Regeneration of spent etchant

Abstract

Abstract THIS INVENTION RELATES TO A PROCESS FOR EXTRACTING DISSOLVED METAL AS METAL FROM A USED ETCHANT SOLUTION CONTAINING FERRIC IONS AS AN OXIDANT WHILE SIMULTANEOUSLY REGENERATING THE ETCHANT FOR FURTHER USE. THE PROCESS COMPRISING ELECTROWINNING A PORTION OF THE METAL FROM SOLUTION UNDER CONDITIONS EFFECTIVE FOR ELECTROWINNING, BUT NOT ETCHING. THESE CONDITIONS INCLUDE A SUBSTANTIAL FREEDOM FROM OXYGEN IN THE VICINITY OF THE CATHODE, SUBSTANTIAL FREEDOM FROM SOLUTION AGITATION DURING THE WINNING OPERATION AND PREFERABLY, FOR GOOD CATHODE EFFICIENCY, RELATIVELY LOW SOLUTION TEMPERATURE AT THE INTERFACE OF THE SOLUTION AND THE CATHODE, TYPICALLY BELOW 120* F. THE PROCESS IS ECONOMICAL BECAUSE THE FERRIC ION REDUCED TO FERROUS ION DURING THE ETCHING OPERATION IS OXIDIZED BACK TO THE FERRIC FORM AT THE ANODE DURING THE ELECTROWINNING PROCESS. THUS, THE ETCHANT IS REGENERATED AND SUITABLE FOR RE-USE. MOREOVER, ONLY A PORTION OF THE DISSOLVED METAL IS REMOVED FROM SOLUTION, THE REMAINDER BEING LEFT IN SOLUTION. THE PROCESS IS AN IMPORTANT CONTRIBUTION TO POLLUTION ABATEMENT EFFORTS AS IT ELIMINATES THE NEED FOR DUMPING SPENT ETCHANT AND DISSOLVED METAL WASTES RESULTING FROM AN ETCHING OPERATION.

Inventors

• 👤 M Gulla

Bibliographic Details