Electrochemical conditioning of mine waters

Term: 08/2006 - 12/2008

Funding: LMBV/VKTA



Since 1995, the VKTA - Radiation Protection, Analytic & Disposal Inc. deals with development of methods for conditioning of sulfur-acidic waters from previous strip mining areas. An efficient method to reduce the sulphate concentration of the mine waters as well as to precipitate heavy metal ions simultaneously is the electrochemical water treatment (coupling of electrolysis and membrane separation process) according to the RODOSAN® process (VKTA). In this process, ionogenic impurities are separated from the mine water using an ion exchange membrane in conjunction with an electric field. Thus, the pH value of the water increases. By conversion of the separated sulphate ions into reusable substances (e. g. ammonium sulphate), the electrochemical water treatment can be combined with a product synthesis. The process integration enhances the economical efficiency as well as the environmental sustainability of the process.

R&D Activities

The crucial factors for the efficiency of the electrochemical water treatment are the minimisation of the specific energy consumption as well as the optimisation of the sulphate ion separation and the processing of the by-products. For that purpose, process supporting investigations for optimisation of the electrochemical process as well as laboratory experiments regarding the by-product processing have been carried out by the HZDR (formerly FZD).

Cell design optimisation at laboratory scale

  • optimisation of flowed cell internals
  • reliable discharge of electrolysis gas and precipitated hydroxides
Lab-scale electrolytic cell Bubbly flow inside the cell


  • prototype design of a electrolytic cell for water treatment

Determination of process parameters and chemical conversions at industrial electrolytic cells

  • design and installation of an electrolysis test facility for determination of process parameters at industrial conditions
  • determination of process parameters during electrolysis to identify capabilities for optimisation
  • study of residence time distributions and velocity profiles in pilot-scale electrolytic cells using laser induced fluorescence (LIF) to optimise cell design and process conditions
Electrolytic cell with subdivided cathode Bubbly blow inside the cathode channel

Investigations regarding the by-product processing

  • investigation of the solubility and crystallisation behaviour at laboratory scale
  • estimation of thermodynamic crystallisation parameters
  • investigations regarding the product quality
  • mass and energy balancing of the process stage by-product processing
Crystallisation experiment in the RC1 Crystalline by-product




Dr. H. Kryk, M. Schubert