Copper ore is mined in our X41 and Enterprise underground mines, where it is roughly crushed, then hoisted to the surface for processing. From here, it is fed through a series of ball mills that grind the rock into a fine dust.
This dust is then mixed with water and reagents in our concentrator's flotation circuit. The reagents help us to separate the valuable mineral content from waste rock and iron sulphide particles like pyrite – or "fools gold". Air is forced through the slurry creating bubbles, which float to the surface and attract and bind to the copper particles. The glossy, mineral-laden "froth" is then skimmed off the top and dried. The greenish powder that remains once the water content of the froth has evaporated is copper concentrate. But it's not pure copper yet, it's a copper iron sulphide, made up of about 35 per cent pure copper. Now, it's ready for smelting.
Copper concentrate is fed into the ISASMELT furnace, where it is heated to 1185 degrees Celsius. This process melts the concentrate into liquid, drawing out impurities and releasing sulfur dioxide gas, which is captured and piped to the Incitec Pivot Acid Plant adjacent to our smelter stack for conversion into sulphuric acid, used in crop fertilisers.
The molten copper concentrate is then tapped into two holding furnaces, which maintain the temperature and allow the mixture to settle. The heavy copper content sinks to the bottom of the furnace while the slag, or waste material, floats to the top and is siphoned off. This slag is then processed again, as it can still contain up to six per cent copper.
The copper left at the bottom of the holding furnace is fed through two more furnaces for further refining, where it is heated to temperatures of up to 1250 degrees Celsius. What's left is 99.7 per cent pure, molten copper. This glowing, golden substance is then poured into a cast to set into a 350 kilogram copper anode slab. The anode slabs are then loaded onto trains bound for our Townsville Copper Refinery, where they undergo further refining into 99.995 per cent pure copper cathode. Copper cathode is then exported overseas via Glencore'sTownsville Port facility.