Froth pumping remains one of the advanced engineering challenges in mineral processing. Here, Weir Minerals presents advice for coping with the key challenges on this operation, tips on 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 tools, it can outcome in the loss of priceless minerals and earnings.
Froth pumping stays some of the complicated engineering challenges in mineral processing. This is basically due to the truth that air administration points within the hopper, sump and pump itself can typically result in inefficient pumping, increased maintenance and even lost product.
“We’ve began to note a pattern among our prospects who are having hassle with their froth pumps,” said Les Harvey, regional product supervisor for Slurry Pumps at Weir Minerals. “By using more flocculants and different chemicals designed to improve mineral recovery, they’re exacerbating present problems in circuit design and decreasing the returns they’re on the lookout for.”
Close ร้านซ่อมเครื่องวัดความดันโลหิต of the froth’s make-up and bodily qualities is commonly needed to resolve issues. Ensuring operators’ froth dealing with gear adheres to greatest design practices is a vital first step in resolving issues.
Maintaining stress The key challenge in froth pumping is coping with air in the pump itself, as 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 through the pump.
In addition to lowering the pump’s effectivity, the air build-up within the pump will cut back its flow and improve the slurry level within the suction hopper. The increased slurry stage might push the pocket of air by way of the pump, causing surging and excessive vibration which might injury the pump bearings, impeller and shaft. “The finest way to manage air in a froth pump is to invest in a froth pump with a continuous air removing 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 assortment chamber within the back via a vent gap within 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 prime of the pump, or at a 45° angle as this will give air trapped at the prime of the casing a way to escape the pump.”
Solving issues “A persistent problem we see is when hoppers designed to satisfy the calls for of slurry pumping are utilized in a froth pumping application. Slurry hoppers require turbulence to forestall 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 circular 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 may be removed. This ‘whirlpool’ movement can 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 floor, further enhance the move of minerals and froth into the pump.
Smooth sailing To prevent blockages, the intake pipe which hyperlinks the tank to the pump ought to have a large diameter and slope downwards in the course of the pump. This design permits escaped air to separate and travel again up the pipe where it can escape from the sump, somewhat than build up into blockages.
“The shorter your consumption pipe, the tougher it is for blockages to build up. However, along with a maintenance spool and isolation valve, it’s a good idea to leave enough house for a water injection port, which is useful for flushing out any solids build up,” stated Harvey.
“To make upkeep easier, 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 empty slurry from the pump and the discharge pipe system when stopping the pump for upkeep.”
Tenacious froths Froths are sometimes categorized as either brittle, with large air bubbles that break simply, or tenacious, where air forms tight bubbles around minerals and is difficult to separate. Froth being more tenacious than was accounted for is a frequent explanation for blockages as air cannot successfully be removed.
“Two things are taking place available in the market 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 along with customers to search out ways to handle these more tenacious froths, by taking a look at their circuit design and dealing with areas the place the air may accumulate and block the system, paying explicit attention to their pumps, pipes and sumps.
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