The metallurgical industry is one of the main industries in various countries and has made great contributions to economic construction. However, the metallurgical industry produces a large amount of waste gas and waste water during production. If not properly treated, it will cause great harm to environmental pollution. Using anionic polyacrylamide to treat metallurgical wastewater, the metal particles in the wastewater are formed into flocculation groups, flocculation and sedimentation are fast, the surface water is clear, and the sewage treatment effect is good.
Source and characteristics of metallurgical wastewater:
Mainly include: cooling water, pickling wastewater, dust removal and coal gas, flue gas washing wastewater, slag washing wastewater and wastewater condensed, separated or overflowed from the production process. Iron and steel metallurgical wastewater contains a large amount of heavy metal ions such as mercury, lead, arsenic, and zinc, as well as BOD, COD, phenol, cyanide, and sulfide. The sewage has the characteristics of complex composition, many suspended particles, and high metal concentration.
Metallurgical wastewater treatment method:
Washing water treatment:
Dust removal wastewater and coal gas and flue gas washing water of metallurgical plants are mainly blast furnace gas washing water, open hearth and converter flue gas washing water, dust removal wastewater from sintering and coking processes,
Non-ferrous metallurgical furnace flue gas washing water, etc. The common characteristics of this type of wastewater are: it contains a large amount of suspended matter, the water quality changes greatly, and the water temperature is relatively high. For every ton of molten iron produced, 2~4 meters of blast furnace gas is discharged
Washing wastewater, the water temperature is generally above 30C, and the suspended solids content is 600~3000 mg/L, mainly iron ore, coke powder and some oxides. The wastewater also contains highly toxic cyanide
And sulfides, phenols, inorganic salts and metal ions such as zinc and cadmium. The suspended solids in the blast furnace flue gas scrubbing water for producing special pig iron (such as ferromanganese, etc.) are difficult to settle, and tailings are usually used
Physical flocculant for flocculation precipitation.
Cooling water treatment:
Cooling water accounts for the largest proportion in metallurgical wastewater. The treatment method is to first remove particles with a particle size of 100 microns or more through a coarse particle sedimentation tank or a hydrocyclone, and then remove the waste
The water is sent to the sedimentation tank to settle and remove suspended particles; to improve the sedimentation effect, polyacrylamide can be added; the floating oil in the water can be removed with a scraper. The wastewater can be recycled after purification and cooling
use. The direct cooling water in the cold rolling workshop contains emulsified oil. It is necessary to use chemical coagulation, heating or pH adjustment to destroy the emulsified oil, and then float and separate, or directly
Then use ultrafiltration to separate. The collected waste oil can be recycled and used as fuel.
Application of flocculant for metallurgical industry wastewater treatment: It has fast sewage clarification, high flocculation of cotton alum, high dehydration rate, deodorization, decontamination, reduction of COD and BOD, and has a good and obvious effect on water purification.
Metallurgical industry wastewater treatment generally adopts oxidation-reduction method, wastewater oxidation-reduction method: the toxic and harmful substances dissolved in wastewater are converted into non-toxic and harmless new substances through oxidation-reduction reaction. This wastewater treatment method is called Redox method of wastewater.
Selection of water treatment chemicals:
Due to the high temperature of metallurgical industry wastewater and a lot of organic matter such as oil, ordinary flocculants can hardly achieve the ideal treatment effect. Many years of experiments by Capitel Chemical have proved that the treatment of metallurgical wastewater using Capitel anionic polyacrylamide is better. Anionic polyacrylamide can quickly form flocculation clusters of metal particles in wastewater, clear surface water and good sludge dehydration, so as to achieve the purpose of sewage treatment.
Instructions for use:
1. The water for dissolving polyacrylamide should be clean water (tap water).
2. The product is usually prepared into 0.05%-0.5% (W/W) solution for later use.
3. When dissolving, the product should be evenly dispersed, and stirring can help dissolve. The stirring speed should not be too fast. If the speed is too fast, the molecular chain of polyacrylamide will be cut and the use effect will be reduced. The general speed is controlled at 60 rpm linear speed.
4. Increasing the water temperature can speed up the rapid dissolution rate, but generally the water temperature should not exceed 50°C.
5. When using, avoid using metal materials and other dissolving tanks and pools that can easily affect water quality.
Metallurgical wastewater mainly includes washing wastewater and cooling water.