Froth pumping remains one of the complicated engineering challenges in mineral processing. Here, Weir Minerals provides recommendation for coping with the necessary thing challenges in this operation, how to maximise pump availability and minimise upkeep in operators’ flotation circuits.
To counteract declining ore grades, more and more mine operators are investing in methods to increase 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 gear, it can lead to the lack of useful minerals and earnings.
Froth pumping remains one of the most complex engineering challenges in mineral processing. This is essentially due to the fact that air management issues in the hopper, sump and pump itself can typically lead to inefficient pumping, increased upkeep and even lost product.
“We’ve began to notice a sample amongst our prospects who are having hassle with their froth pumps,” mentioned Les Harvey, regional product supervisor for Slurry Pumps at Weir Minerals. “By using more flocculants and different chemicals designed to improve mineral recovery, they’re exacerbating current issues in circuit design and decreasing the returns they’re in search of.”
Close examination of the froth’s make-up and physical qualities is often wanted to resolve points. Ensuring operators’ froth handling equipment adheres to greatest design practices is a crucial first step in resolving problems.
Maintaining เกจวัดแรงดันถังลม in froth pumping is coping with air in the pump itself, as it tends to naturally centrifuge into the impeller’s eye, the place it builds up into an “air lock” which impedes the motion of slurry through the pump.
In addition to decreasing the pump’s effectivity, the air build-up within the pump will reduce its flow and enhance the slurry stage in the suction hopper. The increased slurry stage could push the pocket of air through the pump, inflicting surging and extreme vibration which may harm the pump bearings, impeller and shaft. “The greatest way to manage air in a froth pump is to spend money on a froth pump with a continuous air removal 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 collection chamber within the back via a vent gap in the impeller. From the chamber, a move inducer removes the air from the pump through a vent pipe. “It’s additionally necessary to place the pump’s discharge pipe at the prime of the pump, or at a 45° angle as this will give air trapped at the prime of the casing a method to escape the pump.”
Solving problems “A persistent drawback we see is when hoppers designed to satisfy the calls for 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,” stated Harvey.
Tanks designed for froth pumping promote continuous round movement, the place solids and liquids are despatched to the outside of the sump for additional transport while air centrifuges into the centre where it could be eliminated. This ‘whirlpool’ motion can be encouraged by introducing the slurry from the highest of the tank at a tangential angle. Conical designs, quite 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 in the direction of the pump. This design allows escaped air to separate and travel back up the pipe where it could escape from the sump, quite than build up 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 sufficient house for a water injection port, which is useful for flushing out any solids construct up,” mentioned Harvey.
“To make maintenance simpler, a dump valve may be included on the suction facet 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 often categorised as either brittle, with massive air bubbles that break easily, or tenacious, the place air forms tight bubbles around minerals and is tough to separate. Froth being extra tenacious than was accounted for is a frequent reason for blockages as air can not effectively be removed.
“Two things are happening available within the market today. On one hand, mine operators are grinding the product a lot finer than before to liberate more from the waste rock. They’re also utilizing flocculants that produce much smaller bubbles which lock up the air a lot more than brittle froths,” said Harvey. “We’re working together with prospects to search out methods to handle these extra 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 consideration to their pumps, pipes and sumps.
Share