Modern Mining September 2016


Realising possibilities...

declared a non-JORC hard rock resource of 275 166 tonnes at 20,2 % Zn with a cut-off grade of 14 % Zn. Recent investigation work by GeoQuest (Zambia) has identified considerable potential tonnages of karst fill/saprolitic material in the vicinity of the open pit, reporting grades up to 20 % Zn, the extent of which has never been fully explored and which remain undrilled and untested. Bushbuck engaged Skorpion Mineral Processing to undertake a metallurgical programme of test work on grab samples from trenches and stockpiled ore of the Star Zinc hard rock ore and karst fill material. This included gravity and magnetic separation, froth flotation and acid/alkaline leaching. The acid leach Zn recoveries were reported to be in excess of 90 %. BMR has also carried out preliminary scoping metallurgical tests using the services of Alfred H Knight and ZCCM, Kitwe, Zambia on a 30 kg grab sample of the karst fill material and achieved a similar Zn recovery. Both the Skorpion and BMR tests required approximately 400 kg acid per tonne of ore treated to achieve these recoveries. Future test work will focus on optimising these results using larger representative samples.  “The StepWise approach was instrumental in Advisian having been awarded the second project as the client realised the extensive ben- efits of the early ascertainment of financial viability,” says Munro. The Selkirk BFS is using the StepWise methodology to evaluate pre- vious recommendations that were made in the PFS. The focus of this project is to enhance the ore producing potential of the mine as well as to explore the most financially beneficial transportation options when moving the ore from the mine to the Phoenix concentrator. WorleyParsons is also currently in the process of developing a high level execution schedule aimed at achieving BCL’s objective of first ore by year end 2016.  value to the project and so secure potential for return on investment. The Maibele North prospect is located 50 km north of the Selebi-Phikwe nickel and copper mine and smelter owned by BCL. Exploration in 2010 confirmed nickel, copper and platinum group metals mineralisation and additional drilling in 2014 yielded further finds. Advisian was appointed to undertake a PFS to evaluate results from the previous study that recommended an underground mine based on traditional economic modelling. Using the StepWise approach, twelve underground mining con- figurations were evaluated against open-pit mining configurations. These initial StepWise results helped focus drilling activities into areas of higher mining interest and, when the revised geological model was completed, only the more viable options were re-evaluated. Advisian concluded that none of the underground options identified were financially robust enough to justify underground mining at Maibele; however, an open pit was proposed as having potential advantages. Following the successful utilisation of the StepWise methodology for Maibele North, Advisian was given the opportunity to undertake a BFS for an open-pit mine at Selkirk commencing in February 2016, which is now being undertaken underWorleyParsons branding, allow- ing a seamless progression to execution. Underground mining operations began at the Selkirk nickel mine in 1989 but the mine was put on care and maintenance in 2002 due to the depletion of the massive sulphide copper and nickel ores acces- sible for underground mining.

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