Aluminothermic production of metals and alloys

Abstract:In this paper, the theoretical and industrial definitions of metallic calcium production by the metallothermic process in a vacuum atmosphere were investigated. In the experiments, Al is the only reductant used for metallothermic calcium production. The effects of Al stoichiometry, time variances, and temperature changes were investigated. The experiments were carried out at 1200 • C, 1250 • C, and 1300 • C, and with 100% Al, 125% Al, and 150% Al stoichiometry to produce metallic calcium from the residue of metallic magnesium production. Both the raw materials and the residue phases were characterized by atomic absorption spectrometry (AAS), X-ray diffraction (XRD) spectrometry, and chemical analysis techniques. Experimental results were investigated to determine the highest efficiency of reduction conditions. From the results of the experiments, reaction kinetics and activation energy were calculated. According to the experimental results, the highest recovery rate parameters for the reduction of calcium are 150% stoichiometric Al for 480 min at 1300 • C, with 72% recovery.

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“…In 2017, Turkey produced 5000 tons of magnesium. The production residue includes high amounts of CaO [3,14].…”

Section: Mineralmentioning

confidence: 99%

“…Calcium metal oxidizes immediately in the air at temperatures above 300 • C [1,2]. The heat of oxide formation is −304 kcal/mole O 2 at 25 • C, and the boiling point of the element and the melting point of calcium oxide are 1482 • C and 2580 • C, respectively [3]. The main calcium-containing minerals are given in Table 1.…”

Section: Introductionmentioning

confidence: 99%

Reduction Conditions of Metallic Calcium from Magnesium Production Residues

Tasyürek

Buğdaycı

Yücel

2018

Metals

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“…Almost thirty years later, in 1893, the German Johannes Goldschmidt experimented with aluminothermic reactions to produce high purity chromium and manganese, which led him to patent the thermite process in 1895, and already in 1899, the thermite gained its first commercial application in rail welding in Essen [8]. Later, thermite gained other applications including a power plant patented by Johnson [9], the development of a high-regression solid fuel composition by Allen [10], and the aluminothermic production of metals and alloys [11]. Moreover, the use of thermite was adopted in the production of highpressure gases at high velocities [12], high-temperature sintering and self-propagating (SHS) ceramics and composite materials [13], and the development of igniters [14].…”

Section: Introductionmentioning

confidence: 99%

Detailed Numerical Modeling and Simulation of Fe₂O₃−Al Thermite Reaction

Souza

Lemos

2021

Propellants Explo Pyrotec

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A thermite reaction is a self-propagating exothermic reaction with many practical applications in welding processes, material synthesis, pyrotechnic and initiator technologies. Motivated by the above-mentioned, the present study involves modeling and simulation of common hematite-aluminum thermite reaction with the aim of predicting temperature levels and radial burning speeds in a thin disk ignited at the center. Balance equations of species and energy conservation were solved in one dimension space by applying a finite difference method, considering no species transport and a one-step mechanism. The Arrhenius equation was adopted to model the kinetics rate. Phase change and temperature dependence of the thermochemical properties were also considered. Analyses of spatial and temporal meshes revealed that numerical results were independent of the grid used. Predictions show that the ignition procedure affects the formation of the reaction-front, higher temperatures, and longer ignition zones can start the self-sustained reaction earlier. However, once the reaction wave is established, its velocity and peak temperature are the same, independent of the initial temperature profile. Simulations herein also show that an increase of the activation energy and decrease of the pre-exponential factor slows down the reaction speed considerably, impacting on accurate prediction of reactionwave velocity. Further, the activation energy influences the burning velocity much more drastically than the pre-exponential factor. The maximum temperature observed in the model is around the melting temperature of alumina (2327 K), which is in agreement with the experimental results reported in the literature.

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“…In this regard, pre-alloyed powders are of great interest, given their superior homogeneity in composition, grain structure, and porosity [8]. Currently, the majority of ferro molybdenum powder is produced via an aluminothermic reaction, where silicon and aluminum metal are used to reduce a mixture of molybdic oxide and iron oxide in the presence of calcium fluoride or lime [9]. This approach produces ferro-molybdenum particles in the typical size range of microns to millimeters.…”

Section: Introductionmentioning

confidence: 99%

“…ferro molybdenum powder is produced via an aluminothermic reaction, where silicon and aluminum metal are used to reduce a mixture of molybdic oxide and iron oxide in the presence of calcium fluoride or lime [9]. This approach produces ferro-molybdenum particles in the typical size range of microns to millimeters.…”

Section: Introductionmentioning

confidence: 99%

Investigation of the Reduction of a Molybdenum/Iron Molecular Nanocluster Single Source Precursor

Esquenazi

Barron

2018

Inorganics

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The thermolysis of the polyoxometalate cluster [HxPMo12O40⊂H4Mo72Fe30(O2CMe)15O254(H2O)90−y(EtOH)y] (1) under air, argon, and reducing conditions (5%, 10%, 50% H2 with Ar balance) has been investigated. The resulting products have been characterized by XRD, SEM, and EDX analysis. Thermolysis in air at 1100 °C yields predominantly Fe2O3, due to sublimation of the molybdenum component; however, under Ar atmosphere, the mixed metal oxide (Fe2Mo3O8) is formed along with Mo and MoO2. Introduction of 5% H2 (1100 °C) results in the alloy Fe2Mo3 in addition to Fe2Mo3O8 and Mo; in contrast, reduction at a lower temperature (900 °C) yields the carbide (Fe3Mo3C) and the analogous oxide (Fe3Mo3O), suggesting that these are direct precursors of Fe2Mo3. Increasing the H2 concentration (10%) promotes carbide rather than oxide formation (Fe3Mo3C and Mo2C), until alloy formation (Fe7.92Mo5.08) predominates under 50% H2 at 1200 °C. The effect of temperature and H2 concentration on the composition, grain size, and morphology has been investigated by EDX, SEM, and XRD. The relationship of the composition of 1 (i.e., Fe:Mo = 30:84) with the product distribution is discussed.

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Aluminothermic production of metals and alloys

Cited by 8 publications

References 2 publications

Reduction Conditions of Metallic Calcium from Magnesium Production Residues

Reduction Conditions of Metallic Calcium from Magnesium Production Residues

Detailed Numerical Modeling and Simulation of Fe₂O₃−Al Thermite Reaction

Investigation of the Reduction of a Molybdenum/Iron Molecular Nanocluster Single Source Precursor

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Aluminothermic production of metals and alloys

Cited by 8 publications

References 2 publications

Reduction Conditions of Metallic Calcium from Magnesium Production Residues

Reduction Conditions of Metallic Calcium from Magnesium Production Residues

Detailed Numerical Modeling and Simulation of Fe2O3−Al Thermite Reaction

Investigation of the Reduction of a Molybdenum/Iron Molecular Nanocluster Single Source Precursor

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Detailed Numerical Modeling and Simulation of Fe₂O₃−Al Thermite Reaction