Weir’s resolution for froth challenges

Froth pumping stays one of the most complicated engineering challenges in mineral processing. Here, Weir Minerals presents advice for dealing with the key challenges in this operation, tips on how to maximise pump availability and minimise upkeep in operators’ flotation circuits.
To counteract declining ไดอะแฟรม , increasingly more mine operators are investing in methods to increase the minerals reclaimed from froth pumping. However, when these strategies are deployed without making allowances for the design of the mine’s froth pumping tools, it can result in the lack of priceless minerals and profits.
Froth pumping remains one of the advanced engineering challenges in mineral processing. This is essentially due to the truth that air administration points within the hopper, sump and pump itself can sometimes result in inefficient pumping, increased maintenance 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 manager for Slurry Pumps at Weir Minerals. “By using more flocculants and different chemicals designed to enhance mineral recovery, they’re exacerbating existing issues in circuit design and decreasing the returns they’re on the lookout for.”

Close examination of the froth’s makeup and physical qualities is usually wanted to resolve issues. Ensuring operators’ froth dealing with equipment adheres to finest design practices is a vital first step in resolving issues.
Maintaining strain 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, where it builds up into an “air lock” which impedes the movement of slurry by way of the pump.
In addition to reducing the pump’s effectivity, the air build-up within the pump will cut back its move and increase the slurry degree within the suction hopper. The increased slurry level may push the pocket of air via the pump, inflicting surging and extreme vibration which may damage the pump bearings, impeller and shaft. “The finest way to handle air in a froth pump is to put cash into a froth pump with a continuous air removal system (CARS), which we’ve 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 assortment chamber within the back via a vent gap within the impeller. From the chamber, a flow inducer removes the air from the pump by way of a vent pipe. “It’s additionally necessary to place the pump’s discharge pipe on the prime of the pump, or at a 45° angle as this can give air trapped at the prime of the casing a approach to escape the pump.”

Solving issues “A persistent drawback we see is when hoppers designed to fulfill the calls for of slurry pumping are used in a froth pumping utility. Slurry hoppers require turbulence to forestall the mineral content material from settling, whereas turbulence in a froth pump prevents the air from escaping and results in blockages,” said Harvey.
Tanks designed for froth pumping promote steady circular movement, the place solids and liquids are despatched to the surface of the sump for additional transport whereas air centrifuges into the centre where it may be eliminated. This ‘whirlpool’ motion may be encouraged by introducing the slurry from the highest of the tank at a tangential angle. Conical designs, rather than those with a flat or rounded floor, further enhance the circulate of minerals and froth into the pump.
Smooth sailing To stop 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 the place it can escape from the sump, quite than building up into blockages.
“The shorter your consumption 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 go away sufficient space for a water injection port, which is helpful for flushing out any solids build up,” mentioned Harvey.
“To make maintenance simpler, a dump valve can be included on the suction facet of the pump, between the pump and the isolation valve. This will permit customers to empty slurry from the pump and the discharge pipe system when stopping the pump for maintenance.”

Tenacious froths Froths are sometimes classified as both brittle, with large air bubbles that break simply, or tenacious, the place air varieties tight bubbles round minerals and is troublesome to separate. Froth being more tenacious than was accounted for is a frequent cause of blockages as air can’t effectively be removed.
“Two issues are taking place in the market today. On pressure gauge 10 bar , mine operators are grinding the product much finer than before to liberate extra from the waste rock. They’re also utilizing flocculants that produce a lot smaller bubbles which lock up the air a lot more than brittle froths,” said Harvey. “We’re working together with clients to find methods to handle these more tenacious froths, by looking at their circuit design and coping with areas the place the air might accumulate and block the system, paying specific attention to their pumps, pipes and sumps.

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