Filter-pressing of alumina dispersions

Conference · Sat Jun 01 04:00:00 EDT 1996

OSTI ID:229995

Fries, R; Rand, B ^[1]

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1. Univ. of Leeds (United Kingdom)

The filter-pressing characteristics of aqueous alumina dispersions containing either submicron or nano-sized particles have been compared with respect to ionic strength. The highest green densities for both systems were achieved at electrolyte concentrations < 0.01 mol dm{sup -3} where long-range repulsive interparticle forces stabilize the slips. A slight increase in density with ionic strength in this range was attributed to an increase in the ratio of particle radius-to-double layer thickness, Ka. At higher electrolyte concentrations, above the critical coagulation concentration, the green densities dropped to significantly lower values due to the onset of flocculation and the formation of open particle networks characterized by strong attraction which resisted rearrangement into a dense green microstructure. The green densities of the compacts consolidated from the submicron dispersions at ionic strength > 1 mol dm{sup -3} were significantly higher than those prepared close to the critical coagulation concentration although the slips exhibited properties typical for a flocculated structure. The results may indicate the presence of short-range repulsive forces at high salt concentration for the submicron slips not accounted for by the classical DLVO-theory. In order to characterize the early stages of filter-cake consolidation the initial cake permeability was determined from the compaction curves.

• OSTI ID: 229995
• Report Number(s): CONF-9505249--
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM OXIDES
COMPACTS
FLOCCULATION
GRAIN DENSITY
MICROSTRUCTURE
PERMEABILITY
PH VALUE
PRESSING
SLIP