Flotation is about creating the proper energy dissipation rate in the cells to obtain optimal contact between the air bubbles and the particles for extracting the minerals. The function of the rotor/stator is to make bubbles from the forced air, suspend the particles, and create an environment for bubbles and particles to make contact and rise to the top as froth for concentration and collection.
Our forced-air flotation design features a streamlined, high-efficiency rotor that works as a very powerful pump. Working together the stator, these components generate an energy-intensive turbulence zone in the bottom of the cell. The forced-air design allows for control of the air flow. The well-defined turbulence zone results in multiple passes of unattached particles through the highest energy dissipation area of the cell where fine particles are driven into contact with the air bubbles.
The stator design, in addition to providing good separation of the cell zones, also serves to redirect the rotor jet uniformly across the tank. This allows dispersion, or distribution, of the maximum amount of air into the cell without disturbing the surface an important consideration for fine particle recovery. The air dispersion capabilities of our Dorr-Oliver cell design exceed all competitive forced-air designs.
By containing the intense circulation energy at the bottom of the cell, the upper zones of the cell remain quiescent, or passive, to maximise recovery of marginally attached coarse particles and minimise the carriage of undesired material.
We have equipped our forced-air flotation tank cells with a uniquely designed, high-efficiency radial launder system that accelerates froth removal as it reaches the surface. Bubble-particle aggregates travel vertically through the froth lattice. The high-efficiency radial launder is shaped to receive the froth uniformly from the cell surface, as well as from the typically heavy-loaded area near the centre of a forced-air machine. On passing over the lip, the froth accelerates to the perimeter of the cell. This unique design rarely requires launder water.
The two factors having the strongest impact on a flotation circuits performance are metallurgical recovery and flotation cell availability. Our forced-air flotation machines provide superior performance in both of these important areas, while offering additional, distinct advantages.
Superior metallurgical performance: Intense recirculation in a well-defined mixing zone multiplies the chances of contact between mineral particles and air bubbles, providing for greater mineral recoveries and higher concentrate grades.
Greater availability: Non-clogging design of the rotor reduces maintenance requirements, minimising failure, and increases availability. Our flotation mechanisms also can be removed for maintenance without process interruption.
Low reagent costs: Air is a natural reagent in the flotation process. Having a wide air dispersion capability permits you to fine-tune your flotation plant to deliver the optimum value for your process.
FLSmidth provides sustainable productivity to the global mining and cement industries. We deliver market-leading engineering, equipment and service solutions that enable our customers to improve performance, drive down costs and reduce environmental impact. Our operations span the globe and we are close to 10,200 employees, present in more than 60 countries. In 2020, FLSmidth generated revenue of DKK 16.4 billion. MissionZero is our sustainability ambition towards zero emissions in mining and cement by 2030.