Bisha University, Bisha, Kingdom of Saudi Arabia:

El-Mofty S. E., Vice Dean, PhD in Mining Engineering, Professor, mpm_cu@yahoo.com

Abuhasel K. A., Associate Professor, PhD in Industrial Engineering

Central Metallurgical Research & Development Institute, Cairo, Arab Republic of Egypt:

Elbendari A. M., PhD Candidate

Cairo University, Giza, Arab Republic of Egypt:

El-Midany A. A., Professor, PhD in Mining Engineering, Professor, aelmidany@gmail.com

The team of authors includes Professor, PhD in Inorganic Chemistry M. K. Abdel-Rahman

Ultrafine grinding is required in most industrial applications of talc. In this work, a planetary mill was used to produce a d50 product of less than 5 μm. The effects of grinding time, media size, mill filling, rotational speed, and media-to-powder ratio, as the main grinding parameters, were initially investigated by the one-variable-at-a-time strategy. In addition, the statistical design method was applied to optimize and correlate the d90 and d50 of the ground product to the media-to-talc percentage and grinding time, being the most significant variables for talc grinding in a planetary mill. The results indicate that the ball size significantly affects the product fineness up to a certain ball size (i. e., 4 mm), after which the product becomes coarser. At the same time, lower mill filling and higher mill rpm yield finer products. The agglomeration of particles under dry conditions is the main constraint to size reduction below certain limits. The maximum size reduction obtained in grinding with the 85 % media-to-powder ratio, 30 % mill filling, and higher rotational speed (300 rpm) during 30 min grinding cycles was 14.6 μm and 4.5 μm for d90 and d50 of the ground product, respectively.

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