Multiple effect, gravity classification crystallization method and apparatus

Claim 1

IN A CRYSTALLIZATION PROCESS, THE STEPS OF PASSING THROUGH A PLURALITY OF CONSECUTIVE TREATMENT STAGES MAINTAINED AT PROGRESSIVELY DECREASING TEMPERATURES A STREAM OF A CONCENTRATED AQUEOUS OF CRYSTALLIZABLE MATERIAL THE SOLUBI.ITY OF WHICH IN SAID AQUEOUS PROGRESIVELY DECREASES AT THE PROGRESSIVELY DECREASING TEMPERATURES MAINTAINED IN SAID CONSECUTIVE TREATMENT STAGES SO AS TO CAUSE IN EACH OF SAID TREATMENT STAGES FORMATION OF SMALL CRYSTALS WHICH UPON PASSAGE INTO THE FOLLOWING TREATMENT STAGES WILL INCREASE IN SIZE SO AS TO FORM LARGER CRYSTALS, SAID STREAM OF CONCENTRATED AQUEOUS BEING MOVED IN UPWARD DIRECTION AT EACH OF SAID CONSECUTIVE TREATMENT STAGES AT A SPEED SMALLER THAN THE SPPEED AT THE PRECEDING TREATMENT STAGE SO AS TO FORM AT EACH TREATMENT STAGE AN UPWARDLY DIRECTED STREAM PORITON MOVING UPWARDLY AT A SPEED WHICH IS SMALLER THAN THE SPEED OF UPWARD MOVEMENT AT THE PRECEDING TREATMENT STAGE BUT GREATER THAN THE SPEED OF UPWARD MOVEMENT AT THE FOLLOWING TREATMENT STAGE SO THAT AT EACH OF SAID TREATMENT STAGES THE SIZE OF SAID LARGER CRYSTALS WHICH WILL BE ADAPTED TO MOVE DOWNWARDLY IN SAID UPWARDLY DIRECTED STREAM DUE TO THEIR WEIGHT WILL BE GREATER THAN THE SIZE OF DOWNWARDLY MOVING LARGER CRYSTALS IN THE UPWARDLY DIRECTED STREAM OF THE FOLLOWING AND SMALLER THAN AT THE PRECEDING TREATMENT STAGE; REINTRODUCING SAID DOWNWARDLY MOVING LARGER CRYSTALS FROM EACH OF SAID TREATMENT STAGES INTO THE IMMEDIATE PRECEDING TREATMENT STAGE AT A POINT LOCATED UPWARDLY OF SAID UPWARDLY DIRECTED STREAM PORTION IN WHICH SAID THUS REINTRODUCED LARGER CRYSTALS DUE TO THEIR LARGER SIZE WILL ALSO MOVE DOWNWARDLY IN A DIRECTION OPPOSITE TO THE FLOW OF THE RESPECTIVE UPWARDLY DIRECTED STREAM PORTION THEREBY FURTHER INCREASING IN SIZE; AND REPEATING SAID REINTRODUCTION OF LARGER CRYSTALS FROM ANY TREATMENT STAGE INTO THE PRECEDING TREATMENT STAGE AT A POINT LOCATED ABOVE SAID UPWARDLY DIRECTED STREAM PORTION UNTIL SUBSTANTIALLY ALL OF SAID LARGER CRYSTALS WHILE GROWING LARGER ARE ACCUMULATING AT A POINT OF THE FIRST ONE OF SAID CONSECUTIVE TREATING STAGES LOCATED BELOW SAID UPWARDLY DIRECTED STREAM PORITON THEREOF.