Submitted on: 11 October 2013.
Revised on: 17 November 2013.
Accepted on: 19 December 2013.
___________________Journal of the Southern African Institute of Mining and Metallurgy
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Submitted on: 20 January 2003.
Revised on: 23 March 2003.
Accepted on: 05 April 2003.
___________________Journal of the Southern African Institute of Mining and Metallurgy
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Submitted on: 03 May 2023.
Revised on: 01 July 2023.
Accepted on: 16 July 2023.
___________________Journal of the Southern African Institute of Mining and Metallurgy
Submitted on: 14 February 1999.
Revised on: 15 March 1999.
Accepted on: 04 April 1999.
___________________Journal of the Southern African Institute of Mining and Metallurgy
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