Mechanism of Mg2+ dissolution from olivine and serpentine: Implication for bioleaching of high-magnesium nickel sulfide ore at elevated pH
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To inhibit the dissolution of Mg2+ during the bioleaching process of high-magnesium nickel sulfide ore, the effect of major bi-oleaching factors on the dissolution of Mg2+ from olivine and serpentine was investigated and kinetics studies were carried out. The results indicated that the dissolution rate-controlling steps are chemical reaction for olivine and internal diffusion for serpentine. The most influential factor on the dissolution of Mg2+ from olivine and serpentine was temperature, followed by pH and particle size. A novel method of bi-oleaching at elevated pH was used in the bioleaching of Jinchuan ore. The results showed that elevated pH could significantly reduce the dissolution of Mg2+ and acid consumption along with slightly influencing the leaching efficiencies of nickel and cobalt. A model was used to explain the leaching behaviors of high-magnesium nickel sulfide ore in different bioleaching systems. The model suggested that olivine will be depleted eventually, whereas serpentine will remain because of the difference in the rate-controlling steps. Bioleaching at elevated pH is a suitable method for treating high-magnesium nickel sulfide ores.
Keywordsolivine serpentine high-magnesium nickel sulfide ore bioleaching shrinking core model elevated pH
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This work was financially supported by the National Natural Science Foundation of China (Nos. 51574036 and 51404033). The authors are grateful to all the members of the National Engineering Laboratory of Biohydrometallurgy, GRINM Group Corporation Limited, China.
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