Recovery of alumina from fly ash by high-temperature chlorination

Conference · Sat Jan 01 04:00:00 EST 1977

OSTI ID:6944060

Burnet, G; Murtha, M J; Wijatno, H

The large volume of fly ash being produced, largely in centralized locations, and the composition of the ash present unique opportunities for the recovery of minerals. A typical United States fly ash will contain about 21% alumina and 17% iron oxide, the balance being primarily silica. Up to 85% of the iron oxide can be removed from the ash by magnetic separation. Since 1972, three different processes for recovering alumina from the non-magnetic fraction of fly ash have been under investigation at the Ames Laboratory. The processes are lime-sinter, hydrochemical and high-temperature chlorination. Significant progress has been made with the latter and it will be discussed in detail. In the chlorination process, the non-magnetic fraction of the fly ash is mixed with carbon and chlorinated in a fixed bed. Because the iron has a high chlorine affinity, the iron remaining in the ash can be removed as volatile iron chloride at 400/sup 0/C to 600/sup 0/C; very little aluminum and silicon react. The temperature is then raised to 850/sup 0/C to 950/sup 0/C where a mixture consisting mostly of volatile aluminum and silicon chlorides forms. When the vapors are cooled, solid aluminum chloride condenses at 120/sup 0/C to 150/sup 0/C while the silicon tetrachloride remains in a vapor state because of its low condensation temperature. The silicon tetrachloride can be easily decomposed to form silica and HCl thus recycling the chlorine.

• Research Organization: Ames Lab., IA (USA)
• DOE Contract Number: W-7405-ENG-82
• OSTI ID: 6944060
• Report Number(s): IS-M-142; CONF-7705131-1
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
010800* -- Coal
Lignite
& Peat-- Waste Management
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION
320305 -- Energy Conservation
Consumption
& Utilization-- Industrial & Agricultural Processes-- Industrial Waste Management
AEROSOL WASTES
ALUMINIUM CHLORIDES
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CARBONACEOUS MATERIALS
CHALCOGENIDES
CHEMICAL COMPOSITION
CHEMICAL REACTIONS
CHLORIDES
CHLORINATION
CHLORINE
CHLORINE COMPOUNDS
COAL
CONCENTRATORS
CONSUMPTION RATES
ELEMENTS
ENERGY SOURCES
FEASIBILITY STUDIES
FLY ASH
FOSSIL FUELS
FOSSIL-FUEL POWER PLANTS
FUELS
HALIDES
HALOGEN COMPOUNDS
HALOGENATION
HALOGENS
IRON CHLORIDES
IRON COMPOUNDS
IRON OXIDES
MAGNETIC SEPARATORS
MINERALS
NONMETALS
NORTH AMERICA
OXIDES
OXYGEN COMPOUNDS
POWER PLANTS
PRODUCTION
RECOVERY
RECYCLING
SEPARATION PROCESSES
SILICA
SILICON CHLORIDES
SILICON COMPOUNDS
SILICON OXIDES
THERMAL POWER PLANTS
TRANSITION ELEMENT COMPOUNDS
USA
WASTE PRODUCT UTILIZATION
WASTES