Model for the description of oxidation in sulfidic waste rock dumps.

Abstract

Basic mathematical equations which describe the processes of sulfide oxidation and gas and water transport in waste rock dumps are presented and discussed. The governing equations account for gas and water flow vaporisation and condensation with latent heat effects heat transport and mass balance. Gas water and solid phases are assumed to be in local thermal equilibrium at all times. Air is approximated as an ideal three-component gas. Different semi-empirical relationships between physical values are used: Darcy's law for fluid flow ideal gas law the Van Genuchten formula for the relationship between degree of water saturation and pressure head Mualem's formula for the relative hydraulic conductivity as a function of pressure head etc. Some important global quantities such as the fraction of sulfide sulfur oxidised and the global oxidation rate are defined and considered as functions of time. The full set of equations is collected and presented in explicit form convenient for further numerical modelling. The glossary of some technical terms and the table of definitions of the main parameters as well as their units and characteristic values are displayed.