Weir’s answer for froth challenges

Froth pumping stays one of the most complicated engineering challenges in mineral processing. Here, Weir Minerals presents advice for dealing with the key challenges on this operation, tips on how to maximise pump availability and minimise upkeep in operators’ flotation circuits.
To counteract declining ore grades, increasingly 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 tools, it can lead to the lack of valuable minerals and profits.
Froth pumping remains some of the complex engineering challenges in mineral processing. This is essentially as a result of the fact that air administration points in the hopper, sump and pump itself can typically result in inefficient pumping, elevated upkeep and even lost product.
“We’ve started to notice a sample amongst our prospects who are having hassle with their froth pumps,” mentioned Les Harvey, regional product manager for Slurry Pumps at Weir Minerals. “By using more flocculants and other chemical substances designed to enhance mineral recovery, they’re exacerbating current problems in circuit design and lowering the returns they’re looking for.”
Close examination of the froth’s make-up and physical qualities is usually needed to resolve points. Ensuring operators’ froth handling gear adheres to best design practices is a crucial first step in resolving problems.
Maintaining pressure The key challenge in froth pumping is coping 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 via the pump.
In addition to reducing the pump’s efficiency, the air build-up in the pump will reduce its circulate and enhance the slurry degree in the suction hopper. The elevated slurry level could push the pocket of air through the pump, inflicting surging and excessive vibration which might injury the pump bearings, impeller and shaft. “The greatest way to manage air in a froth pump is to put money into 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 move from the pump’s impeller eye to an air assortment chamber within the again by way of a vent gap in the impeller. From the chamber, a flow inducer removes the air from the pump via a vent pipe. “It’s additionally essential to place the pump’s discharge pipe on the prime of the pump, or at a 45° angle as this will give air trapped at the top of the casing a approach to escape the pump.”
Solving problems “A persistent problem we see is when hoppers designed to meet the demands of slurry pumping are utilized in a froth pumping utility. Slurry hoppers require turbulence to forestall the mineral content from settling, while turbulence in a froth pump prevents the air from escaping and leads to blockages,” said Harvey.
Tanks designed for froth pumping promote steady round motion, the place solids and liquids are despatched to the surface of the sump for additional transport whereas air centrifuges into the centre the place it might be eliminated. This ‘whirlpool’ motion may be inspired by introducing the slurry from the highest of the tank at a tangential angle. Conical designs, somewhat than those with a flat or rounded ground, additional improve the flow of minerals and froth into the pump.
Smooth crusing To stop blockages, the intake pipe which hyperlinks the tank to the pump ought to have a big diameter and slope downwards towards the pump. This design allows escaped air to separate and journey 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, in addition to a maintenance spool and isolation valve, it’s a good idea to go away enough space for a water injection port, which is helpful for flushing out any solids build up,” stated Harvey.
“To make upkeep easier, a dump valve may be included on the suction facet 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 upkeep.”
Tenacious froths Froths are sometimes classified as either brittle, with massive air bubbles that break simply, or tenacious, where air forms tight bubbles round minerals and is difficult to separate. Froth being more tenacious than was accounted for is a frequent reason for blockages as air can’t effectively be removed.
“Two things are occurring out there today. 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 using flocculants that produce much smaller bubbles which lock up the air a lot more than brittle froths,” stated Harvey. “ เกจวัดแรงดันน้ําไทวัสดุ ’re working along with clients to search out ways to manage these extra tenacious froths, by taking a glance at their circuit design and coping with areas where the air may accumulate and block the system, paying explicit consideration to their pumps, pipes and sumps.
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