Recovery of zinc from zinc sulphides by direct pressure leaching

Claim 1

THE PROCESS FOR EXTRACTING ZINC FROM IRON CONTAINING ZINCIFEROUS MINERAL SULPHIDES WHICH COMPRISES THE STEPS OF DISPERSING FINELY DIVIDED IRON CONTAINING ZINCIFEROUS SULPHIDES IN AN AQUEOUS SULPHUR ACID SOLUTION TO FORM A SLURRY; ADJUSTING THE RELATIVE AMOUNTS OF ACID AND SAID SULPHIDES IN THE SLURRY SUCH THAT THERE IS AT LEAST SUFFICIENT ACID PRECENT TO COMBINE WITH THE ZINC CONTENT OF SAID SULPHIDES AS ZINC SULPHATE, PROVIDING IN SAID SLURY AN EFFECTIVE AMOUNT OF A SURFACE ACTIVE COMPOUND COMPATIBLE WITH THE ACID SULPHATE LEACH SOLUTION WHICH IS OPERATIVE, UNDER THE REACTION CONDITIONS OF THE FOLLOWING OXHGEN REACTION STEP, TO RENDER SAID SULPHIDES WETTABLE BY AQUEOUS ACID SOLUTION IN PREFERENCE TO MOLTEN SULPHUR, REACTING THE SLURRY WITH FREE OXYGEN BEARING GAS IN A CLOSED REACTION VESSEL AT A TEMPERATURE ABOVE THE MELTING POINT OF SULPHUR BUT BELOW THAT TEMPERATURE AT WHICH ANY SUBSTANTIAL PORTION OF THE SULPHIDE SULPHUR IS OXIDIZED TO SULPHATE FORM, CONTINUING SAID REACTION WITH ACTIVE AGITATION TO EFFECT SUBSTANTIALLY COMPLETE EXTRACTION OF ZINC VALUES FROM SAID SULPHIDES AS SOLUBLE ZINC SULPHATE WITH CONCURRENT CONVERSION OF SULPHIDE SULPHUR ASSOCIATED WITH SAID ZINC VALUES TO ELEMENTAL FROM, AND SEPARATING PRODUCT LEACH SOLUTION CONTAINING DISSOLVED ZINC VALUES FROM THE UNDISSOLVED RESIDUE.