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

The Mineral Resource estimates for X41 and Enterprise were updated and depleted. The Resource model update for X41 increased the tonnage by 0.8Mt. Enterprise tonnage decreased by 0.1Mt. The Mineral Resources were depleted by 3.7Mt and 2.9Mt respectively, including both mining and sterilisation.

Mining depletion, sterilisation and changes to mine design amounted to a net 0.4Mt increase in the X41 and 2.4Mt decrease in the Enterprise Ore Reserves.

Mount Isa Open pit:
Copper mineralisation occurs generally as breccia hosted massive to disseminated copper minerals in “silica dolomite” altered pyritic dolomitic siltstone. The copper mineralisation consists primarily of chalcopyrite, the remainder being oxidised or partially oxidised, with a minor amount of supergene chalcocite mineralisation. The 2019 Mineral Resource is reported inside an optimised pit shell using a cut-off grade of 0.5% Cu.

Black Rock Cave:
Copper mineralisation occurs generally within a Chalcocite Zone that lies above the Leached Primary material. The zone is interpreted to lie outside of the SilicaDolomite alteration. Reinterpretation and estimation of the Black Rock Cave Resource during 2019 resulted in a 0.6Mt increase in the Resource. This Resource is reported using a cut-off grade of 2.0% Cu.

The Black Rock Cave reserves increased by 0.3Mt as a result of changes to mine designs and optimisation of production plans.

The underground life of mine estimate for the X41, Enterprise, and the Black Rock Cave is 4 years (2023) with the tenements due to expire in 17 years (2035).

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 c ........