our-process-1024x400.jpg

WHO WE ARE

Our process

McArthur River Mine is the world’s second largest zinc and lead deposit.

We mine and process zinc and lead ore onsite and transport it to Bing Bong Loading Facility for export to customers around the world.

Mining ingenuity

McArthur River Mine’s success is a testament to the ingenuity of the local and Australian mining communities in developing technologies, solutions and efficiencies that transform our zinc and lead deposit into valuable products for everyday use.

The mine’s mineral-rich HYC (Here's Your Chance) deposit is still being mined 25 years on. HYC comprises eight zinc and lead ore zones covering two square kilometres and is 55 metres thick. Natural earth movements change zone orientations and angle over time, complicating our mining process.

our-process-1-540x355.jpg
our-process-2-540x355.jpg

Turning ore from rock into a finished product is a complex process. First geologists and surveyors mark out the ore’s location in the pit. They identify what is ore and what is waste rock and ensure we develop the pit safely.

Our team excavates the open pit in stages, targeting the shallowest ore first. We drill the rock and pack it with explosives. The blast breaks the ore and waste rock into a smaller size that can be loaded into trucks.

An excavator in place to load trucks in McArthur River Mine’s open pit.

After blasting, we excavate overburden in horizontal benches to expose and remove ore for processing. Separating as much waste as possible at mining stage ensures ore fed to the processing plant is relatively pure.

Large-scale haulage

Excavators up to 550 tonnes in capacity load 175 to 220 tonne haul trucks with ore to take to stockpiles and waste to transfer to the waste rock pile.

A birds-eye view of haul roads and trucks at McArthur River Mine

We truck the ore to the crusher for processing in our onsite processing plant. Overburden rock is trucked to a waste pile where it is shaped for later rehabilitation.

Our processing plant at McArthur River Mine extracts the zinc and lead from the ore in preparation for export to smelters.

A conveyor transports raw material to the processing plant.

Crushing and grinding

The impure zinc-lead ore transported from the mine is ground into a fine dust.

Crusher machines break the ore down into nine millimetre rock sizes, then grinding mills further reduce it to 45 microns – just big enough for the eye to see.

After crushing and grinding, the saleable zinc-lead product is separated from waste rock through a flotation process.

The ball mill at McArthur River Mine grinds ore into fine particles.

Flotation process

The fine dust is mixed with water and chemicals to form a slurry.

Air is forced into the slurry, creating air bubbles which attract the zinc, lead and silver particles and draw them to the surface, leaving the waste rock behind.

The 'froth' is skimmed off the top and dried, leaving valuable zinc and lead concentrate containing small traces of silver.

McArthur River Mine’s zinc-lead processing plant.

Refining process

The recovered concentrate is further reground and passed through conditioner tanks to upgrade it to client-required product quality.

Particles are now as tiny as seven microns.

Further processes involving acid, heat, air and flotation separate the zinc from the lead.

A processed product and concentrates are now ready to transport offsite to be smelted into zinc and lead metals, used in a wide range of commercial and household products.

We place the lead concentrate in large, lined bulk bags packed into steel containers and truck it 800 kilometres to our lead smelter at Mount Isa Mines.

The bulk product and zinc concentrates are transported 120 kilometres to Bing Bong Loading Facility at the southern end of the Gulf of Carpentaria for transfer by barge to ocean-going vessels.

Export process

Our contract road-train fleet features prime movers with fully covered, side-tipping trailers, capable of transporting 120 tonne payloads. We store the zinc concentrate in a 90,000 tonne storage shed at Bing Bong Loading Facility.

Ore concentrate leaves the mine in road trains.

A purpose-built barge, the MV Aburri, transfers the concentrate 28 kilometres north of the Bing Bong Loading Facility. From here, covered conveyors transfer the concentrate on to ocean-going vessels to ship to refineries around the world.

Road train safety procedures

Rigid safety measures for the road-trains include:

  • wheel washes at the mine site exit and Bing Bong Loading Facility
  • protective covers over each trailer to prevent dust and spillage
  • speed limits of a maximum of 85 kilometres per hour
  • a fully covered unloading dock at Bing Bong Loading Facility
  • procedures to tip into the storage shed, clearing all concentrate from the road train and preventing spill on ramps.
Bing Bong Loading Facility, located 120 kilometres north of McArthur River Mine, is an integral part of our operation.

Shipping process

McArthur River Mine manages Bing Bong Loading Facility and the loading of bulk and zinc concentrate onto the MV Aburri bulk carrier barge.

Carpentaria Shipping Services, a joint venture between Indigenous Business Australia, P&O Maritime Services and local Mawurli and Wirriwangkuma Aboriginal Association, operates the barge.

Designed specifically for our operations, MV Aburri is 79.95 metres long by 18.5 metres wide with a draft of 3.5 metres and capacity to carry 3,200 tonnes. It self-loads and discharges 900 to 1,000 tonnes an hour. The cargo capacity of each shipping consignment varies between 6,400 and 45,000 tonnes.

The bulk carrier was built to applicable Northern Territory Marine and Australian Standards and has an International Lloyd's classification of '100 A1'. Lighting of MV Aburri, the wharf and navigation channel enables 24-hour operations.

Offshore transfer zone

The Offshore Transfer Zone, where we transfer bulk and zinc concentrate from MV Aburri to ocean-going ships is defined by a precise longitude and latitude and has an average depth at low tide of 14.75 metres.

We manage all loading and discharging with computer process control systems, overseeing the operation with closed-circuit cameras. Safety procedures ensure the security of the concentrate against spillage and include:

  • an auto-dock system to secure the MV Aburri in a set position against the wharf using a hydraulic claw and swing arm, which guarantees its precise location under the loading chute and ensures concentrate is enclosed at all stages during loading—controls on the conveyor only operate if the loading chute is securely in place.
  • preventative maintenance and inspection processes
  • automatic shutdowns in case of a fault between the MV Aburri and the concentrate loader
  • water containment and management to ensure small amounts of concentrate caught in the system (including the conveyor and MV Aburri) can be hosed, collected and managed through the wharf sump and site run-off pond
  • discharge procedures which consider prevailing weather conditions.