Froth pumping remains some of the advanced engineering challenges in mineral processing. Here, Weir Minerals offers recommendation for dealing with the necessary thing challenges on this operation, the way to maximise pump availability and minimise maintenance in operators’ flotation circuits.
To counteract declining ore grades, increasingly mine operators are investing in strategies to increase the minerals reclaimed from froth pumping. However, when these strategies are deployed with out making allowances for the design of the mine’s froth pumping gear, it can lead to the loss of valuable minerals and income.
Froth pumping remains some of the complex engineering challenges in mineral processing. This is largely as a end result of the fact that air administration points in the hopper, sump and pump itself can sometimes result in inefficient pumping, elevated maintenance and even misplaced product.
“We’ve began to note a sample among our prospects who are having trouble with their froth pumps,” mentioned Les Harvey, regional product supervisor for Slurry Pumps at Weir Minerals. “By utilizing more flocculants and other chemicals designed to improve mineral restoration, they’re exacerbating present issues in circuit design and lowering the returns they’re on the lookout for.”
Close examination of the froth’s make-up and physical qualities is commonly wanted to resolve points. Ensuring operators’ froth dealing with equipment adheres to best design practices is a vital first step in resolving issues.
Maintaining pressure The key problem in froth pumping is dealing with air within 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 by way of the pump.
In addition to reducing the pump’s efficiency, the air build-up in the pump will reduce its circulate and increase the slurry degree in the suction hopper. The elevated slurry level may push the pocket of air via the pump, inflicting surging and excessive vibration which can harm the pump bearings, impeller and shaft. “The best method to handle air in a froth pump is to spend cash on a froth pump with a steady air elimination system (CARS), which we 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 again by way of 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 also essential to place the pump’s discharge pipe on the high of the pump, or at a 45° angle as it will give air trapped on the high of the casing a method to escape the pump.”
Solving problems “A persistent downside we see is when hoppers designed to fulfill the demands of slurry pumping are utilized in a froth pumping utility. 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,” mentioned Harvey.
Tanks designed for froth pumping promote steady circular motion, where solids and liquids are despatched to the outside of the sump for additional transport while air centrifuges into the centre the place it can be eliminated. 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 floor, additional enhance the move of minerals and froth into the pump.
Smooth sailing 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 permits escaped air to separate and travel back up the pipe where it could escape from the sump, somewhat than building up into blockages.
“The shorter your consumption pipe, the tougher it’s for blockages to build up. However, along with a upkeep spool and isolation valve, it’s a good suggestion to go away enough area for a water injection port, which is helpful for flushing out any solids build up,” mentioned Harvey.
“To make upkeep easier, a dump valve could be included on the suction aspect of the pump, between the pump and the isolation valve. This will permit customers to drain slurry from the pump and the discharge pipe system when stopping the pump for upkeep.”
Tenacious froths Froths are sometimes categorised as both brittle, with large 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 can not effectively 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 more from the waste rock. They’re additionally using flocculants that produce much smaller bubbles which lock up the air much more than brittle froths,” stated Harvey. “ differential pressure gauge ราคา ’re working together with clients to find ways to manage these more tenacious froths, by looking at their circuit design and dealing with areas where the air may accumulate and block the system, paying particular attention to their pumps, pipes and sumps.
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