Recovering treatment of hydrated hydrazine by-product saline-alkali by urea method

Abstract

A process for reclaiming the salt and alkali as the by-product generated in preparing hydrazine hydrate from urea, sodium hypochlorite and sodium hydroxide by oxidizing method includes such steps as preparing slurry by use of rejected hot water, separating salt slurry from alkali slurry, treating the salt slurry through recovering solid salt, dissolving to become saline, refining and reusing it, treating the alkali slurry through calcining low-grade monohydrated sodium carbonate and absorbing tail gas by water, and reusing the mother liquid to prepare slurry.

Description

technical field [0001] The invention relates to a method for treating by-products in the process of producing hydrazine hydrate by oxidizing urea, sodium hypochlorite and sodium hydroxide, more specifically, a method for recovering and treating the by-product saline in the evaporation process. Background technique [0002] Hydrazine hydrate, also known as: hydrazine hydrate, chemical formula: N 2 h 4 ·H 2 O, molecular weight: 50.07, is a fine chemical product. As a chemical intermediate, hydrazine hydrate has a wide range of potential uses and application fields, which are mainly divided into three aspects: first, the production of plastic foaming agents; second, in the steam cycle of the power industry, it is used to prevent The pipes are rusted and aged in advance, thereby greatly improving the safety and reliability of the power station; in addition, hydrazine hydrate is also an important raw material for medicine and pesticides. Various production...

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Problems solved by technology

[0009] Visible, urea method produces hydrazine hydrate method to have following shortcoming: sodium chloride, sodium carbonate, caustic soda, N 2 h 4 ·H 2 O all have certain economic value, did not realize full recovery in the past, such as disclosed in Chinese patent 00120610.9 "a kind of method for separating hydrazine hydrate containing alkali salt mud" and 01133711.7 disclosed "a kind of method for recovering hydrazine hydrate and steaming salt mud" and 02113204.6 discloses "a method of carbonizing, drying and recovering hydrazine hydrate-containing salt mud", these three methods of treating salt mud are all to separate and utilize sodium chloride and sodium carbonate in salt mud, or convert caustic soda into Sodium carbonate is recycled, but there are still the shortcomings of low by-product recovery rate and incomplete recovery, it is difficult to realize large-scale industrial recycling, as these methods do not recycle the N 2 h 4 ·H 2 O, directly discharged into rivers after being diluted with water, causing a great waste of resources. Simultaneously, the saline-alkali mixture contains a certain amount of hydrazine hydrate and ammonia. If it is directly discharged, the ammonia nitrogen index exceeds the standard by about 300--500 times ( The industrial wastewater discharge standard (ammonia nitrogen index is 15mg / l) and has a high alkalinity (PH value ≥ 11), the pollution to the environment is very serious

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