brief introduction

        Metallurgical industrial wastewater refers to the wastewater discharged from the production process of metallurgical industry. It is characterized by large amount of water, many kinds of water and complex water quality. According to the sources and characteristics of wastewater, there are mainly cooling water, pickling wastewater, dust removal wastewater, gas, slag flushing water and coking wastewater.

Classification of Metallurgical Wastewater

According to the sources and characteristics of waste water, it mainly includes:

        1. Cooling water. The cooling water of iron and steel plant accounts for about 70% of the total wastewater. The direct cooling water, such as the cooling water of rolling mill roll and roller table, the cooling water of metal ingot and so on, contains oil, scale and other substances in addition to the rising water temperature. Indirect cooling water, such as blast furnace body, hot air path and other cooling water, after use, the water temperature rises and is not polluted by other factors;

        2. Acid washing wastewater. Steel rolling and other metal processing plants produce pickling wastewater, including waste acid and workpiece washing water. 1 ~ 2 m3 of waste water will be discharged from each ton of steel in pickling, which contains free acid and metal ions;

        3. Dust removal wastewater and gas and flue gas washing water. It is mainly blast furnace gas washing water, open hearth and converter flue gas washing water, dust removal wastewater in sintering and coking process, etc. it contains a large amount of suspended solids, the water quality changes greatly, and the water temperature is high. For every 1t hot metal production, 2-4m3 blast furnace gas washing wastewater is discharged. The water temperature is above 30 ℃, and the content of suspended solids is 600-3000mg / L. it is mainly composed of iron ore, coke powder and some oxides. It also contains cyanide, sulfide, phenol, inorganic salt, zinc, chromium and other metal ions;

        4. Slag flushing water. The water temperature is high, and the water contains a lot of suspended solids and a small amount of metal ions;

        5. Coking wastewater. For every 1 t coke produced in a coking plant of a ferrous metallurgical enterprise, about 0.25-0.50 m3 of wastewater containing phenol, benzene, tar, cyanide, sulfide and pyridine is produced.

Treatment process

        According to the characteristics of Metallurgical Wastewater, we use multi effect evaporation process or multi effect evaporation + drying process or multi effect evaporation + crystallization process to treat sewage or wastewater, so that the water separated by evaporation can reach the discharge standard, and the water content of dry matter after evaporation is less than 20%. The problem of sewage and wastewater treatment is not only to make the treated water meet the national allowable discharge standard, but also to reduce the treatment cost