Weir’s resolution for froth challenges

Froth pumping stays some of the advanced engineering challenges in mineral processing. Here, Weir Minerals offers advice for coping with the key challenges in this operation, how 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 techniques are deployed with out making allowances for the design of the mine’s froth pumping tools, it can result in the loss of priceless minerals and income.
Froth pumping remains one of the advanced engineering challenges in mineral processing. This is largely due to the truth that air management points within the hopper, sump and pump itself can sometimes result in inefficient pumping, elevated maintenance and even misplaced product.
“We’ve began to notice a pattern amongst our prospects who’re having trouble with their froth pumps,” stated Les Harvey, regional product manager for Slurry Pumps at Weir Minerals. “By using more flocculants and other chemicals designed to enhance mineral recovery, they’re exacerbating present problems in circuit design and decreasing the returns they’re looking for.”
Close examination of the froth’s make-up and physical qualities is usually needed to resolve issues. Ensuring operators’ froth dealing with gear adheres to finest design practices is a crucial first step in resolving issues.
Maintaining pressure The key problem in froth pumping is coping 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 via 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 level in the suction hopper. The elevated slurry level may push the pocket of air by way of the pump, causing surging and excessive vibration which may injury the pump bearings, impeller and shaft. “The best approach to handle air in a froth pump is to spend cash on 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 maneuver from the pump’s impeller eye to an air collection chamber within the back through a vent gap within the impeller. From the chamber, a move inducer removes the air from the pump via a vent pipe. “It’s additionally important to position the pump’s discharge pipe at the high of the pump, or at a 45° angle as this can give air trapped at 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 used in a froth pumping software. Slurry differential pressure gauge ราคา require turbulence to forestall the mineral content from settling, while turbulence in a froth pump prevents the air from escaping and results in blockages,” mentioned Harvey.
Tanks designed for froth pumping promote steady circular movement, 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 might be eliminated. This ‘whirlpool’ movement may be encouraged by introducing the slurry from the highest of the tank at a tangential angle. Conical designs, quite than these with a flat or rounded floor, additional improve the flow of minerals and froth into the pump.
Smooth sailing To forestall blockages, the consumption pipe which links 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 might possibly escape from the sump, somewhat than increase into blockages.
“The shorter your consumption pipe, the more durable it is for blockages to build up. However, along with a upkeep spool and isolation valve, it’s a good idea to go away enough area for a water injection port, which is beneficial for flushing out any solids construct up,” mentioned Harvey.
“To make เครื่องมือที่ใช้ในการวัดความดัน , a dump valve may be included on the suction facet of the pump, between the pump and the isolation valve. This will permit users to empty slurry from the pump and the discharge pipe system when stopping the pump for maintenance.”
Tenacious froths Froths are often categorised as either brittle, with massive air bubbles that break simply, or tenacious, where air forms tight bubbles around minerals and is tough to separate. Froth being more tenacious than was accounted for is a frequent explanation for blockages as air can not effectively 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 using flocculants that produce much smaller bubbles which lock up the air a lot more than brittle froths,” said Harvey. “We’re working along with prospects to find ways to handle these more tenacious froths, by taking a glance at their circuit design and dealing with areas where the air may accumulate and block the system, paying particular consideration to their pumps, pipes and sumps.

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