Particle size reduction ball-mill

After the molten glass has become a homogeneous Hquid, it is poured in a thin stream into water or between closely spaced, water-cooled rotating metal rollers. This quenched glass, termed frit, is a friable material easily reduced to small-sized particles by a ball-milling operation. Ball-milling the glass frit into small-sized particles can be carried out whether the frit is to be used wet or dry (see Size reduction). 

Nc PARTICLE SIZE REDUCTION AND ENLARGEMENT Critical speed of rotation of ball mill (rev/time) Units in SI System s-1 145 Dimensions in M, L, T T-l... 

Fig. 3.6b). It must be mentioned that both alanates NaAlH and LiAlH are extremely difficnlt to be effectively refined during ball milling. As can be seen the particle size redaction of LiAlH is only twofold after 20 h of milling. This can be compared with almost 40-fold particle size reduction of MgH milled for a mnch shorter time (Fig. 2.15 in Sect. 2.1.3). 

DSC experiments were conducted up to 500 and 600°C for the ball-milled mixtures of NaBH with 12, 55, 73 and 92 wt%Mg (DSC traces not shown here). The temperatures of melting and decomposition peaks of NaBH are plotted in Fig. 3.46a. It is seen that the data points for the equivalent content of 12, 55 and 73 wt%Mg follow quite closely the data points for MgH. Only data points for the equivalent content of 92 wt%Mg show slightly higher decomposition temperature than their MgH counterpart and lie slightly above the ROM line for MgH. This behavior is probably related to different mechanical properties of Mg and MgH which results in different abilities to particle and grain size reduction during the milling process as can be seen in Fig. 3.47. The particle size reduction of ductile... 

It is not clear, however, whether electron radiation would have beneficial effects upon the enzymatic hydrolysis of cellulose. It has been shown that the particle size reduction and surface area increase upon ball milling are probably more important than the reduction of crystallinity (19). Electron irradiation may not disrupt the shielding layer provided by the lignin to expose fresh cellulose to the action of large enzyme molecules. 

The magnitude of the above-mentioned increase in viscosity depends on the hydrolysis conditions as well as on the particular corn gluten chosen for the experiments the latter is illustrated by the fact that after a reduction in size (by ball milling) of the corn gluten particles, the viscosities obtained were considerably lower (28). It is therefore to be expected that corn gluten from different sources would yield rather different results. Conclucion... 

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