Froth pumping remains one of the most complicated engineering challenges in mineral processing. Here, Weir Minerals provides recommendation for coping with the necessary thing challenges on this operation, tips on how to maximise pump availability and minimise upkeep in operators’ flotation circuits.
To counteract declining ore grades, increasingly more mine operators are investing in methods to increase the minerals reclaimed from froth pumping. However, when these methods are deployed without making allowances for the design of the mine’s froth pumping equipment, it may end up in the loss of valuable minerals and earnings.
Froth pumping stays one of the advanced engineering challenges in mineral processing. This is largely because of the fact that air administration issues in the hopper, sump and pump itself can generally lead to inefficient pumping, elevated upkeep and even misplaced product.
“We’ve began to notice a sample among our customers who are having trouble with their froth pumps,” mentioned Les Harvey, regional product supervisor for Slurry Pumps at Weir Minerals. “By utilizing more flocculants and different chemicals designed to improve mineral recovery, they’re exacerbating current issues in circuit design and decreasing the returns they’re in search of.”
Close examination of the froth’s make-up and bodily qualities is usually wanted to resolve points. Ensuring operators’ froth dealing with equipment adheres to greatest design practices is a vital first step in resolving problems.
Maintaining stress 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 movement of slurry through the pump.
In addition to decreasing the pump’s efficiency, the air build-up within the pump will reduce its circulate and enhance the slurry stage within the suction hopper. The elevated slurry level may push the pocket of air by way of the pump, inflicting surging and excessive vibration which might injury the pump bearings, impeller and shaft. “ เพรสเชอร์เกจน้ำ to manage air in a froth pump is to invest in 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 permits air to move from the pump’s impeller eye to an air assortment chamber within the again through a vent gap in the impeller. From the chamber, a move inducer removes the air from the pump through a vent pipe. “It’s also necessary to position the pump’s discharge pipe at the high of the pump, or at a 45° angle as it will give air trapped on the high of the casing a approach to escape the pump.”
Solving problems “A persistent problem we see is when hoppers designed to meet the demands of slurry pumping are used in a froth pumping application. Slurry hoppers require turbulence to prevent the mineral content from settling, whereas turbulence in a froth pump prevents the air from escaping and results in blockages,” mentioned Harvey.
Tanks designed for froth pumping promote steady round movement, the place solids and liquids are despatched to the surface of the sump for further transport while air centrifuges into the centre where it can be removed. This ‘whirlpool’ motion could be inspired by introducing the slurry from the highest of the tank at a tangential angle. Conical designs, rather than those with a flat or rounded flooring, additional enhance the move of minerals and froth into the pump.
Smooth sailing To stop blockages, the consumption pipe which hyperlinks the tank to the pump should have a big diameter and slope downwards in path of 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 more durable it is for blockages to construct up. However, along with a upkeep spool and isolation valve, it’s a good idea to depart sufficient house for a water injection port, which is helpful for flushing out any solids construct up,” said Harvey.
“To make maintenance simpler, a dump valve can be included on the suction side of the pump, between the pump and the isolation valve. This will enable users to drain slurry from the pump and the discharge pipe system when stopping the pump for upkeep.”
Tenacious froths Froths are often categorised as both brittle, with large air bubbles that break easily, or tenacious, where air types tight bubbles round minerals and is difficult to separate. Froth being extra tenacious than was accounted for is a frequent reason for blockages as air cannot successfully be removed.
“Two things are happening out there at present. 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 a lot smaller bubbles which lock up the air a lot more than brittle froths,” mentioned Harvey. “We’re working together with clients to search out ways to handle these more tenacious froths, by looking at their circuit design and dealing with areas the place the air could accumulate and block the system, paying explicit attention to their pumps, pipes and sumps.
Share
November 3, 2023
No Comments
