Mintek also specialises in hydrometallurgy, including leaching, precipitation, solvent extraction and
electrowinning.
The PCBs were converted into fine ash powder and subjected to
electrowinning process for the recovery of metals.
EAF dust is firstly leached with distilled water to remove traces of soluble chlorides which could cause damage to electrode and complexities in reaction during
electrowinning [36, 37].
Sulfuric acid is widely used leaching medium for both zinc and iron; although it requires
electrowinning step for the purification of zinc, whereas sodium hydroxide selectively removes zinc at low concentrations thus avoiding need of
electrowinning [3].
This proprietary, new technology (also announced in 2010) uses a wet-chemical,
electrowinning process instead of a heat-based smelting process, greatly reducing sulfur dioxide and lead emissions.
The increased reserve at Kipoi Central will be mined and processed through the Stage 2 solvent extraction
electrowinning (SXEW) plant which is currently under construction and due to commence production in Q2 2014.
The 35 papers consider such topics as the reductive leaching of limonitic laterites using ferrous sulphate, comparing intercell contact bars for
electrowinning plants, the mineralogical characterization of cobaltic oxides from the Democratic Republic of Congo, the influence of thermo-mechanical treatment on structures and properties of a cobalt-based superalloy, and the starved acid leaching technology (SALT) for recovering nickel and cobalt from saprolites and Caron plant residues.
This technique uses heap leaching, solvent extraction and
electrowinning meaning that the copper will be dissolved out of the rock and then recovered from the solution.
In addition, the company has announced the completion of Stage 2 of the crusher expansion to increase crusher throughput by 8,000 t/d; the replacement of existing conveyors with larger ones to meet increased crushing and stacking capacity; the arrival of a second stacker; the installation of a second carbon strip column to increase carbon strip capacity; modifications to ADR columns to increase efficiency; the expansion of the
electrowinning circuit; installation of larger tertiary crusher in main crushing circuit; and installation of new screen in main crushing circuit.