The aim is to develop new techniques for the concentration of high values elements, for instance by controlled oxidation.
Due to new environmental restrictions, the processing of sulphur containing minerals by pyrometallurgical techniques is no longer desirable. Research was carried out in order to develop an electrochemical technique to extract metals from sulphide minerals. The process must not be detrimental to the environment and hence, the emission of sulphur dioxide and hydrogen sulphide must be eliminated.
It has been confirmed that the extraction of copper from chalcopyrite ores in the porous pulsed percolated electrode (3PE) reactor is possible. Moreover, copper dissolution may be more selective than that of iron under cathodic electrolysis conditions. However, the observed current efficiencies are as yet rather low. It is suggested that modification of the basic reactor design may overcome some of these problems.

A mechanism for the electrodissolution of chalcopyrite has been established using conventional electrochemical techniques which has lead to the formulation of a systematic method for the large scale electrolysis of chalcopyrite ores. Further work must be performed to establish the nature of the film formation which occurs on the mineral surface during its anodic dissolution.

The establishment of a highly efficient procedure for the removal of iron ions from the electrolyte solution will lead to a significant simplification of the copper extraction flowsheet. There is however a need to integrate this extraction procedure into the overall process which would require further research into both the extraction method and the engineering requirements of such an integrated copper extraction process.
New developments in electrochemistry will be used to achieve the goal. The techniques involve the treatment of concentrates in a granulated bed reactor by the following methods.
Direct electrodissolution (electrochemical oxidation) of copper and unwanted mineral components. The minerals used to demonstrate the feasibility of the technique will be copper concentrates and industrial byproducts such as slag from the tin industry. The elimination of unwanted metals from these solids will be the first attempt.
Mineral treatment by alternating pH fields generated electrochemically within the reactor (enrichment of tin slag through acid base reactions).

Tasks to be performed are as follows.
Physicochemical characterization of chosen minerals involving: chemical and physical analyses (atomic absorption(AA), scanning electron microscopy(SEM), particle size distribution, electrical conductivity etc); electrochemical behaviour analysis (polarization curves, photoelectrochemical surface analysis etc); thermodynamic and mineralogical property analysis (data banks etc).
Construction and primary experimentation of the modified 3PE granulated bed or volumic bed electrochemical reactors. These will correspond to the research strategies described above.
Selective dissolution in the 3PE reactors. Pure copper will be used for reactor characterization and the results applied to chalcopyrite. A narrow particle size range will be employed. Predefined electrical potentials and an alternating local in situ generated pH gradient will be used. Optimization with respect to potential, time frequency of flow pulsation and average flow velocity.
Technical assessment of the process and general implications to mineral processing and purification treatments.