Weir’s solution for froth challenges

Froth pumping remains some of the complex engineering challenges in mineral processing. Here, Weir Minerals offers advice for dealing 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 mine operators are investing in methods to extend the minerals reclaimed from froth pumping. However, when these methods are deployed with out making allowances for the design of the mine’s froth pumping gear, it can result in the lack of valuable minerals and profits.
Froth pumping remains one of the complicated engineering challenges in mineral processing. This is basically because of the fact that air administration issues within the hopper, sump and pump itself can sometimes result in inefficient pumping, elevated upkeep and even misplaced product.
“We’ve started to note a sample among our customers who’re having bother with their froth pumps,” said Les Harvey, regional product manager for Slurry Pumps at Weir Minerals. “By using more flocculants and other chemicals designed to enhance mineral restoration, they’re exacerbating current issues in circuit design and lowering 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 tools adheres to best design practices is a vital first step in resolving issues.
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, where it builds up into an “air lock” which impedes the motion of slurry via the pump.
In addition to reducing the pump’s efficiency, the air build-up within the pump will cut back its flow and increase the slurry degree in the suction hopper. The elevated slurry degree could push the pocket of air via the pump, inflicting surging and excessive vibration which can injury the pump bearings, impeller and shaft. “The finest way to manage air in a froth pump is to put money into a froth pump with a continuous air elimination system (CARS), which we’ve in our Warman AHF, MF and LF pumps,” says Harvey.
This system permits air to maneuver from the pump’s impeller eye to an air assortment chamber in the back by way of a vent hole in the impeller. From the chamber, a flow inducer removes the air from the pump through a vent pipe. “It’s additionally important to place the pump’s discharge pipe at the high of the pump, or at a 45° angle as this can give air trapped at the prime of the casing a way to escape the pump.”
Solving issues “A persistent drawback we see is when hoppers designed to meet the calls for of slurry pumping are utilized in a froth pumping application. Slurry hoppers require turbulence to forestall the mineral content material from settling, while turbulence in a froth pump prevents the air from escaping and results in blockages,” said Harvey.
Tanks designed for froth pumping promote steady circular movement, the place solids and liquids are despatched to the skin of the sump for additional transport whereas air centrifuges into the centre the place 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 these with a flat or rounded floor, additional enhance the flow 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 large diameter and slope downwards in the direction of the pump. This design permits escaped air to separate and journey back up the pipe the place it may possibly escape from the sump, quite than increase into blockages.
“The shorter your intake pipe, the tougher it is for blockages to build up. However, in addition to a upkeep spool and isolation valve, it’s a good idea to leave enough area for a water injection port, which is beneficial for flushing out any solids build up,” mentioned Harvey.
“To make เกจวัดแก๊สlpg , a dump valve can be included on the suction aspect 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.”
Tenacious froths Froths are sometimes classified as both brittle, with large air bubbles that break simply, or tenacious, where air varieties 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 cannot successfully be eliminated.
“Two things are taking place in the market today. On one hand, mine operators are grinding the product much finer than before to liberate extra from the waste rock. They’re also using flocculants that produce much smaller bubbles which lock up the air much more than brittle froths,” stated Harvey. “We’re working together with prospects to search out ways to handle these extra tenacious froths, by looking at their circuit design and coping with areas where the air might accumulate and block the system, paying explicit consideration to their pumps, pipes and sumps.
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