Froth pumping stays some of the complicated engineering challenges in mineral processing. Here, Weir Minerals presents advice for dealing with the key challenges on this operation, the means to maximise pump availability and minimise upkeep in operators’ flotation circuits.
To counteract declining ore grades, increasingly mine operators are investing in strategies to extend the minerals reclaimed from froth pumping. However, when these methods are deployed without making allowances for the design of the mine’s froth pumping tools, it can outcome in the loss of useful minerals and earnings.
Froth pumping stays one of the advanced engineering challenges in mineral processing. This is essentially because of the truth that air administration points in the hopper, sump and pump itself can sometimes result in inefficient pumping, elevated maintenance and even lost product.
“We’ve began to note a pattern among our clients who’re having trouble with their froth pumps,” stated Les Harvey, regional product manager for Slurry Pumps at Weir Minerals. “By using more flocculants and different chemical compounds designed to improve mineral recovery, they’re exacerbating present issues in circuit design and reducing the returns they’re on the lookout for.”
Close examination of the froth’s makeup and physical qualities is often wanted to resolve points. Ensuring operators’ froth handling tools adheres to finest design practices is a crucial first step in resolving problems.
Maintaining strain The key challenge in froth pumping is dealing with air within the pump itself, as 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 เกจวัดถังแก๊ส to reducing the pump’s efficiency, the air build-up in the pump will scale back its move and improve the slurry stage in the suction hopper. The elevated slurry degree might push the pocket of air via the pump, causing surging and extreme vibration which might harm the pump bearings, impeller and shaft. “The best method to manage air in a froth pump is to spend cash on a froth pump with a steady air removal system (CARS), which we now 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 through a vent hole within the impeller. From the chamber, a circulate inducer removes the air from the pump via a vent pipe. “It’s also necessary to position the pump’s discharge pipe on the high of the pump, or at a 45° angle as this will give air trapped on the prime of the casing a method to escape the pump.”
Solving issues “A persistent drawback we see is when hoppers designed to meet the demands of slurry pumping are used in a froth pumping software. Slurry hoppers require turbulence to forestall the mineral content from settling, while turbulence in a froth pump prevents the air from escaping and results in blockages,” mentioned Harvey.
Tanks designed for froth pumping promote continuous circular movement, the place solids and liquids are despatched to the skin of the sump for further transport while air centrifuges into the centre the place it may be eliminated. This ‘whirlpool’ movement can be encouraged by introducing the slurry from the highest of the tank at a tangential angle. Conical designs, rather than these with a flat or rounded flooring, further improve the move of minerals and froth into the pump.
Smooth sailing To forestall blockages, the consumption pipe which hyperlinks the tank to the pump should have a big diameter and slope downwards towards the pump. This design allows escaped air to separate and travel again up the pipe the place it can 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 suggestion to depart sufficient house for a water injection port, which is useful for flushing out any solids construct up,” said Harvey.
“To make upkeep easier, a dump valve may be included on the suction aspect of the pump, between the pump and the isolation valve. This will enable users to empty 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 forms tight bubbles round minerals and is tough to separate. Froth being more tenacious than was accounted for is a frequent reason for blockages as air can not effectively be removed.
“Two issues are occurring out there at present. 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 utilizing flocculants that produce much smaller bubbles which lock up the air a lot more than brittle froths,” stated Harvey. “We’re working together with clients to find ways to manage these more tenacious froths, by taking a look at their circuit design and dealing with areas the place the air could accumulate and block the system, paying specific attention to their pumps, pipes and sumps.
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