Grinding equipment selection

Bond, F. C. Chem. Eng., Albany 59 (October 1952) 169. New grinding theory aids equipment selection. 

Grinding is the first step following selection and requires attention and accuracy in design to ensure optimum homogeneity of the ground product. Several types of grinding equipment in common use have been described earlier. 

Grinding equipment used for comminution operations in chemical analysis varies in design and layout with application requirements, i.e., sample make-up, desired degree of particle size decrease, etc. The selection of the grinding kit to be used depends on... 

Filtration may also serve as the preparatory step for the operation following it. The latter stages may be drying or incineration of solids, concentration or direct use of the filtrate. Filtration equipment must be selected on the basis of their ability to deliver the best feed material to the next step. Dry, thin, porous, flaky cakes are best suited for drying where grinding operations are not employed. In such cases, the cake will not ball up, and quick drying can be achieved. A clear, concentrated filtrate often aids downstream treatment, whereby the filter can be operated to increase the efficiency of the downstream equipment without affecting its own efficiency. 

Hewlett-Packard 5890A gas chromatograph with capillary split/splitless inlet with HP5970B mass-selective detector equipped with a Model 7673A autosampler Hobart VCM-40 or other apparatus suitable for grinding frozen plant tissue... 

The main factors to be considered when selecting equipment for crushing and grinding are ... 

The selection guides given by Lowrison (1974) and Marshall (1974), which are reproduced in Tables 10.12 (see p. 465) and 10.13, can be used to make a preliminary selection based on particle size and material hardness. Descriptions of most of the equipment listed in these tables are given in Volume 2, Chapter 2 or can be found in the literature Perry et al. (1997), Hioms (1970), Lowrison (1974). The most commonly used equipment for coarse size reduction are jaw crushers and rotary crushers and for grinding, ball mills or their variants pebble, roll and tube mills. 

Studies on the application of the theory of statistical moments in the description of grinding in ball mills have been carried out in the Department of Process Equipment, Lodz Technical University [1-3]. The research was carried out in a laboratory scale for selected mineral materials. Results obtained confirmed applicability of the theory of statistical moments in the description of particle size distribution during grinding. 

These pilot units along with the associated coal grinding and slurry preparation equipment form the basis for evaluating selected coals and provide design information for a number of commercial projects that are under way. 

The particle size reduction tests for various selected biomass types have been executed in the pilot installation of CIEMAT. A flow diagram of the installation is shown in Figure 1. Basically, the equipment consists of two hammer mills connected in series, the first one has a nominal power of 11 kW and is used for pre-grinding (emshing). The second hammer mill has a nominal power of 15 kW and is used for refining the pre-ground biomass. 

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