Weir’s resolution for froth challenges

Froth pumping stays some of the advanced engineering challenges in mineral processing. Here, Weir Minerals provides recommendation for dealing with the key challenges on this operation, tips on how to maximise pump availability and minimise maintenance in operators’ flotation circuits.
To counteract declining ore grades, more and more mine operators are investing in methods 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 tools, it can lead to the loss of valuable minerals and income.
Froth pumping remains one of the advanced engineering challenges in mineral processing. This is essentially because of the truth that air administration points within the hopper, sump and pump itself can sometimes lead to inefficient pumping, increased upkeep and even misplaced product.
“We’ve began to note a pattern amongst our prospects who’re having bother with their froth pumps,” mentioned Les Harvey, regional product manager for Slurry Pumps at Weir Minerals. “By using extra flocculants and different chemicals designed to enhance mineral restoration, they’re exacerbating current problems in circuit design and decreasing the returns they’re in search of.”
Close examination of the froth’s make-up and bodily qualities is usually wanted to resolve points. Ensuring operators’ froth dealing with gear adheres to best design practices is a vital first step in resolving problems.
Maintaining pressure The key challenge in froth pumping is coping with air within 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 movement of slurry through the pump.
In addition to reducing the pump’s effectivity, the air build-up within the pump will cut back its move and increase the slurry level within the suction hopper. The elevated slurry stage may push the pocket of air via the pump, inflicting surging and excessive vibration which may harm the pump bearings, impeller and shaft. “The best method to handle air in a froth pump is to spend money on a froth pump with a steady air removing system (CARS), which we’ve in our Warman AHF, MF and LF pumps,” says Harvey.
This system permits air to maneuver from the pump’s impeller eye to an air collection chamber within the back through a vent gap within the impeller. From the chamber, a flow inducer removes the air from the pump via a vent pipe. “It’s also necessary to place the pump’s discharge pipe on the high 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 issues “A persistent drawback we see is when hoppers designed to fulfill the demands of slurry pumping are used in a froth pumping software. Slurry เกจวัดแรงดัน require turbulence to prevent 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 sent to the outside of the sump for further transport whereas air centrifuges into the centre where it may be eliminated. This ‘whirlpool’ movement may be encouraged by introducing the slurry from the top of the tank at a tangential angle. Conical designs, quite than those with a flat or rounded floor, additional enhance the circulate of minerals and froth into the pump.
Smooth sailing To prevent blockages, the consumption pipe which links the tank to the pump should have a large diameter and slope downwards towards the pump. This design allows escaped air to separate and travel back up the pipe where it can escape from the sump, rather than building up into blockages.
“The shorter your consumption pipe, the harder it is for blockages to construct up. However, along with a upkeep spool and isolation valve, it’s a good suggestion to depart enough space for a water injection port, which is helpful for flushing out any solids construct up,” stated Harvey.
“To make maintenance easier, a dump valve can be included on the suction facet of the pump, between the pump and the isolation valve. This will enable customers 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 massive air bubbles that break easily, or tenacious, where air forms tight bubbles round minerals and is tough to separate. Froth being more tenacious than was accounted for is a frequent reason for blockages as air can not successfully be removed.
“Two issues are occurring out there at present. On one hand, mine operators are grinding the product much finer than earlier than to liberate more from the waste rock. They’re additionally using flocculants that produce a lot smaller bubbles which lock up the air much more than brittle froths,” said Harvey. “We’re working together with customers to search out methods to handle these extra tenacious froths, by looking at their circuit design and dealing with areas where the air might accumulate and block the system, paying explicit consideration to their pumps, pipes and sumps.
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