An experimental study on the ultra-fine grinding of gypsum ore in a dry ball mill

• Batch grinding tests of gypsum ore were performed using a ball mill.
• We have systematically investigated some important grinding parameters.
• The grinding operation was sensitive to the grinding parameters except for one.
• The final product had a particle size of d50 = 4.25 μm.
• PSD width calculations showed that their values increased with grinding time.

Gypsum is a crystalline form of hydrated calcium sulfate (CaSO4·2H20) generally used in cements and plasters in the construction industry, though also in paints, fertilizers, medicines, papers, and textiles. For use in these materials, gypsum must be ground finely (< 100 μm), if not ultra-finely (< 10 μm), for which ball mills are most effective. Despite gypsum's widespread use and the regular need to grind it, studies concerning the grinding of gypsum ore remain scarce. In response, in this study, we have systematically investigated how certain grinding parameters (i.e., mill speed, ball filling ratio, ball size distribution, powder filling ratio, grinding aid ratio, and grinding time) of conventional dry ball mills affect the grindability of gypsum ore. We determined the properties of the micronized gypsum products obtained in optimal grinding conditions, and the results showed that the dry ball mill grinding process can effectively produce ultra-fine gypsum products.

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