Froth pumping remains some of the complex engineering challenges in mineral processing. Here, Weir Minerals provides advice for dealing with the necessary thing challenges in this operation, the way to maximise pump availability and minimise maintenance 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 equipment, it can lead to the lack of valuable minerals and profits.
Froth pumping stays some of the advanced engineering challenges in mineral processing. This is essentially because of the fact that air management points in the hopper, sump and pump itself can typically lead to inefficient pumping, increased maintenance and even misplaced product.
“We’ve started to note a sample amongst our prospects who are having hassle with their froth pumps,” mentioned Les Harvey, regional product manager for Slurry Pumps at Weir Minerals. “By utilizing extra flocculants and different chemical substances designed to enhance mineral restoration, they’re exacerbating current problems in circuit design and reducing the returns they’re on the lookout for.”
Close examination of the froth’s make-up and physical qualities is often wanted to resolve points. Ensuring operators’ froth handling tools adheres to finest design practices is an important first step in resolving problems.
Maintaining pressure 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 decreasing the pump’s effectivity, the air build-up in the pump will scale back its flow and improve the slurry degree in the suction hopper. The increased slurry stage may push the pocket of air through the pump, inflicting surging and extreme vibration which may harm the pump bearings, impeller and shaft. “The best method to manage air in a froth pump is to invest in a froth pump with a continuous air elimination system (CARS), which we now have 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 assortment chamber in the back via a vent gap within the impeller. From the chamber, a flow inducer removes the air from the pump via a vent pipe. “It’s additionally essential to place the pump’s discharge pipe on the top of the pump, or at a 45° angle as this can give air trapped on the top of the casing a approach to escape the pump.”
Solving issues “A persistent problem we see is when hoppers designed to fulfill the demands of slurry pumping are utilized 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,” said Harvey.
Tanks designed for froth pumping promote continuous circular movement, where solids and liquids are sent to the outside of the sump for further transport while air centrifuges into the centre where it might be eliminated. เกจวัดแรงดัน10bar ‘whirlpool’ movement can be inspired by introducing the slurry from the top of the tank at a tangential angle. Conical designs, rather than these with a flat or rounded flooring, further enhance the flow of minerals and froth into the pump.
Smooth crusing To prevent blockages, the consumption pipe which hyperlinks the tank to the pump ought to have a big diameter and slope downwards towards the pump. This design allows escaped air to separate and travel back up the pipe where it may possibly escape from the sump, rather than building up into blockages.
“The shorter your intake pipe, the harder it’s for blockages to construct up. However, in addition to a upkeep spool and isolation valve, it’s a good idea to depart enough space for a water injection port, which is helpful for flushing out any solids build up,” mentioned Harvey.
“To make maintenance easier, a dump valve can be included on the suction aspect of the pump, between the pump and the isolation valve. ความหมายของเครื่องวัดความดัน will permit customers to drain slurry from the pump and the discharge pipe system when stopping the pump for maintenance.”
Tenacious froths Froths are often classified as both brittle, with massive air bubbles that break easily, or tenacious, the place air varieties tight bubbles round minerals and is tough to separate. Froth being more tenacious than was accounted for is a frequent reason for blockages as air can not successfully be eliminated.
“Two things are taking place out there right now. On one hand, mine operators are grinding the product much finer than before to liberate more from the waste rock. They’re also utilizing flocculants that produce a lot smaller bubbles which lock up the air much more than brittle froths,” stated Harvey. “We’re working along with customers to search out methods to handle these more tenacious froths, by taking a glance at their circuit design and coping with areas where the air may accumulate and block the system, paying particular attention to their pumps, pipes and sumps.