Froth pumping stays one of the complex engineering challenges in mineral processing. Here, Weir Minerals offers recommendation for coping with the key challenges on this operation, the method to maximise pump availability and minimise upkeep in operators’ flotation circuits.
To counteract declining ore grades, more and more mine operators are investing in techniques 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 gear, it can end result in the lack of useful minerals and earnings.
Froth pumping remains one of the complex engineering challenges in mineral processing. This is essentially because of the truth that air administration issues in the hopper, sump and pump itself can generally lead to inefficient pumping, increased maintenance and even lost product.
“We’ve started to notice a pattern amongst our customers who’re having bother with their froth pumps,” mentioned Les Harvey, regional product supervisor for Slurry Pumps at Weir Minerals. “By using more flocculants and different chemical compounds designed to improve mineral recovery, they’re exacerbating present problems in circuit design and reducing the returns they’re in search of.”
Close เกจ์วัดแรงดันแก๊ส of the froth’s make-up and physical qualities is often wanted to resolve points. Ensuring operators’ froth handling tools 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 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 by way of the pump.
In addition to reducing the pump’s effectivity, the air build-up within the pump will scale back its flow and improve the slurry degree within the suction hopper. The increased slurry stage might push the pocket of air via the pump, inflicting surging and excessive vibration which can damage the pump bearings, impeller and shaft. “The best approach to manage air in a froth pump is to invest in 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 move from the pump’s impeller eye to an air assortment chamber within the back through a vent gap in the impeller. From the chamber, a flow inducer removes the air from the pump via a vent pipe. “It’s also necessary to place the pump’s discharge pipe at the top of the pump, or at a 45° angle as it will give air trapped at the prime of the casing a approach to escape the pump.”
Solving problems “A persistent downside we see is when hoppers designed to satisfy the demands of slurry pumping are used in a froth pumping application. Slurry hoppers require turbulence to stop 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 round movement, the place solids and liquids are despatched to the outside of the sump for additional transport while air centrifuges into the centre the place it might be removed. This ‘whirlpool’ movement could be encouraged by introducing the slurry from the top of the tank at a tangential angle. Conical designs, rather than these with a flat or rounded floor, further enhance the move of minerals and froth into the pump.
Smooth sailing To forestall blockages, the intake pipe which hyperlinks the tank to the pump should have a big diameter and slope downwards towards the pump. This design permits escaped air to separate and journey back up the pipe where it might possibly escape from the sump, somewhat than increase into blockages.
“The shorter your consumption pipe, the more durable it’s for blockages to construct up. However, in addition to a upkeep spool and isolation valve, it’s a good suggestion to go away enough area for a water injection port, which is beneficial for flushing out any solids build up,” mentioned Harvey.
“To make upkeep easier, a dump valve may be included on the suction aspect of the pump, between the pump and the isolation valve. This will permit customers to drain slurry from the pump and the discharge pipe system when stopping the pump for maintenance.”
Tenacious froths Froths are sometimes categorized as either brittle, with massive air bubbles that break easily, or tenacious, the place air forms tight bubbles round minerals and is troublesome to separate. Froth being more tenacious than was accounted for is a frequent explanation for blockages as air can’t successfully be eliminated.
“Two things are taking place in 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 additionally using flocculants that produce a lot smaller bubbles which lock up the air a lot more than brittle froths,” said Harvey. “We’re working along with customers to find ways to manage these more 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 attention to their pumps, pipes and sumps.