An investigation on the potential recovery of copper from a low-grade copper resource containing high silica content

Abstract

The present research aimed to experimentally peruse the tank leaching of copper from a low-grade ore containing 0.57% Cu, 24.69% Si, and 10.367% Fe. To this end, firstly, the behaviour of important variables influencing the dissolution process was examined using the one factor at a time (OFAT) method and response surface modelling (RSM), and then the leaching kinetics was scrutinized to obtain further recognition of the leaching operations. The findings derived from the OFAT technique demonstrated that the particle size of 0-2 mm was a better choice for the tank leaching relative to other fractions. The presence of clay compounds in the ore led to a high increase in acid consumption. The leaching rate improved with an increase in the solid percentage from 20 to 40% and then decreased with a further increase due to lack of proper mixing. Additionally, the pulp stirring speed had a little effect on the dissolution of copper, confirming that the mixing rate of pulp should be at a level that suspends the particles and prevents them from settling. Then, the RSM was utilized to model and optimize the process and determine the possible interaction between operating parameters. The results showed that copper leaching was significantly dependent on the interaction between the factors. The optimized amounts of parameters were found to be 90 kg/t acid concentration, 35% solid content, 150 rpm pulp mixing rate, 2.5 h leaching time, and 0-2 mm size range. The kinetic analysis showed that the diffusion model through the production layer with an activation energy of 14.15 kJ/mol was the rate-controlling stage of the reaction, and based on that, a new model describing the dissolution kinetics of copper was proposed.