Weir’s solution for froth challenges

Froth pumping stays one of the advanced engineering challenges in mineral processing. Here, Weir Minerals presents advice for coping with the necessary thing challenges in this operation, tips on how to maximise pump availability and minimise maintenance in operators’ flotation circuits.
To counteract declining ore grades, increasingly mine operators are investing in techniques to increase 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 end result in the lack of useful minerals and income.
Froth pumping stays some of the complex engineering challenges in mineral processing. This is essentially due to the fact that air administration issues within the hopper, sump and pump itself can generally result in inefficient pumping, elevated upkeep and even lost product.
“We’ve began to notice a sample among our clients who’re having bother with their froth pumps,” said Les Harvey, regional product supervisor for Slurry Pumps at Weir Minerals. “By using more flocculants and different chemical compounds designed to enhance mineral restoration, they’re exacerbating present problems in circuit design and lowering the returns they’re looking for.”
Close examination of the froth’s makeup and bodily qualities is commonly wanted to resolve points. Ensuring operators’ froth dealing with tools adheres to best design practices is a crucial first step in resolving problems.
Maintaining stress 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, the place it builds up into an “air lock” which impedes the motion of slurry via the pump.
In addition to decreasing the pump’s effectivity, the air build-up within the pump will reduce its flow and increase the slurry stage in the suction hopper. The increased slurry degree could push the pocket of air by way of the pump, inflicting surging and excessive vibration which might harm the pump bearings, impeller and shaft. “The finest way to manage air in a froth pump is to spend cash on a froth pump with a steady air elimination system (CARS), which we’ve 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 again through a vent gap in the impeller. From Try before you buy , a move inducer removes the air from the pump via a vent pipe. “It’s also important to place the pump’s discharge pipe on the high of the pump, or at a 45° angle as this can give air trapped on the top of the casing a way to escape the pump.”
Solving issues “A persistent problem we see is when hoppers designed to meet the calls for of slurry pumping are utilized in a froth pumping application. Slurry hoppers require turbulence to forestall the mineral content 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 continuous circular motion, the place solids and liquids are sent to the outside of the sump for additional transport whereas air centrifuges into the centre the place it can 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 these with a flat or rounded floor, further enhance 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 large diameter and slope downwards towards the pump. This design allows escaped air to separate and travel again up the pipe where it could escape from the sump, rather than increase into blockages.
“The shorter your consumption pipe, the harder it’s for blockages to construct up. However, along with a upkeep spool and isolation valve, it’s a good idea to leave sufficient space for a water injection port, which is beneficial for flushing out any solids construct up,” said Harvey.
“To make maintenance easier, a dump valve may be included on the suction facet of the pump, between the pump and the isolation valve. This will permit customers to drain slurry from the pump and the discharge pipe system when stopping the pump for maintenance.”
Tenacious froths Froths are often classified as either brittle, with massive air bubbles that break easily, or tenacious, the place air varieties tight bubbles round minerals and is difficult to separate. Froth being more tenacious than was accounted for is a frequent explanation for blockages as air cannot successfully be removed.
“Two things are occurring out there right now. On one hand, mine operators are grinding the product much finer than earlier than to liberate extra from the waste rock. They’re also utilizing flocculants that produce much smaller bubbles which lock up the air much more than brittle froths,” stated Harvey. “We’re working along with customers to search out ways to manage these more tenacious froths, by taking a look at their circuit design and coping with areas the place the air could accumulate and block the system, paying specific consideration to their pumps, pipes and sumps.
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