Abstract: The invention relates to a method of providing an electric current taker made from silver and having a highly electroconductive contact surface into an aluminium support bar to be used in electrolysis.

Abstract: The process uses hydrochloric acid solutions to extract zinc from electric arc furnace dusts containing zinc oxide and zinc ferrite. To selectively leach zinc and minimize iron dissolution by precipitating as FeO.OH and Fe2O3, hot acid leaching with the aqueous solution containing 37 g/l-74 g/l HCl and 104 g/l-270 g/l ZnCl2 is used. New dust is introduced to remove iron from the filtrate of the hot acid leaching. The zinc chloride solutions purified by activated carbon and metallic zinc powder is electrolysed in electrowinning cells which had cation exchange membrane to produce high purity zinc metal and to regenerate hydrochloric acid. Electrolysing an aqueous solution of zinc chloride with Zn concentration of 50-130 g/litre below 40° C. in a cell divided by cation exchange membrane, whereby coherent zinc is yielded at the cathode with high current efficiency of exceeding 90%. HCl is directly regenerated with a very small loss below 2% and low energy consumption below 5.

Abstract: A process for the extraction of precious metals from a copper sulphide ore or concentrate, by treating a leach residue of the ore or concentrate, includes the steps of removing elemental sulphur from the leach residue to obtain a low sulphur residue and subjecting the low sulphur residue to an oxidative leach at elevated temperature and pressure to oxidize sulphur and precious metal compounds present in the low sulphur residue to produce a residue for the extraction of the precious metals therefrom.