Shrinking core model with variable activation energy: A kinetic model of manganiferous ore leaching with sulphuric acid and lactose

A kinetic model of manganiferous ore dissolution varying sulphuric acid and lactose as reducing agent was developed here. The Shrinking Core Model (SCM) was modified to take into account both the variable reagent concentrations and the reaction rate change with respect to the manganese dioxide conversion: this last aspect is due to several oxidation reactions of the carbohydrates in a hot sulphuric acid medium. The effects of three factors were investigated for three ore size fractions: temperature, lactose and sulphuric acid concentrations. The application of the kinetic model to different size ore fractions with and without the particle size effect shows that the best results in data fitting were gained by applying the model separately to each particle size fraction. The influence of the particle size in the kinetic model is discussed with the support of SEM analysis and BET surface measurements before and after leaching.

[1]  Francesco Vegliò,et al.  Fractional factorial experiments in the development of manganese dioxide leaching by sucrose in sulphuric acid solutions , 1994 .

[2]  O. Levenspiel.  Chemical Reaction Engineering , 1972 .

[3]  M. Brittan.  Variable activation energy model for leaching kinetics , 1975 .

[4]  Alan P. Prosser,et al.  Review of uncertainty in the collection and interpretation of leaching data , 1996 .

[5]  Andrea P. Reverberi,et al.  New Procedure for Optimal Design of Sequential Experiments in Kinetic Models , 1994 .

[6]  R. P. Das,et al.  Extraction of metals from manganese nodules of the Indian Ocean by leaching in aqueous solution of sulphur dioxide , 1988 .

[7]  David Mautner Himmelblau,et al.  Process analysis by statistical methods , 1970 .

[8]  L. Toro,et al.  Surface Response Methodology and Preliminary Process Analysis in the Study of Manganiferous Ore Leaching by Using Whey or Lactose in Sulfuric Acid Solutions , 2000 .

[9]  L. R. Freitas,et al.  Sulphation of Carajás manganese ore , 1995 .

[10]  Giuliana Taglieri,et al.  Acid leaching process by using glucose as reducing agent : A comparison among the efficiency of different kinds of manganiferous ores , 2000 .

[11]  Luigi Toro,et al.  Reductive leaching of manganiferous ores by glucose and H2SO4 : effect of alcohols , 2001 .

[12]  F. Veglio,et al.  Reductive leaching of a concentrate manganese dioxide ore in acid solution: stoichiometry and preliminary kinetic analysis , 1994 .

[13]  A. Adamson.  Physical chemistry of surfaces , 1960 .