Froth pumping remains some of the complex engineering challenges in mineral processing. Here, Weir Minerals provides recommendation for dealing with the necessary thing challenges on 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 tools, it may find yourself in the loss of useful minerals and profits.
Froth pumping stays some of the complex engineering challenges in mineral processing. This is basically due to the fact that air administration points in the hopper, sump and pump itself can typically lead to inefficient pumping, increased maintenance and even lost product.
“ pressure gauge nuova fima ราคา ’ve began to notice a sample among our prospects who are having hassle with their froth pumps,” mentioned Les Harvey, regional product supervisor for Slurry Pumps at Weir Minerals. “By utilizing more flocculants and different chemical compounds designed to enhance mineral recovery, they’re exacerbating existing problems in circuit design and reducing the returns they’re in search of.”
Close examination of the froth’s make-up and bodily qualities is often needed to resolve points. Ensuring operators’ froth dealing with equipment adheres to finest design practices is an important first step in resolving problems.
Maintaining pressure The key challenge 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 motion of slurry by way of the pump.
In addition to reducing the pump’s efficiency, the air build-up in the pump will reduce its circulate and increase the slurry degree in the suction hopper. The increased slurry level could push the pocket of air via the pump, causing surging and excessive vibration which may harm the pump bearings, impeller and shaft. “The best method to handle air in a froth pump is to spend cash on a froth pump with a continuous air elimination system (CARS), which we’ve in our Warman AHF, MF and LF pumps,” says Harvey.
This system permits air to maneuver from the pump’s impeller eye to an air collection chamber within the again by way of a vent gap in the impeller. From the chamber, a flow inducer removes the air from the pump through a vent pipe. “It’s additionally important to place the pump’s discharge pipe on the high of the pump, or at a 45° angle as it will give air trapped on the top of the casing a way to escape the pump.”
Solving issues “A persistent downside we see is when hoppers designed to satisfy the calls for 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,” stated Harvey.
Tanks designed for froth pumping promote continuous round movement, the place solids and liquids are despatched to the skin of the sump for additional transport whereas air centrifuges into the centre where it can be removed. This ‘whirlpool’ motion could be encouraged by introducing the slurry from the top of the tank at a tangential angle. Conical designs, quite than those with a flat or rounded flooring, additional improve the flow 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 large diameter and slope downwards towards the pump. This design allows escaped air to separate and travel again up the pipe the place it could escape from the sump, quite than increase into blockages.
“The shorter your intake pipe, the tougher it’s for blockages to construct up. However, in addition to a maintenance spool and isolation valve, it’s a good suggestion to leave enough space for a water injection port, which is useful for flushing out any solids construct up,” said Harvey.
“To make upkeep easier, a dump valve can be included on the suction aspect of the pump, between the pump and the isolation valve. This will permit 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 both brittle, with massive air bubbles that break easily, or tenacious, the place air forms tight bubbles around minerals and is difficult to separate. Froth being extra tenacious than was accounted for is a frequent cause of blockages as air can’t successfully be eliminated.
“Two issues are occurring out there at present. 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,” said Harvey. “We’re working together with prospects to find methods to handle these extra tenacious froths, by looking at their circuit design and dealing with areas where the air might accumulate and block the system, paying specific attention to their pumps, pipes and sumps.
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