Removal of iron from sandstone by magnetic separation and leaching: case of El-Aouana deposit (Algeria)

To improve the quality of raw materials from North East Algeria and their application in the field of flat glass manufacturing, the sandstone of El-Aouana (Jijel) was subjected to a physicochemical characterization. Analysis techniques such as X-ray diffraction, atomic absorption spectrophotometry and a chemical analysis of size fractions by sieving were used. According to this characterization it is noticed that sandstone feedstock contains primarily quartz (SiO2), as well as ferriferous minerals considered as impurities during glass manufacturing. This work concerns the removal of iron oxide from silica sandstone to obtain a material acceptable for flat glass manufacturing. For this, we have studied the silica enrichment process using a magnetic separation. Moreover, a leaching process by using hydrochloric acid has been studied under various experimental conditions; the parameters studied were: hydrochloric concentration, temperature, and time of contact. The results obtained show that the leaching studied presents a better removal of iron oxide after 150 min of treatment at temperature 90°C with a 3 mol/L, a concentrate obtained final of 99.16% SiO2 with a content of 0.01% Fe2O3.