Separation of salt and alkali from waste salt and alkali residue in production of hydrazine hydrate and technique of cyclic utilization

• Main Author: DAYUAN,CHEN CHEN
• Format: Patent
• Language: English
• Published: 05.07.2006
• Subjects: CHEMISTRY; COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM,RUBIDIUM, CAESIUM, OR FRANCIUM; COMPOUNDS THEREOF; INORGANIC CHEMISTRY; METALLURGY; NON-METALLIC ELEMENTS

This invention describes a process for the recovery and recycle of industrial waste solids, especially the salt-alkali separation and recycle of the waste salt-alkali solids from the manufacturing of hydrated nitriles. This invention uses water, mother liquid and sodium bicarbonate to wash the waste salt-alkali solids from the manufacturing of hydrated nitriles, so that Na2CO3 and NaOH in the waste salt-alkali solids are washed into the solution. The washing solution is then cooled to 0-5deg.C, and filtrated and separated to obtain solid sodium carbonate decahydrate, which can be commercialized after washing. The mother liquid, after separating the solid alkali, is directed to the next process for washing the waste salt-alkali solids without discharge. During the circulatory washing of the waste salt-alkali solids, the table salt keeps in the solid state. After centrifugal separation, the table salt containing 3% of alkali can be obtained and used for sodium carbonate industry. The said table salt NaCl, after washing and separation to remove a small amount of hydrazine and amine, can be used for chlorine-alkali industry. Chlorine Cl2 and sodium hydroxide NaOH are raw materials for sodium hypochlorite NaClO, which is a raw material for producing hydrazine hydrate. In addition, sodium hydroxide is directly involved in the reaction for producing hydrazine hydrate N2H4íñH2O, thus constituting an internal recycling system of a manufacturing plant without discharging, which not only is environmentally friendly but also reduces transportation load and production cost. This invention describes a rational process for large-scale hydrazine hydrate manufacturing plants.