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Wet spherical agglomeration of binary mixtures. II. Mechanism and kinetics of agglomeration and the crushing strength of agglomerates.

1981; Pharmaceutical Society of Japan; Volume: 29; Issue: 5 Linguagem: Inglês

10.1248/cpb.29.1403

1347-5223

Yoshiaki Kawashimà, Hiroaki Takagi, H. Takenaka,

Coagulation and Flocculation Studies

A binary mixture of lactose (47 μm) and sulfisomidine (73 μm) dispersed in chloroform was agglomerated with a small amount of buffered sodium phosphate solution. A number of large agglomerates were produced at the initial stage of agglomeration. Thereafter, fine particles preferentially adhered to the large ones and finally all the particles were converted to agglomerates. This process could be followed in terms of the changes in the profile of the size distribution curve of agglomerates with residence time. The median diameter of agglomerates was related linearly with the residence time on a log-log plot except at the later stages of agglomeration. These findings indicated that the agglomeration can be described by a "non-random coalescence"model. The population balance for this agglomeration process is given by equation (4) in the text. The agglomeration rate constant increased with increasing amount of bridging liquid used and depended on the mixing ratio of the raw materials. The crushing strength of the agglomerate obtained at the equilibrium state was a function of agglomerate size, as expressed by equation (9). The parameters k and n in equation (9) depended on the mixing ratio of the raw materials and are related to the packing properties of the mixture.