High grade but small capacity SXEW circuit built in Southern Peru that was capital cost efficient. Flowsheet includes a two-stage wet screening for slimes removal and a separate in a CCD circuit using E-Cat high capacity thickeners for treatment. The coarse ore fraction is then crushed and placed on a “Dynamic” Heap Leach pad. Leach solutions are combined and treated in a reverse-flow SX configuration before going to the EW circuit, where "acid mist" is captured by individual cell hood system. The plant achieved design rates within the first month of operation at below forecasted Opex.
Starting in 1985, the mine went into a series of expansions and the mill capacity was doubled every 18 months from 12.5k to 52k mtpd. During this expansions plant improvements were also made that resulted in metal recovery increases; Copper by 5% and Gold by as much as 10%. These improvements included: Inclined cyclones with Flash Flotation, crusher speed increases achieving a 5 micron product combined with primary wet screening, two-stage column flotation for final concentrate cleaning, Tower mill regrinding for concentrate pipe transport (100k) protection, and Expert Process Controls systems for both grinding and flotation column circuits.
Original Grinding Circuits were single stage SAG mills followed by Ball mills. Because the initial Oxide ores were "Jasperoid " and had higher than expected work index, the mill capacity was less than 50% of design. By successfully converting to an ABC grinding circuit, the throughput was increased to over 15% of design while lowering operating cost to less than plan.
JohnsonMCS will assist in this process for each stage. Below is an example of key discussion topics for the Project Identification or Concept Development Phase:
Inputs considered during this stage may include: