Method for recovering and preparing sodium nitrate from nitrification waste liquid

• Main Authors: YAO GUOBIN, CHEN HAIHUA, ZHOU JIANJUN, ZHANG XIANGHUA, ZHENG JINPENG
• Format: Patent
• Language: Chinese; English
• Published: 30.07.2024
• Subjects: CHEMISTRY; COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM,RUBIDIUM, CAESIUM, OR FRANCIUM; INORGANIC CHEMISTRY; METALLURGY; TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE

The invention relates to the technical field of chemical medicines, in particular to a method for recovering and preparing sodium nitrate from nitration waste liquid, which comprises the following steps: neutralizing the nitration waste liquid in the production process of 5-nitroisophthalic acid by using an alkaline metal compound until the pH value is 2-8; evaporating the pH-adjusted waste liquid until the water content of the feed liquid is below 80%; cooling the evaporated material to 10-50 DEG C, preserving heat for 2-8 hours, and filtering to obtain filtrate I and a filter cake I; concentrating the filtrate I until the water content of feed liquid is 70% or below, cooling to 10-50 DEG C, and preserving heat for 2-8 hours; adding sodium carbonate, controlling the pH value of the solution to be 7-10 to obtain a white precipitate, keeping the temperature at 10-50 DEG C for 2-8 hours, and filtering to obtain a filter cake II and a filtrate II; and cooling the filtrate II to 5-20 DEG C, crystallizing and filt