Cooling water accounts for a large proportion of metallurgical wastewater. For instance, cooling water makes up 70% of wastewater generated in steel plants, which can be divided into direct cooling water and indirect cooling water. Below, we will briefly introduce the types of metallurgical wastewater together with manufacturers of Online Water Quality Monitors.

As mentioned above, indirect cooling water serves equipment including hot blast valves, hot blast stoves, converters, blast furnace jackets and other metallurgical furnace jackets. Its temperature rises after use. If the water is not contaminated after heating, it can be recycled after cooling. In contrast, direct cooling water is mainly used for metal ingot casting and roller tables. After contact with products, its temperature rises, and the water contains oil, iron oxide and other substances. Discharging such water may lead to sediment accumulation and thermal pollution in water bodies, and floating oil poses significant threats to aquatic organisms.

Metal processing plants such as steel rolling mills produce pickling wastewater containing abundant iron ions as well as small amounts of zinc, chromium and other metal ions, which requires treatment prior to recovery. It should be noted that neutral electrolytic processes adopted for removing iron scale will not generate pickling wastewater. Nevertheless, the electrolyte needs to be treated via filtration or magnetic separation before reuse.

Dust removal wastewater and flue gas washing water from metallurgical facilities mainly include dust removal wastewater from sintering and coking processes, and flue gas washing water from non-ferrous metallurgical furnaces. Wastewater of this category shares common characteristics: high suspended solids, fluctuating water quality, elevated water temperature, and hazardous substances such as cyanide’s, sulfides and phenol’s.

Moreover, wastewater containing heavy metal ions is produced in smelters processing zinc, copper and other metals. It mainly originates from equipment rinsing and smelting flue gas cleaning. Apart from target metals, ores contain a variety of non-ferrous metals, resulting in multiple metal ions and harmful substances in the wastewater.

After gaining a general understanding of metallurgical wastewater categories, operators shall carry out targeted treatment of various harmful substances in wastewater. Online Water Quality Monitoring helps track real-time changes in water quality to guarantee compliant wastewater discharge.