Stainless steel pickling wastewater treatment process
In the treatment of ferrous sulfate method, this method is characterized by the reuse of iron in the waste liquid. Therefore, researchers have paid attention to it and gradually formed a more mature practical technology. Through the sulfuric acid solution, the use of ferric sulfate treatment, can receive better results, and has been put into production practice. Especially concentrated - Filtration - natural crystallization method known as iron method, the first full reaction of sulfuric acid waste iron filings and placed in a reaction vessel, then the solution is heated to 100 DEG C, the reaction 2h, then heating the concentrated after natural cooling, the ferrous sulfate crystallization, and finally by the dryer drying dehydration. This method can be used to recover low, medium and high grade ferrous sulfate from acid washing wastewater for industrial, agricultural, pharmaceutical and chemical reagents. Has the advantages of simple and easy operation, less investment, low cost, but only recycled ferrous sulfate, sulfuric acid can not be recovered, small processing capacity; poor product quality, long production cycle, is suitable for the production of small township enterprises.
The waste acid solution is sprayed on the burning flame by a nozzle with high atomizing efficiency, and the moisture content is evaporated. Generally, about 35% of sulfuric acid and part of FeSO4 H2O are obtained. The operating principle is that the evaporator and the crystallizer are kept at a certain vacuum by means of a steam ejector and a condenser. When the temperature is suitable for waste water through, the water evaporation in the adiabatic condition, thus concentrated waste, reducing waste water temperature, decrease the solubility of ferrous sulfate, it increases the degree of supersaturation. At the same time, the degree of supersaturation of ferrous sulfate is further increased due to the addition of sulfuric acid in the evaporator. In this case, the crystallization of ferrous sulfate is precipitated. This method requires that the material used has higher corrosion resistance, easy to produce two pollution or unstable operation, and can not be normal production. In addition, according to the ecological concept to establish a centralized online monitoring system of pollution control, sewage drainage system, strictly implement the "rain sewage diversion, sewage diversion" principle, fully consider their own laboratory, monitoring equipment at the same time, establish and improve the monitoring network and the environmental protection department joint supervision platform, improve the level of environmental monitoring, to prevent stealing occurs row, row leakage phenomenon, to ensure a stable discharge sewage, pollution control and achieve economic and social win-win "".
