Valorization of Solid Residue from the Lateritic Nickel Ore Leaching Process for Ferronickel Production

The hydrometallurgical process of nickel laterite leavesa residue that still contains critical metals such as iron and nickel. Its utilization can improve overall process efficiency and reduce environmental damage. In this work, the recovery of nickel and iron from nickel residue resulting from the citric acid leach process has been carried out using the selective reduction followed by a magnetic separation process (RMS). The effect of reductant and additive dosage, reduction temperature, and holding time on metal grade and recovery, phase transformation, and microstructure of ferronickel has been investigated clearly. The nickel residue was mixed with 5-20 wt% of sodium sulfateas additive and 1-5 wt% of anthracite coal as reductant, respectively. It was agglomerated into pellets with a diameter of 10-15 mm. The reduction process of pellets was conducted at 950-1250 degrees C for 15 to 75 min. The reduced pellets were ground and put into a magnetic separation unit using a 500 Gausses magnetic field to produce the magnetic ferronickel and the non-magnetic impurities. The optimum result obtained by reducing the pellet contains 10 wt% of sodium sulfate and 1 wt% of anthracite at 1150 degrees C for 60 min, producing ferronickel has 5.67% and 71.58% of nickel and iron grade with 97.77% and 32.50% of recovery, respectively.