Ultrafine dry grinding of talc by planetary mill: effects of operating conditions

Abstract

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.

Aspects of Talc Grinding in the Presence of Sodium Dodecyl Sulfonate

“…This behavior is referred to the coating of the talc particles with SDS molecules that resulted in their electrostatic dispersion and consequently to a higher probability of the particles to be hit by balls. However, the effect of SDS diminishes by increasing the grinding time due to the production of very fine particles, change in the particle surface roughness, and even the structure alteration of talc particles with long grinding, which affects the talc‐SDS interaction (El‐Mofty et al, 2020; Yekeler et al, 2004). In addition, the higher surface area of the product at longer grinding time needs a higher SDS dosage to maintain the same dispersibility of the particles, therefore, SDS is not effective enough (see Fig.…”

Foam in grinding and role of ground mineral in its stability

“…Grinding is one of the primary steps in the preparation and processing of minerals. The operating conditions are crucial in achieving the required size and maintaining the surface and structural properties of the ground materials (El‐Midany & Ibrahim, 2010; El‐Mofty et al, 2020; Ibrahim et al, 2010; Khairy et al, 2022). However, it consumes most of the mineral processing plant power (Stehr et al, 1987).…”