Engineering simulation of sulfation roasting reactions

A modified thermodynamic calculation procedure was used to simulate the beh avior of a number of minor components in sulfation roasting. To account for uncertain mineralogy and probable non-equilibrium situations it was assume d that the calcine formed pseudo solid solutions and that the minor compone nts had large values of activity coefficient, which were referred to as 'ad justment coefficients.' The calculation method was a combination of the fre e energy minimization procedure coupled with the introduction of the imagin ary phases involving non-equilibrium forms of the minor constituents. The a ppropriate choice of adjustment coefficients allowed the calculated behavio r of the non-equilibrium minor components to reflect the results observed i n practice and could be used to explore the relative effects of variables s uch as temperature, pressure and concentration. The existence of narrow reg ions of optimum temperature and gas compositions was confirmed for the sele ctive sulfation-roasting of copper-nickel sulfide concentrate. Application of the procedure to the sulfation roasting of a zinc plant residue was also discussed. The proposed simulation method is useful for the complex system including non-equilibrium components like waste treatment and recycling.