Strength of Agglomerates

Theoretical Strength of Agglomerates. Based on statistical-geometrical considerations, Rumpf developed the following equation for the mean tensile strength of an agglomerate in which bonds ate localized at the points of particle contact (9) ... 

Fig. 2. Compression strength of agglomerates formed into spherical shape by tumbling where = mean disperse particle diameter (8). To convert kPa to...

FIG. 20-65 Theoretical tensile strength of agglomerates. [Adapted from Rumpf Strength of Granules and Agglomerates, in Knepper (ed.). Agglomeration, Wiley, New York, 1962.]... 

Although measurement of the compressive strength of agglomerates is certainly more convenient for routine checking and quality control, the tensile strength is a more fundamental property, since in theory it can be... 

Figure 5.2 Tensile strength of agglomerates. From Smith, P.G., Introduction to food process engineering, Kluwer, 2003, figure 13.22. With kind permission of Springer Science and Business Media.

Pietsch, W.B., The strength of agglomerates bound by salt bridges. Can.. Chem. Eng., 47 (1969b) 403-409. 

From approximate calculations, Rumpf concluded that electrostatic forces have negligible influence on the strength of agglomerates. Goldstick [7] estimated that the maximum interparticle force due to magnetic attraction may be many times larger than the maximum strength due to electrostatic forces but is nevertheless small, even in comparison with van der Waals forces. 

Fig. 2.8. Relationsip between tensile and compression strengths of agglomerates [1].

Fig. 2.10. Theoretical tensile strength of agglomerates with various bonding mechanisms [1].

Linder rotating furnace procedure, 36 research and control methods, 32 tablet disintegration test, 36 tensile testing, 32 see also Strength of agglomerates Suppliers of size enlargement equipment, 177... 

If the entire pore volume of the agglomerate is filled with a liquid such that concave menisci are formed at the agglomerate surface, a negative capillary pressure develops in the interior. Because the membrane forces at the surface are negligibly small in relation to the capillary pressure, the tensile strength of agglomerates filled with a liquid can be approximated by the capillary pressure ... 

Therefore, the maximum tensile strength of agglomerates filled with a liquid is proportional to a porosity function (1 -e)/e and the surface tension of the liquid a it is inversely proportional to the grain size x of the particles forming the agglomerate. The factor a has a value between 6 and 8. 

By inserting equation (17) into the basic formula, equation (6), and assuming that A e 7T, the maximal tensile strength of agglomerates bound by van der Waals forces becomes... 

For these reasons, Rumpf proposed the determination of tensile strength of agglomerates for scientific investigations. Data from such tests can be compared with each other, approximated by physical models, and described by theories. Because, with a high degree of probability, failure occurs always due to the highest tensile strain, Rumpf s proposal is justified. 

Figure 45. Methods for scientific determination of the strength of agglomerates and particle collectives, (a) Crushing strength (b) shear strength (c) and (d) tensile strength of strongly bonded agglomerates (e) and (f) tensile strength of loosely bonded particle collectives...

Figure 48. Determination of the tensile strength of agglomerates in a tensile tester...

For the experimental determination of these agglomerate characteristics specific tests must be used. One will be described in the following because in some way it also measures the strength of agglomerates and demonstrates the many possible variations of carrying out the task. 

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