The 7th Southern African Base Metals Conference was held in Mpumalanga from 2 to 3 September 2013, with a visit to Nkomati Nickel Mine on 3 September. The Conference attracted 22 papers from sub-Saharan Africa (DRC, Zambia, Namibia, and South Africa) as well as from Finland and Australia. The scope of the papers was wide-ranging, including geology, engineering design, and process metallurgy. This edition of the SAIMM Journal includes a selection of four papers from the conference. It is regrettable that four papers were withdrawn from publication for a variety of reasons at the request of the authors.
Sulphuric acid plant water savings options by R.J. Forzatti, et al. considers strategies for saving water in sulphur-burning acid plants, although the principles also apply to acid plants burning sulphide minerals such as pyrite, sphalerite, etc. Acid plants basically involve exothermic reactions on a huge scale, and require extensive cooling. The paper presents an economic evaluation of various options to achieve this goal against various backgrounds of localized power and water costs. Given the current sensitivity to environmental factors throughout the world, this paper provides an important contribution to the debate. In general, mines tend to be found in remote locations where both power and water are at a premium and indeed, sometimes not available at all. The northern regions of Chile provide a good example of this with the challenges of the Atacama Desert.
Challenges and successes at the Nkomati Nickel JV: pit to product process improvements by G. Cockburn is of particular interest in that the deposit was first subjected to a feasibility study in the 1970s (INCO/Anglo American). Several subsequent attempts all failed to build a viable case. However, today there exists a successful operating mine with a growth profile that can only be described as spectacular – 10 000 t/month to 700 000 t/month. A mine-to-mill optimization programme is described along with the consequent benefits – significantly the effect of blasthole patterns and explosive powder factors on primary crusher feed size distribution and the critical role that a stable plant throughput plays in milling and flotation performance.
Evaluation of a versatic 10 acid/Nicksyn™ synergistic system for the recovery of nickel and cobalt from a typical lateritic leach liquor by A.C. Du Preez and M.H. Coetzee is a valuable contribution to high-pressure acid leach (HPAL) nickel technology, given the probability that nickel lateritic ores will be increasingly exploited in the future in comparison to sulphide ores. Although HPAL was first implemented many decades ago at Moa Bay in Cuba, the technology has faced many techno-economic challenges. One has been the difficulties associated with calcium as encountered in the Australian ‘dry lateritic’ projects during the 1990s. This paper presents the results of laboratory test work which demonstrates that calcium co-extraction can be avoided in the extraction and stripping stages of the solvent extraction plant by judicious selection of reagents and operating conditions.
Evaluation of different absorbents for copper removal from cobalt electrolyte by V. Yahorava, et al. Several fibrous ion exchangers were investigated and compared to the more conventional granular ion exchangers for the removal of copper from cobalt electrolytes. A comparison of the design parameters and indicative costs for the impurity removal process is presented for the two alternatives.