A Study of the Variables in the Optimisation of a Platinum Precipitation Process

Authors: Tebogo Phetla, Edison Muzenda, M Belaid

Abstract:

This study investigated possible ways to improve the efficiency of the platinum precipitation process using ammonium chloride by reducing the platinum content reporting to the effluent. The ore treated consist of five platinum group metals namely, ruthenium, rhodium, iridium, platinum, palladium and a precious metal gold. Gold, ruthenium, rhodium and iridium were extracted prior the platinum precipitation process. Temperature, reducing agent, flow rate and potential difference were the variables controlled to determine the operation conditions for optimum platinum precipitation efficiency. Hydrogen peroxide was added as the oxidizing agent at the temperature of 85-90oC and potential difference of 700-850mV was the variable used to check the oxidizing state of platinum. The platinum was further purified at temperature between 60-65oC, potential difference above 700 mV, ammonium chloride of 200 l, and at these conditions the platinum content reporting to the effluent was reduced to less than 300ppm, resulting in optimum platinum precipitation efficiency and purity of 99.9%.

Keywords: Platinum Group Metals (PGM), Potential difference, Precipitation, Redox reactions.

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1079414

References:

[1] F. L. Bernardis, A.R. Grant & S.D. Sherrrington, "A review of methods of separation of the platinum-group metals through their chlorocomplexes," Reactive & functional polymers, vol. 65, pp. 205-207, 2005.
[2] F. R. Hartley (ed), "Chemistry of the Platinum Group Metals, Recent Development," Elsever Science Publisher, pp. 9-30, 1991.
[3] C. R. M. Rao & G. S. Reddi ," Platinum group metals (PGM); Occurrence, use and recent trends in their determination," Hyderabad 500068, India, vol.19. no.9,2000.
[4] D. McDonal, "A History of Platinum," Johnson Matthey and Co.Ltd., London, 1960.
[5] P. Charlesworth, "Separating the Platinum Group Metals by liquid-liquid extraction," Platinum Metals Rev., vol. 25, no. 31, pp. 106-112, 1981.
[6] J. L. Bray, Non-Ferrous Production Metallurgy. New York, Wiley& Sons, 2nd Edition , 1947.
[7] L. Pauling, General Chemistry. New York Dover, 1988.
[8] G. B. Kauffman, Ammonium Hexachloroplatinate Inorganic Synthesis. New York, Wiley and Sons, 1967.
[9] R. J. Angelic, Reagent for Transition Metals Complex and Organometallic Synthesis. New York, Wiley and Sons, 1990.
[10] W. Watson, Phil. Trans., vol. 46, no. 584, 1951.
[11] W. Lewis, Phil.Trans., vol. 18, no. 638, 1755.
[12] D. Ms Donald, and L. B. Hunt, "A History of Platinum and its Allied Metals," Johnson Matthey and Co.Ltd., Hatton Garden, London, 1982.
[13] G. G. Robson, "Platinum 1985," Johnson Matthey plc, 1985.
[14] Rustenburg Platinum Mines, "Productivity in Platinum Mining: A Continuing Programme of Successful Development in Underground Mechanisation," Platinum Metals Rev., vol. 24, no. 4, pp. 138-143, 1980.
[15] L. J. Cabri, "Platinum-Group Elements: Mineralogy, Geology and Recovery," Canadian Institute of Mining and Metallurgy, vol. 23, Montreal, 1981.
[16] D. W. Bullet, "The surface properties of platinum metals," Platinum Metals Rev., vol. 23, no. 3, pp. 109 - 111, 1979.
[17] F. R. Hartley, "The Chemistry of Platinum and Palladium: With particular reference to complexes of the elements," Platinum Metals Rev., vol. 17, no. 3, pp. 105. 1973.
[18] W. P. Griffith, The Chemistry of the Rarer Platinum Metals. Interscience, London 1967.