Froth pumping stays one of the most advanced engineering challenges in mineral processing. Here, Weir Minerals provides advice for dealing with the key challenges on this operation, how to maximise pump availability and minimise maintenance in operators’ flotation circuits.
To counteract declining ore grades, increasingly more mine operators are investing in methods to extend the minerals reclaimed from froth pumping. However, when these strategies are deployed without making allowances for the design of the mine’s froth pumping equipment, it can lead to the lack of priceless minerals and earnings.
Froth pumping remains some of the complex engineering challenges in mineral processing. This is basically because of the fact that air administration issues in the hopper, sump and pump itself can generally lead to inefficient pumping, increased maintenance and even lost product.
“We’ve began to note a sample amongst our clients who’re having bother with their froth pumps,” stated Les Harvey, regional product supervisor for Slurry Pumps at Weir Minerals. “By utilizing more flocculants and other chemical compounds designed to improve mineral recovery, they’re exacerbating present problems in circuit design and lowering the returns they’re in search of.”
Close examination of the froth’s makeup and bodily qualities is usually needed to resolve issues. Ensuring operators’ froth handling equipment adheres to finest design practices is an important 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 movement of slurry through the pump.
In addition to lowering the pump’s efficiency, the air build-up within the pump will scale back its move and enhance the slurry degree in the suction hopper. The elevated slurry degree may push the pocket of air by way of the pump, inflicting surging and extreme vibration which may harm 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 allows air to move from the pump’s impeller eye to an air collection chamber within the back through a vent hole within the impeller. From the chamber, a flow inducer removes the air from the pump by way of a vent pipe. “It’s additionally necessary to position the pump’s discharge pipe at the high of the pump, or at a 45° angle as this can give air trapped at the high of the casing a way to escape the pump.”
Solving problems “A persistent drawback we see is when hoppers designed to meet the calls for of slurry pumping are utilized in a froth pumping software. Slurry hoppers require turbulence to prevent the mineral content material from settling, whereas turbulence in a froth pump prevents the air from escaping and leads to blockages,” mentioned Harvey.
Tanks designed for froth pumping promote continuous circular movement, where solids and liquids are despatched to the surface of the sump for additional transport while air centrifuges into the centre where it may be removed. This ‘whirlpool’ movement may be inspired by introducing the slurry from the top of the tank at a tangential angle. Conical designs, quite than these with a flat or rounded floor, additional improve the circulate of minerals and froth into the pump.
Smooth crusing To stop blockages, the consumption pipe which links the tank to the pump should have a large diameter and slope downwards towards the pump. This design allows escaped air to separate and journey back up the pipe where it can escape from the sump, quite than increase into blockages.
“ pressure gauge 0 10 bar ราคา , the more durable it’s for blockages to build up. However, along with a upkeep spool and isolation valve, it’s a good idea to leave sufficient house for a water injection port, which is helpful for flushing out any solids construct up,” mentioned Harvey.
“To make maintenance easier, a dump valve may 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 maintenance.”
Tenacious froths Froths are often classified as both brittle, with giant air bubbles that break simply, or tenacious, where air forms tight bubbles around minerals and is troublesome to separate. Froth being more tenacious than was accounted for is a frequent explanation for blockages as air can not effectively be eliminated.
“Two issues are taking place in the market at present. On one hand, mine operators are grinding the product much finer than before to liberate more from the waste rock. They’re additionally using flocculants that produce much smaller bubbles which lock up the air a lot more than brittle froths,” said Harvey. “We’re working along with customers to find ways to manage these more tenacious froths, by looking at their circuit design and coping with areas the place the air could accumulate and block the system, paying particular attention to their pumps, pipes and sumps.
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