| 摘要 |
<p>PURPOSE: To recover Zn from steel scrap contg. Zn and to recover the steel scrap in a reusable state with good fuel efficiency by heating the steel scrap by using a first heating furnace and second heating furnace in and under a specific atmosphere and temp. conditions. CONSTITUTION: The scrap of galvanized steel sheets is charged into a first rotary furnace 1, where fuel is burnt in an oxygen deficient state of an oxygen ratio of 0.5 to 0.8 from a burner 3 and the scrap is heated by maintaining the in-furnace atmosphere at a reducing atmosphere. The Zn is thus recovered as Zn vapor without oxidation. The high-temp. waste gases contg. noncombustible gases, such as Co, discharged from the first rotary furnace 7 are charged by a duct 5 into a second rotary furnace 2, to which the air is supplied from a nozzle 6 and where the high-temp. Co-contg. waste gases are burned in the state of an oxygen ratio 1. The Zn-contg. steel scrap in the second rotary furnace 2 is preheated to the oxidation temp. of Zn or below by the combustion heat formed in such a manner and the heat quantity possessed by the waste gases themselves, and thereafter, this scrap is transferred into the first rotary furnace 1. The Zn is thus recovered with the excellent thermal efficiency and the Zn-free steel scrap usable as a steel making source is recovered.</p> |
