| 摘要 |
<p>THE PRESENT INVENTION RELATES TO AN IMPROVED PROCESS FOR THE PURIFICATION OF MELAMINE OBTAINED BY SYNTHESIS FROM UREA WHICH COMPRISES THE FOLLOWING STEPS: A) BRINGING RAW MELAMINE CONTAINING IMPURITIES OF POLYCONDENSATES AND OTHER BY-PRODUCTS OF THE SYNTHESIS REACTION, INTO SOLUTION, OBTAINING A SOLUTION/SUSPENSION IN WHICH THE INSOLUBLE PRODUCTS ARE DISPERSED; B) SUBJECTING THE SOLUTION/SUSPENSION THUS OBTAINED TO TREATMENT TO REMOVE THE C02 DISSOLVED, REDUCING ITS CONCENTRATION TO VALUES LOWER THAN 0.5% BY WEIGHT; C) TREATING THE SOLUTION/SUSPENSION OBTAINED IN STEP B) , HAVING A CONTENT OF C02 LOWER THAN 0.5% BY WEIGHT, WITH AMMONIA IN A QUANTITY RANGING FROM 1 TO 15%, PREFERABLY FROM 3 TO 9% BY WEIGHT, AT A TEMPERATURE RANGING FROM 110 TO 180ºC, PREFERABLY FROM 130 TO 140ºC; D) PUTTING THE SOLUTION LEAVING STEP C) IN CONTACT WITH A SOLID CATALYST, UNDER THE SAME CONDITIONS AS STEP C). THE PRESENT INVENTION ALSO RELATES TO THE EQUIPMENT FOR EFFECTING SAID PROCESS.</p> |
