Application of response surface methodology and central composite rotatable design for modeling and optimization of sulfuric leaching of rutile containing slag and ilmenite

In this study, application of the Response Surface Methodology and the Central Composite Design (CCD) technique for modeling and optimization of the influence of several operating variables on titanium recovery in a leaching process were investigated. The four main leaching parameters, namely temperature, acid concentration, leaching time and solid to liquid ratio, were changed during-the leaching experiments based on the CCD. A total of 30 leaching experiments were designed and carried out in the CCD method according to software-based designed matrix. According to the results, i.e., titanium recoveries with these four parameters as well as empirical model equations were developed. The model equations were then individually optimized by using quadratic programming to maximize titanium recoveries for both ilmenite and slag within the experimental range. The predicted values for titanium recoveries for both ilmenite and slag were found to be in a reasonable agreement with the experimental values, with R2 as correlation factor being 0.963 and 0.916 for ilmenite and slag, respectively.