Weir’s resolution for froth challenges

Froth pumping remains some of the advanced engineering challenges in mineral processing. Here, Weir Minerals provides 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 methods to extend 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 can outcome in the lack of priceless minerals and profits.
Froth pumping remains one of the complex engineering challenges in mineral processing. This is largely due to the reality that air management points in the hopper, sump and pump itself can typically result in inefficient pumping, increased upkeep and even lost product.
“We’ve began to notice a sample amongst our clients who are having trouble with their froth pumps,” stated Les Harvey, regional product supervisor for Slurry Pumps at Weir Minerals. “By utilizing extra flocculants and different chemical substances designed to enhance mineral recovery, they’re exacerbating existing problems in circuit design and reducing the returns they’re looking for.”
Close examination of the froth’s make-up and physical qualities is usually needed to resolve points. Ensuring operators’ froth dealing with gear adheres to finest design practices is an important first step in resolving issues.
Maintaining pressure The key challenge in froth pumping is coping with air within 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 scale back its flow and increase the slurry stage within the suction hopper. The elevated slurry level might push the pocket of air through the pump, inflicting surging and extreme vibration which may injury 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 steady air elimination 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 again by way of a vent gap in the impeller. From the chamber, a move inducer removes the air from the pump by way of a vent pipe. “It’s also important 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 high of the casing a method to escape the pump.”
Solving problems “A persistent downside we see is when hoppers designed to satisfy the calls for 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 steady circular motion, the place solids and liquids are despatched to the outside of the sump for further transport while air centrifuges into the centre the place it can be eliminated. This ‘whirlpool’ movement may be inspired by introducing the slurry from the highest of the tank at a tangential angle. Conical designs, quite than those with a flat or rounded ground, additional enhance the move of minerals and froth into the pump.
Smooth sailing To prevent blockages, the consumption pipe which links the tank to the pump ought to have a large diameter and slope downwards towards the pump. เกจวัดแรงดันลม permits escaped air to separate and travel again up the pipe the place it can escape from the sump, somewhat than building up into blockages.
“The shorter your consumption pipe, the tougher it’s for blockages to build up. However, along with a maintenance spool and isolation valve, it’s a good idea to go away sufficient area for a water injection port, which is helpful for flushing out any solids construct up,” stated Harvey.
“To make upkeep simpler, a dump valve could be included on the suction side of the pump, between the pump and the isolation valve. This will enable customers to empty slurry from the pump and the discharge pipe system when stopping the pump for upkeep.”
Tenacious froths Froths are often categorized as either brittle, with giant air bubbles that break easily, or tenacious, the place air varieties tight bubbles around minerals and is tough to separate. Froth being more tenacious than was accounted for is a frequent cause of blockages as air can’t successfully be eliminated.
“Two issues are occurring out there right now. On one hand, mine operators are grinding the product much finer than earlier than to liberate more from the waste rock. They’re also using 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 manage these more tenacious froths, by looking at their circuit design and dealing with areas the place the air might accumulate and block the system, paying specific consideration to their pumps, pipes and sumps.
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