Flotation properties of silicon carbide: I. Flotation of silicon carbide with anionic and cationic collector

Abstract

This article deals with the results of investigations on the flotation of silicon carbide by means of anionic and cationic collectors. On the basis of a wide range of physico-chemical and flotation tests, a mechanism explaining the effect of these reagents on the flotation of silicon carbide has been suggested. The deficient flotation of SiC in the presence of anionic reagents may be related to the negative charge occurring at the surface of silicon carbide in a wide region of pH (2.7–14), as has been proved by measurements of the electrokinetic potential. It was observed that in the presence of an anionic collector the negative charge increased at the surface of silicon carbide. This may be related to the adsorption of the anionic collector influenced by intermolecular forces between the hydrocarbon chain of the collector and the carbon atoms in the lattice of SiC. Silicon carbide easily flotates by means of cationic collectors. The maximum flotation, when dodecylammonium chloride is being used as collector, occurs at pH = 9. Concentration of amine necessary for obtaining complete flotation recovery of SiC is two orders lower than in the case of quartz. The mechanism of amine action in the flotation of SiC consist in the adsorption of amine as a result of its electrostatic interaction with the negatively charged SiC surface. The negative charge of the surface originates from the silanol groups which are the oxidation product of SiC.