Froth pumping remains one of the most complex engineering challenges in mineral processing. Here, Weir Minerals presents recommendation for coping with the vital thing challenges in 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 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 tools, it may find yourself in the lack of useful minerals and income.
Froth pumping stays some of the advanced engineering challenges in mineral processing. This is essentially as a result of the fact that air administration points within the hopper, sump and pump itself can sometimes result in inefficient pumping, elevated upkeep and even lost product.
“We’ve began to notice a pattern amongst our prospects who are having hassle with their froth pumps,” stated Les Harvey, regional product supervisor for Slurry Pumps at Weir Minerals. “By utilizing more flocculants and different chemical compounds designed to improve mineral restoration, they’re exacerbating present issues in circuit design and reducing the returns they’re in search of.”
Close examination of the froth’s make-up and bodily qualities is commonly wanted to resolve issues. Ensuring operators’ froth dealing with equipment adheres to finest design practices is an important first step in resolving issues.
Maintaining pressure The key challenge in froth pumping is dealing 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 via the pump.
In addition to lowering the pump’s effectivity, the air build-up within the pump will scale back its move and enhance the slurry stage within the suction hopper. The elevated slurry degree could push the pocket of air through the pump, causing surging and extreme vibration which might injury the pump bearings, impeller and shaft. “The greatest method to handle air in a froth pump is to put money into a froth pump with a steady air elimination system (CARS), which we now have 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 collection chamber within the back via a vent hole within the impeller. From ราคาเพรสเชอร์เกจ , a flow inducer removes the air from the pump through a vent pipe. “It’s additionally important to place the pump’s discharge pipe on the top of the pump, or at a 45° angle as it will give air trapped on the top of the casing a method to escape the pump.”
Solving problems “A persistent downside we see is when hoppers designed to satisfy the calls for of slurry pumping are used in a froth pumping utility. Slurry hoppers require turbulence to prevent the mineral content material from settling, whereas turbulence in a froth pump prevents the air from escaping and results in blockages,” stated Harvey.
Tanks designed for froth pumping promote steady round movement, where solids and liquids are sent to the surface of the sump for additional transport while air centrifuges into the centre where it can be removed. This ‘whirlpool’ movement can be inspired 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, further enhance the circulate of minerals and froth into the pump.
Smooth crusing To forestall blockages, the consumption pipe which hyperlinks the tank to the pump should have a big diameter and slope downwards towards the pump. This design allows escaped air to separate and journey back up the pipe the place it could possibly escape from the sump, somewhat than building up into blockages.
“The shorter your consumption pipe, the tougher it’s for blockages to construct up. However, in addition to a upkeep spool and isolation valve, it’s a good suggestion to go away enough space for a water injection port, which is useful for flushing out any solids build up,” said Harvey.
“To make upkeep easier, a dump valve may be included on the suction facet 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 often categorised as both brittle, with massive air bubbles that break simply, or tenacious, where air forms tight bubbles round minerals and is tough to separate. Froth being more tenacious than was accounted for is a frequent cause of blockages as air cannot successfully be removed.
“Two issues are taking place out there right now. On one hand, mine operators are grinding the product a lot finer than earlier than to liberate extra from the waste rock. They’re additionally utilizing flocculants that produce much smaller bubbles which lock up the air much more than brittle froths,” mentioned Harvey. “We’re working along with customers to find ways to handle these extra tenacious froths, by looking 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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