Direct shipment of high grade nickel laterite ores, Ni grade ≥ 1.2%, has been the dominant practice of nickel mining industries in the country. Upon the diminishment of these high grade nickel deposits, beneficiation/processing of the quantitatively increasing low grade nickel laterites (limonites) is apparently necessary. As of November 2018, there are only two (2) mining companies (Coral Bay Nickel Corporation in Palawan and Taganito HPAL Nickel Corporation in Surigao del Norte) in the country who are engaged in the beneficiation of low grade nickel laterite ores.
In this study, nickel laterite ores were subjected to atmospheric leaching and column leaching to produce leach solution (PLS) for precipitation. Nickel and cobalt were recovered from the solution by two stage precipitation. During the first stage precipitation, Fe, Cr and Al were precipitated by adding CaCO3 while nickel and cobalt precipitated using NaOH and MgO. Parameters such as retention time, temperature, precipitant and pH were investigated. 2k factorial design were applied in the study to determine significant factors which will increase recovery of iron and nickel. 99.50 % Fe were removed from the PLS and 99% Ni and 88.75% Co were precipitated from the barren solution. Using statistical analysis, retention time and pH were identified as significant factor that affects iron removal and nickel precipitation, respectively.
E.A. Daruca, C.G. Arnejo, C.V. Pecson and R.V. Perucho
Engineer III, Mineral Processing Research and Development Section (MPRDS)
2 Engineer IV, MPRDS
Metallurgical Technology Division, Mines and Geosciences Bureau