Bb. Kar et Yv. Swamy, Some aspects of nickel extraction from chromitiferous overburden by sulphatization roasting, MINER ENG, 13(14-15), 2000, pp. 1635-1640
Nickel bearing chromitiferous overburden of Sukinda region. Orissa, India,
was pugged with sulphuric acid and subjected to roasting in two stages. Var
ious operating parameters, such as roasting temperature, rime, acid concent
ration and role of additives were studied. Addition of moisture, during pug
ging, helped in the formation of insoluble ferric hydroxy sulphate that mai
ntains the equilibrium of SO2/SO3 partial pressure. The double stage roasti
ng improved the nickel extraction over the single stage isothermal roasting
of the material at 700(degrees)C. An extraction of 85% nickel with 2-3% ir
on could be achieved at a temperature of 700 degreesC when roasted for 15 m
ins, 25 wt% sulphuric acid and 20 wt% moisture in two stages. The nickel ex
traction was improved a further 8-10% by the addition of alkali and alkalin
e earth metal salts. The role of additives during roasting was also investi
gated. (C) 2000 Elsevier Science Ltd. All rights reserved.