Resourceful treatment method of TDI industrial wastewate

Abstract

The invention relates to a resourceful treatment method of TDI industrial wastewater. The resourceful treatment method sequentially comprises the following steps: (1) removing calcium and magnesium ions and bicarbonate radicals from mixed miscellaneous salt wastewater rich in sodium nitrate, sodium chloride and sodium sulfate through a pretreatment unit; (2) realizing separation of divalent salt and monovalent salt through a salt separation unit; (3) re-concentrating the divalent salt to enable the concentration of the sodium sulfate solution to reach 9.86%, and performing freezing crystallization in a sodium sulfate freezing crystallization unit at 0 DEG C; re-concentrating the monovalent salt mixed solution to enable the concentration of sodium chloride to reach 4% and the concentrationof sodium nitrate to reach 9.9%; (4) the monovalent salt mixed solution enters a sodium chloride evaporative crystallization unit for multiple-effect evaporation so that sodium chloride is crystallized and separated out and is separated from a sodium nitrate solution; and (5) cooling the sodium nitrate solution by flash evaporation of the sodium nitrate flash evaporation unit, and cooling to normal temperature in the sodium nitrate cooling crystallization unit to crystallize sodium nitrate, and carrying out hot melting crystallization on sodium sulfate, and drying to obtain sodium sulfate withthe purity of 99%. Mixed miscellaneous salt is classified and recycled, the productivity is high, and the quality of crystalline salt is good.

Description

technical field [0001] The invention relates to an industrial wastewater treatment method, in particular to a TDI industrial wastewater resource treatment method, and belongs to the technical field of wastewater resource utilization. Background technique [0002] Toluene diisocyanate (TDI for short) is the main chemical raw material in the polyurethane industry and is widely used in the production of polyurethane series products such as sponges, high-grade paints, high-grade adhesives, and high-resilience elastomers. [0003] In the production process of TDI, a large amount of wastewater will be generated: red water, hydrogenated water, organic wastewater, inorganic wastewater, acidic water, etc. The wastewater has the characteristics of high salt content, high aniline concentration, high chroma and high content of refractory organic matter. [0004] For this kind of wastewater, a single biochemical method and conventional chemical method are traditionally used for treatmen...

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Problems solved by technology

At present, mixed miscellaneous salts have been classified as hazardous waste and require special disposal, which increases the pressure on environmental protection of enterprises and the cost of wastewater treatment

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