Hot rolled strip steel will form surface iron scale in the process of high temperature coiling, and the iron scale must be removed (phosphorus removal) in the production. The commonly used method of phosphorus removal is pickling, but pickling will produce a large amount of waste acid, residue and cleaning solution, which will pollute the environment. At present, the technology of free pickling is highly recommended, one of which is mechanical phosphorus removal.
Specifically divided into:
1. SCS, smooth and clean surface technology
The principle of the smooth clean surface technology is that in a closed space, according to the thickness of the plate roll, the Fe2O3 and Fe3O4 of the iron sheet on the surface of the steel sheet are washed off by the grinding roller which is automatically adjusted up and down, leaving only the FeO layer, and the iron sheet is washed off by the circulating filtration water. The surface of the steel plate was washed continuously by grinding and filtering circulating water, and finally FeO sheet iron with thickness of about 7 m was formed.
The SCS technology was first proposed by Nippon Steel in Japan and patented in TMW in the United States. It was successfully applied to plate production in 2003 and further promoted to coil production in 2006. At present, there are 12 production lines in Europe and America using this technology for surface treatment, stretching straightening, trimming, leveling, etc.
2. Surface ecological pickling technology EPS
The basic principle of surface ecological pickling technology is to use abrasive (the mixture of steel sand and water) to spray the upper and lower surface of plate coil to remove surface iron scale, so as to avoid pickling. Stainless steel gravel abrasive, can achieve phosphorus removal effect, but the cost is higher. And carbon steel gravel abrasive, adding high PH additives, that is to reduce the cost and effectively prevent carbon steel gravel corrosion.
In 2007, TMW company developed EPS technology and constructed the first EPS processing line. In 2010, JAS, a South Korean company, purchased the technology from TMW company for the phosphorus removal of Steel pipe, and then promoted it to Stripco of the United States and Steel Technologies of South America. Recently, Hemnil of India and Tisco of China respectively introduced EPS technology from TMW company and put it into production.
Mechanical phosphorus removal technology has unique advantages in energy saving, energy saving and cost reduction. It has a strong development prospect and will gradually replace the traditional pickling technology