Comparison of hexamethylenedithiocarbamate and tetramethylenedithiocarbamate as flotation reagents for the concentration of zinc

A procedure for zinc flotation separation from fresh water prior to its determination by atomic absorption spectrometry (AAS) has been developed. Hexamethyleneammonium hexamethylenedithiocarbamate (HMA-HMDTC) added to the first precipitate collector of hydrated Fe(III) oxide (Fe₂O₃· xH₂O) gives the second precipitate collector of Fe(HMDTC)₃. After addition of a surfactant, the precipitate of collectors is separated from the water phase by a stream of air bubbles, dissolved by strong acid and the solution then tested by AAS. The experimental parameters (amount of collector used, pH, ionic strength, type of foaming reagent, ζ potential, induction time etc.) affecting the flotation efficiency were optimized. At a pH of 6, Zn is separated quantitatively (98.5%) by addition of 5 mg Fe(III) and 3 mL 0.1 mol/L HMA-HMDTC to the sample. Results are compared with those obtained by ammonium tetramethylenedithiocarbamate.