New collectors for sphalerite flotation

A series of N-arylhydroxamic acids (31) were synthesized and tested as collectors to float sphalerite from a Canadian copper–zinc ore. The compounds were classified into four types namely, N-aryl-C-alkyl, N-aryl-C-aryl, N-aryl-C-aralkyl, and dihydroxamic acids based on the type of substitution. Dihydroxamic acids were found to be poor mineral collectors while the efficiency of sphalerite flotation increased in the order N-aryl-C-aryl < N-aryl-C-alkyl < N-aryl-C-aralkyl. Sphalerite was floated without activation by copper sulfate, and the best sphalerite recovery of about 80% (grade 32%) was achieved with N-hydrocinnamoyl-N-phenylhydroxylamine (HCNPHA) 67 g/t collector dosage. However, pyrite also floated along with sphalerite and this appeared as a major disadvantage to be addressed.