Metallothermic reduction of MoO3 through making Ni–Mo alloys by the ESR method

Jamshidi, K.; Abdizadeh, Hossein; Ebrahimi, S.A. Seyyed; Hanai, K.

doi:10.1016/j.ijrmhm.2004.07.001

Cited by 8 publications

(3 citation statements)

References 3 publications

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“…Specially, the thermite process uses high cost aluminum and silicon as reducing agents of MoO 3 . 3,4) Therefore, it would be highly desirable to develop an alternative process to manufacture ferromolybdenum alloy. Generally, the two-step hydrogen reduction process to produce pure molybdenum powders is well known: The first step is to reduce MoO 3 powders to MoO 2 powders at the temperature of below 923 K and the second step is to produce molybdenum powders from MoO 2 powders at the temperature of around 1373 K. 1,5) Although hydrogen used as a reducing agent of MoO 3 is expensive now, the process has many advantages because slag and dust are not generated in the process and additional additives are not needed.…”

Section: Introductionmentioning

confidence: 99%

Study on the Reduction of Molybdenum Dioxide by Hydrogen

Kim

Jeon

et al. 2008

Mater. Trans.

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The reduction of MoO 2 powder by hydrogen is one of the most important steps for manufacturing ferromolybdenum alloy and molybdenum powder. The results of experiments on the kinetics of this reaction are presented in this paper. The experiments were carried out under nonisothermal condition in hydrogen atmosphere using TGA equipment. The nonisothermal experiments were carried out at various linear heating rates up to 1273 K. It was found that the reduction reaction is very fast under the whole heating rate until the reduction ratio of MoO 2 approaches to about 0.92. The reduction ratio of MoO 2 was about 0.98 after finishing the reduction reaction at a heating rate of 4 K/min. Kinetics of the reaction was analyzed from the dynamic TGA data by means of Coats and Redfern equation. The nucleation and growth model yielded a satisfactory fit to these experimental data.

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Section: Introductionmentioning

confidence: 99%

Study on the Reduction of Molybdenum Dioxide by Hydrogen

Kim

Jeon

et al. 2008

Mater. Trans.

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“…In the past few decades, much effort has been done on carbothermic reduction of metal oxides [9,10], but these findings could not account for carbothermic reduction of molybdenum trioxide because of low melting point, high activity, and sublimation characteristic of molybdenum trioxide [11,12]. Kirshenbaum and other researchers [13][14][15] studied reduction of molybdenum trioxide with various metals; however, aluminum and silicon were not involved. Reductions of molybdenum trioxide with aluminum and silicon are normally applied in catalysis field [16,17].…”

Section: Introductionmentioning

confidence: 99%

Reduction characteristics of molybdenum trioxide with aluminum and silicon

et al. 2015

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Thermodynamics for reduction of molybdenum oxides by aluminum and silicon were calculated, and the results show that reduction reaction is feasible at a certain temperature region. Compared to the presence of CaO or CaCO 3 , reduction products of molybdenum trioxide with aluminum and silicon at various temperatures were detected by X-ray diffraction (XRD). Results show that molybdenum trioxide is reduced by aluminum or silicon step by step, and the intermediate product is MoO 2 . At 1000°C, molybdenum trioxide could be reduced to metal Mo by aluminum, and in the presence of CaO, metal Mo as the reduction product appears even at 800°C. In contrast, silicon could barely reduce molybdenum trioxide to metal Mo even at 1200°C. In the presence of CaO or CaCO 3 , reducibility of silicon increases significantly, and the reduction products are metal Mo and MoSi 2 . Altogether, CaO or CaCO 3 performs two major roles in reduction process: restraining sublimation of MoO 3 and decreasing the temperature of reducing MoO 3 to metal Mo.

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“…1) At the present time, ferromolybdenum alloy is produced by either a thermite process or a carbon reduction process. [2][3][4] However, in the processes large amounts of slag and dust which cause environmental problems are inevitably generated. Specially, the thermite process uses high cost aluminum and silicon as a reducing agent of MoO 3 .…”

Section: Introductionmentioning

confidence: 99%

A Novel Process for Producing Ferromolybdenum Powder Master Alloy without Generating Secondary Pollutants through a Two-Step Hydrogen Reduction Process

Kim

Lee

et al. 2011

Mater. Trans.

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A new process for producing ferromolybdenum powder master alloy without generating secondary pollutants by a two-step hydrogen reduction process involving MoO 3 and mill scale has been developed. In this process, mill scale which is an iron byproduct generated from the steel rolling process is used as an iron source. Experimentally, ferromolybdenum powder master alloy was produced by a two-step hydrogen reduction process: The first hydrogen reduction stage was carried at a horizontal furnace for 60 min at 848 K under a hydrogen gas at a partial pressure of 101.3 kPa, and the second hydrogen reduction stage was done at the same furnace for 40 min at 1123 K under the same hydrogen partial pressure. In the process, the reduction reactions of MoO 3 to MoO 2 and mill scale to Fe proceed simultaneously in the first reduction step, and then the reduction reaction of MoO 2 to Mo does in the second reduction step. The reaction rate of the second step in the two-step hydrogen reduction process of MoO 3 -Fe 2 O 3 mixture was also measured under isothermal condition in hydrogen atmosphere using TGA equipment. As an example, at 1173 K under a hydrogen partial pressure of 101.3 kPa, almost 100% of MoO 2 was reduced to Mo in 5 min. The nucleation and growth model were found to be applicable to the reaction rate. The reaction was first order with respect to hydrogen partial pressure and had an activation energy of 83.8 kJ/mol (20.1 kcal/mol).

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Metallothermic reduction of MoO3 through making Ni–Mo alloys by the ESR method

Cited by 8 publications

References 3 publications

Study on the Reduction of Molybdenum Dioxide by Hydrogen

Study on the Reduction of Molybdenum Dioxide by Hydrogen

Reduction characteristics of molybdenum trioxide with aluminum and silicon

A Novel Process for Producing Ferromolybdenum Powder Master Alloy without Generating Secondary Pollutants through a Two-Step Hydrogen Reduction Process

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