Froth pumping stays one of the most complicated engineering challenges in mineral processing. Here, Weir Minerals provides advice for coping with the key challenges in this operation, the way to maximise pump availability and minimise upkeep in operators’ flotation circuits.
To counteract declining ore grades, more and more mine operators are investing in techniques to extend the minerals reclaimed from froth pumping. However, when these techniques are deployed with out making allowances for the design of the mine’s froth pumping equipment, it can result in the loss of priceless minerals and profits.
Froth pumping remains some of the complex engineering challenges in mineral processing. This is largely because of the fact that air administration points in the hopper, sump and pump itself can generally result in inefficient pumping, increased maintenance and even misplaced product.
“We’ve began to notice a pattern among our prospects who are having trouble with their froth pumps,” said Les Harvey, regional product supervisor for Slurry Pumps at Weir Minerals. “By utilizing extra flocculants and other chemical compounds designed to improve mineral recovery, they’re exacerbating present problems in circuit design and lowering the returns they’re on the lookout for.”
Close examination of the froth’s makeup and bodily qualities is often wanted to resolve points. Ensuring operators’ froth dealing with equipment adheres to greatest design practices is a crucial first step in resolving problems.
Maintaining pressure The key problem in froth pumping is dealing with air in the pump itself, because it tends to naturally centrifuge into the impeller’s eye, where it builds up into an “air lock” which impedes the motion of slurry through the pump.
In addition to decreasing the pump’s effectivity, the air build-up within the pump will cut back its circulate and improve the slurry level within the suction hopper. The increased slurry stage could push the pocket of air through the pump, causing surging and extreme vibration which can damage the pump bearings, impeller and shaft. “ ที่วัดแรงดันน้ำ to handle air in a froth pump is to put cash into a froth pump with a steady air elimination system (CARS), which we now have in our Warman AHF, MF and LF pumps,” says Harvey.
This system allows air to maneuver from the pump’s impeller eye to an air collection chamber in the back by way of a vent hole in the impeller. From the chamber, a move inducer removes the air from the pump through a vent pipe. “It’s also necessary to place the pump’s discharge pipe on the top of the pump, or at a 45° angle as it will give air trapped on the prime of the casing a method to escape the pump.”
Solving problems “A persistent problem we see is when hoppers designed to fulfill the calls for of slurry pumping are used in a froth pumping utility. Slurry hoppers require turbulence to forestall the mineral content material from settling, whereas turbulence in a froth pump prevents the air from escaping and results in blockages,” stated Harvey.
Tanks designed for froth pumping promote steady circular movement, where solids and liquids are despatched to the skin of the sump for further transport whereas air centrifuges into the centre where it could be eliminated. This ‘whirlpool’ movement could be encouraged by introducing the slurry from the top of the tank at a tangential angle. Conical designs, somewhat than these with a flat or rounded floor, additional improve the circulate of minerals and froth into the pump.
Smooth sailing To forestall blockages, the intake pipe which hyperlinks the tank to the pump ought to have a big diameter and slope downwards in direction of the pump. This design permits escaped air to separate and travel again up the pipe where it could escape from the sump, quite than increase into blockages.
“The shorter your intake pipe, the tougher it is for blockages to construct up. However, in addition to a upkeep spool and isolation valve, it’s a good suggestion to leave enough house for a water injection port, which is useful for flushing out any solids construct up,” said Harvey.
“To make upkeep easier, a dump valve can be included on the suction aspect of the pump, between the pump and the isolation valve. This will permit users to drain slurry from the pump and the discharge pipe system when stopping the pump for maintenance.”
Tenacious froths Froths are sometimes classified as either brittle, with large air bubbles that break simply, or tenacious, where air varieties tight bubbles around minerals and is difficult to separate. Froth being extra tenacious than was accounted for is a frequent cause of blockages as air can’t successfully be removed.
“Two things are happening available within the market at present. On one hand, mine operators are grinding the product much finer than before to liberate extra from the waste rock. They’re additionally utilizing flocculants that produce much smaller bubbles which lock up the air a lot more than brittle froths,” said Harvey. “We’re working together with clients to find ways to handle these extra tenacious froths, by looking at their circuit design and dealing with areas the place the air could accumulate and block the system, paying particular attention to their pumps, pipes and sumps.
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