Treatment of toxic copper-containing solutions

Claim 1

A PROCESS FOR THE TREATMENT OF A USED ETCHING SOLUTION CONTAINING COPPER SALTS INCLUDING A COPPER AMMONIUM COMPOUND AND A MINOR AMOUNT OF AMMONIUM PERSULFATE TO FREE THE SOLUTION FROM ITS TOXIC AMMONIA AND COPPER CONTENT FOR DISCARDING THE TREATED SOLUTION AS WASTE WHICH COMPRISES, ADDING AN EXCESS OF A STRONG NEUTRALIZING ALKALI OF THE NATURE OF CAUSTIC SODA TO THE SOLUTION, MAINTAINING AN EXCESS OF THE ALKALI IN THE SOLUTION THROUGHOUT THE TREATMENT IN AN AMOUNT SUFFICIENT TO PROVIDE MINIMUM PH OF ABOUT 12; HEATING THE SOLUTION TO AN ELEVATED TEMPERATURE ABOVE ROOM TEMPERATURE AND MAINTAINING THE EXCESS OF THE ALKALI AND THE ELEVATED TEMPERATURE WHILE CONVERTING ITS ANNOMIUM CONTENT INTO AMMONIA GAS AND DRIVING-OFF THE AMMONIA GAS, AND WHILE PROGRESSIVELY WITH THE DRIVING-OFF TO THE AMMONIA GAS, FREEING ITS COPPER CONTENT FROM ITS AMMONIUM COMPOUND AND CONVERTING ITS FREED COPPER CONTENT INTO AND PRECIPITATING IT OUT OF THE SOLUTION AS COPPER OXIDE; AND CONTINUING THE DEFINED TREATMENT UNTIL THE SOLUTION IS ESSENTIALLY FULLY FREED OF ITS TOXIC AMMONIA AND COPPER CONTENT.