Continuous preparation of pure metals by gaseous reduction

Claim 1

IN A PROCESS FOR CONTINUOUSLY RECOVERING METALLIC COPPER, NICKEL, COBALT, SILVER OR GOLD FROM AN AQUEOUS SOLUTION CONTAINING A SOLUBLE SALT OF ONE OR MORE OF THESE METALS, AND HAVING A SELECTED PH AND A SELECTED FREE AMMONIA-TO-METAL RATIO RANGING FROM 0:1 UP TO ABOUT 6:1, DEPENDING UPON THE METAL TO BE RECOVERED, BY CONTINUOUSLY MIXING THE SOLUTION WITH A REDUCING GAS IN A TUBULAR REACTOR, THE IMPROVEMENT WHICH COMPRISES: CONTINUOUSLY CHARGING THE SOLUTION AND ANY NEEDED PARTICULATE CATALYST TO A TUBULAR REACTOR WHILE SIMULTANEOUSLY INTRODUCING A REDUCING GAS TO SAID REACTOR AT A POINT SPACED FROM THE POINT AT WHICH THE SOLUTION IS CHARGED TO THE REACTOR IN A FLOW DIRECTION CONTERCURRENT TO THE FLOW DIRECTION OF THE SOLUTION; HEATING THE MIXTURE OF THE SOLUTION AND THE GAS TO A TEMPERATURE OF AT LEAST 200*F PRIOR TO PASSING OUT OF THE REACTOR, SAID REACTOR BEING MAINTAINED, DURING THE CHARGING OF THE SOLUTION AND INTRODUCTION OF THE GAS, UNDER SUBSTANTIALLY STEADY STATE CONDITIONS IN WHICH A. THE PARTIAL PRESSURE OF THE REDUCING GAS IS AT LEAST 50 PSIG, AND THE TOTAL PRESSURE ON THE SOLUTION IS SUFFICIENT TO PREVENT BOILING OF THE SOLUTION; B. THE QUANTITY OF REDUCING GAS PASSED THROUGH THE REACTOR COUNTERCURRENTLY WITH THE AQUEOUS SOLUTION IS IN EXCESS OF THAT REQUIRED FOR STOICHIOMETRIC REDUCTION OF THE METAL VALUES TO BE RECOVERED AND IN SUFFICIENT QUANTITY AND FLOW RATE TO AGITATE THE MIXTURE TO A STATE OF MODIFIED PLUG FLOW IN WHICH LOCALIZED, LIMITED BACKMIXING OCCURS, AND IN WHICH C. THE MIXTURE IS OF HETEROGENEOUS CHARACTER OVER THE LENGTH AND THE REACTOR; THEN SEPARATING THE METAL POWDER TO BE RECOVERED FROM THE EFFLUENT MIXTURE OF SPENT SOLUTION AND SOILDS DISCHARGED FROM THE REACTOR.