Nickel laterite resources compose a major part of the world’s reserves of nickel. however, the majority of nickel production comes from sulfide sources. This distinction is due to the complex mineralogy of nickel laterite ores, which complicates the physical separation of nickel-bearing minerals. Although many studies have been conducted to achieve qualitative and economic separation by physical methods, none of these methods have been used in industry. In this research, the simultaneous benefication of nickel and iron from a low-grade laterite ore (Sarbisheh, South Khorasan) was investigated by magnetizing roasting followed by low-intensity magnetic separation to produce a nickel-bearing magnetic concentrate. The effect of several key parameters of the reduction roasting process, such as temperature, reduction time, type of reducing agent, amount of coal, and particle size, on the grade and recovery of both nickel and iron was investigated. The effect of magnetic field intensity and magnetic separator fluctuations was also eva‎luated on the separation efficiency. Maximum recovery (%) was obtained in the magnetic intensity of 900 gauss and the fluctuation of 80 rpm. The highest nickel grade was obtained in the conditions of reduction roasting with a temperature of 850 °C, in 2 hours, a mass ratio of coal to ore of 11%, and the grinding time of 15 minutes. In the obtained concentrate, the content of nickel increased from 1.0 to 4.0% and the content of iron increased from 22.0 to 61.4%, and recovery of 66.6% and 61.4% was obtained for nickel and iron, respectively. However, the highest recovery of iron and nickel in the mentioned reduction roasting conditions was obtained with a grinding time of 5 minutes, which was a concentrate with nickel grade of 3.4% and iron grade of 56.5%, nickel recovery of 73.6% and iron recovery of 70%. The reduction roasting with biomass fuel was investigated and the the highest nickel grade was obtained in the mass ratio (corn to ore) of 15%, temperature of 600 °C and roasting time of 1.5 hours. The grade of the concentrate was 2.9% nickel and 36.2% iron with the recovery of 57.2% for nickel and 42.5% for iron. Then, the concentrate obtained with the highest nickel grade was subjected to the leaching process and the effect of the leaching agent and the solid content was investigated. Finally, nearly complete extractions of nickel, cobalt, and iron were achieved with 3 M sulfuric acid in 0.5 hours and a pulp density of 10% at 95°C. The results of this research show that the method of magnetizing roasting – low-intensity magnetic separation is a new and efficient strategy for the simultaneous enrichment of nickel and iron from limonite resources, which can be an effective solution for the treatment of laterite ores.

علي احمدي عامله

محمد رئوف حسيني، مهدي احمديان