A study of the pyrite flotation efficiency of dithiocarbamates using factorial design techniques

Abstract

The flotation of pyrite using a selection of dithiocarbamate collectors having different alkyl functional groups has been studied. Factorial design techniques were used to determine the importance of the following variables: dithiocarbamate alkyl group type, pH, collector dosage, conditioning time, copper sulphate dosage, and ore particle size or ore condition. The factors which had the greatest effect on the grade and recovery were the alkyl group type, pH and copper sulphate dosage. The highest pyrite yield (83.4% recovery, 19.7% grade) was obtained when using di-n-propyl dithiocarbamate at a pH = 4. In the case of di-n-propyl dithiocarbamate the addition of copper sulphate had little effect on the recovery or final grade whereas in the case of n-propyl and n- and cyclo- hexyl dithiocarbamates addition of copper sulphate had a depressing effect on the flotation of pyrite. Proposals are made to explain these observations in terms of the influence which pH has on the copper ion, dithiocarbamate ion and pyrite surface interactions and the resultant effect on the hydrophobicity of the particle-collector complex.