Froth pumping remains one of the most complicated engineering challenges in mineral processing. Here, Weir Minerals provides recommendation for coping with the key challenges on this operation, the way to maximise pump availability and minimise upkeep in operators’ flotation circuits.
To counteract declining ore grades, more and more mine operators are investing in techniques 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 equipment, it may find yourself in the lack of useful minerals and income.
Froth pumping remains one of the complicated engineering challenges in mineral processing. This is largely because of the reality that air administration issues in the hopper, sump and pump itself can sometimes lead to inefficient pumping, elevated maintenance and even lost product.
“We’ve started to note a sample among our prospects who are having bother with their froth pumps,” stated Les Harvey, regional product manager for Slurry Pumps at Weir Minerals. “By using more flocculants and other chemicals designed to enhance mineral recovery, they’re exacerbating existing problems in circuit design and lowering 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 operators’ froth handling equipment adheres to greatest design practices is an important first step in resolving issues.
Maintaining differential pressure gauge ราคา 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 movement of slurry through the pump.
In addition to lowering the pump’s efficiency, the air build-up in the pump will cut back its move and improve the slurry level within the suction hopper. The elevated slurry level could push the pocket of air via the pump, causing surging and extreme vibration which might damage the pump bearings, impeller and shaft. “The finest way to manage air in a froth pump is to spend money on a froth pump with a steady air elimination system (CARS), which we now have 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 collection chamber within the again through a vent gap within the impeller. From the chamber, a move inducer removes the air from the pump by way of a vent pipe. “It’s also essential to position the pump’s discharge pipe at the top of the pump, or at a 45° angle as it will give air trapped at the prime of the casing a way to escape the pump.”
Solving problems “A persistent downside we see is when hoppers designed to satisfy the calls for of slurry pumping are utilized in a froth pumping application. Slurry hoppers require turbulence to forestall 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 steady round movement, 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 could be eliminated. This ‘whirlpool’ motion may be encouraged by introducing the slurry from the top of the tank at a tangential angle. Conical designs, quite than these with a flat or rounded floor, additional enhance the flow of minerals and froth into the pump.
Smooth sailing To forestall blockages, the consumption pipe which hyperlinks the tank to the pump should have a big diameter and slope downwards in the direction of the pump. This design allows escaped air to separate and travel again up the pipe where it could possibly escape from the sump, rather than increase into blockages.
“The shorter your intake pipe, the harder it’s for blockages to build up. However, in addition to a maintenance spool and isolation valve, it’s a good idea to go away sufficient space for a water injection port, which is helpful for flushing out any solids construct up,” stated Harvey.
“To make maintenance easier, a dump valve can be included on the suction side of the pump, between the pump and the isolation valve. This will enable customers to empty slurry from the pump and the discharge pipe system when stopping the pump for upkeep.”
Tenacious froths Froths are sometimes classified as either brittle, with massive air bubbles that break easily, or tenacious, the place air forms tight bubbles round minerals and is difficult to separate. Froth being more tenacious than was accounted for is a frequent cause of blockages as air cannot successfully be eliminated.
“Two issues are taking place available in the market at present. On one hand, mine operators are grinding the product a lot finer than earlier than to liberate more 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 together with clients to search out methods to handle these more tenacious froths, by looking at their circuit design and coping with areas where the air may accumulate and block the system, paying explicit attention to their pumps, pipes and sumps.
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