Froth pumping stays one of the complicated engineering challenges in mineral processing. Here, Weir Minerals offers advice for coping with the necessary thing challenges in this operation, the method to maximise pump availability and minimise maintenance in operators’ flotation circuits.
To counteract declining ore grades, more and more mine operators are investing in techniques to extend 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 lack of priceless minerals and profits.
Froth pumping stays some of the complicated engineering challenges in mineral processing. This is basically as a result of the fact that air administration points within the hopper, sump and pump itself can typically result in inefficient pumping, increased maintenance and even misplaced product.
“We’ve started to note a sample among our customers who are having trouble with their froth pumps,” said Les Harvey, regional product supervisor for Slurry Pumps at Weir Minerals. “By using extra flocculants and other chemicals designed to improve mineral recovery, they’re exacerbating present issues in circuit design and reducing the returns they’re looking for.”
Close pressure gauge หน้าปัด 4 นิ้ว of the froth’s make-up and bodily qualities is commonly needed to resolve points. Ensuring operators’ froth dealing with gear adheres to finest design practices is an important first step in resolving problems.
Maintaining stress The key problem in froth pumping is dealing with air in 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 motion of slurry by way of the pump.
In addition to lowering the pump’s effectivity, the air build-up in the pump will scale back its move and improve the slurry degree in the suction hopper. The increased slurry stage may push the pocket of air by way of the pump, inflicting surging and excessive vibration which might harm the pump bearings, impeller and shaft. “The greatest way to handle air in a froth pump is to spend money on a froth pump with a continuous air removal 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 collection chamber in the back via a vent hole in the impeller. From the chamber, a circulate inducer removes the air from the pump through a vent pipe. “It’s also 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 high of the casing a way to escape the pump.”
Solving issues “A persistent drawback we see is when hoppers designed to meet the calls for of slurry pumping are utilized in a froth pumping application. Slurry hoppers require turbulence to stop 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 continuous round movement, where solids and liquids are sent to the outside of the sump for additional transport while air centrifuges into the centre where it can be eliminated. This ‘whirlpool’ movement may be encouraged by introducing the slurry from the top of the tank at a tangential angle. Conical designs, rather than these with a flat or rounded ground, further improve the circulate of minerals and froth into the pump.
Smooth crusing To stop blockages, the consumption pipe which links the tank to the pump ought to have a big diameter and slope downwards in direction of the pump. This design permits escaped air to separate and travel again up the pipe where it can escape from the sump, somewhat than building up into blockages.
“The shorter your consumption pipe, the tougher 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 sufficient area for a water injection port, which is helpful for flushing out any solids construct up,” said Harvey.
“To make maintenance simpler, a dump valve can be included on the suction aspect of the pump, between the pump and the isolation valve. This will allow customers to drain slurry from the pump and the discharge pipe system when stopping the pump for upkeep.”
Tenacious froths Froths are often categorized as both brittle, with giant air bubbles that break easily, or tenacious, where air varieties tight bubbles around minerals and is troublesome to separate. Froth being extra tenacious than was accounted for is a frequent explanation for blockages as air can not effectively be eliminated.
“Two things are taking place in the market at present. On one hand, mine operators are grinding the product much finer than earlier than to liberate more 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,” said Harvey. “We’re working together with customers to search out ways to handle these more tenacious froths, by looking at their circuit design and coping with areas where the air could accumulate and block the system, paying specific attention to their pumps, pipes and sumps.
Share