Weir’s resolution for froth challenges

Froth pumping stays one of the advanced engineering challenges in mineral processing. Here, Weir Minerals presents recommendation for coping with the necessary thing challenges on this operation, the way to maximise pump availability and minimise upkeep in operators’ flotation circuits.
To counteract declining ore grades, increasingly more mine operators are investing in methods to extend the minerals reclaimed from froth pumping. However, when these strategies are deployed with out making allowances for the design of the mine’s froth pumping gear, it can end result in the loss of priceless minerals and earnings.
Froth pumping stays some of the complex engineering challenges in mineral processing. This is largely because of the fact that air management issues within the hopper, sump and pump itself can typically result in inefficient pumping, increased maintenance and even lost product.
“We’ve started to notice a pattern amongst our customers who’re having bother with their froth pumps,” mentioned Les Harvey, regional product manager for Slurry Pumps at Weir Minerals. “By utilizing extra flocculants and other chemical substances designed to enhance mineral restoration, they’re exacerbating current issues in circuit design and decreasing the returns they’re in search of.”
Close examination of the froth’s make-up and bodily qualities is commonly wanted to resolve points. Ensuring operators’ froth handling gear adheres to best design practices is a crucial first step in resolving problems.
Maintaining strain The key problem in froth pumping is dealing with air within the pump itself, as it tends to naturally centrifuge into the impeller’s eye, where it builds up into an “air lock” which impedes the movement of slurry by way of the pump.
In addition to lowering the pump’s effectivity, the air build-up within the pump will scale back its move and increase the slurry level in the suction hopper. The elevated slurry degree might push the pocket of air via the pump, inflicting surging and extreme vibration which might injury the pump bearings, impeller and shaft. “The best approach to manage air in a froth pump is to invest in a froth pump with a continuous air elimination system (CARS), which we 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 within the back by way of a vent hole in the impeller. From the chamber, a circulate inducer removes the air from the pump via a vent pipe. “It’s also เกจวัดแรงดันเครื่องกรองน้ำ to place the pump’s discharge pipe on the top of the pump, or at a 45° angle as this can give air trapped on the top of the casing a approach to escape the pump.”
Solving issues “A persistent drawback we see is when hoppers designed to meet the demands of slurry pumping are used in a froth pumping application. Slurry hoppers require turbulence to stop the mineral content from settling, whereas turbulence in a froth pump prevents the air from escaping and results in blockages,” mentioned Harvey.
Tanks designed for froth pumping promote continuous round movement, where solids and liquids are despatched to the surface of the sump for additional transport whereas air centrifuges into the centre where it might be eliminated. This ‘whirlpool’ motion may be inspired by introducing the slurry from the top of the tank at a tangential angle. Conical designs, rather 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 consumption pipe which links the tank to the pump ought to have a big diameter and slope downwards in the course of the pump. This design permits escaped air to separate and travel again up the pipe where it may possibly escape from the sump, rather than build up into blockages.
“The shorter your intake pipe, the harder it’s for blockages to construct up. However, in addition to a maintenance spool and isolation valve, it’s a good suggestion to go away sufficient space for a water injection port, which is helpful for flushing out any solids construct up,” stated Harvey.
“To make maintenance simpler, a dump valve may be included on the suction aspect of the pump, between the pump and the isolation valve. This will enable customers to empty slurry from the pump and the discharge pipe system when stopping the pump for maintenance.”
Tenacious froths Froths are often categorised as either brittle, with giant air bubbles that break easily, or tenacious, where air forms tight bubbles round minerals and is troublesome to separate. Froth being more tenacious than was accounted for is a frequent cause of blockages as air cannot effectively be eliminated.
“Two things are occurring out there today. On one hand, mine operators are grinding the product much finer than before to liberate extra from the waste rock. They’re also using flocculants that produce a lot smaller bubbles which lock up the air much more than brittle froths,” stated Harvey. “We’re working together with prospects to find methods to handle these more tenacious froths, by taking a look at their circuit design and coping with areas where the air may accumulate and block the system, paying particular consideration to their pumps, pipes and sumps.
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