Major improvements highlight promising future for the lead smelter

The Mount Isa Mines Lead Smelter has undergone a $4 million upgrade to replace the main conveyor into the smelter and top floors of the Flux Tower that allows for an increase in processing product into the future.

There were a range of works as part of the structural improvements, including increasing the size of the C2 conveyor for additional future throughput, while improving chute design geometry to enhance the flow of material, and reduce blockages and bottlenecks.

Safety controls were engineered to significantly improve safety and occupational hygiene for our Lead Smelter operators. Access to the conveyor and chute system has been upgraded for our operators, with platforms installed throughout to enable them to gain better access for maintenance and reducing the need for manual handling.

The improved chute geometry reduces blockages which previously would have required an operator to manually unblock the chute.

Flooring has been installed under the entire length of the C2 conveyor to eliminate the risk of objects falling from the conveyor, which was a safety concern.

Dust collection devices have been installed on high emission points on the conveyor and transfer points to reduce airborne dust emissions and improve occupational hygiene for our operators.

Acting Manager Engineering, Nick Donker says out-of-the-box engineering was needed to come up with an installation method for the works, without needing an extended shutdown period.

“The conveyor was designed in three modular sections which were pre-built and fitted out prior to the shutdown period commencing,” says Nick.

“The new upper Flux Tower structure was built on the ground, and installed by a 250-tonne crane to safely lift the Flux Tower structure in just one lift, which was completed in about 12 hours, significantly reducing the period of high-risk works.”

“The initial concept was developed by Principal Engineer, Peter Woodall, with detailed design and execution by Mechanical Engineer, Dylan Lampard but would not have been possible without the valued input and teamwork from the operations, maintenance, electrical and engineering teams”.

“The $4 million project demonstrates to the workforce and the community that the Lead Smelter has a promising future with Mount Isa Mines,” says Nick.

“Glencore is committed to the long-term future of the Lead Smelter and is committed to improving the health and safety of our operators in the Lead Smelter.”

Role of the Lead Smelter

The smelting process takes the mineral rich concentrates produced by the zinc-lead concentrator and heats these in furnaces to burn off any remaining impurities.

Lead concentrate is mixed with high grade silica, limestone and copper slag. These ingredients are known as fluxes, and help to maintain the heat and chemical reactivity needed to separate the valuable lead content from the waste material within the lead concentrate.

The concentrate mixture is fed into our 30-metre long, three-metre wide sinter plant. A blast furnace heats the concentrate to 1,450 degrees Celsius, which 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 99.6 per cent pure lead bullion. Lead bullion is cast into 4.1-tonne blocks, railed to Townsville and shipped to Britannia Refined Metals in England for further refining and sale on the London Metal Exchange.

Flux Tower

The Flux Tower is the transfer point between C2 and C3 conveyor where there are a series of chutes and a vibrating screen. All dry product that enters the lead smelter passes through this transfer point.