for an aqueous:resin ratio of 100 ml/g and at an equilibrium pH value of 2.5. Copper adsorption data were found to follow a Langmuir isotherm with kinetic studies demonstrating a second-order reaction rate. Changes in the resin after adsorption of copper were identified by comparison of the Fourier transform infrared spectra of activated and copper-loaded resins. Copper (99.7%) could be eluted from the copper-loaded resin using 10% sulphuric acid at an aqueous:resin ratio of 25 and a contact time of 20 min to furnish a copper-enriched solution. A process flowsheet for the recovery of copper from waste solutions is proposed.

Methods are discussed for improving the leaching rates of chalcopyrite with reference to the model developed by Hiroyoshi et al, which suggests that a zone of rapid leaching exists between the critical potential E(c), the equilibrium redox potential for the reduction of CuFeS2 to Cu2S, and the oxidation potential E(ox), the equilibrium redox potential for the oxidation of Cu2S. Leaching tests were carried out in chloride, sulphate and mixed solutions using a chalcopyrite concentrate from the Omine mine in Japan. The results showed that the leaching rate in hydrochloric acid solution was the fastest and that the relationship between the Cu leaching rate and oxidation-reduction potential followed Hiroyoshi’s model. Thermodynamic calculations indicated that increasing the chloride concentration resulted in an increase in the concentration of cuprous ions due to the formation of chlorocuprate(I) complex ions, and the contribution of cuprous ions to the critical potential is greater than that of cupric ions even though the concentration of cuprous ions is lower. This suggests that the formation of chlorocuprate(l) ions in a chloride solution may improve the chalcopyrite leaching rate by increasing the critical potential., Methods are discussed for improving the leaching rates of chalcopyrite with reference to the model developed by Hiroyoshi et al, which suggests that a zone of rapid leaching exists between the critical potential E(c), the equilibrium redox potential for the reduction of CuFeS2 to Cu2S, and the oxidation potential E(ox), the equilibrium redox potential for the oxidation of Cu2S. Leaching tests were carried out in chloride, sulphate and mixed solutions using a chalcopyrite concentrate from the Omine mine in Japan. The results showed that the leaching rate in hydrochloric acid solution was the fastest and that the relationship between the Cu leaching rate and oxidation-reduction potential followed Hiroyoshi’s model. Thermodynamic calculations indicated that increasing the chloride concentration resulted in an increase in the concentration of cuprous ions due to the formation of chlorocuprate(I) complex ions, and the contribution of cuprous ions to the critical potential is greater than that of cupric ions even though the concentration of cuprous ions is lower. This suggests that the formation of chlorocuprate(l) ions in a chloride solution may improve the chalcopyrite leaching rate by increasing the critical potential.

The use of Acidithiobacillus ferrooxidans was investigated to reduce the pH and metal concentrations in wastewater with high concentrations of Cr, Ni and Li. Samples of a 9 K medium with different metal concentrations were treated and the oxidation ratio of Fe2+ ions measured to study the activity of the bacteria. In the treatment of synthetic wastewater the presence of Cr and Ni ions at concentrations of 8 000 and 13 000 g/m3, respectively, did not inhibit bacterial activity, while the oxidation ratio of Fe2+ ions was low when Li ions were present at a concentration at 5 000 g/m3, indicating that the Li ions suppressed bacterial activity. In the treatment of actual wastewater containing Cr, Ni and Li, the Fe2+/Fe3+oxidation ratio was low and the Fe concentration and pH were reduced to 21.633 g/m3 and 1.8, respectively. The results confirm that the wastewater can be treated effectively for recycling to the spent battery treatment process., The use of Acidithiobacillus ferrooxidans was investigated to reduce the pH and metal concentrations in wastewater with high concentrations of Cr, Ni and Li. Samples of a 9 K medium with different metal concentrations were treated and the oxidation ratio of Fe2+ ions measured to study the activity of the bacteria. In the treatment of synthetic wastewater the presence of Cr and Ni ions at concentrations of 8 000 and 13 000 g/m3, respectively, did not inhibit bacterial activity, while the oxidation ratio of Fe2+ ions was low when Li ions were present at a concentration at 5 000 g/m3, indicating that the Li ions suppressed bacterial activity. In the treatment of actual wastewater containing Cr, Ni and Li, the Fe2+/Fe3+oxidation ratio was low and the Fe concentration and pH were reduced to 21.633 g/m3 and 1.8, respectively. The results confirm that the wastewater can be treated effectively for recycling to the spent battery treatment process.