Bioleaching of six nickel sulphide ores with differing mineralogies in stirred-tank reactors at 30 °C

► Examined the bioleaching of six nickel sulphide ores at 30 °C and several pH levels. ► Nickel was present primarily in pentlandite and secondarily in pyrrhotite. ► Nickel extraction after 3 weeks at pH 2 and 3 ranged from 49% to 86%. ► An increase in pH from 2 to 3 resulted in approximately the same nickel extraction. ► Same pH increase resulted in a significant decrease in acid consumption.