Water treatment in steel mills covers a wide range, including blast furnace wastewater treatment, converter wastewater treatment, boiler water treatment, cold rolling, hot rolling, and formed steel treatment, etc. There are also factors such as equipment and processes. Therefore, there are certain differences in the selection of chemicals.
Anionic polyacrylamide is specially used as a flocculant to treat the wastewater produced by steel mills. Anionic polyacrylamide, as long as it is applied in industrial wastewater treatment, has a very good effect on the treatment of suspended particles, particles with high concentration and positive charge, wastewater with neutral or alkaline PH value, wastewater from steel mills, electroplating plants, metallurgical plants, coal washing plants, etc.
The working principle of polyacrylamide specifically designed for steel mills
1) The principle of flocculation: When polyacrylamide is used for flocculation, it is related to the type and surface properties of the flocculated substances, especially the zeta potential, viscosity, turbidity and PH value of the suspension. The zeta potential on the particle surface is the reason for the particle's resistance to aggregation. Adding polyacrylamide with opposite surface charge can reduce the zeta potential and cause aggregation.
2) Adsorption bridging: The polyacrylamide molecular chains are fixed on the surfaces of different particles, forming polymer Bridges between the particles, causing the particles to aggregate and settle.
3) Surface adsorption: Various adsorptions of polar groups on polyacrylamide molecules to particles.
4) Reinforcing effect: Through various mechanical, physical and chemical actions, the polyacrylamide molecular chains connect the dispersed phase together, forming a network, thereby exerting a reinforcing effect.
Notes:
1. Dissolution temperature. Dissolution requires a certain temperature to accelerate the dissolution rate. However, if the temperature is too high, it will cause the molecular chains of the polymer to break, reducing the application effect. The more suitable dissolution temperature is 50 to 60 degrees Celsius.
2. Stirring conditions. Dissolution should avoid excessive shear force stirring. Excessive stirring can cause the molecular chains to break, thereby reducing the application effect. Stirring should preferably use low-speed impellers, such as anchor type, frame type, multi-layer impeller type, etc. The stirring speed is about 60 revolutions per minute. When transporting, high-speed centrifugal pumps should also be avoided. Piston pumps or diaphragm pumps are more suitable.
3. Evenly distribute the feeding materials. The key step in dissolving polyacrylamide is the uniform dispersion of the feedstock. After starting the mixer, it is advisable to use a mechanical vibrating screen for feeding (with a mesh size of 10) to avoid the formation of "large lumps" or "fish-eye" insoluble particles as much as possible, so that the polyacrylamide can be fully dissolved and achieve the best application effect.
4. Avoid contact with iron. In the dissolution, stirring, conveying and dosing system, materials such as plastic, enamel, aluminum and stainless steel are adopted.
