Dry Fine Grinding of Calcite Powder by Stirred Mill

Abstract

The demand for fine powder is increasing in many fields such as chemical, pharmaceutical, and material industries. Therefore, research in fine grinding has gained in importance. In this study, the effects of various operating parameters, such as grinding time (min), stirrer speed (rpm), feed quantity (% of ball weight), and ball filling ratio (%) on fine grinding of calcite powder (CaCO₃) (d ₅₀ = 34.04 µm) were studied using a laboratory vertical stirred mill under dry conditions. A series of laboratory experiments using 2⁴ full factorial designs was conducted to determine the optimum grinding parameters. The main and interaction effects on the volumetric surface area (S_v) (m²/cm³) of the ground product were evaluated using Yates’ analysis. The grinding time, media filling ratio, and stirrer speed play distinct roles (positive) in product surface area and fineness.

Keywords:

• Dry fine grinding
• operating parameters
• statistical design
• stirred mill
• volumetric surface area

Acknowledgments

The author would like to thank the Nigde University Scientific Research Projects Directorate (project no. FEB2010/01) for funding of this research work. And the author acknowledges Nidas Company (Nigde, Turkey) for providing of sample.

Notes

S_v: Volumetric surface area (m²/cm³); DF: degree of freedom; (a) grinding time (min); (b) stirrer speed (rpm); (c); feed quantity; (d) ball load. Center Point Responses (CPR); (1) 2.87 m²/cm³, (2) 2.92 m²/cm³, (3) 3.02 m²/cm³