Froth pumping remains some of the complex engineering challenges in mineral processing. Here, Weir Minerals offers recommendation for dealing with the necessary thing challenges on this operation, the method to maximise pump availability and minimise maintenance in operators’ flotation circuits.
To counteract declining ore grades, increasingly mine operators are investing in methods to increase the minerals reclaimed from froth pumping. However, when these techniques are deployed with out making allowances for the design of the mine’s froth pumping tools, it may find yourself in the lack of valuable minerals and income.
Froth pumping remains one of the advanced engineering challenges in mineral processing. This is largely due to the fact that air administration points in the hopper, sump and pump itself can generally result in inefficient pumping, increased maintenance and even lost product.
“We’ve started to notice a pattern among our clients who’re having trouble with their froth pumps,” stated Les Harvey, regional product manager for Slurry Pumps at Weir Minerals. “By utilizing extra flocculants and different chemicals designed to improve mineral restoration, they’re exacerbating present issues in circuit design and decreasing the returns they’re on the lookout for.”
Close examination of the froth’s makeup and bodily qualities is usually wanted to resolve points. Ensuring operators’ froth dealing with equipment adheres to best 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, the place 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 within the pump will scale back its circulate and increase the slurry level within the suction hopper. The elevated slurry degree might push the pocket of air through the pump, inflicting surging and extreme vibration which may harm the pump bearings, impeller and shaft. “The best approach to manage air in a froth pump is to put cash into a froth pump with a steady air removing 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 collection chamber within the again through 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 additionally necessary to place the pump’s discharge pipe at the top of the pump, or at a 45° angle as this will give air trapped on the high of the casing a way to escape the pump.”
Solving เกจวัดแรงดัน250bar “A persistent drawback we see is when hoppers designed to meet the demands of slurry pumping are utilized in a froth pumping application. 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,” stated Harvey.
Tanks designed for froth pumping promote continuous circular motion, the place solids and liquids are sent to the skin of the sump for further transport while air centrifuges into the centre where it can be eliminated. This ‘whirlpool’ movement can be inspired by introducing the slurry from the highest of the tank at a tangential angle. Conical designs, somewhat than those with a flat or rounded flooring, additional enhance the flow of minerals and froth into the pump.
Smooth sailing To prevent blockages, the consumption pipe which hyperlinks the tank to the pump should have a big diameter and slope downwards in the path of the pump. This design permits escaped air to separate and travel again up the pipe the place it can escape from the sump, somewhat than building up into blockages.
“The shorter your intake pipe, the more durable it is for blockages to construct up. However, along with a maintenance spool and isolation valve, it’s a good idea to leave enough house for a water injection port, which is beneficial for flushing out any solids build up,” stated Harvey.
“To make maintenance easier, a dump valve may be included on the suction facet of the pump, between the pump and the isolation valve. This will allow users to drain slurry from the pump and the discharge pipe system when stopping the pump for maintenance.”
Tenacious froths Froths are often classified as both brittle, with giant air bubbles that break simply, or tenacious, the place air types tight bubbles around minerals and is difficult to separate. Froth being more tenacious than was accounted for is a frequent explanation for blockages as air cannot effectively be removed.
“Two issues are happening in the market today. On one hand, mine operators are grinding the product a lot finer than earlier than to liberate more from the waste rock. They’re also utilizing flocculants that produce a lot smaller bubbles which lock up the air much more than brittle froths,” stated Harvey. “We’re working along with customers to find ways to handle these more tenacious froths, by looking at their circuit design and coping with areas the place the air could accumulate and block the system, paying explicit consideration to their pumps, pipes and sumps.