Mechanisms of trithiocarbonate adsorption: A flotation perspective

In recent years the use of trithiocarbonates (TTC) in combination with dithiocarbonates (xanthates) in the platinum industry has indicated increases in flotation grades and recoveries. A great number of studies performed on the mechanism of adsorption of xanthates onto substrates have indicated that xanthate adsorbs via charge transfer processes. It would appear from spectroscopic investigations that the TTC has two mechanisms of adsorption; one dominating in reducing conditions and the other in oxidising conditions. The TTC is thus able to be used in reducing or non-oxidising conditions – such as in the milling circuit – to render the target mineral hydrophobic before the possible oxidation of the target mineral. The current study indicated that the TTC is very unstable in solution. The TTC decomposition reaction follows a first-order reaction rate and the TTC decomposes to its corresponding thiol. Microflotation of pyrite indicated that the TTC significantly increases the rate of flotation compared to xanthate flotation. This would suggest that the TTC possible removes faster-floating minerals before xanthate targets the slower-floating minerals. This could account for the apparent synergism between xanthate and TTC when used simultaneously.