Production

Processing

Run of Mine ore is trucked from the open pit to the processing plant where it goes through three stages of crushing and screening, grinding, flotation and dewatering. The steps in this process are summarised as follows:
  • Crushing
    The ore is crushed down to rock sizes of around 8-15mm through a stand-alone jaw crushing machine, followed by secondary and tertiary crushing using cone crushers. 
  • Primary grinding
    The ore then moves through a primary grinding circuit at a rate of around 280-320 tonnes per hour. This circuit consists of a SAG Mill in closed circuit with hydrocyclones and a Vertimill. Through this circuit, the ore is slurried and produces a material of around 40-70 microns. 
  • Flotation circuit
    The slurried ore is pumped to the flotation circuit. Here, various reagents are introduced which attach themselves to the ore (sulphide materials) and enable them to float. The zinc and lead bearing minerals are then recovered. 
  • Pre-cycloning
    The rougher concentrate material is then pumped through a pre-cycloning stage to produce two products: fine and coarse material. The fine material is sent to the cleaning conditioner tanks and the coarse material is sent to the regrinding circuit.
  • Final concentrate
    The fine ground materials are then conditioned with reagents prior to passing to a seven stage cleaner circuit to produce a final zinc/lead bulk concentrate. The concentrate and tailings products are pumped to different thickening tanks. Thickened concentrate is then sent to storage tanks prior to filtering and stockpiling. 
  • Tailings removal
    Thickened tailings are pumped to the tailings storage facility via a pipeline. The tailings storage facility is located west of the mine. It plays a key role in recycling water for use within the processing plant. 

At the end of this process, the bulk concentrate has a moisture content of around 13%, which reduces dust generation during handling. All trucking, loading and shipping operations are fully contained to protect against spillage and ensure environmental security.

 

More information
MRM processing diagram
Media releases
McArthur River Mining Expands Concentrator Capacity, March 2007