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Utilization of large doses of inorganic reagents in mineral industry not only leads to high cost but also increases the toxicity in the environment. This research provides a new, environmentally friendly, biodegradable, and cost-effective depressant reagent, namely tricarboxylate sodium starch (TCSS), in chalcopyrite and pyrrhotite flotation systems. The selective depression and adsorption mechanism of TCSS on the two minerals were studied through the laboratory based measurements such as microflotation experiments, XPS spectral analysis, IR spectral analysis, adsorption amount analysis and zeta potential measurements. The addition of TCSS exhibited a much better depressive performance towards pyrrhotite than chalcopyrite in a wide pH range. Binary mineral flotation experiments indicated that an effective separation between the two minerals could be possible at a low concentration of TCSS, at which an improved recovery and grade of chalcopyrite of more than 75% could be achieved. All of the analytical measurements justified the flotation results and revealed that TCSS behaved differently with the two minerals. TCSS showed significantly much greater affinity towards pyrrhotite, the reason of which may be the presence of large amount of metal hydroxyl species on its surface.
A novel double flotation machine allows parallel flotation tests to be run simultaneously.Hot float tests conducted in parallel circumvent the effect of pulp ageing.Selectivity curves suggest that the main effects of ageing were due to pyrrhotite.
Hot batch flotation tests are often applied to reduce risks in plant trials as they combine the benefits of matching complex plant feed stream compositions with the high precision of lab scale batch flotation testwork. One of the weaknesses of hot flotation tests is the sequential nature of the testwork, where ageing of pulp samples can influence metallurgical performance. When present this interference could at best generate inconclusive results, and at worst, inaccurate conclusions. To improve the reliability of test data, CP Kelco has developed a novel, double batch flotation machine for conducting parallel hot flotation tests on live flotation streams. Hot flotation tests with a sensitive Ni cleaner feed stream, principally containing pyrrhotite, pentlandite, magnesite and talc, were used to demonstrate the principles and potential of the device. Parallel tests with the double flotation machine were shown to afford reproducible Ni recovery-grade curves, while sequential tests conducted with a 30min ageing period showed a marked change in Ni recovery-grade curves. In this study, selectivity curves have been beneficial in identifying the sources of the changes caused by ageing, which appear to be due to an increased recovery of pyrrhotite.