Re-generation of hydrofluoric acid and selective separation of Si(IV) in a process for producing ultra-clean coal

Steel, KM and Patrick, JW (2004) Re-generation of hydrofluoric acid and selective separation of Si(IV) in a process for producing ultra-clean coal. Fuel Processing Technology, 86 2: 179-190. doi:10.1016/j.fuproc.2004.02.003


Author Steel, KM
Patrick, JW
Title Re-generation of hydrofluoric acid and selective separation of Si(IV) in a process for producing ultra-clean coal
Journal name Fuel Processing Technology   Check publisher's open access policy
ISSN 0378-3820
Publication date 2004-11-01
Year available 2004
Sub-type Article (original research)
DOI 10.1016/j.fuproc.2004.02.003
Open Access Status
Volume 86
Issue 2
Start page 179
End page 190
Total pages 12
Place of publication Amsterdam, Netherlands
Publisher Elsevier
Language eng
Abstract A technique for selectively separating approximately 65 wt.% of the Si(IV) in coal has been developed. The technique first uses aqueous hydrofluoric acid (HF) to react with aluminosilicates and quartz to form fluoride complexed Al and Si species in solution. Aluminium cations, in the form of Al(NO3)(3), are then added to the solution to complex fluoride as AlF2+ and hydrolyse the silicon fluoride species to silicon hydroxide, which precipitates as a gel and is removed by filtration. The solution is then distilled to recover a water stream, a nitric acid stream and a solid residue. The water stream is used to pyrohydrolyse the solid residue at temperatures in excess of 500 degreesC to liberate HF for recycling. To complete the circuit, the solid remaining after pyrohydrolysis is treated with the nitric acid stream to produce Al(NO3)(3) for recycling. The technique satisfies the objective of not requiring on-going purchase of chemicals. The application of this work is primarily as part of a process for producing ultra-clean coal. As it is a technique for the selective separation of Al and Si from aluminosilicates, it may have application in other areas of mineral processing.
Keyword silica
Selective Separation
Aluminosilicates
Ultra-clean coal
Hydrofluoric acid
Re-generation
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Unknown

Document type: Journal Article
Sub-type: Article (original research)
Collection: Faculty of Engineering, Architecture and Information Technology Publications
 
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Created: Sat, 11 Jul 2009, 01:45:47 EST by Dr Karen Steel on behalf of School of Chemical Engineering