As IM’s October issue begins mailing to readers with the annual commi9nution review, we examine a mill that space prevented us from including in that review. The advantages of MBE Coal & Minerals Technology’s Palla mill® include cost benefits, which always remain a major factor in crushing and grinding applications, irrespective of the material being processed. The Palla mill offers flexibility as this vibrating mill is suitable for wet and dry applications in primary and secondary grinding and for pulverising materials of any hardness.
“The Palla mill has a major advantage over other such machines as it is capable of grinding more than 100 different materials, including a range of minerals and commodities previously considered unviable due to the costs involved,” Johannes Kottmann, managing director of MBE Minerals, MBE’s South African operation, says. “Add to this that ultra fine grinding can be done at maximum production with the lowest expenditure on installation, grinding media and maintenance, and it becomes obvious why this vibrating mill has become the standard internationally,” he says.
Designed as a single-mass vibrator operating in the supercritical zone of materials fracture, the vibrating structure is excited by unbalanced weights comprising two parallel grinding cylinders joined by webs. These two parallel tubes are rigidly mounted in a frame and elastically separated from a base frame by rubber springs. The tubes can be lined with steel or ceramic depending on the application requirements and may be charged with rods, balls or cylpebs. The tubes are excited by eccentric drives mounted in the frame, creating a circular action of the tubes. Material passed into the tubes is comminuted between the oscillating grinding elements.
Another advantage is that operation of the vibrating mill can be either continuous or intermittent. Grinding can be carried out in an atmosphere of inert, protective or reactive gas and at temperatures well below zero if necessary.
Depending on the feed characteristics, product sizes of as low as 10 micron can be obtained, particularly when grinding in closed circuit with the MBE Minerals range of dry classifiers. Subject to specific duty throughputs from 20 kg/h to 20 t/h can be realised with the different sizes available.
Applications include non-metallic minerals, cement, ceramics, refractories, glass, abrasives, chemicals, coal and other fossil fuels and more. Burnt lime, zirconium sand, barium ferrite, slags, zinc oxide and corundum are some other materials which can be treated in a Palla mill.
