Characteristics of Leaching of Nickel from a Mafic Overburden in Sulfuric Acid and Sodium Chloride Medium at Atmospheric Pressure

• Published in: JOM (1989) 2019-12, Vol.71 (12), p.4616-4623
• Main Authors: Thubakgale, Catherine K., Mbaya, Richard K. K., Shongwe, Mxolisi B.
• Format: Article
• Language: English
• Subjects: Atmospheric pressure; Calcite; Chemistry/Food Science; Chloride; Cobalt; Earth Sciences; Engineering; Environment; Leaching; Magnesium; Minerals; Nickel; Particle size; Physics; Plagioclase; Preconditioning; Quartz; Rare Metal Recovery from Secondary Resources; Reagents; Silica; Sodium; Sodium chloride; Sulfuric acid; Temperature
• ISSN: 1047-4838; 1543-1851
• DOI: 10.1007/s11837-019-03824-x

The characteristics of leaching of a Ni mafic overburden using H 2 SO 4 with addition of NaCl at 25°C to 90°C and 10% to 35% solids have been studied. The overburden containing hornblende, chlorite, plagioclase, quartz, and calcite was crushed, ground to − 75  µ m, and leached for 480 min under stirring at a rate of 200 rpm. Three leaching tests were conducted: (1) in 4 M H 2 SO 4 , (2) in 4 M H 2 SO 4  + 3.5% NaCl (per dry ore sample mass), and (3) after preconditioning for 24 h in 4 M H 2 SO 4  + 3.5% NaCl prior to leaching. Maximum Ni extraction of 46.52% was achieved when using 4 M H 2 SO 4 at 90°C and 35% solids. Under similar conditions, leaching and preconditioning in 4 M H 2 SO 4  + 3.5% NaCl produced 20.93% and 13.44% Ni, respectively. Addition of NaCl increased the Fe dissolution while decreasing that of Mg. X-ray diffraction analysis suggested that Ni was extracted from chlorite followed by hornblende.