Weir’s answer for froth challenges

Froth pumping remains some of the complex engineering challenges in mineral processing. Here, Weir Minerals provides recommendation for coping with the important 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 methods to increase the minerals reclaimed from froth pumping. However, when these methods are deployed without making allowances for the design of the mine’s froth pumping equipment, it can lead to the loss of valuable minerals and earnings.
Froth pumping stays one of the most advanced engineering challenges in mineral processing. This is largely as a result of the reality that air administration points within the hopper, sump and pump itself can generally result in inefficient pumping, increased upkeep and even lost product.
“We’ve began to note a sample among our clients who’re having hassle with their froth pumps,” said Les Harvey, regional product manager for Slurry Pumps at Weir Minerals. “By using extra flocculants and other chemical substances designed to improve mineral recovery, they’re exacerbating existing issues in circuit design and lowering the returns they’re in search of.”
Close examination of the froth’s makeup and physical qualities is commonly wanted to resolve issues. Ensuring operators’ froth handling equipment adheres to finest design practices is an important first step in resolving issues.
Maintaining stress The key challenge in froth pumping is dealing with air in the pump itself, as 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 via the pump.
In addition to decreasing the pump’s efficiency, the air build-up in the pump will reduce its flow and increase the slurry degree within the suction hopper. The elevated slurry level might push the pocket of air through the pump, inflicting surging and extreme vibration which can injury the pump bearings, impeller and shaft. “The finest method to manage air in a froth pump is to spend money on a froth pump with a continuous air removing system (CARS), which we now have in our Warman AHF, MF and LF pumps,” says Harvey.
This system permits air to move from the pump’s impeller eye to an air collection chamber within the back by way of a vent hole within the impeller. From the chamber, a move inducer removes the air from the pump by way of a vent pipe. “It’s additionally important to position the pump’s discharge pipe on the prime of the pump, or at a 45° angle as this can give air trapped at the prime of the casing a approach to escape the pump.”
Solving issues “A persistent problem we see is when hoppers designed to satisfy the calls for of slurry pumping are used in a froth pumping software. Slurry hoppers require turbulence to forestall the mineral content from settling, while turbulence in a froth pump prevents the air from escaping and leads to blockages,” stated Harvey.
Tanks designed for froth pumping promote continuous round motion, the place solids and liquids are despatched to the surface of the sump for further transport while air centrifuges into the centre where it can be eliminated. This ‘whirlpool’ motion 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 floor, additional improve the flow of minerals and froth into the pump.
Smooth sailing To prevent blockages, the intake pipe which hyperlinks the tank to the pump ought to have a large diameter and slope downwards in direction of the pump. This design permits escaped air to separate and travel again up the pipe the place it could possibly escape from the sump, rather than increase into blockages.
“The shorter your consumption pipe, the harder it is for blockages to build up. However, along with a upkeep spool and isolation valve, it’s a good idea to leave enough area for a water injection port, which is helpful for flushing out any solids build up,” mentioned Harvey.
“To make maintenance easier, a dump valve could be included on the suction aspect of the pump, between the pump and the isolation valve. This will enable customers to drain slurry from the pump and the discharge pipe system when stopping the pump for maintenance.”
Tenacious froths Froths are sometimes classified as both brittle, with giant air bubbles that break easily, or tenacious, where air varieties tight bubbles around minerals and is troublesome to separate. เกจวัดแรงดันเชื้อเพลิง being extra tenacious than was accounted for is a frequent explanation for blockages as air can not effectively be eliminated.
“Two issues are occurring in the market right now. On one hand, mine operators are grinding the product a lot finer than before to liberate more from the waste rock. They’re additionally 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 clients to find methods to manage these extra tenacious froths, by looking at their circuit design and coping with areas the place the air may accumulate and block the system, paying particular attention to their pumps, pipes and sumps.

Leave a Comment