Pebble Mill Application and Design
Pebble mills also known now as ceramic lined mills are a type of ball mill and are used in the size reducing or milling of hard materials such as minerals, glass, advanced ceramics, minerals for ceramics and semiconductor materials down to 1 micron or less. The residence time in pebble mills is assures that all particles are given consistent treatment with a resultant narrow distribution of particle size.
Many years ago pebble mills were actually used flint rocks as the grinding media. Now we use high-alumina brick and grinding media with 90%-96% aluminum oxide content. The new pebble mills are lined with aluminum oxide (alumina) brick, which is very hard (9 on the Mohs hardness scale) and will not contaminate most products. Ceramic lined mills are simple in design and consist of horizontal cylinder lined with 1.5” to 2” thick alumina brick.
The slow rotating vessels is half filled alumina grinding media between ¼” and 1.” In diameter and as the vessel rotates and the media is lifted and cascades down, the particles are milled between the grinding media by continuous impacts. Pebble mills have the advantage of being self-contained, which helps keep operators from being exposed to the milled product. Pebble mills can be used equally well for either wet or dry grinding. In the case of wet grinding the particles are also being dispersed in the liquid medium.
Ceramic lined mills can be jacketed to maintain temperatures for heat sensitive products – the alumina brick has a high heat transfer coefficient, which makes cooling effective. Pebble mills also scale up well and will actually improve in performance the large the diameter. Pebble mills are available in sizes from laboratory scale (also called milling jars) as small as ¼” usg to 5,000 usg mills. Mills are also available with liners made from made polyurethane or natural rubber.
Click to request a pebble mill quote online or call 630-350-3012 to speak with an expert at Paul O. Abbe® to help you determine which design and size ball mill would be best for your process.
See our Size Reduction Options