Theoretical tensile strength of agglomerates

Distinction must be made between systems in which bonds are localized at the points of particle contact and those in which the void space between particles is partially or completely filled with strength-transferring substance. Localized bonding is considered first, while some binder-filled systems are treated in Section 2.4. 

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

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

Figure 57. Approximation of the theoretical tensile strength of agglomerates as a function of size of the particles forming the agglomerate. Porosity e = 0.35...

The theoretical tensile strength of agglomerates in the funicular and capillary states has been derived by Rumpf et al. (1974) ... 

Figure 5.6 Theoretical tensile strength of agglomerates (Rumpf ...

Therefore, Rumpf (see Chapter 1) proposed to determine the tensile strength of agglomerates. It is defined by the tensile force at failure divided by the cross section or, if the test body has no uniform shape, the area of the failure plane(s) of the ag-glomerate(s) (see Section 5.2.2). Because failure occurs in aU stressing situations with great probabiHty under the influence of the highest tensile force, this proposal is justified. Moreover, tensile force and strength can be approximated by models and theoretical calculations. 

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) ... 

It can be assumed that, depending on porosity, up to saturations of = 20-40970 the liquid in moist agglomerates is present in the form of discrete liquid bridges at the coordination points between the particles forming an agglomerate. The tensile strength of such agglomerates is predicted theoretically by equations (13) and (45), respectively. 

All methods for the determination of tensile strength described above are too complicated and time consuming to be suitable for routine industrial quality control applications. In those cases it is the task of the test procedure to determine a specific characteristic of the agglomerate easily, quickly, and reliably. The results must only be reproducible and comparable within the own organization and a relation to theoretical predictions is normally not required comparisons with results from other plants are often not necessary or, in case of competing products, not desired. 

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