The recovery of sulphuric acid from copper tankhouse electrolyte bleeds - a case study on the development of solvent extraction processes.

The copper solvent extraction-electrowinning process used at the Mount Gordon mine, North Queensland, produces a concentrated sulphuric acid tankhouse bleed. A solvent extraction process has been developed to recover sulphuric acid selectively using a branched long-chain aliphatic tertiary amine, tris(2-ethylhexyl)amine (TEHA), as extractant, Shellsol 2046 as diluent and octanol as modifier. Up to 90% of the sulphuric acid was recovered as a pure aqueous acid stream at a concentration of up to 130 g/l, which can be recycled to the tankhouse circuit. The raffinate's acid concentration was cut from 180 g/l to 18 g/l, reducing the environmental impact of waste disposal. Equilibrium data and simulation results were compared using an alternative extractant, CYANEX 923, a phosphine oxide; both extractants cold be used in the acid recovery process. Pilot scale investigations in a pulsed plate column with TEHA were used to scale the process for industrial application.
The copper solvent extraction-electrowinning process used at the Mount Gordon mine, North Queensland, produces a concentrated sulphuric acid tankhouse bleed. A solvent extraction process has been developed to recover sulphuric acid selectively using a branched long-chain aliphatic tertiary amine, tris(2-ethylhexyl)amine (TEHA), as extractant, Shellsol 2046 as diluent and octanol as modifier. Up to 90% of the sulphuric acid was recovered as a pure aqueous acid stream at a concentration of up to 130 g/l, which can be recycled to the tankhouse circuit. The raffinate's acid concentration was cut from 180 g/l to 18 g/l, reducing the environmental impact of waste disposal. Equilibrium data and simulation results were compared using an alternative extractant, CYANEX 923, a phosphine oxide; both extractants cold be used in the acid recovery process. Pilot scale investigations in a pulsed plate column with TEHA were used to scale the process for industrial application.