Weir’s resolution for froth challenges

Froth pumping stays one of the complicated engineering challenges in mineral processing. Here, Weir Minerals offers advice for dealing with the key challenges in this operation, how to maximise pump availability and minimise upkeep in operators’ flotation circuits.
To counteract declining ore grades, more and more mine operators are investing in methods 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 tools, it can lead to the lack of priceless minerals and earnings.
Froth pumping stays one of the complex engineering challenges in mineral processing. This is basically because of the fact that air administration issues within the hopper, sump and pump itself can generally lead to inefficient pumping, elevated upkeep and even misplaced product.
“We’ve started to note a sample among our customers who’re having hassle with their froth pumps,” mentioned Les Harvey, regional product supervisor for Slurry Pumps at Weir Minerals. “By using more flocculants and different chemical compounds designed to improve mineral restoration, they’re exacerbating existing problems in circuit design and reducing the returns they’re on the lookout for.”
Close examination of the froth’s make-up and bodily qualities is often wanted to resolve points. Ensuring operators’ froth dealing with tools adheres to finest design practices is a vital 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 through the pump.
In addition to lowering the pump’s effectivity, the air build-up within the pump will scale back its flow and increase the slurry degree in the suction hopper. The increased slurry stage could push the pocket of air through the pump, causing surging and excessive vibration which might damage the pump bearings, impeller and shaft. “The finest approach to manage air in a froth pump is to put money into a froth pump with a steady air removal 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 via a vent hole in the impeller. From the chamber, a circulate inducer removes the air from the pump through a vent pipe. “It’s additionally essential to place the pump’s discharge pipe at the prime of the pump, or at a 45° angle as this can give air trapped at the top of the casing a way to escape the pump.”
Solving problems “A persistent problem we see is when hoppers designed to meet the calls for of slurry pumping are used 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 leads to blockages,” mentioned Harvey.
Tanks designed for froth pumping promote continuous round motion, where solids and liquids are despatched to the surface of the sump for additional transport while air centrifuges into the centre where it can be removed. This ‘whirlpool’ movement can be inspired by introducing the slurry from the highest of the tank at a tangential angle. Conical designs, quite than those with a flat or rounded floor, further enhance the circulate of minerals and froth into the pump.
Smooth sailing To stop blockages, the intake pipe which hyperlinks the tank to the pump should have a large diameter and slope downwards in direction of the pump. This design permits escaped air to separate and travel back up the pipe the place it can escape from the sump, quite than build up into blockages.
“The shorter your consumption pipe, the more durable it’s for blockages to build up. However, along with a upkeep spool and isolation valve, it’s a good suggestion to depart enough house for a water injection port, which is beneficial for flushing out any solids build up,” said Harvey.
“To make upkeep simpler, a dump valve could be included on the suction side of the pump, between the pump and the isolation valve. This will permit customers to empty slurry from the pump and the discharge pipe system when stopping the pump for upkeep.”
Tenacious froths Froths are sometimes categorized as either brittle, with massive air bubbles that break easily, or tenacious, the place air types tight bubbles round minerals and is tough to separate. Froth being more tenacious than was accounted for is a frequent cause of blockages as air cannot effectively be eliminated.
“Two issues are happening available in the market today. 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 a lot smaller bubbles which lock up the air much more than brittle froths,” mentioned Harvey. “ pressure gauge วัด แรง ดัน ’re working along with customers to search out methods to handle these more tenacious froths, by looking at their circuit design and coping with areas where the air may accumulate and block the system, paying specific attention to their pumps, pipes and sumps.
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