Optimization of the atmospheric acid leaching process for the recovery of nickel and cobalt from iron-rich lateritic ore

Abstract

Currently, millions of tons of iron-rich laterite ore are considered waste in the mining industry, and the sector is seeking technological solutions to use them. Atmospheric acid leaching is a potential alternative to obtain cobalt and nickel from laterite ore due to its low implementation and maintenance costs compared to conventional industrial methods. Identifying and optimizing the leaching parameters are crucial for advancing the state of the art in this field and promoting local socio-economic development, considering the extractive activity. Thus, the present study aimed to investigate and optimize the atmospheric acid leaching parameters that maximize the recovery of cobalt and nickel from an iron-rich lateritic ore (Fe > 35%) from Goiás, Brazil. The effects of the type of mill, the additive in mechanical activation, the ascorbic acid and sulfuric acid concentrations, and the solid/liquid ratio on the leaching process are evaluated using experimental designs. Under the studied conditions, ascorbic acid increased the recovery of cobalt and nickel by more than 40% and 10%, respectively. Optimized conditions provided maximum recoveries of 80.6% for cobalt and 51.8% for nickel. The diffusion through the residual ash layer best fitted the kinetic data for nickel.