Froth pumping stays some of the advanced engineering challenges in mineral processing. Here, Weir Minerals presents recommendation 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, increasingly more mine operators are investing in strategies to increase 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 result in the lack of priceless minerals and earnings.
Froth pumping stays one of the advanced engineering challenges in mineral processing. This is basically due to the truth that air administration issues within the hopper, sump and pump itself can typically lead to inefficient pumping, elevated maintenance and even misplaced product.
“We’ve began to notice a sample amongst our clients who are having bother with their froth pumps,” stated Les Harvey, regional product supervisor for Slurry Pumps at Weir Minerals. “By utilizing more flocculants and different chemicals designed to enhance mineral recovery, they’re exacerbating present problems in circuit design and lowering the returns they’re in search of.”
Close examination of the froth’s makeup and bodily qualities is commonly needed to resolve points. Ensuring pressure gauge octa to greatest design practices is a crucial first step in resolving issues.
Maintaining stress The key challenge in froth pumping is dealing with air within 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 motion of slurry through the pump.
In addition to reducing the pump’s effectivity, the air build-up in the pump will cut back its move and enhance the slurry stage within the suction hopper. The increased slurry stage might push the pocket of air through the pump, inflicting surging and extreme vibration which may harm the pump bearings, impeller and shaft. “The greatest approach to handle air in a froth pump is to invest in 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 permits air to maneuver from the pump’s impeller eye to an air collection chamber in the back via a vent gap in the impeller. From the chamber, a move inducer removes the air from the pump by way of a vent pipe. “It’s additionally essential to position the pump’s discharge pipe on the high of the pump, or at a 45° angle as this can give air trapped on the high of the casing a way to escape the pump.”
Solving issues “A persistent problem we see is when hoppers designed to satisfy the demands 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,” said Harvey.
Tanks designed for froth pumping promote continuous circular movement, where solids and liquids are sent to the skin of the sump for further transport while air centrifuges into the centre the place it can be eliminated. This ‘whirlpool’ movement may be encouraged by introducing the slurry from the top of the tank at a tangential angle. Conical designs, quite than those with a flat or rounded flooring, further enhance the move of minerals and froth into the pump.
Smooth sailing To forestall blockages, the intake pipe which links the tank to the pump should have a large diameter and slope downwards in the direction of the pump. This design permits escaped air to separate and travel back up the pipe the place it might possibly escape from the sump, quite than increase into blockages.
“The shorter your consumption pipe, the more durable it’s for blockages to build up. However, along with a maintenance spool and isolation valve, it’s a good idea to go away sufficient space for a water injection port, which is helpful for flushing out any solids construct up,” mentioned Harvey.
“To make maintenance simpler, a dump valve could 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 upkeep.”
Tenacious froths Froths are sometimes categorized as either brittle, with giant air bubbles that break simply, or tenacious, where air varieties tight bubbles around minerals and is difficult to separate. Froth being more tenacious than was accounted for is a frequent reason for blockages as air can not effectively be removed.
“Two things are occurring available within the market right now. On one hand, mine operators are grinding the product much finer than before to liberate extra from the waste rock. They’re additionally utilizing flocculants that produce a lot smaller bubbles which lock up the air much more than brittle froths,” stated Harvey. “We’re working together with customers to find ways to manage these extra tenacious froths, by looking at their circuit design and dealing with areas where the air might accumulate and block the system, paying particular consideration to their pumps, pipes and sumps.
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