Froth pumping stays some of the advanced engineering challenges in mineral processing. Here, Weir Minerals presents advice for dealing with the vital thing challenges on 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 techniques to extend the minerals reclaimed from froth pumping. However, when these techniques are deployed with out making allowances for the design of the mine’s froth pumping equipment, it can end result in the lack of valuable minerals and profits.
Froth pumping remains one of the most complex engineering challenges in mineral processing. This is essentially due to the fact that air administration issues in the hopper, sump and pump itself can sometimes lead to inefficient pumping, elevated upkeep and even misplaced product.
“We’ve began to notice a sample among our customers who are having hassle with their froth pumps,” mentioned Les Harvey, regional product supervisor for Slurry Pumps at Weir Minerals. “By utilizing extra flocculants and different 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 equipment adheres to best design practices is an important first step in resolving problems.
Maintaining stress The key problem 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 movement of slurry via the pump.
In เกจวัดแรงดันน้ำ to lowering the pump’s efficiency, the air build-up in the pump will cut back its circulate and increase the slurry stage in the suction hopper. The elevated slurry degree might push the pocket of air through the pump, causing surging and extreme vibration which may injury the pump bearings, impeller and shaft. “The finest approach to manage air in a froth pump is to spend money on a froth pump with a steady air removing system (CARS), which we 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 assortment chamber in the again by way of a vent hole in the impeller. From the chamber, a move inducer removes the air from the pump via a vent pipe. “It’s also important to position the pump’s discharge pipe on the top of the pump, or at a 45° angle as this will give air trapped at the high of the casing a approach to escape the pump.”
Solving issues “A persistent downside we see is when hoppers designed to satisfy the calls for of slurry pumping are utilized 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 results in blockages,” stated Harvey.
Tanks designed for froth pumping promote steady circular motion, 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 might be eliminated. This ‘whirlpool’ movement could be encouraged by introducing the slurry from the top of the tank at a tangential angle. Conical designs, somewhat than these with a flat or rounded floor, additional enhance the flow 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 in the direction of the pump. This design permits escaped air to separate and journey again up the pipe the place it can escape from the sump, quite than building up into blockages.
“The shorter your consumption pipe, the more durable it is for blockages to build up. However, in addition to a maintenance spool and isolation valve, it’s a good suggestion to go away sufficient space for a water injection port, which is useful for flushing out any solids construct up,” said Harvey.
“To make maintenance simpler, a dump valve can be included on the suction side 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 both brittle, with massive air bubbles that break simply, or tenacious, where air types tight bubbles around minerals and is tough to separate. Froth being extra tenacious than was accounted for is a frequent explanation for blockages as air can not successfully be removed.
“Two issues are occurring in the market 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 a lot smaller bubbles which lock up the air much more than brittle froths,” stated Harvey. “We’re working along with customers to search out methods to manage these extra tenacious froths, by taking a glance at their circuit design and dealing with areas the place the air could accumulate and block the system, paying explicit attention to their pumps, pipes and sumps.
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