ELECTROLYSIS OF GRANULATED COPPER-NICKEL MATTE

Abstract

The paper justifies the method of processing sulfide-metal melts including their granulation and subsequent electrolysis of granules. High-speed crystallization ensures ultrafine structure formation and stabilizes non-stoichiometric high-temperature phases leading to an increase in the reactivity of granules during subsequent hydrometallurgical processing. Copper powder was isolated at the cathode, and sulfur-sulfide slime (NiS–Сu9S5–Cu7S4–S) was isolated at the anode in a sulfuric acid solution during the electrolysis of granular copper-nickel matte (Cu : Ni = 1 : 1). The influence of current density and process duration on electrolysis parameters and the quality of copper powder isolated was estimated. Sulfur sulfide slime (containing more than 50 % sulfur) forms a passivation layer on granule surfaces, which prevents reagent feeding and reaction product removal from the interaction zone. Anodic current density of up to 100 A/m2 ensures metal conversion into a solution and copper powder (PMS-1 grade) formation at the cathode. Powder is represented by 1 to 100 μm particles of dendritic and fragmented shapes. High-quality copper powder isolation was achieved when saturating electrolyte with nickel to 28,0 g/dm3 . In this case, anode efficiency was 37 % with respect to sulfur, and cathode efficiency was 92,8 % for copper. The process is recommended for copper and nickel separation when processing sulfide-metal alloys. Copper content of in the solution during electrolysis ranged from 0,4 to 2,0 g/dm3.