Proses Reduksi Selektif Bijih Nikel Limonit Menggunakan Zat Aditif CaSO4 [Selective Reduction Process of Nickel Limonite With Adictive CaSO4]

Abstract

This research aims to determine the optimum selective reduction conditions process of limonite nickel ore using additives CaSO4 and followed by magnetic separation to improve the nickel content. The selective reduction process was carried out at temperature range of 800 – 1100 °C, 1-4 h of reduction time, and the addition of the reducing agent and additives 5% - 20%. Limonite nickel ore was prepared by heating the ore inside the oven, size reduction and sieving to get ore with size under 100 mesh. Then, limonite nickel ore was mixed with reducing agent and additive. In addition, the limonite nickel ore which was mixed with the reducing agent and additive, was reduced in muffle furnace carbolite at certain temperature and time. Reduction result was weighed and concentrated by magnetic separation process, and the result was analysed by AAS (atomic absorption spectrometry) to determine of Ni contents in concentrates. The results showed that the higher a reduction temperature, Ni content and metallization of Ni was improved with the formation of Ni metal which separated from the Fe metal. The similar result was found with longer of reduction time. On the contrary, the higher an addition of reducing agent in the reduction mixture, the Ni content decreased slightly. The addition of CaSO4 can increasing the nickle content but it was not given the tendency for the good results. The highest increasing of nickel contents i.e. 2.44% was achieved at 1100 ºC of reduction temperature, 1 h of reduction time, 10% addition of reducing agent and 20% addition of CaSO4 additive. The recommended reduction temperature are 1100 °C for 1 h of reduction time, with 10% addition of reducing agent and 20% addition of CaSO4 additive.