In the face of growing health and safety challenges, stringent government regulations and rapid transformation, the local mining industry has one success record that it can look back on with pride. This year marks 100 years of hoist rope testing in South Africa, which was celebrated at a centenary event held at the Cottesloe testing facility of CSIR Mining Technology on Friday 26 November 2004.
Vishnu Pillay, director of CSIR Mining Technology, explains that as depths increase, along with the demand for bigger and heavier payloads, rope testing is an increasingly important part of mine safety. CSIR Mining Technology currently runs one of only two hoist rope testing facilities approved by the Department of Minerals and Energy (DME) in South Africa, at its Cottesloe laboratory in Johannesburg.
"The records of the Department of Minerals and Energy (DME) show more than 1000 registered mines in South Africa, of which an estimated 135 are underground operations," says Pillay. "The CSIR's own rope database reflects more than 1150 hoist ropes in use, illustrating the responsibility that rests with our laboratory to provide mine engineers with accurate test data and results."
The statutory testing of mine hoist ropes was introduced following the failure of a winding rope in No. 2 shaft, Robinson Deep, on 25 April 1904. This accident caused the death of over 40 men and led to the immediate introduction of a government regulation that stipulated the periodic removal of a section of head rope adjacent to the skip, to be tested at the Government Mechanical Laboratory of the Department of Mines.
The Department of Mines relinquished control over the Government Mechanical Laboratory in 1964, when it was taken over by the CSIR and incorporated into its National Mechanical Engineering Research Institute. This laboratory now forms part of CSIR Mining Technology and continues to conduct statutory tests on mine hoist ropes and provide related mechanical testing services.
Hoist rope facts
* South African mines hoist about 280 000 people up and down mine shafts each day.
* The same mines hoist about 10 million tons of ore every month.
* An eight compartment, 2 km deep shaft contains more than 16 km of hoist rope.
* In the deepest shaft each hoist rope is more than 3 km long.
* DME regulations stipulate that ropes installed on licensed winders must be tested every six months.
* Canada has adopted certain South African standards relating to rope discard criteria.
* CSIR Mining Technology's hoisting and mechanical testing laboratory tests between 2000 and 3000 ropes every year, including hoist ropes, scraper ropes, dragline ropes and ropes for marine applications.
* The biggest specimen the centre has ever tested is a 153 mm diameter steel wire rope, which was locally manufactured, and was to be used as one element of a sling for an engineering application.
* The biggest steel wire rope used for mine hoisting in South Africa is 63 mm in diameter, and weighs 17 kg a metre. For working depths of more than 2 km, the weight of this rope alone - without any skip or cage attached - is some 34 tons.
* Although mines sometimes experience winding accidents, they are rarely due to rope failure. Rope testing allows mines to predict and prevent such failure. Testing also keeps costs down, as it helps mines to avoid premature replacement of expensive steel wire rope.
* CSIR Mining Technology maintains the largest database of rope tests in Africa, to ensure the traceability of all specimens tested.
CSIR Mining Technology's Cottesloe testing facility
The largest tensile test machine in use at Cottesloe is a 15 MN (1529 metric tonne force) MFL machine that was commissioned in 1989. In addition to the testing of mine hoist ropes, the MFL machine is able to accommodate large diameter wire ropes (~160 mm) as used in the oil drilling, bridge and shipping industries. The capacity of the 15 MN machine also caters for tensile tests on conveyor belts up to 1,2 m wide and large-link chains, such as those used on coalmine draglines.
The hoist rope tests evaluate a rope's absolute breaking force, mechanical properties, modes of wire and strand failure, extent of corrosive and abrasive damage, and the state of lubrication. If the results of the test show that the rope does not conform to the code of practice (SABS 0293, 1996), then the recommendation is that the rope be discarded.
The majority of ropes, however, only reach this condition following several years of service. The results of the test, a graphical history thereof and subsequent visual examination of the test specimen, are recorded on a test certificate supplied to the mine.
The smallest diameter hoist rope that CSIR Mining Technology tests is approximately 16 mm in diameter, and the largest is currently 63 mm. Peake says that in terms of hoist ropes, the predominant size ranges between 30 mm and 50 mm in diameter.
In addition to the testing of mine hoist ropes, CSIR Mining Technology offers a range of other mechanical tests including tensile, proof and compression tests of a broad range of mining and industrial products.
For more information contact Andrew Peake, head: Mining, Engineering, Technology and Laboratories, CSIR Mining Technology, 011 853 4550, miningtek@csir.co.za, www.csir.co.za/miningtek
About the CSIR
The Council for Scientific and Industrial Research) is the largest public R&D, technology and innovation institution in Africa. Established by Parliament, it has a track record spanning close to 60 years. The CSIR is structured around operational research units and strategic technology centres. It strives for excellence in all its endeavours in order to improve the quality of life of South Africa's people.
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