Planetary Ball Mills

Tumbler, jar, drum, or cannon ball mills Szegvari attritor vertical mills and other vertical stirred ball mills Planetary Fritsch and Retsch model mills Shaker (vibratory) SPEX model mills... 

Planetary Ball Milling This is a method of increasing the gravitational force acting on balls in a ball mill. For example, refractoiy metals and carbides can be ground to 1 to 2.6 [Lm in 5 to 20 min in an apparatus capable of applying a centrifugal force of 10 to 50 G. [Dobrovol sldi, Poroshk. MetalL, 7(6), 1-7 (1967)]. 

Pulverit planetaiy mills are available from Geoscience Inc. Highspeed planetary-baU mills can be used to perform rapid tests to sinmlate ball milhng of materials [Vock, DECHEMA-Monogr, 69, HI-8 (1972)]. The size of high-speed mills will be much smaller than the size of same-capacity ball mills [Bradley, S. Afr Mech. Eng., 22, 129 (1972)]. 

The S-form can be obtained by treating Copper Phthalocyanine Blue in benzene or toluene with aqueous sulfuric acid in the presence of a surfactant [21], The e-phase is produced by comminution of the a-, 7-, or 8-modification, for instance in a planetary ball mill. The mill base is then aftertreated in an organic solvent at elevated temperature. It is important to realize that the temperature, depending on the solvent, must be kept below the transition temperature at which the e-phase converts to the (3-modification (30 to 160°C). The e-modification is made best from the 7-phase, and the most preferred solvents are alcohols [22], For the industrially hitherto insignificant tt, X, and R-forms of Copper Phthalocyanine Blue (see [1], Vol. II, 34-35). 

At this frequency of impacts the energy transferred to the powder would be comparable with that achieved in a planetary ball mill. The milling cylinder suitable for reactive milling is shown in Fig. 1.8. 

There are other advantages of employing magnetic ball mills besides the control of mechanical milling modes. Since the centrifugal force becomes a secondary factor in milling, and the reactor shell rotates at low RPM, contamination from balls and shell wear is lower than in a vibrational or a planetary mill there is less ball wear involved and contaminations with Fe from steel become less of the problem. Also lower rotations and uniaxial movement of reactors paced on horizontal axle allow... 

A typical task is the milling of minerals in the pm-range with power consumption of approximately 50 Wh kg-1. A tumbling ball mill would need 1 hour of milling time at a specific power input of 50 W kg-1 for the comminution, a stirred media mill would need 2 min at 1400 W kg-1, a vibration mill 40 s at 4500 W kg-1, and a planetary mill 5 s at 36,000 W kg-1 (Fig. 14.4). 

Mechanical activation was performed in a high energy (acceleration up to 70 g) planetary ball mill with stainless steel reactor and balls under an argon atmosphere during 1 h. All the sample handling has been operated in Ar-filled glow box (MBraun), in which the water/oxygen levels were below 1 ppm. 

Note 1. In contrast to the procedure used by Matsumoto et al. (1986), reduction with sodium borohydride prior to ozonation was not performed. Before ozonation, extracted wood meal was milled in a planetary ball mill in the dry state for a total of 36 h (9-12 h/day over 3 or 4 successive days to prevent excessive heat build-up). 

There are many types of mechanical grinding equipment available ball mills, ball and mortar sets, planetary mortars, impact mills, etc. These are available in a variety of materials steels, porcelain, agate, mullite, silicon carbide, tungsten carbide and others. Prices range from 200 to about 2,000. Unfortunately, the cost increases rather markedly as one goes to the harder materials, especially the carbides. 

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