Optimizing the Extraction Conditions of Gold in AuCN Solution

Jacob Sawai Ben

Abstract


The refinery section of Porgera Gold Mine utilizes carbon in leach, carbon in pulp, elution, and electrowinning processes to extract gold from low-grade ores. This paper aims to discuss the optimum conditions that must be maintained to optimize gold recovery. Gold leaching is optimized at pulp density of 28 – 29 % solids, pH 10.5, 160 – 180 ppm cyanide concentration, 5 – 6 mg/L oxygen concentration, and 25 tonnes of activated carbons in a 765 m3 agitated leach tank with residence time up to 32 and 24 hours for low-grade and high-grade ores respectively. The amount of carbon in each 392 m3 carbon in pulp tank is the main determining factor for gold extraction efficiency. Each tank requires up to 12 tonnes of carbon and 5 ppm dissolved oxygen to concentrate 93 – 96 % of soluble gold at 95 % carbon activity rate, achieving up to 10,000 ppm gold-cyanide in feed and 0.001 ppm in tails solution. The gold-loaded carbon is then stripped to remove gold into an alkaline cyanide solution via two 20 m3 pressurized vessels at 400 kPa and 140 °C. The produced eluate enters 12 electrowinning cells, where electricity is passed through the cells, causing gold to deposit onto stainless steel wool cathodes. These are regularly removed, pressure filtered in a plate, and frame pressed to collect gold in the form of a solid cake. This is finally mixed with flux, and smelted to produce gold bullion containing 80 – 83 % gold and 17 – 20 % silver.

Full Text:

PDF

References


E.B. Nsimba, (2009). “Cyanide and cyanide complexes in the gold-mine polluted land in the East and Central Rand goldfields, South Africa”. Masters Thesis, Faculty of Science, University of the Witwatersrand, Johannesburg.

S. Kaspin and N. Mohamad, “Investigating the standard process of conventional gold refining process in Kelantan, Malaysia”, Presented at 2015 International Conference on Sustainable Energy and Environmental Engineering (SEEE 2015), Thailand, Bangkok (2015).

A. Feather, K.C. Sole and L.J. Bryson, “Gold refining by solvent extraction – the Minataur Process”, The Journal of The South African Institute of Mining and Metallurgy, vol. 97 , no. 4 , (1997), pp. 169-174.

L.R.P. de Andrade Lima, “Dynamic simulation of the carbon-in-pulp and carbon-in-leach processes”, Brazilian Journal of Chemical Engineering, vol. 24, no. 04, (2007), pp. 623 – 635.

S. Clesceri, E. Greenberg and R. Rhodes. (1989). “Standards methods for the examination of water and waste”. 17th Edition, 22 – 45.

S.J. Robuck and R.G. Luthy, “Destruction of iron-complexed cyanide by alkaline hydrolysis”. Water Science and Technology Journal, vol. 21, no. 6-7, (1998), pp. 547 – 558.

C.A. Fleming, A. Mezei, E. Bourricaudy, M. Canizares and M. Ashbury, “Factors influencing the rate of gold cyanide leaching and adsorption on activated carbon, and their impact on the design of CIL and CIP circuits”, Journal of Minerals Engineering 24, (2011), pp. 484 – 494.

W. Stange, “The process design of gold leaching and carbon-in-pulp circuits”. The Journal of The South African Institute of Mining and Metallurgy, vol. 99, no. 1, (1999), pp. 13 – 26.

M. Latva-Kokko, T. Hirsi, T. Ritasalo, and J. Tiihonen, “Improving the process performance of gold cyanide leaching reactors”, Presented at 2015 World Gold Conference, Gauteng, South Africa (2015).

B.J. Vorster and S.R. Flatman, “Cyanide control in the metallurgical process of gold extraction in AngloGold (S.A.)”. The Journal of The South African Institute of Mining and Metallurgy, vol. 101, no. 07, (2001), pp. 359 – 366.

B. Ghobadi1, M. Noaparast, S. Z. Shafaei, and M. Unesi, “Optimization of cyanidation parameters to increase the capacity of Aghdarre gold mill”. Journal of Mining and Environment, vol. 5, no. 2, (2014), pp. 121 – 128.

J.H. Schubert, I.J. Barker and C.L.E. Swartz, “Performance evaluation of a carbon-in-pulp plant by dynamic simulation”. Journal of the South African Institute of Mining and Metallurgy, vol. 93, no. 11/12, (1980), pp. 293 – 299.

G.D. Buson, D.S. Ngandu, J.C. LeRoux, and E.J. Rogans, “The West Driefontein reclamation carbon in pulp plant; pilot plant testwork, design, commissioning and optimization”. Journal of the South African Institute of Mining and Metallurgy, vol. 99, no. 02, (1999), pp. 673 – 767.

Y. Shimin, Y. Tingting, S. Wenping, Y. Xiyang, Q. Jianxin, W. Wuyi, D. Huijuan, W. Zhiguang, D. Lizhou and L. Tianlong, “Ultrasound-assisted cyanide extraction of gold from gold concentrate at low temperature”. Ultrasonics Sonochemistry, vol. 64 (2020), pp. 1 – 10.

L. Tahli and T. Wahyudi, “Desorption of gold and silver from activated carbon”. Indonesian Mining Journal, vol. 20, no. 1, (2017), pp. 39 – 47.

T. P. Oladele (2015) “Effect of temperature, contact time and agitation speed during pre-treatment on elution of gold”. Stellenbosch University.

A.L. Lunga (2006). “Optimizing the operating conditions of gold elution and electrowinning for Tau Lekoa stream at Kopanang Gold Plant”. Masters Thesis, School of Chemical & Metallurgical Engineering, University of the Witwatersrand, Johannesburg.

L.A.D. Barbosa, L.G.S. Sobral, and A.J.B. Dutra, “Gold electrowinning from diluted cyanide liquors: Performance evaluation of different reaction systems”. Minerals Engineering, vol. 14, no. 9, (2001), pp. 963 – 974.

G. A. Ocran, “Optimization of influential factors in gold electrowinning using response surface methodology”. International Journal of Science and Research, vol. 6, no. 7, (2017), pp. 479 – 490.

J. Steyn and R.F. Sandenbergh, “A study of the influence of copper on the gold electrowinning process”. The Journal of The South African Institute of Mining and Metallurgy, vol. 104, no. 03, (2004), pp. 177 – 182.




DOI: http://dx.doi.org/10.52155/ijpsat.v31.1.4032

Refbacks

  • There are currently no refbacks.


Copyright (c) 2022 Jacob Sawai Ben

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.