Benefication of kaolin clay by froth flotation using hydroxamate collectors

Abstract

The kaolin clays mined in Georgia contain two major impurities: anatase (TiO 2) and iron oxide. The anatase contains a considerable amount of iron in its lattice, which gives a brownish tint to the clays. This mineral is, therefore, removed by froth flotation to produce coating-grade (bright) clays. Anatase is commonly activated by divalent cations and floated using fatty acid collectors. The very small particle size anatase, however, necessitates long retention times in flotation. Often the separation efficiencies obtained with fatty acids are not adequate to produce high-brightness clays. Our recent studies have revealed that alkyl hydroxamates are much more effective than fatty acids in floating the colored anatase impurity from clays. No activators are required, and retention times in flotation are shorter than those for fatty acids. Promising results have been obtained in laboratory flotation tests. A viable process has also been developed for the large-scale manufacture of alkyl hydroxamates in novel formulations which were found to offer both metallurgical and economic advantages.