Marzieh Hosseini Nasab - Department of Mining Engineering, University of Sistan and Baluchestan, Zahedan, Iran
Mohammad Noaparast - School of Mining Engineering, College of Engineering, University of Tehran, Tehran, Iran
Hadi Abdollahi - School of Mining Engineering, College of Engineering, University of Tehran, Tehran, Iran

The Recovery of nickel from lateritic ores as the main oxide resources has been always debated. Since it consists of ۱.۷۴% Ni, ۰.۱۴% Co and ۴۰.۸% Fe, co-dissolution of iron occurred by using common lixiviation like sulfuric acid. Therefore, some leaching agents should be sought due to promoting a high dissolution of nickel/cobalt and a negligible iron recovery. This research investigates the effect of using organic acids such as gluconic, lactic and citric acid along with sulfuric acid on recoveries of Ni/Co from an iron-rich laterite ore. The results showed that adding sulfuric acid to the optimal combined ratio of the organic acids (gluconic: lactic: citric= ۱: ۲: ۳) to obtain the combined ratio of ۶ : ۱: ۲: ۳ (sulfuric: gluconic: lactic: citric acid), simultaneously increasing the temperature from ۶۰ to ۹۰ °C, and increasing the final combined concentration of the acids from ۳.۵ M to ۵ M, significantly increased nickel and cobalt recoveries by ۸۰.۴ and ۶۸.۷%, respectively, and slightly increased iron extraction by ۵.۰۵% all when compared to using the optimal combined ratio of organic acids. The use of ۵ M sulfuric acid alone as a leaching agent, at ۹۰ ° C, resulted in an ۸۱.۱۱% increase in iron dissolution than the ۶: ۱: ۲: ۳ combination. The results obtained indicated that the reaction rate was controlled by the chemical reaction, and the activation energies of ۴۲.۷۱ kJ/mol for nickel and ۸۴.۵۷ kJ/mol for cobalt were consistent with this conclusion.

Laterite, nickel, Cobalt, Organic acids, Atmospheric leaching