Improvements in Autoclave Availability at Vale’s Long Harbour Refinery

Abstract

Vale base metals started operating the Long Harbour Refinery in 2014 using a novel hydrometallurgical process (Reference Derek Kerfoot, US patent 6,428,604) to produce high-purity electrolytic nickel, cobalt, and copper, from the (nickel sulphide concentrate produced at the mining operation at Voisey’s Bay. Over the years, many challenges were successfully overcome. A particular area for attention was the pressure leaching circuit, where difficulties with plugging and corrosion of the autoclave discharge dip tubes were frequent. The regular plugging and corrosion of these dip tubes resulted in reduced autoclave availability. In collaboration with Caldera Engineering, supplier of dip tubes, a non-metallic liner was developed and proved successful in addressing the operational difficulties. This improvement resulted in a reduction of unplanned downtime, lower replacement costs, and increased safety. This paper reviews the evolution from problem to solution over the past 5 years of operation.