open-hearth furnace with roof oxygen lance

例句：

1. 1. Theopen-hearth furnace is a type of steelmaking process that uses coal as fuel.
   开放式平炉是一种使用煤炭作为燃料的钢铁制造过程。
2. 2. The open-hearth furnace is an essential tool for metallurgical engineers in the production of steel.
   开放式平炉是冶金工程师在生产钢铁过程中不可或缺的工具。
3. 3. The open-hearth furnace is used to produce high-quality pig iron and ferroalloys.
   开放式平炉用于生产高质量的生铁和合金钢。