US EPA

1710190 

Journal Article 

Use of sulphur dioxide as reducing agent in cobalt leaching at Shituru hydrometallurgical plant 

Mwema, MD; Mpoyo, M; Kafumbila, K 

2002 

Yes 

Journal of South African Institute of Mining and Mineralogy
ISSN: 0038-223X 

102 

1 

1-4 

WOS:000175156000002 

Copper oxide ores deposits in the Katanga province of the Democratic Republic of Congo (DRC) contain at variable level cobalt oxide minerals. in contrast to copper oxide minerals which readily dissolve in the sulphuric acid solution, the cobalt oxide bearings are difficult to dissolve, especially if cobalt is present in the third oxidation state (CO2O3). This species become soluble after reduction of Co+3 in CO+2. In practice, the use of reducing agent is therefore necessary in order to transform the insoluble minerals into soluble cobalt sulphate species. The following reducing agents are currently used at the Shituru plant: ferrous ions, which are present in leach solutions, pulverised copper or sodium meta bisulphite (NIBS).



Due to the high consumption of reducing agents (0,8 t MBS/t of solubilized Co; 1,2 t Cu/t-Co), cobalt production is expensive. The use of sulphur dioxide as reducing agent was then investigated in order to reduce operating cost. This reagent also presents the advantage of sulphuric acid production during the leaching process. It has been added in the leaching vessel (tank).



From the laboratory and industrial tests, selective leaching of cobalt (78%) has been performed. The cobalt leaching kinetic depend on sulphur dioxide dosage. Dissolution of copper, iron and manganese remained very low. No emanation Of SO2 gas was observed during the process.