Weir’s answer for froth challenges

Froth pumping remains some of the advanced engineering challenges in mineral processing. Here, Weir Minerals presents recommendation for coping with the key challenges on this operation, how to maximise pump availability and minimise upkeep in operators’ flotation circuits.
To counteract declining ore grades, more and more mine operators are investing in techniques to extend the minerals reclaimed from froth pumping. However, when these strategies are deployed without making allowances for the design of the mine’s froth pumping equipment, it can lead to the loss of priceless minerals and income.
Froth pumping stays one of the most complicated engineering challenges in mineral processing. This is basically as a end result of the fact that air management issues 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 pattern amongst our clients who’re having hassle with their froth pumps,” said Les Harvey, regional product manager for Slurry Pumps at Weir Minerals. “By utilizing more flocculants and other chemical substances designed to enhance mineral restoration, they’re exacerbating current issues in circuit design and decreasing the returns they’re looking for.”

Close examination of the froth’s makeup and bodily qualities is often wanted to resolve points. Ensuring operators’ froth handling tools adheres to finest design practices is a vital first step in resolving problems.
Maintaining pressure The key challenge in froth pumping is coping with air within 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 by way of the pump.
In addition to reducing the pump’s efficiency, the air build-up in the pump will scale back its circulate and improve the slurry degree within the suction hopper. The increased slurry degree may push the pocket of air by way of the pump, inflicting surging and extreme vibration which can injury the pump bearings, impeller and shaft. “The finest approach to handle air in a froth pump is to invest in a froth pump with a continuous air removing system (CARS), which we have in our Warman AHF, MF and LF pumps,” says Harvey.
This system permits air to move from the pump’s impeller eye to an air assortment chamber within the back via a vent gap in the impeller. From the chamber, a circulate inducer removes the air from the pump through a vent pipe. “It’s additionally important to position the pump’s discharge pipe at the prime of the pump, or at a 45° angle as this will give air trapped at the top of the casing a approach to escape the pump.”

Solving issues “A persistent downside we see is when hoppers designed to meet the calls for of slurry pumping are used in a froth pumping software. Slurry hoppers require turbulence to prevent the mineral content material from settling, whereas turbulence in a froth pump prevents the air from escaping and leads to blockages,” mentioned Harvey.
Tanks designed for froth pumping promote steady round motion, the place solids and liquids are sent to the outside of the sump for additional transport whereas 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, somewhat than those with a flat or rounded ground, additional improve the move of minerals and froth into the pump.
Smooth sailing To prevent blockages, the consumption pipe which hyperlinks the tank to the pump should have a big diameter and slope downwards in the direction of the pump. This design permits escaped air to separate and journey again up the pipe the place it could escape from the sump, rather than increase 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 leave sufficient area for a water injection port, which is beneficial for flushing out any solids build up,” mentioned Harvey.
“To make maintenance easier, a dump valve could be included on the suction aspect of the pump, between the pump and the isolation valve. This will permit customers to drain slurry from the pump and the discharge pipe system when stopping the pump for upkeep.”

Tenacious froths Froths are often categorized as both brittle, with massive air bubbles that break simply, or tenacious, where air forms tight bubbles round minerals and is difficult to separate. เครื่องมือที่ใช้วัดความดัน being more tenacious than was accounted for is a frequent cause of blockages as air can not effectively be eliminated.
“Two issues are happening out there 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 also utilizing flocculants that produce much smaller bubbles which lock up the air much more than brittle froths,” stated Harvey. “We’re working along with clients to search out ways to handle these more tenacious froths, by taking a look at their circuit design and coping with areas the place the air may accumulate and block the system, paying particular attention to their pumps, pipes and sumps.

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