More than 40% increase in output of copper since installing ISASMELT™

The Mount Isa Mines Copper ISASMELT™ treats more than 1,100,000 tonnes of copper bearing feed per year. Mount Isa concentrate and purchased concentrates are mixed and stored in a blending plant. The concentrates are mixed with fluxes, reverts and some lump coal, and pelletised in a disc pelletiser, prior to being fed to the ISASMELT™ furnace. Bath temperature is controlled using a mixture of natural gas and lump coal. Process air is enriched to 60-65% oxygen content. The furnace produces a copper matte with a copper content of 60%, which is tapped together with the slag into a rotary holding furnace for separation.

The refractory bricks used to line the furnace shell are high grade magnesite chrome and have no water cooling applied to them. The furnace can run for about 3 years before any refractory repair is required. A shutdown lasting 3-4 weeks is used to replace worn refractory at this time. Replacement of the refractory is simple, given the shape of the furnace. The vertical cylinder can be bricked dry without mortar, allowing very tight tolerances to be achieved. It can be bricked very quickly using minimal personnel. This long furnace life has been achieved with the development of advanced control systems that ensure smooth operation of the furnace.

Offgases from the ISASMELT™ furnace pass into a waste heat boiler, prior to passing into an electrostatic precipitator for cleaning. The cleaned gases pass to a sulphuric acid plant for capture of sulphur.