US 9,802,848 B2Granted

Method for treating waste saline water produced in production process of diphenylmethane diisocyanate (MDI)

AssigneeWanhua Chemical (Ningbo) Co., Ltd.

InventorsHongke Zhang, Weiqi Hua, Xiaogao Liu, Zhenhua Zhao, Shuchang Sun, Jiansheng Ding, Jianfeng Chen, Pengyuan Zhang, Haikui Zou, Guangwen Chu, Limin Xu

Life of this patent

Estimating the term…

patentgrep

Loading patent…

Abstract

The invention relates to a method of circular use of waste brine produced in the manufacture process of MDI, comprising the following steps: (1) the waste brine produced in the manufacture process of MDI is subjected to a high-gravity extraction and then to a column extraction, wherein said waste brine contains aniline, diaminodiphenylmethane and polyamine; (2) the waste brine from step (1) is transmitted to a stripping tower for steam stripping; (3) the waste brine from the stripping tower of step (2) and a chemical oxidant are transmitted to an oxidation reactor to which air is blown for aeration; (4) the waste brine after the treatment of step (3) is transmitted to an absorption tower for absorption. The invention makes the salt water have TOC of less than 8 ppm and TN of less than 2.5 ppm and achieves regeneration of resources in the waste brine such as sodium chloride and water and the like for circular use.

Claims16

Dependent claims

A method for treatment of waste brine produced in the manufacture of diphenylmethane diisocyanate (MDI), comprising the following steps:

(1) transmitting waste brine produced in a MDI manufacture device and a fresh extractant to a high-gravity rotating bed for fast mixing, wherein said waste brine contains aniline, diaminodiphenylmethane and polyamine, and then separating the extractant and the waste brine in a phase separator;
and then transmitting the phase-separated waste brine and a fresh extractant to an extraction column separate from the MDI device for countercurrent extraction;
(2) transmitting the waste brine out of the extraction column of step (1) to a stripping tower separate from the MDI device for steam stripping;
(3) transmitting the waste brine out of the stripping tower of step (2) and a chemical oxidant to an oxidation reactor to which air is blown for aeration;
and
(4) transmitting the waste brine after the treatment of step (3) to an absorption tower for absorption, and then obtaining qualified salt water.

3 more elements

Dependencies are inferred from the claim text.