Weir’s solution for froth challenges

Froth pumping remains one of the complicated engineering challenges in mineral processing. Here, Weir Minerals offers recommendation for coping with the vital thing challenges in 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 strategies to increase 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 equipment, it may find yourself in the lack of priceless minerals and profits.
Froth pumping remains one of the most complicated engineering challenges in mineral processing. This is essentially as a end result of the fact that air management issues within the hopper, sump and pump itself can generally result in inefficient pumping, increased upkeep and even misplaced product.
“We’ve began to note a sample amongst our prospects who are having bother with their froth pumps,” mentioned Les Harvey, regional product supervisor for Slurry Pumps at Weir Minerals. “By utilizing extra flocculants and other chemicals designed to enhance mineral restoration, they’re exacerbating present issues in circuit design and lowering the returns they’re on the lookout for.”
Close examination of the froth’s make-up and physical qualities is usually wanted to resolve points. Ensuring operators’ froth dealing with gear adheres to finest design practices is an important first step in resolving issues.
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 movement of slurry by way of the pump.
In addition to reducing the pump’s effectivity, the air build-up in the pump will reduce its move and improve the slurry level in the suction hopper. The elevated slurry stage may push the pocket of air through the pump, inflicting surging and excessive vibration which might harm the pump bearings, impeller and shaft. “The greatest way to manage air in a froth pump is to spend cash on a froth pump with a continuous air removing 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 assortment chamber in the again by way of a vent gap within the impeller. From the chamber, a move inducer removes the air from the pump by way of a vent pipe. “It’s also necessary to position the pump’s discharge pipe on the high of the pump, or at a 45° angle as this can give air trapped at the top of the casing a approach to escape the pump.”
Solving problems “A persistent drawback we see is when hoppers designed to meet the calls for of slurry pumping are utilized in a froth pumping application. Slurry pressure gauge ราคา ถูก require turbulence to forestall the mineral content material from settling, while turbulence in a froth pump prevents the air from escaping and results in blockages,” mentioned Harvey.
Tanks designed for froth pumping promote steady circular movement, where solids and liquids are despatched to the outside of the sump for further transport while air centrifuges into the centre the place it may be eliminated. This ‘whirlpool’ motion could be encouraged by introducing the slurry from the top of the tank at a tangential angle. Conical designs, rather than those with a flat or rounded flooring, further enhance the flow of minerals and froth into the pump.
Smooth crusing To prevent blockages, the consumption pipe which links the tank to the pump should have a large diameter and slope downwards in path of the pump. This design allows escaped air to separate and journey back up the pipe where it might possibly escape from the sump, somewhat than increase into blockages.
“The shorter your consumption pipe, the more durable it is for blockages to construct up. However, along with a upkeep spool and isolation valve, it’s a good idea to leave enough area for a water injection port, which is helpful for flushing out any solids construct up,” stated Harvey.
“To make upkeep easier, a dump valve may be included on the suction aspect of the pump, between the pump and the isolation valve. This will enable users to drain slurry from the pump and the discharge pipe system when stopping the pump for maintenance.”
Tenacious froths Froths are often categorized as either brittle, with giant air bubbles that break easily, or tenacious, the place air types tight bubbles round minerals and is difficult to separate. Froth being extra tenacious than was accounted for is a frequent explanation for blockages as air cannot successfully be removed.
“Two things are occurring out there at present. On one hand, mine operators are grinding the product a lot finer than earlier than to liberate extra from the waste rock. They’re additionally utilizing flocculants that produce a lot smaller bubbles which lock up the air much more than brittle froths,” mentioned Harvey. “We’re working together with customers to find methods to handle these more tenacious froths, by looking at their circuit design and coping with areas where the air could accumulate and block the system, paying explicit attention to their pumps, pipes and sumps.
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