RECOVERY OF FELDSPAR RAW MATERIAL FROM GRANITE ROCKS FOR CERAMIC AND PORCELAIN INDUSTRIES

Granite is the main source of feldspar for ceramic and porcelain industry after pegmatite. The problem with granite as a source of feldspar is the presence of mica and iron oxides that cause reducing the strength, hardness and density of the final product (low quality ceramics). This study presents the results of applying two phases of separation on Zhejiang granite, Southeastern China, in order to improve the quality of the feldspar obtained from this granite. The first phase is gravitational separation to remove the heavy impurities and the second phase is magnetic separation to further minimize the iron content. Mechanical property tests are conducted on the feldspar product of 3 samples:raw granite, processed granite I (granite after gravity separation, china clay and quartz), and processed granite Ⅱ (granite after complete processing, china clay and quartz). Micro-hardness, strength, fracture toughness and density show sharp improvement in the quality of the processed granite relative to raw one. This improvement is attributed to the absence of undesired impurities (mica and heavy minerals).