Repost: Treatment of turbid ring water in the dust removal system of steelmaking converters
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This post was last edited by cdpulin on 2011-11-28 at 16:15. Hello everyone, I have some questions regarding the dust and wastewater treatment in steelmaking converters, and I hope the experts here can help answer them. Thank you! The method I am using at present is the sodium carbonate softening approach: flocculants and sodium carbonate are added to the water after it has passed through a coarse particle separator, and then a scale-inhibiting dispersant is added in the cold water tank. Using a calcium carbonate hardness meter, the hardness level should be below 100 mg/L. However, the amount of sodium carbonate required is quite large; with a water circulation rate of around 1200 cubic meters per hour, the hardness rises quickly, but it does not drop as rapidly. After treatment, the turbidity of the water exiting the inclined plate sedimentation tank is in the range of 50–80. When the hardness is high, the concentration of P-alkali is 300–500 mg/L, while that of M-alkali is 40–60 mg/L; the pH value is at its optimal level. Are there any better methods for further treatment? . Also, is the level of hardness related to the water temperature after passing through the cooling tower, or to elements such as the grid plates in furnaces or inclined plate sedimentation tanks? Please, thank you all first!
I am also operating a circulation system for the dust removal water from converters. In our approach, we only use coagulants, without adding sodium carbonate. The hardness of this water is generally between 200 and 400. Usually, when the dust removal water from converters is stable, its hardness ranges from 200 to 300 (on a calcium carbonate basis), but its alkalinity is very high, typically ranging from 8000 to 10000 ppm, and sometimes even up to 15000 ppm. Scaling in the system is not severe; even if there is some scaling, it does not cause corrosion. Over a period of 3 years of operation, the thickness of the scale has been around 1 mm, which does not affect production at all. Even in such cases, acid is sometimes used to neutralize the alkalinity, but it’s not possible to adjust it to 10 due to the high cost. Due to the high alkalinity, this system sometimes adds acid online to clean certain pipes and nozzles, but the effect is minimal. The main issue with this type of water is not its hardness, but rather its high alkalinity, which makes treatment more difficult. Of course, the SS levels in both hot and cold water tanks are also well above 20 ppm, and this is due to cost considerations.
Thank you, senior. Also, why does the water in the steelmaking dust removal system turn yellow after adding polypropylene? Could you recommend a book on the circulating water system in steel mills?