Electrochemical dissolution of synthetic heazlewoodite (Ni3S2)
Jari Aromaa 1  
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Aalto University
Jari Aromaa   

Aalto University, Department of Materials Science and Engineering, PO Box 16200, FIN-00076 Aalto, Finland
Publication date: 2011-01-01
Physicochem. Probl. Miner. Process. 2011;46(1):51–64
The aim of the study was to examine the dissolution kinetics of synthetic heazlewoodite and the formation of elemental sulfur by electrochemical methods. Anodic polarisation curves, potentiostatic measurements and cyclic voltammetry were carried out in 1 N sulfuric acid at temperature 25°C. The anodic dissolution of heazlewoodite procceds in two stages. At potentials below 600 mV vs. SCE heazlewoodite is only converted to higher sulfides such as millerite NiS. At higher potential the reaction products dissolve forming first other sulfides and elemental sulfur and later other sulfides, elemental sulfur and sulfate. The percentage of sulfides in the reaction products was high even at high potentials. The formation of elemental sulfur was not seen to hinder dissolution of the sulfide. The part of sulfur oxidized to sulfate increased with increasing potential. Up to 900 mV only elemental sulfur was formed, at 1000 mV 10% of sulfur was oxidized to sulfate and at 1600 mV 90% of the sulfur was sulfate.