Process for the production of potassium sulfate

Claim 1

IN A CONTINUOUS PROCESS FOR THE PRODUCTION OF POTASSIUM SULFATE BY REACTION OF POTASSIUM CHLORIDE IN AQUEOUS SOLUTION WITH KALIMAGNESIA, THE IMPROVEMENT COMPRISING (A) MIXING ABOUT ONE-THIRD OF THE TOTAL AMOUNT OF SULFATE LIQUOR WHICH IS OBTAINED FROM AN EXTRANEOUS RECTION OF POTASSIUM CHLORIDE WITH KALIMAGNESIA AND SUBSEQUENT SEPARATION OF THE RESULTING POTASSIUM SULFATE FROM THE REACTION MASS, WITH KIESERITE AT A TEMPERATURE OF ABOUT 50 TO 80*C., WHEREBY A FIRST PORTION OF KALIMAGNESIA AND A FIRST MOTHER LIQUOR ARE PRODUCED IN THE ENSUING REACTION, (B) MIXING THE REMAINING PORTION OF THE AFORESAID TOTAL AMOUNT OF SULFATE LIQUOR WITH A MEMBER SELECTED FROM THE GROUP CONSISTING OF ANHYDROUS MAGNESIUM SULFATE AND EPSOMITE, AND WITH AN INTERMEDIATE MIXED SALT OBTAINED IN A PREVIOUS RUN IN STEP (E) BELOW, AT ABOUT A TEMPERATURE OF 40 TO 60*C., WHEREBY ANOTHER PORTION OF KALIMAGNESIA AND A SECOND MOTHER LIQUOR ARE OBTAINED IN THE ENSUING REACTION, (C) SEPARATING SAID PORTIONS OF KALIMAGNESIA FROM SAID FIRST AND SECOND MOTHER LIQUORS AND COMBINING THE LATTER, (D) EVAPORATING ABOUT 30 TO 50% OF THE WEIGHT OF SAID COMBINED MOTHER LIQUORS, THEREBY FORMING IN PRECIPITATE OF SAID INTERMEDIATE MIXED SALT IN AN END LIQUOR POOR IN POTASSIUM CHLORIDE, AND (E) SEPARATING SAID INTERMEDIATE MIXED SALT FROM SAID END LIQUOR AND INTRODUCING THE FORMER INTO RECTION WITH SAID REMAINING PORTION OF SULFATE LIQUOR IN SETP (B).