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Fuzzy Logic modelling of non-catalytic, multi-step hydrogen reduction of molybdenum disulfide in the presence of lime

Posted on 15. October, 2015.

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Metal sulfide reduction in the presence of a suitable sulfur-scavenging metal oxide is an attractive process for the direct recovery of metals.

This general scheme, for reduction of MoS2 in the presence of lime can be represented by the reactions:

Some mathematical models are available in the literature for describing the direct reduction of metal sulfides in the presence of lime. Fahim et al. proposed a mathematical model, which describes systems with consecutive reactions taking place in a porous spherical pellet composed of two spherical grains. Sohn and Won proposed a model that was specifically formulated for the reduction of Cu2S by hydrogen in the presence of lime in order to describe systematically the system behaviour, including predicting the rate of the partial reactions and the degree of sulfur fixation. Afsahi et al. used a dimensionless model to predict the behaviour of a cylindrical pellet containing MoS2 and CaO where hydrogen reacts with molybdenum sulfide at high temperature.
When mathematical modelling of a process is too complex, a systematic formulation for characterising this type of problem is possible using Fuzzy Logic.

Investigations have been carried out on the application of the Fuzzy Logic model to the “direct reduction” of molybdenum disulfide by hydrogen in the presence of lime, as an alternative method for producing molybdenum powder. The objective was to seek a predictor model via a well-defined relationship between the vital variables (bulk temperature, ratio of molar quantities of the solid reactants, pellet thickness, hydrogen concentration in the gaseous bulk, normalised weight loss of the pellet, sulfur fixation in the pellet, and time required for completion of reaction). Finally, the results predicted by the Fuzzy Logic model have been evaluated and validated using both a mathematical model and experimental data.

Read the full article in  Progress in Reaction Kinetics and Mechanism, Volume 40, Number 3, 2015, pp. 291-302.

Keywords: Fuzzy Logic, simulation, molybdenum disulfide, lime, reduction

Authors: Mohammad Mehdi Afsahia,b*, Bahador Abolpoura, Ramachndran Vasant Kumarb and Milad Abolpourc

aDepartment of Chemical Engineering, Shahid Bahonar University of Kerman, Kerman 76175, Iran
bUniversity of Cambridge, Department of Materials Science and Metallurgy, Cambridge CB2 3QZ, UK
cDepartment of Electrical Engineering, Shiraz University, Shiraz 71345, Iran

Image: Fuzzy Inference System (FIS) diagram: Inputs and their membership functions appear to the left of the FIS structural characteristics, while outputs and their membership functions appear on the right