ENGINEERING DESIGN FOR A FERRIC-CHLORIDE LEACHING PLANT TO LEACH COMPLEX BASE-METAL SULFIDES

Neill and Gunter limited (NGL) has prepared a preliminary design and a cost estimate fora ferric chloride leach plant to recover copper, lea d, zinc, and silver from a typical complex sulphide ore. This plant de sign is specifically intended to treat unconcentrated ground ore (flot ation feed), but can be readily adapted to treat bulk concentrates. Sa mples of ground ore and bulk concentrate were obtained from Heath Stee le Mines, Miramichi, New Brunswick, laboratory testing, and preliminar y process flow sheet preparation was carried out by the Research and P roductivity Council in Fredericton, New Brunswick. Approximately thirt y drawings have been produced, including process and equipment flowshe ets, process piping and instrumentation drawings, and preliminary gene ral arrangements. Preliminary capital and operating cost estimates wer e prepared for a plant that would treat 1000 t/d of crushed and ground ore to produce about 30 000 tpy of zinc. Capital and operating cost e stimates were also projected for plants up to 4000 t/d of processed or e. Recoveries of 99% for zinc, 98% for lead, and 96% for copper were a chieved in laboratory tests on unconcentrated ore. These recoveries we re higher than the overall recoveries obtained from bulk concentrate, yielding approximately 10% more revenue. A 1000 tonne per day plant wa s determined to have a low return on investment, however, depending on the size and type of mining operations employed and the FCL plant thr oughput. DCF-ROI projections of 20% to over 30% were calculated for 10 0% equity financed ''green field'' mine, mill and FCL plant operations of 2000 t/d and higher.