| 摘要 |
<p>PURPOSE:To separate and recover Zn and Sn as ZnO2 and SnO2 from steel scrap contg. the Zn and Sn by evaporating and separating the Zn and Sn as chlorides by decomposition of NH4Cl, then oxidizing the chlorides by steam. CONSTITUTION:The scrap of a steel plate plated with the Zn and the Sn is charged together with fuel into a heating furnace and is heated to 750 to 1000 deg.C in a neutral or weakly reducing atmosphere. The NH4Cl is supplied to the furnace and is decompose to HCl and NH3. The Zn and Sn in the scrap are brought into reaction with the HCl and are evaporated to ZnCl2 and SnCl2, which are captured in a capturing column; thereafter, the capturing furnace is heated to >=750 deg.C while the steam is passed therethrough to oxidize the ZnCl2 and SnCl2 which are separated and recovered as crude oxides, such as ZnO2 and SnO2. The NH3 in the exhaust gas of the heating furnace reacts with the HCI formed by the oxidation reaction of the ZnCl, and SnCl2 and is reutilized for formation of the ZnCl2 and SnCl2 as the NH4Cl. The scrap discharged from the heating furnace is used for iron making raw materials as the high-grade steel scrap without contg. the Zn, the Sn and Fe2O3.</p> |
