Froth pumping stays one of the most complicated engineering challenges in mineral processing. Here, Weir Minerals provides advice for coping with the important thing challenges on this operation, the means to maximise pump availability and minimise maintenance in operators’ flotation circuits.
To counteract declining ore grades, increasingly more mine operators are investing in strategies to extend the minerals reclaimed from froth pumping. However, when these methods are deployed without making allowances for the design of the mine’s froth pumping tools, it can lead to the lack of valuable minerals and earnings.
Froth pumping stays some of the complicated engineering challenges in mineral processing. This is largely because of the truth that air administration issues in the hopper, sump and pump itself can typically lead to inefficient pumping, increased maintenance and even misplaced product.
“We’ve began to notice a sample amongst our clients who are having trouble with their froth pumps,” said Les Harvey, regional product supervisor for Slurry Pumps at Weir Minerals. “By utilizing more flocculants and different chemical substances designed to improve mineral restoration, they’re exacerbating present issues in circuit design and reducing the returns they’re in search of.”
Close examination of the froth’s make-up and bodily qualities is commonly wanted to resolve issues. Ensuring operators’ froth handling equipment adheres to best design practices is an important first step in resolving issues.
Maintaining เกรดวัดแรงดัน in froth pumping is dealing with air in 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 lowering the pump’s effectivity, the air build-up in the pump will reduce its flow and increase the slurry degree in the suction hopper. The elevated slurry level might push the pocket of air by way of the pump, causing surging and excessive vibration which might damage the pump bearings, impeller and shaft. “The best way to handle air in a froth pump is to spend cash on a froth pump with a steady air removal system (CARS), which we now have in our Warman AHF, MF and LF pumps,” says Harvey.
This system allows air to move from the pump’s impeller eye to an air assortment chamber within the again via a vent gap in the impeller. From the chamber, a circulate inducer removes the air from the pump by way of a vent pipe. “It’s also 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 high of the casing a method to escape the pump.”
Solving problems “A persistent problem we see is when hoppers designed to meet the demands of slurry pumping are utilized in a froth pumping utility. Slurry hoppers require turbulence to stop 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 continuous circular movement, the place solids and liquids are sent to the surface of the sump for additional transport while air centrifuges into the centre the place it can be removed. This ‘whirlpool’ movement could be encouraged by introducing the slurry from the highest of the tank at a tangential angle. Conical designs, quite than those with a flat or rounded floor, additional 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 in the direction of the pump. This design allows escaped air to separate and travel back up the pipe the place it may possibly escape from the sump, somewhat than build up into blockages.
“The shorter your intake pipe, the more durable it is for blockages to construct up. However, in addition to a maintenance spool and isolation valve, it’s a good suggestion to depart enough area for a water injection port, which is helpful for flushing out any solids construct up,” mentioned Harvey.
“To make upkeep easier, 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 drain slurry from the pump and the discharge pipe system when stopping the pump for upkeep.”
Tenacious froths Froths are often classified as both brittle, with large air bubbles that break simply, or tenacious, where air types tight bubbles around minerals and is difficult to separate. Froth being extra tenacious than was accounted for is a frequent explanation for blockages as air can’t effectively be eliminated.
“Two things are taking place available in the market today. On one hand, mine operators are grinding the product much finer than earlier than to liberate extra from the waste rock. They’re additionally 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 clients to find ways to handle these extra tenacious froths, by taking a glance at their circuit design and dealing with areas the place the air may accumulate and block the system, paying explicit attention to their pumps, pipes and sumps.
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