South Africa is one of the biggest coal producing nations in the world. In South Africa it is the second biggest mining sector after gold. Coal is produced mostly for local demand, especially for power stations. Part of the coal is exported, most of it being shipped through Richards Bay coal terminal on the Kwazulu Natal north coast.
The coal mines are located mainly in the north-eastern area of Johannesburg, in the province Mpumalanga, where a large number of open-pit and underground coal mines are in operation. Coal reserves in South Africa, as everywhere else, are not endless and with the current expectations, by 2040 only 7 billion tons will be left of a current estimated reserves of 34 billion tons.
THE REMAINING COAL RESERVES
The remaining reserves are different in nature. The thick high coal seams have been mined extensively in the past. More and more coal is now left in low coal seams, with a height varying from 1m to 2.8m. The quality of the coal is usually quite good and with current coal prizes these seams are economically interesting to mine.
The underground mining method in South Africa is either longwall mining or room amp pillar (board amp pillar). In the latter method, the main excavation methods are drill and blast or preferably with continuous miners.
PROTOTYPING ON LOCATION
Continuous Miner H 4.30 For the low coal seams, WIRTH started the development of a low seam coal header several years ago. This low height continuous miner, has a minimum building height of only 1.1m and is capable to excavate up to 2,5m height. it is equipped with a 3.5m wide cutting drum, powered by two 200kW electric motors. The crawler tracks of the machine are driven by frequency controlled drives, allowing very precise and efficient tramming of the machine underground. The machine is operated through radio remote control.
The first machine went to South Africa as a prototype and has been through the entire learning curve of a prototype machine. It was a hard time for the engineers and operators as well as for our client. In the end the work paid off as the machine improved on performance and reliability over the time.
TSELENTIS COAL MINE
One of the recent jobs carried out by a WIRTH Continuous Miner, was at Xtrata’s Tselentis coal mine. This mine is located near Ermelo, over 200km east of Johannesburg. Although it is a fairly small operation for Xtrata’s standards, it is a significant operation for Grinaker LTA, a specialized underground coal mining contractor.
Tselentis is mined in a board & pillar operation with 13m square pillars and 6.5m wide roadways. Originally it was planned for two drill and blast sections and later on extended with a continuous miner section. This is where WIRTH CM came in. Meanwhile the two drill and blast sections have been discontinued. The mine has produced up to 44.000 tons per month with the continuous miner, in a seam height from 1.7m to 2.2m. This is well above the contractual target of 35.000 tons per month. The success lies with the powerful continuous miner and the good cooperation and skills of Grinaker’s mine crew.
UNTIL THE JOB IS DONE
WIRTH permanently has a service engineer stationed at the mine, to supervise the performance and the maintenance of the machine. From WIRTH South Africa office in Boksburg, near Johannesburg International Airport, logistical support is provided with spare parts management and storage.
With this example of innovation and product development, WIRTH engineering capacities have once again been proven. Furthermore it has also shown that WIRTH stays on the job until success has been achieved. With the continuous miner range, WIRTH will continue to explore the underground coal markets, with innovative products and highly skilled and motivated engineers.