Effects of moisture on grinding of natural calcite by a tumbling ball mill

The effects of moisture on grinding of natural calcite using a tumbling ball mill were investigated by X-ray diffraction (XRD), chemical analysis, scanning electron microscopy (SEM) observation and by measuring the specific surface area. The specific surface areas of calcite ground in dry conditions appear significantly smaller than those of calcite ground with water addition. The XRD analysis also implies that the calcite powder ground with the addition of water transformed partially into aragonite, whereas such a phase transformation does not seem to take place in the calcite powder ground in dry conditions. Additionally, the content of alumina in the ground material due to wear of the mill set is appreciably lowered by the effect of water as a grinding aid. The calcite powder ground with adding 1 and 10 mass% of water was found to be easy to grind to submicron size particles and relatively low levels of contamination were obtained when compared with calcite ground in dry conditions. The moisture control has been confirmed to be a very important factor in the grinding of calcite.