精錬

1. Origins, structure, and basic meaning

• Structure: 精錬 (せいれん) is the noun refining or smelting and the stem of 精錬する.
• Basic usage: 金属の精錬工程 names an industrial process, while 鉱石を精錬する predicates processing ore.

2. Common pitfalls and similar expressions

• Process noun and transitive 精錬する
  • Before 工程 it is linked by の as the type of process; as a verb it takes the ore being treated with を.