A Pilot Optimisation of Sulphate Precipitation in the High-Density Sludge Process

摘要

High sulphate concentrations can cause issues both in a mine's process water recycle and for effluent discharge. This is the case for the Neves-Corvo mine in Portugal. A large study looked at control of sulphate and the part presented here details the optimisation of sulphate removal in the high-density sludge (HDS) process. The HDS process was operated at different pH setpoints, varying sludge recycle rates, and several different reactor retention times for three different water sources. An added step in the process was the addition of carbon dioxide to precipitate calcium carbonate and further minimise the gypsum saturation level. The tests defined optimal HDS conditions to provide improved feed conditions for nanofiltration or for non-scaling process water.