Resource Reutilization Of Steel Pickling Liquors The Preparation Of Nano-sized Iron Oxide

Steel Spent Pickling Liquors (SPL) is produced in the process of steel pickling, which is acidic and contain a large amount of ferric ion. The waste liquors will cause damage harm to environment if it is discharge directly. The traditional treatment of Steel Spent Pickling Liquors is neutralization-precipitation. But, there are problems like unstable effect of treatment, difficulty of sludge discharge and it’s also a waste of resources. Therefore, it is significant to find a way to recycle hydrochloric acid and ferric ion.A new method of recycling pickling waste liquor of hydrochloric is put forward, which is combine vacuum evaporation and the preparation of nano-sized iron oxide and realize the comprehensive utilization both of hydrochloric acid and ferric ion. First, collect regenerate acid while pickling waste liquor of hydrochloric is under vacuum evaporation. Then, collect ferrous chloride crystals from mother liquor after cooling down. At last, add the waste water to ammonia, preparea-Fe2O3 through precipitation, oxidation, desiccation, grind and roast.These following aspects are focused:(1) The effect of vacuum degree, reaction temperature and evaporation capacity was studied with orthogonal experiment. The result showed that the increase of evaporation capacity was beneficial to the improvement of the regenerated acid concentration. The increase of vacuum capacity had no obvious effects on the regenerated acid concentration, but can significantly reduce the boiling point of pickling liquid. Considering the costs and feasibility, the best process parameters were determined through the orthogonal experiment, that vacuum degree is 0.06MPa, reaction temperature is 88℃, and evaporation capacity is 50%.(2) After determine the preparation process of nano-sized iron oxide, investigating the effect of ammonia concentration, Fe2+ concentration, reaction temperature, stirring speed and roast temperature on preparation. Then conduct orthogonal experiment according to the result of primary experiment, make further study of better process parameters. The result shows that the concentration of Fe2O3 in product is up to 98.87% under optimal technological condition. XRD and TEM were made for the final product.(3)According to the test results and the corresponding design specification, make a preliminary design scheme for recycling pickling waste liquor, which discharge waste water 2t/d. The main equipments include evaporator, condenser, crystallizer, reaction kettle, spin flash dryer, etc., all equipment are made by anti-corrosion materials such as glass lining or graphite modified polypropylene. The results of engineering economic analysis shows that the investigation on equipment is 358,300 Yuan, the profit is 150,700 Yuan/a, which can create both economic and environmental benefits.