Process and apparatus for producing dense sludges

Claim 1

IN THE TREATMENT OF A BODY OF LIQUID CONTAINING MINERAL MATTER TO REMOVE SUCH MATTER AND PRODUCE A CLARIFIED LIQUID BY CHEMICAL PRECIPITATION REACTION WHEREIN THE LIQUID IS TREATED WITH A PRECIPITANT IN A MIXING AND REACTION ZONE TO PRECIPITATE A LOWER DENSITY SLUDGE IN A CLARIFICATION ZONE, A PROCESS FOR PREPARING A SLUDGE OF A PREDETERMINED HIGH DENSITY FROM THE LOWER DENSITY SLUDGE COMPRISING: (A) WITHDRAWING THE LOWER DENSITY SLUDGE FROM THE LOWER PORTION OF THE CLARIFICATION ZONE AND RETURN RECYCLING SAID SLUDGE TO THE BODY OF LIQUID IN THE MIXING AND REACTION ZONE; (B) ADDING TO THE SLUDGE DURING EACH RECYCLING PRECIPITANT AND ADDITIONAL UNTREATED LIQUID; (C) CAUSING FLOCCULATION OF THE MIXTURE OF RECYCLED AND NEWLY PRECIPITATED SLUDGE; (D) SETTLING OUT THE FLOCCULATED SOLIDS FROM THE LIQUID IN THE CLARIFICATION ZONE AND WITHDRAWING CLARIFIED LIQUID DURING EACH CYCLE; (E) RETAINING ALL THE SLUDGE IN THE PROCESS; (F) CONTINUING THE WITHDRAWAL AND RECYCLING UNDER ADDITION OF PRECIPITANT AND UNTREATED WATER AT LEAST UNTIL A CONDITION IS REACHED WHEREIN THE SLUDGE VOLUME REMAINS CONSTANT WHILE THE WEIGHT CONTINUES TO INCREASE, AND (G) THEREAFTER WITHDRAWING FROM THE PROCESS SLUDGE NO LONGER REQUIRED TO MAINTAIN THE PREDETERMINED HIGH DENSITY.