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 high-pressure 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. Also supplied were 250mm for pressures up 40 Bar (+/- 580 PSI) and 450mm valves at 16 Bar (+/-232 PSI). This new operation increased ERGO slurry pumping to +/- 4,000 000 Tons per month.
In 1990 two 300mm Corflex Pinch Valves were installed at a Booster Station at a pressure of 50 Bar (+/- 725 PSI) These two valves ran for 15 years with only one sleeve being replaced due to being punctured by a piece of metal as the valve was being closed.
Two 300mm Corflex Pinch Valves were installed on the inlet side of two banks of 8 Pumps for pressures up to 25 Bar (+/- 360 PSI). These valves had no failures. In 1988 Rand Mines developed the Crown Mines Operation to recover gold, uranium sulphur from slimes dams around Johannesburg and in the west. Corflex Pinch Valves up to 500mm were installed in all slurry applications up to pressure of 25 Bar.
Both ERGO and Crown Mines continued to use Corflex Pinch Valves for all their slurry applications. In around 2005 Anglo American stopped its ERGO operation. This was subsequently taken over by Crown Mines.
All equipment that could be salvaged including Corflex Pinch Valves were put back into use. There are many Corflex Pinch Valves of all sizes which have been operating in both operations since 1986 which to date is some 36 years.
Most of the Corflex Pinch Valves are hydraulically operated because of high pressure. In some areas where fail safe is required the pinch valves automatically close and act as a non-return valve.
Corflex Pinch Valves supply Pinch Valves suitable for higher pressures than any other similar valve. The Corflex Pinch Valves have continued to show that they can safely handle high pressures with low maintenance for long periods of time on slurry pipelines.