Leaching in reactive froth of zinc sulphide concentrate

[摘要] Laboratory experimentation were conducted to investigate the regeneration andrecycling of nitric acid during leaching in froth (LIF) processing of Gamsberg zincsulphide concentrate.Two experiments were performed in a mechanically stirred batch reactor at 80-90°C to determine the leaching kinetics of the zinc sulphide concentrate. 93 to97% of zinc was extracted into spent zinc sulphate electrolyte containing 30 to 40g/1nitric acid during 40 to 60 minutes of leaching without regeneration of nitric acid.Between 60.72. and 97.79% of the consumed nitric acid was regenerated after 45minutes of batch L/F experiments carried out at 80·90oC and 50kPa. The resultsshow that the degree of nitric acid regeneration is inversely proportional to theconcentration of nitric acid in the leaching solution. Zinc extraction ranged between56.31 and 78.37% whilst 40.29 to 50.99% of the initial sulphide sulphur wasoxidised to elemental sulphur. In the continuous L/F experiments conducted at 80-90°C and 100·200kPa, the degree of nitric acid regeneration varied from 33.63 to97.22%. Overall zinc extraction was about 62% whilst 47% of the sulphide sulphurreported as elemental sulphur after 60 minutes of processing.A five-stage L/F processing of the concentrate was carried out in which the flotationphenomenon was used for selective separation of the floatable fraction from the nonfloatablefraction. About 40 to 80% of the consumed nitric acid was regenerated,88.94% of zinc was extracted whilst 55.65% of the sulphide sulphur reported iselemental sulphur after 77 minutes of processing. The recoveries of zinc andelemental sulphur increased to over 92% and 58% respectively when the leachresidue was subsequently leached in the batch reactor.

[发布机构] University of the Witwatersrand