Statistical modelling studies on leachability of titania-rich slag obtained from plasma melt separation of metallized ilmenite

In the course of the present study optimization of leaching parameters by HCl was carried out using response surface method with central composite design. Effect of three parameters, viz. acid concentration, residence time and additive concentration on iron leaching (taken as response) were studied to obtain a statistical model. To determine factor response initial experiments were planned by factorial design and orthogonal central composite design methods. Factor level were estimated based on statistical analysis and optimum parameters obtained are at acid concentration of 6.71 M HCl with 94 min of residence time and 6.09 ml of ethylene glycol for 0.5 g of slag in a batch scale. Based on the model obtained by means of variance analysis, about 77.3% Fe could be leached out, which conforms to the model predictions, giving a residue containing about 94% TiO2.