Effect of solids formulation on the manufacture of high shear mixer agglomerates

The strength and morphology of granules generated by high shear agglomeration of powder with a highly viscous surfactant paste were investigated as a function of mixing time and powder particle size. The formulations featured a fine powder (zeolite or calcium carbonate) and linear alkylbenzene sulfonate (LAS) in a ratio of 1.7 : 1 by volume. During agglomeration, the solid material progressed through a number of consistency regimes up to the formation of a smooth dough. Differences in calcium carbonate (calcite) particle size had a significant effect on the agglomeration behavior, in that an increase in the mean diameter reduced the time required to form the dough state. Micrographic visualization, coupled with bulk density and Hausner ratio measurements, suggested that all the systems studied followed the same agglomeration mechanisms up to a certain point, albeit at different rates. The LAS-calcite mixtures appeared to be more compressible than zeolite mixes with similar particle size, although the overall trends in the compaction parameters were similar. None of the LAS-calcite mixtures attained an intermediate 'crumble-agglomerate' regime observed with the zeolite, which is attributed to the extensive hydrate-forming properties of the latter.