Microwave Testing of Bulk Copper-Nickel Concentrates from the Duluth Complex

Abstract

EM Technologies Inc. (EMR), a subsidiary of EMR Technologies Corporation of Fredericton, New Brunswick, Canada, has developed a process to treat sulfide ores using microwave heating in a controlled atmosphere fluidized bed. The controlled atmosphere is designed to convert the sulfur in the sulfide minerals to elemental sulfur and thereby, eliminate the production of sulfur dioxide. In addition, the capital costs are estimated by EMR to be significantly lower than pressure oxidation. The Minnesota Department of Natural Resources (MNDNR), through the Minerals Coordinating Committee (MCC), sponsored preliminary testing of this process on some bulk flotation concentrates produced from copper-nickel mineralization from the Babbitt deposit in the Duluth Complex (Benner et al., 1998). Mr. George Glumac (private consultant who made the original proposal to MCC) monitored the test work at EMR, the Natural Resources Research Institute (NRRI) handled project administration, and the Coleraine Minerals Research Laboratory (CMRL) supplied the sample and critiqued EMR's report. Since the mid-1990s, CMRL has been evaluating methods of processing the copper-nickel bearing material from the Duluth Complex. Research to date has shown that flotation can produce a bulk sulfide concentrate containing about 2% of the weight, 90% of the nickel, and 60% of the total nickel. Pressure oxidation leaching of this bulk concentrate can extract over 99% of both the copper and nickel.