The precipitation of calcium hydroxoaluminate hydrate powders from sodium hydroxoaluminate solutions: Precipitate phases and precipitation mechanisms

✍ Scribed by Dr. A. Packter; A. Derry

• Publisher: John Wiley and Sons
• Year: 1983
• Tongue: English
• Weight: 430 KB
• Volume: 18
• Category: Article
• ISSN: 0232-1300
• DOI: 10.1002/crat.2170180912

✦ Synopsis

Calcium hydroxoaluminate hydrates were precipitated from different sodium hydroxoaluminate and hydroxoaluminate-excess hydroxide solutions at ambient temperature (at CAI = 0.1 t o 0.3 M and at XS OH/Al = 0 to above 8). The precipitations were monitored by potentiometric ( p H ) measurements. Precipitate morphologies were examined by optical microscopy and precipitate compositions were determine by chemical analysis, infra-red spectrophotometry and thermal analysis.

Generally at OH/Al ratios of 4 t o 4.5 (XS OH/Al = 1 t o 1.5), the compound 2 CaO . . A1,0,. 8 H,O (C,AH,) was precipitated with some aluminium hydroxide; then at OH/Al ratios of 5 to above 11 (XS OH/Al = 2 t o above S), the compound 2 CaO A1,0, . 8 H,O was precipitated with increasing amounts of the compound 4 CaO . A1,0, . 13 H,O (C,AH,,).