Evaluation of the Cyanidation Leaching of Gold in a Waste Rock Ore

Document Type : Research Article


1 Department of Materials Science and Engineering, Obafemi Awolowo University, Ile-Ife, NIGERIA

2 Department of Chemical, Metallurgical and Materials Engineering Tshwane University of Science and Technology, Pretoria, Private Bag X680, SOUTH AFRICA


Samples of the waste rock obtained from Marofengin South Africa ground 60, 70 and 80% passing 75µm were leached with cyanide in bottle roll tests. The results obtained showed that the percentage gold dissolution depends more on the ore size consists than on the cyanide concentration with the highest average dissolution rates of 88.75, 94.34 and 95.90% found at 600, 500 and 500 ppm, for 60, 70 and 80% passing sizes, respectively. It was also noted that the lowest average percents cyanide consumption of 62.91, 61.73 and 58.56 at 60, 70 and 80% passing 75 µm were obtained at the 500 ppm cyanide concentrations. It was further observed that a clear pattern of increasing residual lime content was only observed at the 70% grind size, with the least lime content of 150.37 ppm at 500 ppm cyanide concentration being higher than the least lime contents for the 60 and 80% grind sizes. The results obtained thus suggest the 70% grind passing 75 µm ore with the gold dissolution percentage very close to the conventional 80% passing size at the lowest cyanide consumption of 500 ppm, much lower daily power consumption of about 925 kWh and high residual lime content that indicated the minimization of cyanide loss as hydrogen cyanide,a good choice for the leaching of the waste rock.


Main Subjects

[1] Eugene W.W.L., Mujumdar A.S., "Gold Extraction and Recovery Processes. Minerals, Metals and Materials Technology Centre (M3TC)", Faculty of Engineering, National University of Singapore Report, (2009).
[2] Cyanide Managementt-Dept of the Environment, Australia, 06 March (2013)
[3] "Environmental Law Alliance (ELAW) Report, Guidebook for Evaluating Mining Project EIAs", 3-18 (2013).
[4] Zhou J., Jago B., Martin C., Establishing the Process Mineralogy of Gold Ores. SGS Minerals Technical Bulletin No. 2004-03 (2004). (http://www.sgs.co.za/ en/Mining/Metallurgy-and-Process-Design/ Cyanidation -Technologies/Cyanide-Leaching/Cyanide-Bottle-Roll- Test.aspx), Accessed 06 March (2013)
[5] Mular A.L., Halbe D.N., Barrate D.J., "Mineral Processing Plant Design, Practice and Control. Society for Mining, Metallurgy and Exploration", Vol. I, (2002).
[7] Hutchison I., Kiel J.E., "Introduction to Evaluation, Design and Operation of Precious Metal Heap Leaching. Society for Mining, Metallurgy and Exploration" 1st Edn (1988).
[8] Cassagne P., Lohri P., Tüller Y., Optimisation of Fire Assay Analytical Conditions for Gold Determination Inindustrial Environment, "LBMA Assaying & Refining Seminar", March 7 and 8, (2011).
[9] "ISO 11426:1997. Determination of Gold in Gold Jewellery Alloys -- Cupellation Method", (Fire Assay). (http://www.iso.org/iso/catalogue_detail.htm?csnumber=26426), 09 March (2013).
[10] Habashi F., "Kinetics and Mechanism of Gold and Silver Dissolution in Cyanide Solution. Bureau of Mines and Geology", State of Montana Bulletins 5, April 1967
[11] Parga J.R., Valenzuela J.L., Diaz J.A., “New Technology for Recovery of Gold and Silver by Pressure Cyanidation Leaching and Electrocoagulation” (http://www.intechopen.com/download/ pdf/27199, 09 March 2013)
[12] Schlanz J.W., Grinding: An Overview of Operation and Design (2007)  (http://mrl.ies.ncsu.edu/reports/ 87-31-P_Grinding_ Operations_Design.pdf), 09 March (2013).