Analytical chemistry of aluminum salt cake
Component phases of Al salt cake or products from processing salt cake, resist dissolution, a key first step in most analysis procedures. In this work (analysis support to a study of conversion of salt cake fines to value-added oxide products), analysis methods were adapted or devised for determining leachable salt, total halides (Cl and F), Al metal, and elemental composition. Leaching of salt cake fines was by ultrasonic agitation with deionized water. The leachate was analyzed for anions by ion chromatography and for cations by ICP-atomic emission spectroscopy. Only chloride could be measured in the anions, and charge balances between cations and chloride were near unity, indicating that all major dissolved species were chloride salts. For total halides, the chloride and fluorides components were first decomposed by KOH fusion, and the dissolved chloride and fluoride were measured by ion chromatography. Al metal in the fines was determined by a hydrogen evolution procedure adapted for submilligram quantities of metallic Al: the Al was reacted with HCl in a closed system containing a measured amount of high-purity He. After reaction, the H/He ratio was measured by mass spectroscopy. Recoveries of Al metal standards (about 30mg) averaged 93%. Comparison of the acid evolution with caustic reaction of the Al metal showed virtually identical results, but reaction was faster in the acid medium. Decomposition of the salt cake with mineral acids left residues that had to be dissolved by fusion with Na carbonate. Better dissolution was obtained by fusing the salt cake with Li tetraborate; the resulting solution could be used for accurate Al assay of salt cake materials by classical 8-hydroxyquinolate gravimetry.
- Research Organization:
- Argonne National Lab., IL (United States)
- Sponsoring Organization:
- USDOE Assistant Secretary for Energy Efficiency and Renewable Energy, Washington, DC (United States)
- DOE Contract Number:
- W-31109-ENG-38
- OSTI ID:
- 448025
- Report Number(s):
- ANL/CMT-ACL/CP--91517; CONF-970201--13; ON: DE97003227
- Country of Publication:
- United States
- Language:
- English
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