Weir’s answer for froth challenges

Froth pumping stays some 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 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 techniques are deployed without making allowances for the design of the mine’s froth pumping gear, it can lead to the lack of useful minerals and earnings.
Froth pumping remains some of the complicated engineering challenges in mineral processing. This is essentially due to the truth that air administration issues in the hopper, sump and pump itself can generally lead to inefficient pumping, increased maintenance and even lost product.
“We’ve started to notice a pattern among our prospects who are having hassle with their froth pumps,” stated Les Harvey, regional product manager for Slurry Pumps at Weir Minerals. “By using extra flocculants and other chemical compounds designed to enhance mineral recovery, they’re exacerbating present problems in circuit design and lowering the returns they’re on the lookout for.”
Close examination of the froth’s makeup and physical qualities is commonly needed to resolve issues. Ensuring operators’ froth handling tools adheres to finest design practices is an important first step in resolving problems.
Maintaining strain The key problem in froth pumping is dealing with air in 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 via the pump.
In addition to lowering the pump’s effectivity, the air build-up in the pump will cut back its move and increase the slurry level within the suction hopper. The elevated slurry stage could push the pocket of air via the pump, inflicting surging and excessive vibration which might harm the pump bearings, impeller and shaft. “The best way to handle 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 in the back via a vent hole within the impeller. From the chamber, a circulate inducer removes the air from the pump by way of a vent pipe. “It’s additionally important to position the pump’s discharge pipe on the prime of the pump, or at a 45° angle as this can give air trapped on the high of the casing a method to escape the pump.”
Solving issues “A persistent problem we see is when hoppers designed to fulfill the calls for of slurry pumping are utilized in a froth pumping software. Slurry hoppers require turbulence to prevent the mineral content from settling, while turbulence in a froth pump prevents the air from escaping and results in blockages,” stated 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. ที่วัดแรงดันน้ำ ‘whirlpool’ movement may be encouraged by introducing the slurry from the top of the tank at a tangential angle. Conical designs, quite than these with a flat or rounded floor, further improve the circulate of minerals and froth into the pump.
Smooth crusing 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 journey again up the pipe the place it may possibly escape from the sump, somewhat than build up into blockages.
“The shorter your intake pipe, the tougher it’s for blockages to build up. However, in addition to a maintenance spool and isolation valve, it’s a good idea to leave sufficient house for a water injection port, which is useful for flushing out any solids construct up,” stated Harvey.
“To make upkeep easier, a dump valve could be included on the suction side of the pump, between the pump and the isolation valve. This will enable customers to drain slurry from the pump and the discharge pipe system when stopping the pump for maintenance.”
Tenacious froths Froths are sometimes classified as either brittle, with giant air bubbles that break easily, or tenacious, where 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 can’t successfully be eliminated.
“Two issues are occurring in the market today. On one hand, mine operators are grinding the product a lot finer than before to liberate extra from the waste rock. They’re also using flocculants that produce a lot smaller bubbles which lock up the air much more than brittle froths,” mentioned Harvey. “We’re working along with customers to find methods to manage these more tenacious froths, by looking at their circuit design and dealing with areas the place the air might accumulate and block the system, paying explicit attention to their pumps, pipes and sumps.
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