Enhancing the Technical Qualifications of Egyptian White Sand Using Acid Leaching; Response Surface Analysis and Optimization

Abstract

White silica sand samples were collected from Zafarana area along the Red sea coast, Egypt. The samples were mixed and quartered to obtain representative sample for characterization. The silica content in the sample is 99.441% and the iron content is 0.112%. Such geochemical qualifications don't match the technical specification of ceramic, optics, silicon metals and solar cells. RSM in conjunction with CCRD was used to study the removal of iron from silica sand using oxalic acid in terms of three operating parameters (Contact time, Acid concentration, Temperature). The model F values indicated the high significance of the design, also the good agreement between the Actual and the predicted results (R2 > 0.9) indicated suitability of second order quadratic polynomial model to represent the removal process. The best removal process (82%) was achieved at 8gm per ton oxalic acid concentration, 95°C temperature and 120 min leaching time. The final product exhibit high silica content (99.683% SiO2) and lower iron content of (0.017%) which match the requirements of ceramic, silicon carbide, silicon metal and the production of silicon for solar cells.