BENEFICIATION OF A FELDSPAR ORE FOR APPLICATION IN THE CERAMIC INDUSTRY

Beneficiation studies were conducted on a Portuguese feldspar ore, in order to obtain final products capable of being used in the ceramic in dustry. A simple scrubbing operation is enough to break the lumps in t he feed. The ore deposit contains ca 35 x 10(6) tonnes from which, by screening, three main products could be obtained. This paper focuses o n the beneficiation of the 500/74 mu m fraction, which constitutes abo ut 27% of the ore, assaying 9.42% Al2O3, equivalent to approximately c a 46% feldspar, with a mean iron content of 0.29% iron oxides. Magneti c separation and froth flotation testwork was carried out, in order to decrease the iron contamination and increase the feldspar content. Ma gnetic separation alone decreased the iron content of the feed to valu es between 0.04 and 0.08% iron oxides with an average yield greater th an 90%. Flotation with HF, provided a feldspar recovery of 45-46% with a concentrate assaying 17.6% Al2O3. The use of H2SO4, gave a recovery of 35-36% of feldspar concentrate, assaying 16.1% Al2O3. However, eco nomic and environmental advantages of using sulphuric acid may compens ate for the lower mass recovery. The iron content of 0.12% iron oxides in these concentrates, could be reduced to 0.04-0.05%, by further mag netic separation.