Froth pumping stays one of the most complicated engineering challenges in mineral processing. Here, Weir Minerals offers 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 strategies 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 outcome in the loss of priceless minerals and profits.
Froth pumping stays some of the complicated engineering challenges in mineral processing. This is essentially due to the truth that air management issues in the hopper, sump and pump itself can typically result in inefficient pumping, increased upkeep and even lost product.
“We’ve began to notice a sample among our prospects who are having hassle with their froth pumps,” stated Les Harvey, regional product supervisor for Slurry Pumps at Weir Minerals. “By using extra flocculants and other chemicals designed to improve mineral restoration, they’re exacerbating present problems in circuit design and decreasing the returns they’re looking for.”
Close examination of the froth’s makeup and bodily qualities is often wanted to resolve points. Ensuring operators’ froth handling equipment adheres to finest design practices is an important first step in resolving problems.
Maintaining stress The key problem in froth pumping is coping with air in the pump itself, because 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 by way of the pump.
In addition to decreasing the pump’s efficiency, the air build-up in the pump will reduce its flow and improve the slurry level within the suction hopper. The increased slurry level may push the pocket of air through the pump, inflicting surging and excessive vibration which may injury the pump bearings, impeller and shaft. “The best approach to handle air in a froth pump is to invest in a froth pump with a steady 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 assortment chamber within the back via a vent gap within the impeller. From the chamber, a circulate inducer removes the air from the pump through a vent pipe. “It’s also necessary to place the pump’s discharge pipe at the prime of the pump, or at a 45° angle as this can give air trapped at the prime of the casing a approach to escape the pump.”
Solving issues “A persistent drawback we see is when hoppers designed to satisfy the demands of slurry pumping are used in a froth pumping application. Slurry เกจวัดแก๊สหุงต้ม 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 continuous round movement, the place solids and liquids are sent to the skin of the sump for additional transport whereas air centrifuges into the centre the place it could be eliminated. This ‘whirlpool’ movement may be inspired by introducing the slurry from the highest of the tank at a tangential angle. Conical designs, quite than those with a flat or rounded floor, further enhance the flow of minerals and froth into the pump.
Smooth crusing To stop blockages, the intake pipe which links the tank to the pump ought to have a large diameter and slope downwards in path of the pump. This design allows escaped air to separate and journey again up the pipe the place it might possibly escape from the sump, somewhat than building up into blockages.
“The shorter your consumption pipe, 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 area for a water injection port, which is beneficial for flushing out any solids construct up,” stated Harvey.
“To make upkeep simpler, a dump valve could be included on the suction side of the pump, between the pump and the isolation valve. This will enable customers to drain slurry from the pump and the discharge pipe system when stopping the pump for upkeep.”
Tenacious froths Froths are sometimes categorized as both brittle, with massive air bubbles that break easily, or tenacious, where air varieties 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 cannot successfully be removed.
“Two issues are taking place available in the market at present. On one hand, mine operators are grinding the product a lot finer than before to liberate extra from the waste rock. They’re additionally using flocculants that produce a lot smaller bubbles which lock up the air much more than brittle froths,” mentioned Harvey. “We’re working along with prospects to find ways to manage these more tenacious froths, by looking at their circuit design and coping with areas the place the air may accumulate and block the system, paying explicit attention to their pumps, pipes and sumps.