Recovery of Magnetite from Leached Laterite-residue by Magnetic Separation

In order to improve the grade of iron, upgrading of laterite ore was conducted using wet low intensity magnetic separator. The ore was treated through selective reduction followed by sulphuric acid leaching to recover nickel while iron remained in residual solid. The Vibrating Sample Magnetometer measured the magnetic properties of the ore, as a fundamental of magnetic separation. Magnetic separation was carried out using a Davis Tube Tester. The effect of pretreatments on the magnetization and magnetic separation were investigated.The results showed that the ore has similar magnetic property with goethite. The heating of the ore at 673 K did not improve significantly on its properties whether goethite changes to magnetite. However, the reduction treatment increased the magnetic properties of the ore due to the formation of magnetite. The magnetic susceptibilities of the original, heated and reduction treated laterite ores were 2.36×10−5, 2.18×10−5 and 2 357×10−5 emu/g, respectively. The correlation between magnetite content and magnetization of the magnetic concentrate was showed in a linier equation, which could be used for the prediction of magnetite content in the sample based on its magnetization. Magnetic separation was applied only to recover iron from the laterite ore after being treated by the selective reduction in which magnetite was produced. About 93.9% of magnetite was upgraded from the laterite ore with 90% of recovery was obtained. The relatively high iron content in the magnetic concentrate indicated a potential use as raw material for iron making.