Operations in South Africa

The use of Corflex Pinch Valves at the DRD Ergo Operations in South Africa

In 1978 the Anglo American Ergo Operation started on the eastern side of Johannesburg in South Africa for the recovery of pyrite containing gold, uranium and sulphur from old gold mines slimes dams of which there are many as mining of Johannesburg area has been going for many years.

Johannesburg is one of very few cities not built on a river. It was actually built on a river of gold extending +/- 150kms east to west. The valves originally installed on the ERGO slurry pipeline were plug and ball types but these were found to be maintenance intensive. Many other valves were tried as alternatives including sliding disc valves a manual operated non-return ball valve and Corflex Pinch Valves. Corflex Engineering was in the process developing highpressure pinch valves for pipelines handling abrasive product. Pinch Valves are an ideal slurry valve as in the fully open position they are similar to a rubber lined pipe. When closed and not allowed to leak they can last for many years. The Corflex Pinch Valve Sleeves originally had problems of failure due to pressure from water hammer but this was overcome by using stronger reinforcement for the rubber sleeve. To enable this special tooling was built. As the sleeves are hand built Pressure testing of the sleeve for safety reasons was also started which is set at twice the maximum recommended working pressure. Sleeve failure is in excess of three times the recommended working pressure. In 1986 5 x 350mm Corflex Pinch Valves were installed in a major pump station at a pressure of 20 Bar. The flushing valves were eccentric plug valves. These proved to be maintenance intensive and later the manifold was lowered and 4 x 350mm Corflex Pinch Valves installed. The pump station ran like this until it closed in +/ -2005. In 1988 Ergo Daggafontein and Simmergo operation was developed. In 1988 the sleeve had been strengthened enough for 350mm Corflex Pinch Valves and 400mm on Pig Launchers to be installed on all Slurry operations for pressures up to 30 Bar (+/- 435 PSI) 200mm Corflex Pinch Valves were used to charge the pig launchers. The majority of ERGO pipelines were 450mm where the velocity was 1.9m/sec so the velocity through 350mm pinch valves was over 3m/sec.