Weir’s solution for froth challenges

Froth pumping remains some of the complicated engineering challenges in mineral processing. Here, Weir Minerals presents advice for dealing with the important thing challenges on this operation, the way to maximise pump availability and minimise maintenance in operators’ flotation circuits.
To counteract declining ore grades, increasingly more mine operators are investing in methods to extend the minerals reclaimed from froth pumping. However, when these techniques are deployed without making allowances for the design of the mine’s froth pumping gear, it can lead to the lack of priceless minerals and income.
Froth pumping remains one of the complicated engineering challenges in mineral processing. This is largely as a result of the reality that air administration points within the hopper, sump and pump itself can generally result in inefficient pumping, elevated upkeep and even misplaced product.
“We’ve began to notice a pattern amongst our prospects who are having trouble with their froth pumps,” said Les Harvey, regional product manager for Slurry Pumps at Weir Minerals. “By utilizing more flocculants and other chemical compounds designed to improve mineral recovery, they’re exacerbating current problems in circuit design and lowering the returns they’re in search of.”
Close examination of the froth’s make-up and bodily qualities is commonly needed to resolve issues. Ensuring operators’ froth dealing with gear adheres to finest design practices is a vital first step in resolving issues.
Maintaining strain The key problem in froth pumping is dealing 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 motion of slurry via the pump.
In addition to decreasing the pump’s efficiency, the air build-up in the pump will scale back its move and improve the slurry stage within the suction hopper. The increased slurry degree could push the pocket of air through the pump, causing surging and excessive vibration which may harm the pump bearings, impeller and shaft. “The best approach to manage air in a froth pump is to invest in a froth pump with a continuous 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 collection chamber in the again through a vent gap in the impeller. From the chamber, a flow inducer removes the air from the pump by way of a vent pipe. “It’s also เครื่องมือความดัน to position the pump’s discharge pipe on the high of the pump, or at a 45° angle as it will give air trapped at the top of the casing a method to escape the pump.”
Solving issues “A persistent downside 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 forestall the mineral content material from settling, while turbulence in a froth pump prevents the air from escaping and leads to blockages,” said Harvey.
Tanks designed for froth pumping promote continuous round movement, where solids and liquids are sent to the surface of the sump for additional transport while air centrifuges into the centre the place it might be eliminated. This ‘whirlpool’ movement can be encouraged by introducing the slurry from the top of the tank at a tangential angle. Conical designs, rather than those with a flat or rounded floor, additional improve the flow of minerals and froth into the pump.
Smooth crusing To stop blockages, the intake pipe which hyperlinks the tank to the pump ought to have a large diameter and slope downwards in the direction of the pump. This design permits escaped air to separate and travel back up the pipe where it might possibly escape from the sump, rather than increase into blockages.
“The shorter your consumption pipe, the tougher it is for blockages to build up. However, along with a upkeep spool and isolation valve, it’s a good suggestion to leave sufficient area for a water injection port, which is helpful for flushing out any solids build up,” said 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 permit customers to empty slurry from the pump and the discharge pipe system when stopping the pump for upkeep.”
Tenacious froths Froths are sometimes classified as either brittle, with large air bubbles that break easily, or tenacious, where air types tight bubbles round minerals and is troublesome to separate. Froth being extra tenacious than was accounted for is a frequent reason for blockages as air can not effectively be removed.
“Two issues are happening available in the market right now. On one hand, mine operators are grinding the product a lot finer than earlier than to liberate more from the waste rock. They’re additionally utilizing flocculants that produce much smaller bubbles which lock up the air much more than brittle froths,” mentioned Harvey. “We’re working along with clients to seek out ways to manage these extra tenacious froths, by taking a look at their circuit design and dealing with areas where the air could accumulate and block the system, paying explicit attention to their pumps, pipes and sumps.
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