Copper Sulphide Concentrate: Pressure Oxidation, Bioleach or Roast

Sulphide copper does not dissolve in dilute acid without an oxidant. The three commercial answers are pressure oxidation (POX), bioleaching, and roasting followed by leach. The choice depends on grade, impurity penalties and scale.

Route comparison

Route	Conditions	Best for	Main drawback
Pressure oxidation	180–220 °C, 10–30 bar O₂, autoclave	High-grade concentrates, fast kinetics	High capex, titanium autoclave, complex materials
Bioleaching	30–45 °C, mesophile/thermophile bacteria, days	Low-grade, remote sites, low capex	Slow, temperature-sensitive, large footprint
Roast–leach	550–650 °C, fluidised bed	Cost-sensitive, SO₂ capture available	Gas cleaning, arsenic handling

Downstream is the same

All three routes deliver a copper-bearing liquor that goes to SX–EW. The differences show up in impurities: POX sends sulphate and arsenic into solution and needs neutralisation; bioleach produces a dilute liquor that may suit IX or direct EW poorly; roast leaves calcine that leaches cleanly but generates gas.

Arsenic and other penalties

Arsenic is the decisive impurity. It must be fixed as a stable scorodite or equivalent rather than stored as soluble salt, and that step often costs more than the copper recovery. Build the arsenic balance before selecting the route.

Pilot scale

POX pilots run in 2–20 L titanium autoclaves; bioleach pilots in columns or stirred reactors over weeks. Both are slow to iterate, so define the questions before starting: kinetics, oxygen demand, impurity deportment, and materials of construction.

Send the concentrate assay with As, Sb, Bi and Hg, plus your power and oxygen costs, and we will compare the three routes on your numbers.