Froth pumping remains one of the most advanced engineering challenges in mineral processing. Here, Weir Minerals presents advice for dealing with the important thing challenges on this operation, how to maximise pump availability and minimise maintenance in operators’ flotation circuits.
To counteract declining ore grades, increasingly 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 gear, it can outcome in the loss of valuable minerals and earnings.
Froth pumping remains one of the advanced engineering challenges in mineral processing. This is largely as a end result of the reality that air management issues within the hopper, sump and pump itself can generally result in inefficient pumping, increased maintenance and even lost product.
“We’ve began to notice a pattern among our clients who are having bother with their froth pumps,” said Les Harvey, regional product supervisor for Slurry Pumps at Weir Minerals. “By using more flocculants and other chemical compounds designed to improve mineral recovery, they’re exacerbating current problems in circuit design and decreasing the returns they’re in search of.”
Close examination of the froth’s makeup and bodily qualities is commonly wanted to resolve issues. Ensuring operators’ froth handling equipment adheres to greatest design practices is a vital first step in resolving problems.
Maintaining pressure The key challenge in froth pumping is coping with air in the pump itself, because 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 by way of the pump.
In addition to decreasing the pump’s effectivity, the air build-up in the pump will scale back its circulate and improve the slurry level in the suction hopper. The elevated slurry level could push the pocket of air by way of the pump, inflicting surging and excessive vibration which might injury the pump bearings, impeller and shaft. “The greatest way to handle air in a froth pump is to put money into a froth pump with a continuous air removal system (CARS), which we have 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 collection chamber within the again via a vent hole in the impeller. From the chamber, a move inducer removes the air from the pump via a vent pipe. “It’s also necessary to place the pump’s discharge pipe at the prime of the pump, or at a 45° angle as this can give air trapped at the high of the casing a method to escape the pump.”
Solving problems “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 stop the mineral content 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 steady round movement, where solids and liquids are despatched to the skin of the sump for additional transport whereas air centrifuges into the centre the place it could be removed. This ‘whirlpool’ motion may be encouraged by introducing the slurry from the highest of the tank at a tangential angle. Conical designs, rather than these with a flat or rounded flooring, further improve the circulate of minerals and froth into the pump.
Smooth crusing To forestall blockages, the intake pipe which hyperlinks the tank to the pump ought to have a big diameter and slope downwards towards the pump. This design permits escaped air to separate and journey back up the pipe where it could possibly escape from the sump, rather than build up into blockages.
“The shorter your intake pipe, the harder it’s for blockages to construct up. However, in addition to a upkeep spool and isolation valve, it’s a good suggestion to depart enough space for a water injection port, which is beneficial for flushing out any solids construct up,” mentioned Harvey.
“To make maintenance simpler, a dump valve could be included on the suction side of the pump, between the pump and the isolation valve. This will allow customers to drain slurry from the pump and the discharge pipe system when stopping the pump for maintenance.”
เกจแรงดันน้ำ are sometimes categorised as both brittle, with giant air bubbles that break easily, or tenacious, the place air forms tight bubbles round minerals and is tough to separate. Froth being extra tenacious than was accounted for is a frequent explanation for blockages as air can’t effectively be removed.
“Two things are happening in the market at present. 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 a lot smaller bubbles which lock up the air a lot more than brittle froths,” mentioned Harvey. “We’re working together with customers to search out methods to manage these extra tenacious froths, by looking at their circuit design and dealing with areas the place the air could accumulate and block the system, paying specific attention to their pumps, pipes and sumps.
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