Optimization of Granules and Slurries for Press Forming.

Abstract

The present paper deals with the determination of optimal conditions for preparing spray-dried granules and slurries, based on the characteristics of granules and supplied slurries. These characteristics were evaluated by the compression and stress-relaxation method, and by the centrifugal consolidation method, respectively. Spray drying of the flocculated slurry resulted in low-density granules with a spherical and solid morpholo gy, which ensures a high compressibility. Another important factor governing the press forming is to adjust the amount of binder so as to improve the visco-elastic deformation of granules; this leads to a better homogeneity of the resulting compacts.

Simulation of the Spray Drying of Single Granules: The Correlation Between Microscopic Forces and Granule Morphology

“…Under this premise, the simulation results of Section III (1) agree well with the qualitative finding that agglomerated suspensions form dense granules, whereas dispersed suspensions lead to hollow granules. [4][5][6][7][8][9] Figure 9 demonstrates this correlation by using experimental results of Ref. [6] and [7].…”

“…(2) Mechanisms of Granule Formation-A Balance of Forces In the majority of the reports about investigations of the influence of suspension parameters on the granule morphology at spray drying, the influence of surface tension has not been studied in any detail-neither experimentally 2,4,5,8,9,39 nor by means of numerical simulations. [10][11][12][13][14][15]17,18 This lack of information makes it hard to carry out immediate validation of the results by independent reference data.…”

“…3 Numerous experimental investigations showed that the stability of the suspension has a major influence on the final granule morphology, that is, well-dispersed suspensions often lead to hollow granules. [4][5][6][7][8][9] Hence, the interparticle forces, which are responsible for the state of the suspension (e.g., dispersed versus agglomerated), play an important role in the evolution of the granule morphology. On the other hand, there is also the capillary force exerted on the primary particles by the receding liquid surface that creates a compressive drying stress inside the particle network during drying.…”

Effects of sintering additives on dispersion properties of Al2O3 slurry containing polyacrylic acid dispersant

“…It is known that the characteristics of the resulting granules are strongly affected by the dispersion of the slurry. 13,14 Evaluating the change in dispersibility with the change in distance between particles from not only the viscosity of the slurry but also the gravity sedimentation test is extremely important for ensuring that the distance between particles decreases with drying. 15 In the AES12 slurry, dispersibility correlated with apparent viscosity.…”

Simulation of the influence of surface tension on granule morphology during spray drying using a simple capillary force model

“…well dispersed suspensions often lead to hollow granules [4][5][6][7]. Hence, the interparticle forces and the solvent-particle interaction play an important role in the evolution of the granule morphology.…”