It was learned from the China Epoxy Resin Industry Annual Meeting held recently that the China Epoxy Resin Industry Association is promoting environmentally friendly processes in a more in-depth manner, promoting cleaner production, promoting industrial structural adjustment and industrial upgrading.
It is understood that in November 2011, the "Comprehensive List of Environmental and Economic Policies (2011 Edition)" issued by the Ministry of Environmental Protection included "epoxy resins with a bromine weight ≥ 18% and a bromine weight <18%" in high pollution and high environment The risky "double-high" products mean that most epoxy resins will be limited in output and variety, causing great shocks in the industry. Many companies worry that export, expansion and technological transformation will be affected.
The industry association believes that its positive significance is to help companies increase investment in environmental protection, promote cleaner production processes, and promote the concentration of small and medium-sized enterprises in the development of chemical parks, so that the "three wastes" are comprehensively used and effectively treated.
But the association also proposed that aerospace, defense military, electrical and electronic, construction engineering, petrochemicals, shipbuilding, automobiles, wind power, transportation, food, home improvement furniture, sporting goods, etc. are inseparable from the use of epoxy resins. If all epoxy resin products are included in the "double height" without distinction, it is not conducive to the healthy development of the industry and even the national economy. Judging from the current actual situation, most epoxy resin products do not have the "double height" feature, mainly because they may cause pollution during the production process. At present, existing enterprises have mastered mature technology and can effectively deal with Discharge.
According to reports, after continuous efforts, the industry has achieved initial results in the implementation of cleaner production processes in six areas, making the industry more clear from the "double high" prospect.
Firstly, for the wastewater containing epichlorohydrin produced during the reaction, some production enterprises adopt the method of rectification, which can effectively extract epichlorohydrin in the wastewater and recycle it.
Secondly, in view of the large amount of waste water generated in the washing process in the production process of epoxy resin, it is difficult to treat. Some companies use multi-effect evaporation to extract sodium chloride in waste water as industrial salt for printing and dyeing industries Most of the evaporated wastewater is returned to the production process for recycling. After a small amount of excess wastewater is further biochemically treated, the COD concentration can be reduced to below 80 mg/liter. Some companies are experimenting with the direct application of high-concentration brine to the production of ion-exchange membrane caustic soda. The produced caustic soda products can be recycled for epoxy resin production.
The third is for the wastewater containing toluene and epichlorohydrin generated by the operation of vacuum pumps. Some enterprises use vacuum pump circulating water closed-circuit circulation to separate the vacuum pump circulating water separately for the preparation of low-concentration caustic soda to participate in the reaction or biochemical treatment. Do not pollute the entire circulating water system. In addition, a few enterprises have upgraded their equipment and adopted imported dry vacuum pumps instead of ordinary water ring vacuum pumps. Because there is no need to circulate water to cool the vacuum pump, this part of the wastewater pollution problem has been completely solved.
Fourth, for high-concentration waste gas containing organic solvents such as toluene and epichlorohydrin, many enterprises have adopted the method of activated carbon fiber adsorption, which can not only meet the emission standards but also recover the solvent.
Fifth, the waste solids are treated by incineration.
Sixth, the solid epoxy resin is produced using a two-step addition process, without producing "three wastes".
Through the promotion of the above six aspects of the process, together with strict and effective biochemical treatment measures, some epoxy resin manufacturers have been able to achieve the "three wastes" all discharge standards, to meet the requirements of cleaner production. The proportion of enterprises and production capacity in this part of the industry has reached about 25% and 60% respectively.
In the next few years, industry associations will strongly recommend cleaner production processes, namely one-step desalination process and two-step addition process. The typical product of the former is bisphenol A liquid epoxy resin, which is widely used in the epoxy resin industry and has a large output; the latter is mainly used to produce solid epoxy resin.
It is understood that the one-step desalination process is characterized by separate collection and treatment of wastewater generated in production. Because the salt-containing wastewater contains high-concentration salts, as well as alkali and aging substances, it cannot be directly biochemically treated. Therefore, the epoxy resin and solvent in the water should be extracted and recovered first. Hydrochloric acid is neutralized to neutral, and then physical and chemical treatments such as flocculation, precipitation, and filtration are used to remove particulate matter. The clear liquid enters the multi-effect evaporation device, the salt is used in printing and dyeing industries, and the distilled water can be recycled. The two-step addition process is characterized by low organic chlorine content, low energy consumption, and no by-products, which eliminates the generation of "three wastes" from the source.
Practice has proved that through the use of one-step desalination process and two-step addition process, a number of large domestic enterprises such as Kunshan Nanya, Guangzhou Hongchang, Lanxing Nantong Xingchen, Yangnong Jinhu, Kingboard Chemical, Changshu Changchun, Jiangsu Sanmu, etc. Achieved cleaner production and stepped out of the circular economy production model.
In addition, the reporter also learned that some areas where industries are concentrated have implemented industrial upgrading under the leadership of local governments. For example, in the Huangshan area where the one-step solid epoxy resin production is concentrated, the original factory has many sites, small scale, and serious pollution. Today, the local area has adopted the model of establishing a circular economy park to concentrate small and medium epoxy resin production enterprises in the park Establish pollutant treatment and discharge solid and liquid pollutants in a unified manner to meet the standards. This approach also provides new ideas for the healthy development of the industry.