Process for recovering tungsten values from tungsten-bearing ore

Claim 1

A PROCESS FOR RECOVERING TUNGSTEN VALUES FROM A TUNGSTEN-BEARING ORE CONTAMINATED WITH MOLYBDENUM COMPRISING LEACHING SAID TUNGSTEN-BEARING ORE WITH AN EXCESS OF A SODIUM CARBONATE SOLUTION TO PRODUCE AN AQUEOUS LEACH LIQUOR, ADDING SODIUM HYDROXIDE TO SAID LEACH,LIQUOR TO PRODUCE A SOLUTION HAVING A PH OF AT LEAST ABOUT 12? COOLING THE LEACH LIQUOR TO A TEMPERATURE BELOW 0*C. BUT NOT BELOW ABOUT -8*C. WHEREBY ICE AND SODIUM COARBONATE DECAHYDRATE ARE PRECIPITATED FROM SOLUTION, SEPARATING THE PRECIPITATED SOLIDS FROM THE AQUEOUS SOLUTION, PREPARING ADDITIONAL AQUEOUS SODIUM CARBONATE SOLUTION FROM SAID PRECIPITATED-AND-SEPARATED SOLIDS AND RECYCLING SAID AQUEOUS SODIUM CARBONATE SOLUTION FOR THE LEACHING OF ADDITIONAL TUNGSTEN ORE, ADDING SOLUBLE SILICON AND SOLUBLE FLUORIDE TO THE CONCENTRATED SUPERNATANT SOLUTION REMAINING AFTER THE ICE-SODIUM CARBONATE DECAHYDRATE SEPARATION WHEN THE MOLE RATIO OF SOLUBLE SILICON TO MOLYBDENUM PLUS TUNGSTEN IS LESS THAN 1 TO 12 AND THE MOLE RATION OF SOLUBLE FLUORIDE TO SOLUBLE SILICON IS LESS THAN 6 TO 1 AND CONTINUING SAID ADDING UNTIL THE MOLE RATION OF SOLUBLE SILICON TO MOLYBDENUM PLUS TUNGSTEN IS AT LEAST 1 TO 12 AD THE MOLE RATION OF SOLUBLE FLUORIDE TO SOLUBLE SILICON IS AT LEAST 6 TO 1, ACIDIFYING SAID CONCENTRATED SUPERNATANT SOLUTION WITH AT LEAST ONE ACID SELECTED FROM THE GROUP CONSISTING OF HYDROCHLORIC ACID, SULFURIC ACID AND PHOSPHORIC ACID TO A PH BELOW ABOUT 6, CONTACTING THE ACIDIFIED SOLUTION WITH AT LEAST ONE SUBSTANTIALLY WATER-IMMISCIBLE ORGANIC SOLVENT SELECTED FROM THE GROUP CONSISTING OF LOWER ALIPHATIC KETONES AND LOWER ALIPHATIC ESTERS WHEREBY TUNGSTEN VALUES ARE TRANFERRED FROM THE AQUEOUS SOLUTION TO THE ORGANIC SOLVENT, SEPARATING THE PREGNANT ORGANIC SOLVENT FROM THE AQUEOUS SOLUTION? PASSING DRY AMMONIA THROUG THE PREGNANT ORGANIC SOLVENT WHEREBY THE TUNGSTEN VALUES ARE PRICIPATED AS AMMONIUM PARATUNGSTATE, SEPARATING AMMONIUM PARATUNGSTASTE FROM THE ORGANIC SOLVENT, ROASTING THE SEPARATED AMMONIUM PARATUNGSTATE TO TUNGSTEN OXIDE? AND RECOVERING, PURIFYING, DRYING, AND RECYCLING GASEOUS AMMONIA EVOLVED DURING SAID ROASTING OF AMMONIUM PARATUNGSTATE.