Processing anatase ores for pigment production

Abstract

Compared with processing high-TiO2 concentrates such as ilmenite ores, processing an anatase ore to achieve impurity levels acceptable for pigment production is more difficult because of the extensive number of accessory minerals present, the significant intergrowths between minerals and the fact that impurity elements may be distributed in several different minerals. In this paper, conditions applicable to processing anatase ores are reviewed with an aim of identifying conditions that may produce a suitable feedstock for processing to titania pigment by either the sulphate or chloride routes.Anatase ores containing 25–35 wt% TiO2 currently are processed using mineral dressing techniques of crushing and grinding, classification, magnetic separation and flotation to produce a concentrate with around 65 wt% TiO2. This concentrate is then typically upgraded to over 90 wt% TiO2 using combinations of heating and leaching treatments, often with the addition of a fluxing reagent to assist in impurity removal. The suitability of these products as a feedstock for the sulphate and chloride routes to pigment is discussed.