Weir’s solution for froth challenges

Froth pumping remains one of the complex engineering challenges in mineral processing. Here, Weir Minerals offers advice for dealing with the key challenges in this operation, tips on how to maximise pump availability and minimise maintenance 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 methods are deployed with out making allowances for the design of the mine’s froth pumping equipment, it can lead to the lack of valuable minerals and profits.
Froth pumping stays one of the complicated engineering challenges in mineral processing. This is basically due to the reality that air administration points within the hopper, sump and pump itself can generally result in inefficient pumping, elevated maintenance and even lost product.
“We’ve began to note a pattern amongst our clients who’re having hassle with their froth pumps,” said Les Harvey, regional product supervisor for Slurry Pumps at Weir Minerals. “By utilizing extra flocculants and different chemicals designed to enhance mineral recovery, they’re exacerbating existing problems in circuit design and decreasing the returns they’re on the lookout for.”
Close examination of the froth’s makeup and physical qualities is usually wanted to resolve issues. Ensuring operators’ froth dealing with tools adheres to best design practices is a vital first step in resolving problems.
Maintaining pressure The key problem in froth pumping is coping with air within the pump itself, as 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 by way of the pump.
In addition to lowering the pump’s efficiency, the air build-up in the pump will cut back its move and enhance the slurry stage in the suction hopper. The increased slurry degree might push the pocket of air by way of the pump, causing surging and excessive vibration which might harm the pump bearings, impeller and shaft. “ เกจวัดแรงดันน้ำราคา to handle air in a froth pump is to spend money on a froth pump with a continuous air removal system (CARS), which we now have in our Warman AHF, MF and LF pumps,” says Harvey.
This system allows air to move from the pump’s impeller eye to an air collection chamber in the back through a vent gap within the impeller. From the chamber, a circulate inducer removes the air from the pump via a vent pipe. “It’s additionally important to position the pump’s discharge pipe on the top of the pump, or at a 45° angle as this will give air trapped at the prime of the casing a way to escape the pump.”
Solving issues “A persistent problem we see is when hoppers designed to satisfy the calls for of slurry pumping are used in a froth pumping software. Slurry hoppers require turbulence to prevent the mineral content from settling, whereas turbulence in a froth pump prevents the air from escaping and leads to blockages,” mentioned Harvey.
Tanks designed for froth pumping promote steady round movement, where solids and liquids are sent to the outside of the sump for further transport while air centrifuges into the centre the place it can be eliminated. This ‘whirlpool’ movement can be inspired 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, additional enhance the circulate of minerals and froth into the pump.
Smooth crusing To stop blockages, the consumption pipe which links the tank to the pump should have a big diameter and slope downwards in path of the pump. This design allows escaped air to separate and journey again up the pipe where it can escape from the sump, rather than build up into blockages.
“The shorter your intake pipe, the tougher it is for blockages to construct up. However, along with a maintenance spool and isolation valve, it’s a good suggestion to go away sufficient space for a water injection port, which is useful for flushing out any solids build up,” stated Harvey.
“To make upkeep simpler, a dump valve can be included on the suction side 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 upkeep.”
Tenacious froths Froths are often classified as either brittle, with large air bubbles that break easily, or tenacious, the place air forms tight bubbles round minerals and is tough to separate. Froth being extra tenacious than was accounted for is a frequent reason for blockages as air cannot effectively be eliminated.
“Two issues are happening out there at present. On one hand, mine operators are grinding the product much finer than before to liberate more from the waste rock. They’re also using flocculants that produce a lot smaller bubbles which lock up the air a lot more than brittle froths,” said Harvey. “We’re working along with customers to find ways to manage 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 explicit consideration to their pumps, pipes and sumps.
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