An improved model of lime-enhanced reduction of molybdenum disulphide pellet by hydrogen

Abstract

In this study, a mathematical model was developed to describe the progress of the successive gas–solid reactions occurring in a porous pellet and the model was applied to hydrogen reduction of molybdenum disulphide in the presence of lime. To carry out a realistic modelling for the multi-step reactions, effect of the structural changes and non-isothermal conditions during the reaction within the pellet has been taken into account. The effect of structural change was implemented in the modelling through variation of the solid reactant grain sizes and effective diffusion. The results predicted by the model were evaluated and validated by comparing with the experimental data. Structural changes and non-isothermal conditions had no significant effect on the modelling results. Therefore, deviation of the model prediction from the experimental data can be ascribed to the side reaction occurring within the pellet. To compensate the effects of the side reaction, adapted parameters were obtained through the experimental data.

Keywords

Molybdenum disulphide Lime Side reaction Structural change Modelling Reduction

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References

Abolpour

, Afsahi

and Kumar

. 2011. A novel theoretical model for calculating the effective diffusivity of gases in a porous pellet composed of two different grains, Res. Chem. Intermed., 38, 1455–1465.

Afsahi

, Abolpour

, Kumar

and Sohrabi

. 2011. Modeling of non-catalytic hydrogen reduction of molybdenum disulfide in the presence of lime, by complex multi-step gas-solid reactions, Miner. Process. Extract Metall. Rev., 34, 1–25.

Afsahi

, Sohrabi

, Kumar

and Ale Ebrahim

. 2008a. A model for the intrinsic kinetic parameters of the direct reduction of MoS₂ with hydrogen, Int. J. Mater. Res., 99, 1032–1038.

Afsahi

, Sohrabi

, Kumar

and Ale Ebrahim

. 2008b. A study on the kinetics of hydrogen reduction of molybdenum disulphide powders, Thermochim. Acta, 473, 61–67.

Garza-Garze

and Dudukovic

. 1982. A variable size grain model for gas–solid reactions with structural changes, Chem. Eng. J., 24, 35–45.

Georgakis

, Chang

and Szekely

. 1977. A changing grain size model for gas–solid reactions, Chem. Eng. Sci., 34, 1072–1075.

Khoshandam

, Kumar

and Jamshidi

. 2005. Simulation of non-catalytic gas–solid reactions: application of grain model for the reduction of cobalt oxide with methane, Trans. Inst. Min. Metall. C, 114, 10–22.

Niksiar

and Rahimi

. 2009. A study on deviation of noncatalytic gas–solid reaction models due to heat effects and changing of solid structure, Powder Technol., 193, 101–109.

Patisson

, Francois

and Alitzer

. 1998. A non-isothermal, non-equimolar transient kinetic model for gas–solid reactions, Chem. Eng. Sci., 53, 697–708.

10.

Slattery

and Bird

. 1958. Calculation of the diffusion coefficient of dilute gases and of the self-diffusion coefficient of dense gases, Am. Inst. Chem. Eng. J., 4, 137–142.

11.

Sohn

and Won

. 1985. Successive gas-solid reaction model for the hydrogen reduction of cuprous sulfide in the presence of lime, Metall. Trans. B, 16, B645–B661.

12.

Szekely

, Evans

and Sohn

. 1976. Gas-solid reactions, 108–175. New York, Academic Press.

13.

Wakao

and Smith

. 1962. Diffusion in catalyst pellets, Chem. Eng. Sci., 17, 825–834.

14.

Won

and Sohn

. 1985. Kinetics of the reaction between hydrogen sulphide and lime particles, Metall. Trans. B, 16, B163–B168.