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Title: Production of aluminum-silicon alloy and ferrosilicon and commercial purity aluminum by the direct reduction process. Second annual technical report for the period 1978 September 1-1979 December 31

Abstract

A new computer program was developed for simultaneously solving heat and mass balance at steady state for a flowing one-dimensional chemical reactor. Bench scale reactor results confirmed that minimum final stage reaction temperature is 1950 to 2000/sup 0/C, depending on the Fe/sub 2/O/sub 3/ concentration in the burden. Additions of Fe/sub 2/O/sub 3/ to the charge produced significant increase in metallic yield. A new bench reactor was designed, built, and operated to facilitate semi-continuous operation, using O/sub 2/ injection to burn coke supporting the burden, resulting in burden movement. Validity of the equipment and test procedures was demonstrated by successfully operating the reactor as an iron blast furnace at 1500/sup 0/C. Bench scale fractional crystallizer runs were continued to determine the impurity effects of Fe up to 6.9% and Ti up to 1.25% on alloy product purity and yield. High initial impurity concentrations resulted in less pure Al-Si product and product yield below 50% due to Al and Si losses as Fe-Si-Al and Ti-Si-Al intermetallics. Long term testing was continued in the large bench scale membrane cell to evaluate woven cloth membrane and other construction materials, operating procedures, and effects of operating parameters on cell performance. Included in the lattermore » were starting alloy composition, current density, anode-cathode spacing, and electrolyte composition.« less

Authors:
Publication Date:
Research Org.:
Aluminum Co. of America, Alcoa Center, PA. Alcoa Labs.
OSTI Identifier:
7084703
Report Number(s):
CONS-5089-10
DOE Contract Number:
AC01-77CS40079
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ALUMINIUM ALLOYS; REDUCTION; SILICON ALLOYS; PERFORMANCE; PRODUCTION; TEST FACILITIES; ALLOYS; CHEMICAL REACTIONS; 360101* - Metals & Alloys- Preparation & Fabrication

Citation Formats

Bruno, M.J.. Production of aluminum-silicon alloy and ferrosilicon and commercial purity aluminum by the direct reduction process. Second annual technical report for the period 1978 September 1-1979 December 31. United States: N. p., 1980. Web. doi:10.2172/7084703.
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Bruno, M.J.. Production of aluminum-silicon alloy and ferrosilicon and commercial purity aluminum by the direct reduction process. Second annual technical report for the period 1978 September 1-1979 December 31. United States. doi:10.2172/7084703.
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Bruno, M.J.. Wed . "Production of aluminum-silicon alloy and ferrosilicon and commercial purity aluminum by the direct reduction process. Second annual technical report for the period 1978 September 1-1979 December 31". United States. doi:10.2172/7084703. https://www.osti.gov/servlets/purl/7084703.
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@article{osti_7084703,
title = {Production of aluminum-silicon alloy and ferrosilicon and commercial purity aluminum by the direct reduction process. Second annual technical report for the period 1978 September 1-1979 December 31},
author = {Bruno, M.J.},
abstractNote = {A new computer program was developed for simultaneously solving heat and mass balance at steady state for a flowing one-dimensional chemical reactor. Bench scale reactor results confirmed that minimum final stage reaction temperature is 1950 to 2000/sup 0/C, depending on the Fe/sub 2/O/sub 3/ concentration in the burden. Additions of Fe/sub 2/O/sub 3/ to the charge produced significant increase in metallic yield. A new bench reactor was designed, built, and operated to facilitate semi-continuous operation, using O/sub 2/ injection to burn coke supporting the burden, resulting in burden movement. Validity of the equipment and test procedures was demonstrated by successfully operating the reactor as an iron blast furnace at 1500/sup 0/C. Bench scale fractional crystallizer runs were continued to determine the impurity effects of Fe up to 6.9% and Ti up to 1.25% on alloy product purity and yield. High initial impurity concentrations resulted in less pure Al-Si product and product yield below 50% due to Al and Si losses as Fe-Si-Al and Ti-Si-Al intermetallics. Long term testing was continued in the large bench scale membrane cell to evaluate woven cloth membrane and other construction materials, operating procedures, and effects of operating parameters on cell performance. Included in the latter were starting alloy composition, current density, anode-cathode spacing, and electrolyte composition.},
doi = {10.2172/7084703},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Wed Oct 01 00:00:00 EDT 1980},
month = {Wed Oct 01 00:00:00 EDT 1980}
}
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Technical Report:
View Technical Report (16.35 MB)
DOI:  10.2172/7084703
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  • The primary objective of the three year program is to demonstrate technical feasibility of a pilot sized direct reduction process for producing aluminum and aluminum-silicon alloy. The process includes three major tasks, reduction to produce impure alloy, alloy purification and purification to commercial grade aluminum. Goals for the first year are to establish the effects of process operating and design variables in bench scale units, to design the three main pilot units plus auxiliary equipment, and to prepare the sites for installation of the pilot units. Progress toward these goals is reported.

  • Experimental runs were made to determine the effect of a cooler product reservoir on metal alloy yield and recovery. The reservoir temperature had no significant effect. Difficulties were experienced with operation of an oxygen injected bench scale reactor. Many tests were terminated by burden bridging or flooding of the oxygen tuyeres with metal and slag. Runs were made in which refluxing vapors were condensed in a liquid slag. The addition of CaO decreased the tendency for formation of thick, strong burden bridges but did not completely eliminate bridging. Reduction of flame temperatures did not affect the volatilization rate in themore » bench reactor. Operation of VSR-1 pilot reactor with O injection was achieved after resolving reactor shell leakage problems, by replacing the permeable ceramic shell with impermeable fused silica. Various combustion parameters were investigated, including coke size, burden height and oxygen flow rate. Steady state operation of the oxygen-coke system was attained with smooth burden movement and a 2000/sup 0/C bed temperature in the raceway vicinity. To further reduce heat losses from the raceway area. VSR-1 was redesigned to facilitate locating an induction coil below the oxygen inlets. Further evaluation of effects of impurities on alloy purification in the bench scale unit indicated a 50% decrease in product yield for starting charges containing Fe greater than 5%. Site installation for the entire alloy purification complex was completed. Operations were continued in the bench scale units to obtain design information for the pilot commercial grade Al purification unit. Procurement of construction material was established.« less

  • A complete mass and energy balance for real ores was calculated for the carbothermic reduction step. Corrected thermal data for estimated compounds resulted in 70/sup 0/C reduction of the predicted third-stage temperature. Bauxite, clay and coke mixes were agglomerated on a commercial briquetter. A correlation was obtained between compressive strength and calcination temperature plus rate of calcination of extrusions made from ores and coke. Evaluations of coal in place of coke in the burden was initiated. Evaluations of calcined briquettes and extrusions under reaction conditions resulted in the agglomerates retaining shape and solid phase at temperatures up to 1800/sup 0/C.more » Runs were made at various concentrations of Fe/sub 2/O/sub 3/ in the burden. Metallic product yields were improved and final-stage temperature was lowered to 1950/sup 0/C. Two improved methods were developed for preparing reduction product samples. Second stage kinetics runs were made to determine the effects of heating rate and temperature. A computer program was formulated for mathematical modeling of carbothermic reduction kinetics. Refractories were tested at reaction conditions and rated; several carbides were the most promising candidates. Safe, efficient operation of water cooled O/sub 2/ tuyeres was attained in crucible type, self-heated reactors. Metal was produced for the first time in an O/sub 2/ heated reactor. Preliminary design for the continuous vertical shaft reactor was completed. A conceptual large scale pilot reactor was designed. A high temperature bench scale crystallizer was designed. Experiments were continued on crystallization of Al--Si alloys containing critical impurities. Liquidus temperatures were determined for Al--Si--Fe and Al--Si--Ti charges. A preliminary design of the pilot crystallizer was completed. Design was continued on crystallizer auxiliaries.« less

  • Revised heat and mass balance calculations predicted a 36% increase in O/sub 2/ and fuel carbon to offset reactant sensible heats and estimated unit heat losses. Preliminary calculations of heat and mass flows for the conceptual pilot reactor design indicated critical zones at the bottom due to high heat input requirements, and at the top due to excess heat generation by formation of CO/sub 2/ and C from CO. Binderless agglomerates were made from bauxite, clay and metallurgical coke, fired and measured for important physical properties. Extrudates tested at operating conditions maintained integrity up to 1800/sup 0/C. Additional reaction mechanismmore » runs resulted in production of competing reactions at the higher temperatures. It was determined that heat input rate effected product formation. Mathematical modeling of kinetic expressions for predicted reactions was initiated. Several improved versions of crucible type, self-heated reactors were built and operated to evaluate O/sub 2/ tuyere assemblies, raceway formation and O/sub 2/ distribution to a coke bed. The design of a bench scale, self-heated shaft reactor was initiated. The effects of Fe and Ti impurities on fractional crystallization were determined in the bench scale unit. Reduction of Si from 27.6% to 14% was attained in a pilot crystallizer. Design of pilot crystallizer components was started and a site layout was made for the purification equipment. Preliminary designs of alternative holding furnaces were completed. Bench scale tests on purification to commercial grade Al were continued. Feed materials containing Al-Si-Fe and Al-Si-Fe-Ti were used. Efficiencies of 98% and Al purities of 99.9% were attained. Compositions of intermetallic compounds in the residue phase were identified.« less

  • Progress on the program to demonstrate the technical feasibility of a pilot-sized Direct Reduction Process for producing aluminium and aluminium-silicon alloy is reported for Phase C. Progress is reported on reduction including the following tasks: supply burden material; burden beneficiation; effects of pilot operating parameters; pilot modifications; reactor scale-up design; calculating heat and mass balance; processing mathematical modeling; effects of process variables; information on supportive analytical, phase identification, and mechanical engineering data. Progress on alloy purification is reported in the following tasks: pilot unit installation; effects of pilot operating parameters; pilot unit modifications; and supportive mechanical engineering. Progress on purificationmore » to commercial grade aluminum is reported on: pilot unit installation; effects of pilot operating parameters; pilot unit modifications; support pilot operations; and supportive expended man-hours. Plans for Phase D are noted. (MCW)« less