Production of melamine

Claim 1

IN A PROCESS FOR THE PRODUCTION OF MELAMINE FROM UREA AS THE STARING MATERIAL THAT IMPROVEMENT WHICH COMPRISES STEP 1, HEATING SAID UREA AT TEMPERATURES OF ABOUT 160*C. TO ABOUT 215*C. IN A LOW PRESSURE ZONE UNDER A PRESSURE NOT SUBSTANTIALLY ABOVE ATMOSPHERIC WHILE REMOVING FROM CONTACT WITH THE MATERIAL BEING HEATED THE GASEOUS REACTION PRODUCTS, PRINCIPALLY AMMONIA, FORMED DURING SAID HEATING, CONTINUING SAID HEATING UNTIL A HOT UREA PYROLYSIS PRODUCT IS FORMED CONTAINING NO LESS THAN 20% AND NO MORE THAN 45% BIUREET, NO MORE THAN 70% UREA AND NO LESS THAN 24% UREA WHEN THE BIURET AMOUNTS TO 45%, PROPORTIONATELY INCREASING TO NO LESS THAN 33% UREA AS THE BIURET CONTENT DECREASES FROM 45% TO 20%, THE REMAINDER OF SAID UREA PYROLYSIS PRODUCT SUBSTANTIALLY CONSISTING OF CYNAURIC ACID PLUS TRIURET AMOUNTING TO AT LEAST 6%, AND STEP 2, PUMPING RESULTING PYROLYSIS PRODUCT AT A TEMPERATURE NO HIGHER THAN 215*C. AT WHICH IT IS FLUID, INTO A HIGH PRESSURE ZONE AND HEATING IT THEREIN UNDER PRESSURES OF AT LEAST ABOUT 500 P.S.I.G. AT TEMPERATURES OF AT LEAST ABOUT 300* C. TO FORM MELAMINE WHILE MAINTAINING THE PYROLYSIS PRODUCT AND REACTION PRODUCTS FORMED IN THE HIGH PRESSURE ZONE IN CONTACT WITH EACH OTHER.