| 摘要 |
A process for the purification of melamine, deriving from urea, according to a high pressure non catalytic process, by means of polycondensates and other by-products transformation, which by-products derive from the melamine synthesis comprosing the following steps: dissolving in water the raw liquid melamine containing polycondensates and other melamine synthesis by-products, subjecting such solution to a treatment capable to remove dissolved CO2 limiting its concentration to a value lower than 0.5 wt. %, submitting raw melamine solution, to the action of ammonia, in an amount of 5 to 25 wt. %, at a temperature of 100 to 250° C. and leaving the mixture to react for some minutes, recoving a solution having polycondensates concentration lower than 1000 ppm, typically less than 100 ppm.
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