Improved nickel and cobalt recovery from nickeliferous laterites in acidic fluoride media

Minerals & Metallurgical Processing , 2010, Vol. 27, No. 3, pp. 117-123

Luo, Wei; Wang, Dianzuo; Qiming, Feng; Jiankang, Wentian

 Nickeliferous laterites were characterized by particle size analysis, X-ray fluorescence (XRF), X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive X-ray analysis (EDX), Fourier transform infrared (FTIR) spectroscopy and thermal analysis. Results showed that the laterites consist mainly of nickel-substituted lizardite with cobble-like morphology and traces amounts of magnetite and phlogopite. As fluoride ions can react with silicon in the lizardite crystal structure and form metal-fluoride complexes, as well as increase the equilibrium constant of the lizardite dissolution in acid solution dramatically, the addition of minor fluoride salts (0.2wt.% NaF) gave a markedly enhanced metal extraction rate (Ni 81.7% and Co 52.3%) under the experimental conditions of particle size d₅₀= 25 μm, 10% (v/v) H₂SO₄, reaction time 2 h, reaction temperature 90°C, liquid-to-solid ratio 3 mL g^-1 and stirring at 500 rpm compared with H₂SO₄ alone (Ni 69.6% and Co 30.8%).