X41 Copper Mine, Enterprise Copper Mine.
Mineralisation occurs generally as breccia hosted massive to disseminated chalcopyrite in “silica dolomite” altered pyritic dolomitic siltstone.

Mount Isa Open Pit.
Copper mineralisation occurs generally as breccia hosted massive to disseminated copper minerals in “silica dolomite” altered pyritic dolomitic siltstone. Approximately half of the Mineral Resources are defined by primary chalcopyrite, the remainder being oxidised or partially oxidised, with a minor amount of supergene chalcocite mineralisation.

Copper ore is mined in the X41 and Enterprise underground mines using traditional sub-level open stoping methods. Once the ore is loosened by drilling and blasting, it is mucked, crushed and hauled to the surface where it is put through the concentrating process.

Copper ore is mined in the 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 the concentrator’s flotation circuit. The reagents help 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.

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 the smelter stack for conversion into sulphuric acid, used in crop fertilisers. During smelting the molten material is separated into matte and slag.

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 slag is reprocessed, but matte is transferred to the converters, where blister copper is produced. This blister copper is transferred to the Anode Furnace for refining into 99.7% pure Anode Copper. The molten copper is cast into moulds to produce Copper Anodes. The copper anodes, which weigh approximately 350 kilograms each, are transported to the Glencore’s copper refinery in Townsville for refining to 99.9% pure premium cathode copper.

Ore mined is roughly crushed on site, then trucked to the Mount Isa mills for processing. First, the ore is ground into a fine dust via a series of ball mills. This dust is then mixed with water and reagents in our zinc-lead concentrator’s flotation circuit. The reagents help us to separate the valuable mineral content from waste rock. Air is forced through the slurry creating bubbles, which float to the surface and attract and bind to the zinc or lead particles. The glossy, mineral-laden “froth” is then skimmed off the top and dried. What remains once the water content of the froth has evaporated is zinc or lead concentrate. The zinc concentrates are sold in the domestic market and exported overseas, while our lead concentrate undergoes further processing and smelting on site to become crude lead, or lead bullion.

Lead concentrate is mixed with high grade silica, limestone and copper slag, a by product of our copper smelting operations. These ingredients are known as fluxes, and help us to maintain the heat and chemical reactivity required to separate the valuable lead content from the waste material within the lead concentrate.

The concentrate mixture is fed into our sinter plant, then a blast furnace heats the concentrate to 1,450 degrees Celsius. This process melts the concentrate into liquid, separating and drawing out impurities leaving only crude lead.

Liquid crude lead is poured and left to settle in one of six, 100 tonne kettles. As it cools, the heavy molten lead with its relatively low melting point sinks to the bottom of the kettle. The lighter impurities float to the surface and begin to solidify, where they’re scooped off. What remains is lead bullion. Lead bullion is railed to Townsville then shipped to Britannia Refined Metals in England for further refining and sale on the London Metal Exchange.

A by-product of the mining and processing operations, silver is extracted from the lead bullion blocks after export to our Britannia Refined Metals Facility in England for further refining. Approximately 10 kilograms of silver is contained in each lead block.