Froth pumping stays some of the complex engineering challenges in mineral processing. Here, Weir Minerals presents advice for dealing with the important thing challenges in this operation, tips on how to maximise pump availability and minimise upkeep in operators’ flotation circuits.
To counteract declining ore grades, increasingly mine operators are investing in methods to increase the minerals reclaimed from froth pumping. However, when these techniques are deployed with out making allowances for the design of the mine’s froth pumping equipment, it may find yourself in the lack of priceless minerals and earnings.
Froth pumping stays some of the complicated engineering challenges in mineral processing. This is largely because of the truth that air administration points in the hopper, sump and pump itself can typically result in inefficient pumping, increased upkeep and even lost product.
“We’ve started to note a pattern amongst our clients who are having bother with their froth pumps,” said Les Harvey, regional product supervisor for Slurry Pumps at Weir Minerals. “By using extra flocculants and different chemical compounds designed to enhance mineral recovery, they’re exacerbating present problems in circuit design and reducing the returns they’re in search of.”
Close examination of the froth’s make-up 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 strain The key problem in froth pumping is dealing 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 lowering the pump’s effectivity, the air build-up in the pump will cut back its move and improve the slurry degree in the suction hopper. The elevated slurry degree might push the pocket of air through the pump, causing surging and excessive vibration which can injury the pump bearings, impeller and shaft. “The finest method to manage air in a froth pump is to invest in a froth pump with a continuous air elimination system (CARS), which we now have in our Warman AHF, MF and LF pumps,” says Harvey.
This system allows air to maneuver from the pump’s impeller eye to an air assortment chamber within the back through a vent gap in the impeller. From the chamber, a flow inducer removes the air from the pump by way of a vent pipe. “It’s additionally important to position the pump’s discharge pipe at the high of the pump, or at a 45° angle as this will give air trapped on the prime of the casing a approach to escape the pump.”
Solving problems “A persistent problem we see is when hoppers designed to satisfy the demands of slurry pumping are utilized in a froth pumping utility. Slurry hoppers require turbulence to stop the mineral content material from settling, while turbulence in a froth pump prevents the air from escaping and leads to blockages,” said Harvey.
Tanks designed for froth pumping promote continuous round motion, the place solids and liquids are despatched to the skin of the sump for further transport whereas air centrifuges into the centre where it might be removed. This ‘whirlpool’ motion can be encouraged by introducing the slurry from the highest of the tank at a tangential angle. Conical designs, rather than these with a flat or rounded flooring, additional improve the circulate of minerals and froth into the pump.
Smooth crusing To forestall blockages, the intake pipe which hyperlinks the tank to the pump ought to have a large diameter and slope downwards in course of the pump. This design permits escaped air to separate and journey again up the pipe where it can escape from the sump, quite than building up into blockages.
“ เกจวัดแรงดันถังลม , the harder it’s for blockages to construct up. However, along with a upkeep spool and isolation valve, it’s a good idea to go away sufficient house for a water injection port, which is beneficial for flushing out any solids build up,” said Harvey.
“To make upkeep simpler, a dump valve may be included on the suction facet of the pump, between the pump and the isolation valve. This will enable users to empty slurry from the pump and the discharge pipe system when stopping the pump for maintenance.”
Tenacious froths Froths are sometimes categorized as both brittle, with giant air bubbles that break easily, or tenacious, the place air varieties 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 can not effectively be removed.
“Two issues are occurring available within the market 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 a lot smaller bubbles which lock up the air a lot more than brittle froths,” said Harvey. “We’re working together with clients to search out ways to handle these more tenacious froths, by looking at their circuit design and dealing with areas the place the air might accumulate and block the system, paying explicit consideration to their pumps, pipes and sumps.
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