Froth pumping remains one of the complex engineering challenges in mineral processing. Here, Weir Minerals presents recommendation for dealing with the key challenges on this operation, how to maximise pump availability and minimise maintenance in operators’ flotation circuits.
To counteract declining ore grades, increasingly mine operators are investing in techniques to increase 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 may find yourself in the lack of priceless minerals and earnings.
Froth pumping stays some of the complicated engineering challenges in mineral processing. This is basically as a end result of the truth that air administration issues within the hopper, sump and pump itself can sometimes result in inefficient pumping, increased upkeep and even lost product.
“We’ve started to notice a sample amongst our prospects who’re having bother with their froth pumps,” said Les Harvey, regional product manager for Slurry Pumps at Weir Minerals. “By utilizing extra flocculants and other chemical substances designed to enhance mineral recovery, they’re exacerbating present problems in circuit design and reducing the returns they’re on the lookout for.”
Close examination of the froth’s make-up and bodily qualities is commonly needed to resolve points. Ensuring operators’ froth dealing with tools adheres to greatest design practices is a crucial first step in resolving problems.
Maintaining strain 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 via the pump.
In addition to decreasing the pump’s effectivity, the air build-up in the pump will scale back its move and increase the slurry level within the suction hopper. The increased slurry degree might push the pocket of air by way of the pump, inflicting surging and excessive vibration which may injury the pump bearings, impeller and shaft. “The greatest approach to manage air in a froth pump is to invest in a froth pump with a continuous air elimination system (CARS), which we 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 gap within the impeller. From the chamber, a flow inducer removes the air from the pump via a vent pipe. “It’s also important 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 high of the casing a approach to escape the pump.”
Solving issues “A persistent drawback we see is when hoppers designed to satisfy the demands of slurry pumping are used in a froth pumping utility. Slurry hoppers require turbulence to stop the mineral content material from settling, while 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 sent to the skin of the sump for further transport whereas air centrifuges into the centre the place it can be removed. This ‘whirlpool’ movement may 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 flooring, further improve the circulate of minerals and froth into the pump.
Smooth crusing To forestall blockages, the consumption pipe which hyperlinks the tank to the pump should have a large diameter and slope downwards in the path of the pump. This design permits escaped air to separate and travel again up the pipe the place it could escape from the sump, somewhat than build up into blockages.
“The shorter your consumption pipe, the more durable it is for blockages to build up. However, along with a maintenance spool and isolation valve, it’s a good idea to go away enough area for a water injection port, which is useful for flushing out any solids construct up,” mentioned Harvey.
“To make เกจวัดแรงดันสูญญากาศ , 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 drain slurry from the pump and the discharge pipe system when stopping the pump for upkeep.”
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 difficult to separate. Froth being more tenacious than was accounted for is a frequent cause of blockages as air can not successfully be eliminated.
“Two things are happening available in the market today. On one hand, mine operators are grinding the product a lot finer than before to liberate extra from the waste rock. They’re also utilizing flocculants that produce much smaller bubbles which lock up the air much more than brittle froths,” mentioned Harvey. “We’re working along with clients to search out ways to manage these more tenacious froths, by looking at their circuit design and coping with areas the place the air could accumulate and block the system, paying specific consideration to their pumps, pipes and sumps.
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