AEL Zimbabwe, a member of the international AEL Mining Services group, has partnered with Zimplats at its Ngezi Mining Division to provide an explosives solution for the expansion project for the development and production at three portals – the Ngwarati, Rukodzi and Bimha underground mines. The premature closure of the open pit at Ngezi due to the worldwide economic recession in 2008 shifted ore demand to the underground operations with annual production ramping up from 2.1 Mt to an expected 4.2 Mt by 2010.
When the second concentrator started operating in July 2009, AEL Zimbabwe was well-prepared to meet the increase in underground bulk emulsion supply to support each of the mine’s portals. This included the restructuring of its site personnel and equipment to support each of the three portals, managing stock and shafthead deliveries, and providing additional technical back-up to service charging units. Upskilling its on-site personnel was also critical to support the change.
AEL’s relationship with Zimplats’ Ngezi Mining Division dates back to 2001 when the mine issued an explosives tender to provide Prime, Load, Tie and Shoot (PLTS) blasting services for the open-pit mine. With a wealth of experience in PLTS in other African countries, AEL put together a winning bid in the face of stiff competition from other established explosives suppliers.
AEL was awarded an initial three year PLTS contract that heralded the beginning of a long term and fruitful relationship with Zimplats Ngezi Mining Division. Eight years on, that relationship has grown. During the open pit life, in excess of 70,000 t of emulsion was used to blast ore and overburden totalling close to 60 million m3 (bank) using a fleet of four AEL Mobile Manufacturing Units (MMUs).
AEL’s UBS technology in conjunction with Tunnelmaster shock tube system was accepted as the blasting system for Ngezi Mining Division’s room and pillar mining after extensive trials at the start of underground mining in 2003.
Langton Nyandoro, Business Manager of AEL Zimbabwe, comments, “Up until July 2009, AEL R100G was the main product used for underground operations. After reviewing the product and its use at Ngezi Mining Division and other similar operations in the region, AEL developed SDD emulsion as a cost effective alternative to R100G. The bulk emulsion is supplied from AEL’s central manufacturing plant at its head office in Johannesburg and is transported to site by a fleet of dedicated road tankers into AEL storage silos erected on site at Ngezi.”
Through the application of the ‘Mine to Mill’ concept, Ngezi open pit was the first mine in Zimbabwe to use electronic delay detonator technology (SmartDets) supplied by AEL’s sister company, DetNet to optimise the mining-processing value chain. The SmartDet electronic delay system was upgraded by the development of the synchronised blaster, which increased blasting capability from 800 to 1,600 detonators.
AEL Blast Consult continually provides training to the AEL team on site, as well as customer personnel in order to keep up with technological advancements. To meet the future requirements of Ngezi Mining Division, AEL Zimbabwe has embarked on a skills development strategy through an intensive explosives engineering course for its field personnel. Four mining engineers are now at an advanced stage of the course.
Expectations are high that Phase Two expansion of the Ngezi project will commence in the next few years. The volume of explosives consumption is forecast to increase from the current 4,500 t/y to 8,000 t/y. At present, six emulsion charging units have been commissioned for the three portals and an additional three will be deployed as production ramps up at Bimha Mine (Portal 4).
Langton concluded, “As the mine expands and the volume of emulsion increases, AEL will continuously monitor and assess the viability of site based emulsion manufacture, which can be rapidly mobilised in the form of modular plants. AEL’s automated shock tube manufacturing plant at Modderfontein (ISAP) has the capacity and capability to meet Ngezi’s future demands.”
Ngezi Mining Division lies 160 km by road to the south west of Harare, the capital of Zimbabwe. The mine started as an open pit mine in 2001 and then underground mining commenced in 2003. Initially, all the ore mined at Ngezi was trucked 86 km to the north for processing at the Selous Metallurgical Complex, but a second concentrator has since been commissioned at Ngezi to double annual production by 2010 from 2.1 to 4.2 Mt.