Feasibility of the Isfahan feldspars upgrading for applications in the tile and ceramic industries

Isfahan province has a significant number of individual industrial soil deposits where some of them are utilized, but the silica and iron oxide impurities have deteriorate the run of mine quality and reduced the final product value extensively. The goal of this research was to eliminate the mentioned impurities to adopt the product quality with the tile and ceramic industry specifications, and for an additional added-value. Three feldspar samples were collected from Varzaneh, Naein, and Kashan regions, and chemical and mineralogical characterizations were conducted on the head samples after proper comminution and sieving analysis. The -250 µm head samples were treated by a 3 cm hydrocyclone to physically reduce the silica content, which, for all three samples and in the average, resulted in 4% silica reduction in the overflow product while alumina and unexpectedly iron oxide increased by 1.2 and 2%, respectively. Further reductions of iron oxide, 1% in average, were obtained once the overflow products were introduced to a high gradient magnetic separator. The dissolution of the amorphous silica along with iron oxides had made the magnetic products leaching, with sodium dithionite, practically ineffective. It is found that using oxalic acid as the leaching agent for the fresh run of mine feed would present the best results, as reduction of iron oxide below 1% was obtained for Kashan feldspar. Preliminary cost and benefit evaluations for a 150 t/y processing plant, determined a 50k Rl.s benefit per ton of processed product with almost 4 years of overall cost return period.