Feldspar production from dimension stone tailings for application in the ceramic industry

Abstract

Brazil has one of the largest reserves of granite in the world and is in part of the top ten producers of dimension stone. The dimension granite extensive mining in this country generates expressive volumes of tailings, among then rock fragments and fine particles, accounting for more than 50% of the material extracted from the quarries. The dimension stone, commercially known as Marrom-Guaíba granite, is an alkali-feldspar quartz syenite rich in potassium and sodium exploited by Serra Geral Mining in the southern part of Brazil. Due to its chemical composition, Marrom-Guaíba tailings have potential application in the ceramic industry. However, the grade of iron bearing minerals (considered a contaminant) is too high. Tailings samples were grinded, milled, chemical analyzed and tested using magnetic separation and froth flotation in order to reduce the iron and quartz content. The results show that the magnetic separation reduced the iron content from 3.20 to 0.48% and increased the feldspar content from 72.20 to 81.23% with 65.31% of mass recovery and 73.48% of metallurgical recovery. Flotation provided small decreased in quartz content, from 4.40 to 3.90%. A suitable feldspar concentrate for ceramic industry was obtained.