Froth pumping stays one of the most complicated engineering challenges in mineral processing. Here, Weir Minerals presents advice for coping with the key challenges on this operation, tips on 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 increase the minerals reclaimed from froth pumping. However, when these techniques are deployed without making allowances for the design of the mine’s froth pumping gear, it can lead to the lack of priceless minerals and earnings.
Froth pumping remains some of the complicated engineering challenges in mineral processing. This is basically as a result of the reality that air administration issues within the hopper, sump and pump itself can typically lead to inefficient pumping, elevated maintenance and even misplaced product.
“We’ve started to notice a pattern amongst our customers who’re having bother with their froth pumps,” said Les Harvey, regional product supervisor for Slurry Pumps at Weir Minerals. “By utilizing extra flocculants and different chemical compounds designed to improve mineral restoration, they’re exacerbating present issues in circuit design and lowering the returns they’re looking for.”
Close examination of the froth’s makeup and bodily qualities is commonly needed to resolve points. Ensuring operators’ froth handling gear adheres to best design practices is an important first step in resolving issues.
Maintaining strain The key challenge in froth pumping is dealing with air within 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 motion of slurry through the pump.
In addition to reducing the pump’s efficiency, the air build-up within the pump will reduce its move and enhance the slurry degree in the suction hopper. The increased slurry stage may push the pocket of air through the pump, causing surging and excessive vibration which may injury the pump bearings, impeller and shaft. “The best approach to manage air in a froth pump is to spend money on a froth pump with a steady air removal system (CARS), which we’ve 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 via a vent gap in the impeller. From the chamber, a move 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 this can give air trapped at the top of the casing a method to escape the pump.”
Solving issues “A persistent downside we see is when hoppers designed to fulfill the demands of slurry pumping are utilized in a froth pumping software. Slurry hoppers require turbulence to prevent the mineral content from settling, whereas turbulence in a froth pump prevents the air from escaping and leads to blockages,” said Harvey.
Tanks designed for froth pumping promote continuous circular motion, where solids and liquids are despatched to the surface of the sump for further transport while air centrifuges into the centre where it might be removed. This ‘whirlpool’ motion may be inspired by introducing the slurry from the top of the tank at a tangential angle. Conical designs, rather than these with a flat or rounded floor, further improve the flow of minerals and froth into the pump.
Smooth crusing To prevent blockages, the consumption pipe which links the tank to the pump ought to have a big diameter and slope downwards in path of the pump. This design allows escaped air to separate and journey back up the pipe the place it can escape from the sump, quite than increase into blockages.
“The shorter your consumption pipe, the harder it is for blockages to construct up. However, in addition to a upkeep spool and isolation valve, it’s a good idea to go away enough area for a water injection port, which is helpful for flushing out any solids construct up,” stated 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 permit customers to empty slurry from the pump and the discharge pipe system when stopping the pump for maintenance.”
Tenacious froths Froths are often categorised as either brittle, with giant air bubbles that break easily, or tenacious, the place air types tight bubbles around minerals and is difficult to separate. เกจวัดแรงดันถังออกซิเจน being extra tenacious than was accounted for is a frequent reason for blockages as air cannot successfully be eliminated.
“Two issues are occurring available within the market today. On one hand, mine operators are grinding the product a lot finer than before to liberate extra from the waste rock. They’re also utilizing flocculants that produce much smaller bubbles which lock up the air a lot more than brittle froths,” stated Harvey. “We’re working together with prospects to search out ways to manage these extra tenacious froths, by taking a glance at their circuit design and coping with areas where the air could accumulate and block the system, paying explicit consideration to their pumps, pipes and sumps.
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