Gold Recovery from Gold Bearing Materials Using Bio-Diesel, Vegetable Oils and Coal

Anderson Mlaki, Jamidu Katima, Henry Kimweri

.

DOI: 10.4236/eng.2011.35065                

Abstract

The present work is focused on the performance of three types of coal-oil agglomerates on recovery of liberated gold from gold bearing materials. Pre-formed agglomerates developed using bio-diesel, castor oil and mineral diesel as liquid hydrophobic phases were used in the study. The influence of the type of liquid hydrophobic phase on the degree of gold recovery and the effect of factors such as gold particle concentration, viscosity, agglomerate size, agglomerate/ore ratios and particle penetration into agglomerates have been studied as a function of time. It is shown that gold recovery rate can be increased by an increase in agglomerate loading, surface area and the viscosity of the hydrophobic phase and high recoveries are attained up to 98.5%. Increase in concentration of gold particles per unit volume of slurry increased attachment rate but did not change the final recoveries attained. It is shown that gold particle penetration occurs mainly in the coarse agglomerates if contact is prolonged beyond 60 minutes. Examination of sections of gold-loaded agglomerates under reflected light microscope showed gold and some silicate particles penetrated in few cracked agglomerates and only gold particles were observed inside the uncracked agglomerates suggesting the possibility of gold selectivity during particles penetration. It was shown that the increase in gold recovery attained at prolonged contact time is due to both gold penetration and oleophilic attachment.

Keywords

Pre-Formed Agglomerates, Selective Gold Penetration, Oleophilic Attachment

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	A. Y. Ngenya, “Some Chemical Aspects of the Coal-Gold Agglomeration Process,” PhD Thesis UDSM, 2004.
[2]	R. D. Pehlke, “Unit Processes of Extractive metallurgy,” Elsevier, North-Holland Publishing, 1977.
[3]	R. W. Allen and T. D. Wheelock, “Effect of Preparation Techniques on Kinetics of Oil Agglomeration of Fine Coal,” Minerals Engineering, Vol. 5, No. 6, 1992, pp. 649-660
[4]	J. Drzymala, T. D. Wheelock and R. W. Allen, “Basic Principles and Mechanisms of Selective Oil Agglo- meration,” Pittsburgh Energy Technology Center, Pittsburgh, Pennsylvania, 1990.
[5]	C. E. Capes and R. F. Germain, “Selective Oil Agglomeration in Fine Coal Beneficiation,” Mineral Processing and Extractive Metallurgy Review, Vol. 2, 1982, p. 243.
[6]	S. Gaidarjiev, “Coal-gold-Agglomeration of Alluvial Gold,” Fuel and Energy Abstracts, Vol. 38, No. 6, 1997, pp. 447-447.
[7]	W. Kotze and F. W. Petersen, “Free Gold Recovery by Coal-Oil Agglomeration,” Journal South African IMM, Vol. 100, 2000.
[8]	L. B. Moses and F. W. Petersen, “Flotation as Separation Technique in the Coal Gold Agglomeration Process,” Minerals Engineering, Vol. 13, No. 3, 2000, pp. 255-264.
[9]	S. Sen, A. Seyrankaya and Y. Cilingir, “Coal-Oil Assisted Flotation for Gold Recovery,” Minerals Engineering, Vol. 18, No. 11, 2005, pp. 1086-1092.
[10]	X. Q. Wu, R. J. Gochin and A. J. Monhemius, “Adhesion of Gold to Oil-Carbon Agglomerates,” Journal of Minerals Engineering, Vol. 17, No.1, 2004, pp. 33-38.
[11]	A. Marciano, L. Costa and F. Lins, “Utilization of Coal-Oil Agglomerates to Recover Gold Particles,” Minerals Engineering, Vol.7, No. 11, 1994, pp. 1401-1409.
[12]	H. Gavin and A. J. Monhemius, “Improving Environmental, Economic and Ethical Performance in the Mining Industry,” Journal of Cleaner Production, Vol. 14, No. 12-13, 2006, pp. 1158-1167.
[13]	J. R. Ikingura and M. K. Mutakyahwa, “Sources of Mercury Contamination and Exposure in Tanzania,” International Conference on Mining and Environment in Eastern and Southern Africa, SAREC and University of Dar es Salaam, October 1995.
[14]	A. E. Mlaki, J. H. Katima and H. T. Kimweri, paper submitted for publication; Tanzania Journal of Engineering and Technology, 2010.
[15]	M. Elblbesy and A. Hereba, “Effect of Viscosity and Surface Tension on Adhesion,” Current Applied Physics, Vol. 9, No. 4, 2009, pp. 872-874.
[16]	J. P. Calvez, M. J. Kim, P. L. Wong and T. Tran, “Use of Coal-Oil Agglomerates for Particulate Gold Recovery,” Minerals Engineering, Vol. 11, No. 9, 1998, pp. 803-812.
[17]	T. L. Brown and H. E. Lemay Jr, “Chemistry: The Central Science,” Prentice Hall, Inc., New Jersey, 1985.
[18]	A. Santine, (2006) Gold Jewelry publications. Available at: http://goldprice.org/gold-jewelry/2006/01/gold-jewelry-weight.html