Froth pumping stays one of the most advanced engineering challenges in mineral processing. Here, Weir Minerals offers recommendation for dealing with the key 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 strategies are deployed without making allowances for the design of the mine’s froth pumping gear, it may end up in the loss of useful minerals and earnings.
Froth pumping stays one of the complicated engineering challenges in mineral processing. This is largely because of the truth that air management points in the hopper, sump and pump itself can generally lead to inefficient pumping, increased maintenance and even misplaced product.
“We’ve started to note a pattern amongst our customers who are having hassle with their froth pumps,” said Les Harvey, regional product manager for Slurry Pumps at Weir Minerals. “By utilizing extra flocculants and other chemical substances designed to enhance mineral restoration, they’re exacerbating present problems in circuit design and reducing the returns they’re on the lookout for.”
Close examination of the froth’s makeup and physical qualities is commonly needed to resolve points. Ensuring เครื่องมือที่ใช้วัดความดันเลือด to greatest 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, 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 decreasing the pump’s effectivity, the air build-up within the pump will scale back its move and improve the slurry stage in the suction hopper. The elevated slurry degree might push the pocket of air by way of the pump, causing surging and excessive vibration which can harm the pump bearings, impeller and shaft. “The greatest method to manage air in a froth pump is to invest in a froth pump with a steady air removing system (CARS), which we now have in our Warman AHF, MF and LF pumps,” says Harvey.
This system permits air to maneuver from the pump’s impeller eye to an air assortment chamber in the back via a vent gap within the impeller. From the chamber, a move inducer removes the air from the pump via a vent pipe. “It’s additionally necessary to place the pump’s discharge pipe at the high of the pump, or at a 45° angle as this will give air trapped on the high of the casing a approach to escape the pump.”
Solving issues “A persistent drawback we see is when hoppers designed to meet the demands of slurry pumping are used in a froth pumping application. 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 circular motion, the place solids and liquids are sent to the outside of the sump for further transport whereas air centrifuges into the centre the place it can be eliminated. This ‘whirlpool’ movement could be encouraged by introducing the slurry from the highest of the tank at a tangential angle. Conical designs, somewhat than those with a flat or rounded ground, additional enhance the flow of minerals and froth into the pump.
Smooth crusing To prevent blockages, the intake pipe which hyperlinks the tank to the pump ought to have a big diameter and slope downwards in the direction of the pump. This design allows escaped air to separate and journey back up the pipe where it can escape from the sump, rather than increase into blockages.
“The shorter your consumption pipe, the more durable it is for blockages to build up. However, in addition to a maintenance spool and isolation valve, it’s a good idea to depart enough area for a water injection port, which is helpful for flushing out any solids construct up,” mentioned Harvey.
“To make maintenance easier, a dump valve could be included on the suction facet of the pump, between the pump and the isolation valve. This will permit users to empty slurry from the pump and the discharge pipe system when stopping the pump for upkeep.”
Tenacious froths Froths are often classified as either brittle, with massive air bubbles that break simply, or tenacious, where air forms tight bubbles round minerals and is tough to separate. Froth being extra tenacious than was accounted for is a frequent reason for blockages as air cannot effectively be removed.
“Two issues are taking place out there 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,” mentioned Harvey. “We’re working together with prospects to seek out ways to manage these more tenacious froths, by looking at their circuit design and coping with areas where the air might accumulate and block the system, paying particular attention to their pumps, pipes and sumps.
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