Review of flotation of feldspar

Abstract

This paper reviews the application of flotation for the separation of feldspar from the other minerals with which it naturally occurs (such as quartz, clay minerals, mica, ilmenite, rutile, anatase and magnetite) as well as the separation of the individual feldspar minerals themselves. Much of the published information on feldspar flotation relates to fundamental studies seeking to elucidate the mechanism of the separation and recovery of feldspar with anionic or cationic collectors and activators. However, the separation schemes currently being used industrially are largely the same as those first proposed 60 years ago because the processes used are very efficient. The general circuit for commercial separation of feldspar consists of three sequential stages of flotation, all of which are carried out in an acid medium. Usually, before flotation, the feed is deslimed, removing any fine clay minerals present. In the first flotation stage, mica is removed with an amine collector. In the second stage, titanium and iron oxide minerals, such as ilmenite and magnetite, are removed using an anionic collector. In the third stage, feldspar is activated with fluoride ions and floated with an amine. The residual product is usually high grade quartz. This procedure results in feldspar products that meet market specifications, including low iron levels. Depending on the nature of the ore being treated and the particular contaminants it contains, one or more of these stages are used. A commercial feldspar product usually contains more than one feldspar mineral, and flotation conditions for the separation of individual feldspar minerals have been developed to produce individual feldspar minerals for specific applications. Potassium feldspar can be floated from sodium feldspar in a sodium chloride solution with an amine collector at neutral or acidic pH values. To overcome environmental issues when fluoride ions are used to activate the feldspar in the third flotation stage, fluoride free flotation conditions that utilise a combination of anionic and cationic collectors have been developed.