ph control in acid rinse circuit in flotation of phosphate rock

Claim 1

IN A PROCESS FOR REGULATING AND CONTROLLING THE ADDITION OF A CONCENTRATED MINERAL ACID TO ESTABLISH A PH RANGE BETWEEN 1.5 AND 4 OF AN UNCLARIFIED PHOSPHATE ROCK-OIL FLOAT PRODUCT OF PH GREATER THAN 4, AND FROM WHICH THE BULK OF THE GANGUE HAS BEEN REMOVED, SAID PRODUCT CONTAINING A MIXTURE OF MINOR AMOUNTS OF FLOTATION REAGENTS COMPRISING AN ALKALI METAL HYDROXIDE, A HIGHER FATTY ACID AND FUEL OIL, TOGETHER WITH MAJOR AMOUNTS OF THE UNCLARIFIED PHOSPHATE ORE TO BE TREATED, ADDING SUFFICIENT ACID THERETO, AGITATING THE SO-ACIDIFIED MIXTURE SO AS TO NEUTRALIZE AND OTHERWISE INACTIVATE THE SAID FLOTATION REAGENTS, ADDING SUFFICIENT WATER TO ADJUST THE SOLIDSLIQUID RATIO OF RESULTANT PHOSPHATE ROCK-OIL FLOAT PRODUCT, AND SEPARATING THE PHOSPHATE ROCK SOLIDS FROM THE LIQUID, THE IMPROVEMENT WHICH COMPRISES: CONTINUOUSLY AND AUTOMATICALLY DETERMINING THE PH OF THE LATTER MENTIONED CLARIFIED LIQUID SO-OBTAINED BY THE SEPARATION OF PHOSPHATE ROCK SOLIDS FROM SAID LIQUID, INTRODUCING A MINERAL ACID TO UNCLARIFIED PHOSPHATE ROCK-OIL FLOAT PRODUCT TO BE INTIALLY TREATED, AND THEREAFTER ADJUSTING AND MAINTAINING THE PH LEVEL BETWEEN 1.5 AND 4 OF SAID UNCLARIFIED, ROCK-OIL FLOAT PRODUCT BY AN APPROPRIATE PH SENSOR, SAID SENOR CORRELATING THE PH OF SAID UNCLARIFIED PHOSPHATE ROCK-OIL FLOAT PRODUCT WITH THE PH OF SAID CLARIFIED LIQUID.