Ball-mill developments

The dependence of the phase transformation temperature and sequence on the mill type, milling media, time, acceleration is analyzed in this chapter for a few samples of transition aluminas and their mixtures. Mechanical treatment carried out in the high-powerful planetary ball mills developed at the Institute of Solid State Chemistry SB RAS. Since it is known [10] that mechanical activation with and without elimination of heat leads to essentially different processes in the powder under activation, experiments were carried out with the oxides under investigation using mills both with and without aquatic cooling. 

A more practically useful work index based on empirical results from ball milling trials has been developed (7—9) and is expressed by equation 1 ... 

Richard Arkwright invents his spinning water frame to spin yarn and silk later to be used in North America as an industrial mill. Ball-bearings developed. 

Deters (14) vibromilled a blend of cellulose and cellulose triacetate. The acetic acid content of cellulose acetate decreased with grinding time (40 h) while that of the cellulose increased, suggesting the formation of a block or graft copolymer or of an esterification reaction by acetic acid developed by mechanical reaction. Baramboim (/5) dissolved separately in CO polystyrene, poly(methyl methacrylate), and poly(vinyl acetate). After mixing equal volumes of solutions of equivalent polymer concentration, the solvent was evaporated at 50° C under vacuum and the resultant product ball-milled. The examination of the ball-milled products showed the formation of free radicals which copolymerized. 

The most productive two-phase (H-V or H-Lhc) equilibrium apparatus was developed by Kobayashi and coworkers. The same apparatus has been used for two-phase systems such as methane + water (Sloan et al., 1976 Aoyagi and Kobayashi, 1978), methane + propane + water (Song and Kobayashi, 1982), and carbon dioxide + water (Song and Kobayashi, 1987). The basic apparatus described in Section 6.1.1.2 was used in a unique way for two-phase studies. With two-phase measurements, excess gas was used to convert all of the water to hydrate at a three-phase (Lw-H-V) line before the conditions were changed to temperature and pressures in the two-phase region. This requires very careful conditioning of the hydrate phase to prevent metastability and occlusion. Kobayashi and coworkers equilibrated the hydrate phase by using the ball-mill apparatus to convert any excess water to hydrate. 

Stehr, N. (1988) Recent developments in stirred ball milling, J. Mineral Process., 22 431-444. 

The first procedure, developed in England by Stopes and Wheeler (1923), consists in grinding a certain weight of coal in a ball mill, run under fixed conditions and for a stated length of time. The coal is then removed from the mill and the weight of the coal passing a 200-mesh used as a measure of friability. In this country the second procedure has been more widely used, resulting in two more or less widely accepted tests. 

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