During steel production, an oxide layer arises on the surface. Highly aggressive acids are required to remove this layer. In order to recover the acids, Andritz developed a special spray roasting process a good 20 years ago. After the pickling process, the steel is rinsed with highly purified water. The resulting “rinse water” is a mixture of water and acids. Up until now, no process was available in order to regenerate this mixture. After about five years of research and development in Vienna, and intensive trials at a pilot plant in China, Andritz finally announced a breakthrough in 2014.
In the new technology, the rinse water is neutralized with ammonia, the resulting ammonium flouride, ammonium nitrate and metals are “condensed“. The water is then separated from the salts. The water escapes as steam and the highly concentrated liquid is returned to the Pyromars plant, where the acids are recovered again for the pickling section. The treated water can be used again in the rinsing section. ,
Taiwan will be the location for the premiere of both technologies for industrial purposes. The “world’s first stainless steel plant without complex biological treatment and with 100% nitrate-free wastewater“ is scheduled to be put into operation in the summer of 2016.