Upgrading Feldspar by WHIMS and Flotation Techniques

Abstract

Large reserves of feldspar ores exist in the pegmatite veins at Ban Tak district, Tak province. The main impurities of these deposits are muscovite, biotite and garnet which resulted in high Fe-content that does not meet the raw materials specification for the ceramic industry. The chemical compositions of the feldspar ores are 75.93% SiO₂, 14.34% Al₂O₃, 0.63% Fe₂O₃, 4.01% K₂O and 4.34% Na₂O with the fire test results of L = 63.10, a = 2.04 and b = 10.56. The typical specifications of the commercialised feldspar require SiO₂ < 70%, Al₂O₃ > 17%, Fe₂O₃ < 0.1% with K₂O and Na₂O both > 5%. The traditional method using to remove Fe-bearing minerals from the feeds is the reverse flotation methods. However, the existing method consumes high sulphuric acid which may create the environmental impact for the nearby area if the treatment is not completely done or the accident occurs. The proposed process combine the typical process of crushing, grinding and classifying, attrition scrubber, with the wet high intensity magnetic separator (WHIMS) and the feldspar direct flotation. WHIMS was use to remove muscovite, biotite and garnet which are the causes of high Fe-content. The results showed that efficient separation of Fe-bearing minerals could be achieved by WHIMS in the commercial scale and create the environmental friendly process. This process make the recovery of 40% and the chemical compositions of feldspar products are 68.29% SiO₂, 18.69% Al₂O₃, 0.07% Fe₂O₃, 5.83% K₂O and 6.33% Na₂O with the fire test results of L = 82.10, a = -0.56 and b = 3.23 which meet the commercial grade of feldspar.