 (2).jpg)
Application
Application 
Dewatering: Coal Mine.
It is not often that an excess of water is a problem unless it is caused by a natural disaster.
Mining sites
Particularly open cut or open cast coal mines experience this problem all year round.
Water in the mining pits increases mining costs and has to be “moved” away from the operational site.
Sophisticated and powerful hydraulic pumps are utilised to lift water from a depth 90 to 100 m and pump over high walls extending another 40- 50 m.
Requirement:
The mine site estimated the flow of water being pumped out based on the pump curve, pump speed- i.e. the performance of the pump.
In an ideal world the pump curve shows optimum capacity. Often this performance is affected by the age of the pump, suction pressure, fouling, pipe diameter, aeration and a host of problems on site.
Accurate flow measurement at various points on the 4-5 km circuit would quickly identify if the pump in fact was performing to specifications.
Pipe: 280 to 400 mm HDPE, wall thickness 15-24mm. Flow – average 100-130 litres per second.
What we did:
An ultrasonic, non invasive flowmeter was installed close to the pumps and then at a number of strategic points along the circuit.
Why we did it:
The mine engineers suspected that they were not evacuating the flooded areas fast enough. Production was slowed down due to excessive water and it appeared that additional pumps would have to be purchased to cope.
What we used:
Flexim F601 portable ultrasonic flowmeter. 14 hour battery life, logging interval 1 per second. Flow spikes, water hammer, aeration problems were identified.
All data for the flow survey was quickly downloaded via a laptop and a report for management was provided within a few hours.
 (2).jpg)
Problems we overcame:
A quick assessment of flow was required since the big 200 Ton earth movers were about to start the day shift and we had to move off site.
Flow at critical points was quickly measured since no intrusion of the pipes was required.
Typical time at each of the 7 flow points was around 15 minutes.
Unusually low flow was detected at a point where 2 pumps were installed for extra capacity-
It was established after turning pumps off in sequence that one of the pumps was in fact pumping at less than 15% of its capacity.
Fuel costs run at $ 1000 per day and it was evident that one pump could be turned off without loss of capacity.
Engineers have now raised a works order to have the booster pump repaired. Another problem on a second circuit revealed that flow at the pump was within spec but at a point further down flow was less than half the flow at the pump. Further investigation is required- a leaking pipe would have been easily detected so this was eliminated as a possible cause.
More likely causes are - a squashed pipe caused by the extra heavy vehicular traffic - faulty backflow valve- blocked or damaged control valve. Without the of an accurate non invasive flowmeter such as the Flexim F 601 it would have been extremely difficult and time consuming to quickly determine these problems.
