Monontsha - A success story in holistic environmental management. When Impala Platinum encountered waste management and environmental issues at their Rustenburg mine complex they resorted to an original, holistic approach to the problems. The mine had a number of waste streams that needed to be managed and they also wanted to attend to the rehabilitation of the slopes of their tailings dams. Monontsha was an innovative answer to this situation. Established in 2004 as an empowerment project between Impala and the local Luka community, Monontsha enjoys an ongoing contract with the mine currently valued in excess of R6 million per year and provides employment for over 50 people across its’ process, transport and vegetation divisions. The Process Timber wastes in the form of redundant shaft supports and wood fibre from the mineral extraction process are brought into the Monontsha complex. Here the solid timber is shredded in a powerful chipper. Sewage sludge is brought in from both the mines own treatment plant and from plants operated by the local municipality. The materials are mixed together in equal proportions and formed into windrows. Over a period of approximately 12 weeks the windrows are regularly turned and watered promoting the creation of a quality organic compost. The company currently produces around 900m3 of compost per month. The windrows are regularly turned and watered to encourage the natural composting process. The raw materials for the Monontsha composting process. From top, shredded timber from waste mine supports, wood fibre from the mineral extraction process and treated sewage sludge. The company operates its own transport division of trucks, plant and equipment. The Rehabilitation When ready for application the compost is transported to the slopes of the tailings dams. After the slopes have been manually cleared of alien vegetation the compost is applied at a rate of about 100m3 per hectare. It is worked into the ground which is then seeded with a mixture of selected grass species. This process not only stabilises the slopes, preventing erosion by wind and rain, but also beautifies the area and encourages the return of insect and eventually bird and animal life. When the material is fully composted it is transported to the slopes and worked into the ground before seeding can take place. Tailings dam slope showing completed rehabilitation work. The next level will be composted and seeded when it reaches a height of approximately 3 metres. Fully composted material ready to be utilised for rehabilitation. Rehabilitated slope after a single winter season shown against levels still to be attended to. Summer rains will quickly promote healthy growth. The Way Forward Trials are underway to also utilise the compost in the growing of indigenous shrubs and small trees which will be transplanted onto the slopes to further the aim of returning the areas to a natural state. A new vermiculture project is intended to eventually supply the company with high quality vermi-compost which will be blended with the standard product. The resulting premium organic compost will be marketed to local farmers and growers providing additional income for the community. An extension of the companies’ composting efforts, the vermiculture project is showing encouraging results. Telephone 014 569 1145 Indigenous trees and shrubs grown with Monontsha compost will eventually be replanted as part of the slope rehabilitation. Compost not used for slope rehabilitation is screened to a fine consistency and marketed to local growers.
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