Froth pumping remains one of the most advanced engineering challenges in mineral processing. Here, Weir Minerals provides 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, increasingly mine operators are investing in strategies 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 equipment, it may end up in the loss of useful minerals and income.
Froth pumping stays one of the complicated engineering challenges in mineral processing. This is essentially as a result of the truth that air management points within the hopper, sump and pump itself can typically lead to inefficient pumping, increased maintenance and even lost product.
“We’ve began to notice a pattern amongst our prospects who’re having trouble with their froth pumps,” stated Les Harvey, regional product manager for Slurry Pumps at Weir Minerals. “By using extra flocculants and other chemicals designed to improve mineral restoration, they’re exacerbating present problems in circuit design and reducing the returns they’re looking for.”
Close examination of the froth’s make-up and physical qualities is often wanted to resolve issues. Ensuring เกจวัดแรงดันน้ำ4หุน dealing with gear adheres to finest design practices is a crucial first step in resolving issues.
Maintaining stress The key problem 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 through the pump.
In addition to lowering the pump’s efficiency, the air build-up within the pump will cut back its move and increase the slurry level in the suction hopper. The elevated slurry degree might push the pocket of air by way of the pump, inflicting surging and extreme vibration which may damage the pump bearings, impeller and shaft. “The best approach to manage air in a froth pump is to put cash into a froth pump with a continuous air removing 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 assortment chamber in the again via a vent gap within the impeller. From the chamber, a circulate inducer removes the air from the pump by way of a vent pipe. “It’s also necessary to place the pump’s discharge pipe at the high of the pump, or at a 45° angle as this can give air trapped on the top of the casing a way to escape the pump.”
Solving issues “A persistent problem we see is when hoppers designed to satisfy the calls for of slurry pumping are used in a froth pumping utility. 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,” stated Harvey.
Tanks designed for froth pumping promote steady circular motion, where solids and liquids are despatched to the skin of the sump for further transport whereas air centrifuges into the centre the place it could be eliminated. This ‘whirlpool’ motion may be inspired by introducing the slurry from the highest of the tank at a tangential angle. Conical designs, quite than these with a flat or rounded ground, further enhance the move of minerals and froth into the pump.
Smooth crusing To stop 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 permits escaped air to separate and journey back up the pipe the place it can escape from the sump, somewhat than increase into blockages.
“The shorter your intake pipe, the harder it is for blockages to construct up. However, in addition to a maintenance spool and isolation valve, it’s a good idea to go away enough house for a water injection port, which is useful for flushing out any solids build up,” stated 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 allow users to drain slurry from the pump and the discharge pipe system when stopping the pump for maintenance.”
Tenacious froths Froths are often categorized as both brittle, with large air bubbles that break simply, or tenacious, where air types tight bubbles round minerals and is troublesome to separate. Froth being more tenacious than was accounted for is a frequent reason for blockages as air can not successfully be eliminated.
“Two issues are occurring out there right now. On one hand, mine operators are grinding the product a lot finer than earlier than to liberate more from the waste rock. They’re also using flocculants that produce a lot smaller bubbles which lock up the air a lot more than brittle froths,” mentioned Harvey. “We’re working along with customers to seek out ways to handle these more tenacious froths, by looking at their circuit design and coping with areas where the air could accumulate and block the system, paying specific attention to their pumps, pipes and sumps.
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