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Title: Direct utilization - recovery of minerals from coal fly ash. Fossil Energy Program. Technical progress report, 1 July 1984-30 September 1984 including summary of work for FY84

Abstract

The research discussed in this report deals with resource recovery from coal conversion solid wastes. Progress is reported on two methods (the HiChlor and Lime-Sinter processes) for extracting metal values from power plant fly ash. Preliminary work is also reported on a method of making cement from the residue of the lime-sinter process. In the HiChlor Process, metal oxides in the fly ash are converted to volatile chlorides by reaction with chlorine in the presence of a reductant. Several versions of this approach are being investigated. The Lime-Sinter Process utilizes a solid state reaction to selectively convert the alumina in fly ash to a soluble form. Fly ash is mixed with limestone and a suitable mineralizer (to reduce the temperature required for sintering and to enhance alumina recovery) and then sintered in a high temperature kiln. Alumina is recovered by leaching the resulting clinker. A complex relationship between the calcium, alumina, silica, and sulfur constituents in the feed mixture controls the formation and extraction of aluminate compounds. Alumina recovery levels are enhanced by promoting the formation of less-soluble calcium compounds and/or more-soluble aluminum compounds. A study is underway to determine the degree to which flue gas scrubber sludge can bemore » used both as a limestone substitute and as a sulfur bearing mineralizer. Results show that 20 to 25% of the limestone can be provided by the scrubber sludges. 25 refs.,25 figs., 10 tabs.« less

Authors:
; ;
Publication Date:
Research Org.:
Ames Lab., IA (USA)
OSTI Identifier:
5868050
Report Number(s):
IS-4874
ON: DE85011292
DOE Contract Number:
W-7405-ENG-82
Resource Type:
Technical Report
Resource Relation:
Other Information: Portions of this document are illegible in microfiche products. Original copy available until stock is exhausted
Country of Publication:
United States
Language:
English
Subject:
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION; 01 COAL, LIGNITE, AND PEAT; FLY ASH; CHEMICAL COMPOSITION; MATERIALS RECOVERY; HICHLOR PROCESS; RESEARCH PROGRAMS; LIME-SODA SINTER PROCESS; ALUMINIUM; EXPERIMENTAL DATA; FLOWSHEETS; FOSSIL-FUEL POWER PLANTS; IRON; PELLETIZING; REDUCING AGENTS; SCRUBBERS; SLUDGES; X-RAY DIFFRACTION; X-RAY FLUORESCENCE ANALYSIS; AEROSOL WASTES; ASHES; CHEMICAL ANALYSIS; COHERENT SCATTERING; DATA; DIAGRAMS; DIFFRACTION; ELEMENTS; EQUIPMENT; FABRICATION; INFORMATION; MANAGEMENT; METALS; MOLDING; NONDESTRUCTIVE ANALYSIS; NUMERICAL DATA; POLLUTION CONTROL EQUIPMENT; POWER PLANTS; PROCESSING; RECOVERY; RESIDUES; SCATTERING; THERMAL POWER PLANTS; TRANSITION ELEMENTS; WASTE MANAGEMENT; WASTE PROCESSING; WASTES; X-RAY EMISSION ANALYSIS; 320305* - Energy Conservation, Consumption, & Utilization- Industrial & Agricultural Processes- Industrial Waste Management; 010800 - Coal, Lignite, & Peat- Waste Management

Citation Formats

Burnet, G., Murtha, M.J., and Benson, J.D.. Direct utilization - recovery of minerals from coal fly ash. Fossil Energy Program. Technical progress report, 1 July 1984-30 September 1984 including summary of work for FY84. United States: N. p., 1985. Web.
Burnet, G., Murtha, M.J., & Benson, J.D.. Direct utilization - recovery of minerals from coal fly ash. Fossil Energy Program. Technical progress report, 1 July 1984-30 September 1984 including summary of work for FY84. United States.
Burnet, G., Murtha, M.J., and Benson, J.D.. 1985. "Direct utilization - recovery of minerals from coal fly ash. Fossil Energy Program. Technical progress report, 1 July 1984-30 September 1984 including summary of work for FY84". United States. doi:.
@article{osti_5868050,
title = {Direct utilization - recovery of minerals from coal fly ash. Fossil Energy Program. Technical progress report, 1 July 1984-30 September 1984 including summary of work for FY84},
author = {Burnet, G. and Murtha, M.J. and Benson, J.D.},
abstractNote = {The research discussed in this report deals with resource recovery from coal conversion solid wastes. Progress is reported on two methods (the HiChlor and Lime-Sinter processes) for extracting metal values from power plant fly ash. Preliminary work is also reported on a method of making cement from the residue of the lime-sinter process. In the HiChlor Process, metal oxides in the fly ash are converted to volatile chlorides by reaction with chlorine in the presence of a reductant. Several versions of this approach are being investigated. The Lime-Sinter Process utilizes a solid state reaction to selectively convert the alumina in fly ash to a soluble form. Fly ash is mixed with limestone and a suitable mineralizer (to reduce the temperature required for sintering and to enhance alumina recovery) and then sintered in a high temperature kiln. Alumina is recovered by leaching the resulting clinker. A complex relationship between the calcium, alumina, silica, and sulfur constituents in the feed mixture controls the formation and extraction of aluminate compounds. Alumina recovery levels are enhanced by promoting the formation of less-soluble calcium compounds and/or more-soluble aluminum compounds. A study is underway to determine the degree to which flue gas scrubber sludge can be used both as a limestone substitute and as a sulfur bearing mineralizer. Results show that 20 to 25% of the limestone can be provided by the scrubber sludges. 25 refs.,25 figs., 10 tabs.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = 1985,
month = 3
}

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  • This investigation is to develop methods for utilizing coal fly ash through processes for the extraction of alumina and titania, and for the separation and use of an iron-rich fraction. Research of the HiChlor process for the extraction of alumina and titania by high-temperature chlorination of a fly ash-reductant mixture is described. An engineering cost evaluation is presented for a centralized HiChlor processing facility to process the fly ash of several large coal-fueled power stations. Investigations for a high-temperature lime-soda process for extraction of alumina from fly ash included the use of several types of quarry limestones and waste materialsmore » to replace the limestone and/or soda ash. A breakthrough was made on the development of a limestone-fly ash process without soda. The addition of less than 5% by weight waste coal refuse to the sinter mixtures increased alumina recoveries from a 55 to 90%, at a much lower sintering temperature of 1200/sup 0/C. For the lime-soda sinter process, an engineering cost evaluation was prepared for a facility to process the fly ash from a 1000 MWe coal-fueled power station to produce alumina and Portland cement. This facility will process and dispose of the total generated fly ash volume as products rather than as waste, and the facility investment will be less than 10% of the cost of the corresponding power station. The magnetic fly ash fraction, separated before either HiChlor or sinter processing, was shown to have a market value as a heavy medium material for coal and ore beneficiation. Research was also conducted on the upgrading of magnetic fly ash to iron ore quality. Research of coal beneficiation using magnetic fly ash media was expanded.« less
  • Research during the past year has dealt primarily with the fundamentals of the HiChlor process, development of the sintering process, utilization of the fly ash iron-rich fraction, and application of the work to date to the full range of coal conversion solid wastes. Work on the chlorination of coal fly ash to extract metal constituents (HiChlor process) included both chlorination reaction studies and efforts to recover and purify the chloride products. The reaction research comprised an evaluation of several reduction and chlorination agents, the development of techniques for the collection of reaction kinetic data in a form not limited bymore » mass transfer of the reactants, and the use of a fused salt reactor for fly ash chlorination. Chlorination in a fused salt reactor shows promise of providing improved selectivity in the reaction of the metal oxides present and of significantly increasing the reaction rate. A ternary amine organic solvent has been used to extract the Fe ions from an aqueous HCl solution of mixed metal chlorides, followed by precipitation of the Al as AlCl/sub 3/.6H/sub 2/O and extraction of the titanium ions using tributyl phosphate. Sinter research on coal fly ash, cement kiln dust, and coal refuse sinter mixtures has shown that soluble aluminates can be extracted from ground clinker formed by sintering at 1200/sup 0/C. Work has also been conducted on the magnetic separation of an iron-rich fraction from coal fly ash in a water slurry, and on the use of the iron-rich fraction as heavy medium material in coal beneficiation.« less
  • Work has focused on two methods for resource recovery from coal conversion solid wastes. The HiChlor Process recovers Al, Fe, and Ti minerals from coal fly ash by high temperature chlorination in the presence of a reductant. An understanding of the mechanisms of the gas-solid reactions involved is essential to the design and development of the reactor system. Three possible reaction mechanisms are considered, evaluated, and tested. The second method involves a lime-sinter step to produce soluble aluminates. Research on the process includes scale-up of the sinter step using a 5 in. diam electrically heated kilm. Batch samples of limestone-flymore » ash-soda ash mixtures are processed, at a rate of about 4 lb/hr. The resulting clinker is used to fully evaluate processing conditions for the extraction, desilication, and product recovery steps. Experiments are completed which evaluate raw material preparation requirements, for sintering and clinker crushing requirements for extraction.« less
  • Research is reported for two methods for extracting metal values from power plant fly ash. In the first method (HiChlor process), a carbochlorination reaction is used to produce a mixture of volatile metal chlorides from the oxides in the ash. Fractional condensation of the mixed chlorides is being investigated as the first step in their recovery and separation. This effort is accompanied by work on a unique slurry reactor in which the ash is contacted by gaseous chlorine while suspended with finely divided carbon in a molten salt mixture consisting of NaCl and AlCl/sub 3/. In the second method, amore » lime-sinter solid state reaction is used to selectively convert the alumina in the ash to a soluble form. The alumina is recovered by leaching the finely divided clinker. The effects of mineralizers on the sinter reaction are being investigated as a means for increasing alumina yield and reducing the temperature required. A similar study is underway to determine the degree to which the limestone required can be replaced by flue gas scrubber sludge which also has mineralizer properties. Preliminary results show that at least 30% of the limestone can be replaced. Attempts to reduce the sintering temperature required have also been carried out using a laboratory scale rotary kiln. Through kiln modifications, residence time has been increased so that lower temperatures can be used. The alumina-containing extract from the leaching of the clinker will occasionally contain excessive amounts of silica. To meet electrolytic cell feed specifications, the silica content is reduced by digestion with a small amount of lime. Work has been completed on an update of an economic feasibility study of the lime-sinter process. 13 figures, 8 tables.« less
  • Research progress is reported on two methods for extracting metal values from power plant fly ash. In the first method (the HiChlor process), a carbochlorination reaction is used to produce a mixture of volatile metal chlorides from the oxides in the ash. Developmental research is underway on a unique slurry reactor in which the ash is contacted by gaseous chlorine while suspended with finely divided carbon in a molten salt (NaCl + AlCl/sub 3/). Experimental apparatus is being tested and the necessary analytical procedures are being developed. In the second method, a lime-sinter solid state reaction is used to selectivelymore » convert the alumina in the ash to a soluble form. The alumina is recovered by leaching the finely divided clinker. This report deals with the effects of mineralizers on the sinter reaction as a means for increasing alumina yield and reducing the required temperature. Dissolved silica in the alumina-containing extract from the leaching of the lime-sinter clinker can result in an alumina product that fails to meet electrolytic cell feed specifications. Research has shown that the silica content can be reduced by digestion with a small amount of lime. The amount of lime addition, digestion temperatures required, and desilication reactions occurring are reported. New data are also presented on the recovery and purification of the alumina product. Preliminary research on the production of low-alumina, sulfate resistant cement from the extracted sinter residue has resulted in information on the need for such cement, estimated costs, and experimental work required. 5 references, 4 figures, 3 tables.« less