Froth pumping stays one of the complicated engineering challenges in mineral processing. Here, Weir Minerals presents advice for dealing with the important thing challenges in this operation, how to maximise pump availability and minimise upkeep in operators’ flotation circuits.
To counteract declining ore grades, increasingly mine operators are investing in techniques to extend 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 equipment, it may find yourself in the loss of valuable minerals and profits.
Froth pumping remains one of the most advanced engineering challenges in mineral processing. This is essentially due to the reality 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 note a pattern amongst our prospects who’re having bother with their froth pumps,” stated Les Harvey, regional product manager for Slurry Pumps at Weir Minerals. “By using more flocculants and different chemical substances designed to improve mineral restoration, they’re exacerbating present problems in circuit design and decreasing the returns they’re on the lookout for.”
Close examination of the froth’s make-up and physical qualities is usually wanted to resolve issues. Ensuring operators’ froth handling equipment adheres to greatest design practices is a vital first step in resolving issues.
Maintaining stress The key problem in froth pumping is dealing with air in 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 addition to decreasing the pump’s effectivity, the air build-up in the pump will cut back its circulate and improve the slurry level in the suction hopper. The elevated slurry level may push the pocket of air through the pump, inflicting surging and extreme vibration which can damage the pump bearings, impeller and shaft. “ pressure gauge 2.5 นิ้ว to manage air in a froth pump is to invest in a froth pump with a continuous air removing system (CARS), which we now have in our Warman AHF, MF and LF pumps,” says Harvey.
This system allows air to move from the pump’s impeller eye to an air collection chamber in the back by way of a vent hole in the impeller. From the chamber, a flow inducer removes the air from the pump via 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 on the prime of the casing a way to escape the pump.”
Solving problems “A persistent drawback we see is when hoppers designed to fulfill the demands of slurry pumping are used in a froth pumping software. Slurry hoppers require turbulence to prevent the mineral content material 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 steady circular movement, the place solids and liquids are despatched to the outside of the sump for further transport while air centrifuges into the centre the place it can be eliminated. This ‘whirlpool’ motion could be inspired by introducing the slurry from the highest of the tank at a tangential angle. Conical designs, somewhat than these with a flat or rounded floor, additional improve the move of minerals and froth into the pump.
Smooth crusing To forestall blockages, the intake pipe which links the tank to the pump should have a big diameter and slope downwards in direction of the pump. This design permits escaped air to separate and travel again up the pipe where it might possibly escape from the sump, quite than increase into blockages.
“The shorter your consumption pipe, the more durable it is for blockages to construct up. However, in addition to a maintenance spool and isolation valve, it’s a good idea to depart enough house for a water injection port, which is beneficial for flushing out any solids construct up,” mentioned Harvey.
“To make maintenance simpler, a dump valve may 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 upkeep.”
Tenacious froths Froths are sometimes categorised as both brittle, with massive air bubbles that break simply, or tenacious, the place air types tight bubbles round minerals and is tough to separate. Froth being extra tenacious than was accounted for is a frequent cause of blockages as air can not effectively be eliminated.
“Two issues are occurring available in the market right now. On one hand, mine operators are grinding the product much finer than earlier than to liberate more from the waste rock. They’re additionally utilizing flocculants that produce much smaller bubbles which lock up the air much more than brittle froths,” stated Harvey. “We’re working along with clients to search out ways to manage these more tenacious froths, by taking a glance at their circuit design and coping with areas the place the air may accumulate and block the system, paying particular consideration to their pumps, pipes and sumps.
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