The effect of nC12-trithiocarbonate on pyrrhotite hydrophobicity and PGE flotation

C.F. Vos,J.D. Miller,J.C. Davidtz

doi:10.17159/2411-9717/2018/v118n10a11

C.F. Vos, J.D. Miller + Show 1 more

Open Access

https://doi.org/10.17159/2411-9717/2018/v118n10a11

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Abstract

This work presents the potential for improving the flotation recovery of slow-floating sulphide minerals with the use of starvation dosages of a normal dodecyl (n-C12) trithiocarbonate (TTC) co-collector, together with a sodium isobutyl xanthate (SiBX) and dithiophosphate (DTP) collector mixture. At potentials below -150 mV (SHE), addition of nC12-TTC with SiBX improves the hydrophobicity of pyrrhotite, yielding captive bubble contact angles greater than those measured for SiBX or nC12-TTC alone, suggesting a low potential synergistic effect. This synergistic effect is further studied using Fourier transform infrared (FTIR) spectroscopy, the results indicating an increase in the surface concentration of the collector species when in a mixture. Thus, nC12-TTC with SiBX may act as an immobile surface anchor to which SiBX/SiBX2 molecules bond, increasing the localized concentration of collector species. Bench-scale flotation tests using mixtures of SiBX/DTP/nC12-TTC on a platinum group element (PGE)-bearing ore from the Bushveld Complex in South Africa confirm an improved metallurgical performance at very low substitutions (approx. 5 molar per cent) of SiBX. The improved recoveries for PGE, Cu, and Ni are correlated with improvements in the flotation kinetics of their slow-floating components.

Highlights

This work presents the potential for improving the flotation recovery of slow-floating sulphide minerals with the use of starvation dosages of a normal dodecyl (n-C12) trithiocarbonate (TTC) co-collector, together with a sodium isobutyl xanthate (SiBX) and dithiophosphate (DTP) collector mixture
At potentials below –150 mV (SHE), addition of nC12-TTC with SiBX improves the hydrophobicity of pyrrhotite, yielding captive bubble contact angles greater than those measured for SiBX or nC12-TTC alone, suggesting a low potential synergistic effect
This synergistic effect is further studied using Fourier transform infrared (FTIR) spectroscopy, the results indicating an increase in the surface concentration of the collector species when in a mixture

Summary

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(1) 90 g/t with a 70:30 split of SiBX:DTP (2) TTC at 5,10 and 100 % of initial SiBX molar dosage while DTP was constant. As the electrode potential is lowered even further (below –150 mV) for nC12-TTC-containing solutions, it is observed that a finite contact angle is maintained This indicates that the formation of a hydrophobic pyrrhotite surface in the presence of nC12-TTC is much less sensitive to the substrate surface potential. To further study the synergistic mechanism between nC12TTC and SiBX, FTIR spectroscopy was completed on a pyrrhotite crystal conditioned in solutions containing various concentrations of SiBX and nC12-TTC This was done to evaluate the effect of nC12-TTC on the concentration of collector at the pyrrhotite surface, as can be inferred from the intensity of the absorbance peaks at 2925 cm-1 and 2850 cm-1. The absorbance peaks located at approximately 2925 cm-1 indicate that more collector is present at the pyrrhotite surface when contacted with 5% and 10% nC12TTC solutions compared to SiBX only This is mainly because the nC12-TTC molecule contains significantly more CH2functional groups in its hydrophobic tails compared to SiBX. The total collector conditioning time was kept constant

Table II

Findings

PGE Cu Ni