Froth pumping remains some of the complex engineering challenges in mineral processing. Here, Weir Minerals offers recommendation for coping with the necessary thing challenges in 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 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 equipment, it may find yourself in the loss of priceless minerals and earnings.
Froth pumping stays some of the complex engineering challenges in mineral processing. This is basically as a end result of the truth that air management issues within the hopper, sump and pump itself can generally lead to inefficient pumping, elevated upkeep and even misplaced product.
“We’ve started to note a pattern amongst our clients who’re having trouble with their froth pumps,” said Les Harvey, regional product supervisor for Slurry Pumps at Weir Minerals. “By utilizing more flocculants and other chemical substances designed to enhance mineral restoration, they’re exacerbating current issues in circuit design and decreasing the returns they’re in search of.”
Close examination of the froth’s make-up and physical qualities is usually needed to resolve issues. Ensuring operators’ froth handling tools adheres to finest design practices is an important first step in resolving issues.
Maintaining stress The key problem in froth pumping is coping with air in the pump itself, as 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 decreasing the pump’s effectivity, the air build-up in the pump will cut back its move and improve the slurry level within the suction hopper. The increased slurry stage might 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 handle air in a froth pump is to put cash into a froth pump with a continuous air removing 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 by way of a vent gap within the impeller. From the chamber, a circulate inducer removes the air from the pump by way of a vent pipe. “It’s also important to position the pump’s discharge pipe on the top of the pump, or at a 45° angle as this can give air trapped on the top of the casing a approach to escape the pump.”
Solving issues “A persistent drawback we see is when hoppers designed to satisfy the calls for of slurry pumping are used in a froth pumping software. Slurry hoppers require turbulence to prevent 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 continuous round movement, the place solids and liquids are despatched to the surface of the sump for further transport whereas air centrifuges into the centre where it can be eliminated. This ‘whirlpool’ motion could be encouraged by introducing the slurry from the top of the tank at a tangential angle. Conical designs, rather than these with a flat or rounded flooring, additional enhance the circulate of minerals and froth into the pump.
Smooth crusing To stop blockages, the intake pipe which hyperlinks the tank to the pump should have a big diameter and slope downwards in direction of the pump. This design allows escaped air to separate and travel again up the pipe the place it can escape from the sump, quite than increase into blockages.
“The shorter your intake pipe, the harder it’s for blockages to construct up. However, along with a maintenance spool and isolation valve, it’s a good suggestion to go away enough space for a water injection port, which is beneficial for flushing out any solids construct up,” said Harvey.
“To make maintenance easier, a dump valve can be included on the suction aspect of the pump, between the pump and the isolation valve. เกจวัดแรงดันออกซิเจนราคา will allow users to drain slurry from the pump and the discharge pipe system when stopping the pump for upkeep.”
Tenacious froths Froths are often classified as both brittle, with massive air bubbles that break easily, or tenacious, the place air types tight bubbles around minerals and is troublesome to separate. Froth being extra tenacious than was accounted for is a frequent cause of blockages as air can not successfully be removed.
“Two issues are happening available within the market today. On one hand, mine operators are grinding the product much finer than earlier than to liberate extra from the waste rock. They’re also 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 search out ways to handle these extra tenacious froths, by taking a look at their circuit design and coping with areas the place the air might accumulate and block the system, paying specific consideration to their pumps, pipes and sumps.
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