The application of power ultrasound to the surface cleaning of silica and heavy mineral sands

Power ultrasound may be used in the processing of minerals to clean their s urfaces of oxidation products and fine coatings, mainly through the large, but very localised, forces produced by cavitation, Results of the applicati on of power ultrasound to remove iron-rich coatings from the surfaces of si lica sand used in glass making and to improve the electrostatic separation of mineral sand concentrates through lowering the resistivity of the conduc ting minerals (ilmenite and rutile) are presented. Parameters affecting ult rasonic cleaning, such as input power and levels of reagent addition, are d iscussed. In particular, we present data showing the relationship between p ower input and the particle size of surface coatings removed. This can be e xplained by the Derjaguin approximation for the energy of interaction betwe en a sphere and a flat surface. (C) 2000 Elsevier Science B.V. All rights r eserved.