The Spiral Turbo Pulp Lifter (Spiral TPLTM) is the latest in pulp lifter development. It combines industry-leading pumping efficiency with a simpler, lighter design.
Reduced slurry pooling in mill
Increased mill throughput by up to 15 %
Reduced energy consumption by up to 15 %
Suited to high throughputs
A pulp lifter is used in grate discharge mills is to pump the ground ore from the mill. An inefﬁcient pulp lifter can cause a slurry pool to build up in the mill, resulting in partial dissipation of charge (balls and rock) kinetic energy into the ﬂuid, reducing the energy available for breakage.
This is particularly evident in larger mills, which have a reduced grate area relative to their grinding volume and power, and where the pulp is lifted further to reach the discharge through the trunnion.
There are a number of causes of inefﬁciency in a pulp lifter, and these must be addressed together to design an efﬁcient pulp lifter:
Flow-back through the grate as the pulp lifter sweeps past the pool and the saturated portion of the charge
Overtopping within the pulp lifter, by means of a perfect, geometric spiral improving the wear life of the pulp lifter, clearly visible on the rear side of the lifters and centre discharger
Flow-back in the centre discharger triggered by altering the trajectory within the mill affecting the wear rate on the trunnion liner and trommel screens. This is overcome by means of a free-ﬂowing wear-resistant centre discharger design.
Mill flow behaviour remained unobserved and misunderstood until relatively recently when computational modelling packages like DEM (Discrete Element Method) and CFD (Computational Fluid Dynamics) enabled us to “see” inside the mill while it is in operation. Outotec routinely uses both CFD and DEM for mill and pulp lifter design.
Benefits of the Spiral Turbo Pulp Lifter
Reduced slurry pooling in the mill
Increased impact energy, particularly beneficial for hard ores
Increased mill throughput, by up to 15 %
Reduced grinding energy, by up to 15 %
Particularly suited to high throughputs:
Friable ores with low residence time in the mill
Mills with recycle
Low-aspect ratio mills with small diameter heads.
Retrofits to suit increased circuit throughput, or harder ores coming on‑line
Reduced wear in pulp lifter due to better scats evacuation and reduced internal recycle resulting in longer wear life
From the left: CFD image of slurry flow in the Spiral TPL chambers, DEM image of slurry flow in the mill (red) and Spiral TPL (blue), Reduced slurry pooling with Spiral TPL improves grinding efficiency