Method for producing melamine and co-producing ammine and ammonium hydrogen carbonate

Abstract

The invention provides a melamine production method for co-production of ammonia and ammonium bicarbonate; the method comprises the following steps: the melamine production process, namely, raw material is heated in a melamine reactor through molten salt and transformed into melamine, ammonia and carbon dioxide; the ammonia-carbon separation process, namely, one part of the ammonia-carbon mixturepartially enters into an ammonia-carbon separation system and is heated with steam so as to obtain the carbon dioxide containing 5% of water vapor, and the pure ammonia; the aqueous solution of the other part of the ammonia-carbon mixture is added into a carbonation tower; the carbon dioxide separated from the ammonia-carbon separation system is pumped into the carbonation tower from the bottom and reacted with the aqueous solution of the ammonia-carbon mixture to generate ammonium bicarbonate. The invention has the effects that the production method enables urea to be transformed into three products with greater market demand, uses no additional chemicals and discharges no wastewater, waste gas and waste residue; the atom utilization rate is up to 100% and the production of the method belongs to clean production. Compared with the separate production of any of the three products, the method of the invention has significant technical and economic effects and environmental protection effects.

Description

technical field [0001] The invention relates to a production method of melamine, in particular to a melamine production method for co-producing ammonia and ammonium bicarbonate. The method is for the treatment and utilization of carbonized ammonia water or ammonia / carbon dioxide mixed gas produced in the melamine production process. Background technique [0002] The main chemical reaction to produce melamine with urea as raw material is: [0003] 6H 2 NCONH 2 →C 3 N 6 h 6 +6NH 3 +3CO 2 [0004] No matter what process is used to produce melamine, 809.52kg of ammonia and 1047.62kg of carbon dioxide must be by-produced for every ton of product obtained, and they will be separated from melamine in the form of mixed gas or aqueous solution (hereinafter collectively referred to as ammonia-carbon mixture). The utilization rate is only 35%. [0005] The treatment of ammonia-carbon mixture not only affects the economic benefits of enterprises, but also seriously threatens th...

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Problems solved by technology

Theoretically, the latter is the most economical and effective method, but it affects the water / carbon ratio of the original urea system, and the number of comprehensive utilization is limited

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