The choice of mineral to be used for grinding is restricted to minerals of highest hardness. The mineral corundum has a Mohs hardness of 9 while the Mohs hardness of quartz is 7; therefore, corundum would be a suitable media for grinding quartz. However, naturally occurring quartz in the form of sand is more readily available, as river sand, and therefore economically more viable and is extensively used.
Minerals Processing. A wide variety of minerals processing routes are used for REE deposits . For many REE ores, processing techniques for the minerals are unproven on a commercial scale and processing is a major challenge that needs to be considered early in exploration.
MINERAL HARDNESS a Relative Thing Mohs scale is a shortcut methodology for field testing minerals: if Specimen A scratches Specimen B, A is harder than B. Utilizing common minerals as a reference, Mohs Scale has been an invaluable field tool for identification of minerals and has enjoyed widespread acceptance in the mineral processing industry.
for grinding most types of minerals. Hardness of minerals is expressed on Mohs scale a numerical index ranging from 1 for talc to 10 for diamond . Table 2 below shows Mohs scale of hardness. Hardness No. Mineral Common practical test 1 Talc or graphite Marks paper like a pencil