| 摘要 |
PURPOSE:The waste acid, after iron-pickling, is heated by heat-exchange with the oxygen-containing waste gas to effect the concentration of the waste acid to near the saturation point of iron chloride, thus the soluble silicon is insolubilized, filtered off, then pyrolysis is effected to recover high-purity iron oxide and hydrochloric acid. CONSTITUTION:The iron-pickling waste acid resulting from passing iron plates through the hydrochloric acid bath for pickling oxidized surfaces is brought into contact in the heat exchanger with the high-temperature oxygen-containing waste gas from the roaster to raise its temperature up to 60 deg.C to the boiling point, further, waste is circulated under contact with the high temperature gas and effect the concentration of the solution until the content of iron chloride reaches 35% to the saturation point. Consequently, the soluble silicon precipitates. After filtration, the filtrate is heated up in the range from the decomposition point of iron chloride to 950 deg.C to recover iron oxide of less than 0.007 SiO2/Fe2O3 and 2.9-2.4 compression density as well as high-purity hydrochloric acid. |
