YIELDING RESULTS The Tweefontein Optimisation Project’s yield will be about 60%, which will result in about seven-million tons of processed coal product
Diversified miner Glencore’s Tweefontein Optimisation Project (TOP) – a brownfield expansion of the existing Tweefontein operation − was on course to reach steady-state plant production of 12.4-million tons a year by August 2015, the company told Mining Weekly during a site visit last month.
Construction of the TOP, which is about 24 km north-west of Kriel, in Mpumalanga, is about 85% complete. The project’s yield will be about 60%, which will result in about 7.5-million tons of processed coal product.
The initial value of the project, which is expected to have a life-of-mine of 25 years, was estimated at R8.2-billion. However, Glencore is forecasting that the project will be completed on time and under budget. Tweefontein GM Allen Butcher told Mining Weekly that the project was nearing full integration and was on schedule for completion by year-end.
He explained that the TOP would comprise seven opencast mine operations, which Glencore was developing to replace the existing underground operation by mining the old pillar reserves.
Two of the pits are in steady-state operation, while the third is being developed.
Butcher added that the company is planning to mine three pits at a time, as more than one pit was required to create the right blend of coal products and sufficient exposure of the coalface would ensure consistent production.
Project Development
The TOP’s mine infrastructure, which will include workshops, offices and employee facilities, is on schedule for completion by April 2015.
External infrastructure, such as a 1 200-pupil school for the local Phola community and the development of 500 residential stands, has already been completed. The relocation of a provincial road to allow for mining activities will be completed in early 2016.
Butcher stated that the conceptual framework for the development of the TOP started in 2009. However, the project was placed on hold for about nine months in 2011, as the mine awaited environmental permits from the Department of Mineral Resources.
“During these nine months, Glencore placed significant emphasis on ensuring operational readiness,” he emphasised.
This involved identifying the failures of mining projects in South Africa and within Glencore. These failures included mining companies not sufficiently emphasising the integration of completed projects into existing operations.
Butcher highlighted that projects that were not correctly integrated faced a myriad of challenges, such as effectively implementing ramp-up operations, owing to the transition of employees during the various phases of a project’s development.
“Therefore, Glencore compiled a detailed integration plan to prevent these types of challenges arising during the development of the TOP.”
On-site development of the TOP officially started in October 2012, with mining equipment delivered in the first quarter of 2013.
“We built the bulk of the mine’s infrastructure along the Ogies dyke to avoid sterilising the mine’s coal reserves,” he noted.
However, Butcher explained that building along the dyke, which runs east to west across the TOP site, restricted the mine’s construction areas.
“Fortunately, the dyke was reasonably stable and there were only one or two areas where we experienced poor ground conditions.
“Under the product stockpile and coal processing plant (CPP) building, . . . ground conditions were poor. We, therefore, had to excavate large sections and backfill with rock to ensure that it was sufficiently stable,” noted Butcher, adding that it is standard civil engineering practice to improve ground conditions by building a rock mattress.
He further pointed out that the CPP’s and the run-of-mine’s (RoM’s) bin foundations were reinforced using piling.
Butcher said that the RoM’s pad was also stabilised with rockfill and compacted layerworks for stability.
However, he stated that the general ground condition was favourable for construction of the TOP.
“We also undertook earth and civil works – [valued at] about R150-million − on the mine site during the dry seasons to derisk site development,” Butcher concluded.