Around for the long haul - Kress Slag Pot Carriers

Bearing an uncanny resemblance to a mechanised grasshopper, Kress Haulers perform one of the most critical roles at Mount Isa Mines’ Copper Smelter.

Kress Slag Pot Carriers, known around site simply as 'Kress Haulers', have a unique and compact U-frame design and fully articulated steering system for excellent maneuverability to enable them to operate safely in close proximity to our smelter operations.

Kress Haulers incorporate a single cab to house the operator and stand 4.4 metres high, are 9.85 metres long and 5.7 metres wide at the back to accommodate carrying the slag pot.

They carry pots of molten slag which when filled weigh between 75 to 80 tonnes and transport it from the various furnaces at the Copper Smelter to holding dams where it’s cooled and stored for possible re-use in the smelting process.

Mount Isa Mines Manager Surface Operations Istvan Torok says Kress Haulers are specialised vehicles which perform a high-risk activity combining molten metal and mobile equipment operations.

“Kress Haulers use positive hydraulic control to tip the molten slag safely into the holding dams and have a unique ‘pot knock’ or deskulling system to dislodge all the remaining slag from the pot,” Istvan says.

Slag is a by-product of the smelting process. After copper concentrate is fed into the ISASMELT™ furnace it is heated to 1,185 degrees Celsius where it is converted to molten liquid.

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. Once removed, the slag and all its impurities are transported from the Copper Smelter, via Kress Haulers, and taken to holding dams onsite.

“Transporting molten material across site is always going to be a high-risk activity but with the appropriate controls in place we make sure this is carried out safely,” Istvan says.

“Our drivers are highly qualified to operate the specialised vehicles and are trained to use the two on-board fire suppression systems to protect personnel and machinery from potential high intensity fires.”

“Along with the extreme heat from carrying molten material, mobile vehicle interaction is also a risk that needs to be minimised and these vehicles use a designated haul road to separate from other vehicles.”

The three Kress Haulers at Mount Isa Mines transport around 40 slag pots per 12-hour shift to the holding dams, approximately 3,000 tonnes.

In July this year the holding dams were upgraded and seven new steel tipping stations were installed to reduce potential splash-back and further protect the Kress Haulers and our Operators.