Identification of Lignosulphonate By-products from Hydrometallurgical Processing of Vale's Voisey's Bay Ore and their Potential Mitigation

The proposal involves an investigation and analysis of lignosulphonate (LS) by-products which are formed during the hydrometallurgical (Hydromet) processing of nickel sulfide ore concentrate at Vale's Long Harbour plant in Newfoundland. The lignosulphonates are added to, and are involved in, two early stages of the hydromet process in order to preferentially bind and partially disperse elemental sulfur that is formed during the "Chlorine Preleach" and "Pressure Oxidation Preleach" processes. However the process also results in the LS undergoing undesired reactions which then produce by-products that are carried through to the next processing stage. These by-products result in decreased efficiency and economics of metal recoveries in subsequent stages. This is a collaboration between Vale's technical staff and the Chemistry Department of Memorial University to understand the chemical nature of these LS by-products present in representative samples collected from Vale's Hydromet pilot-plant facility with the objective of mitigating their unwanted effects.