verb · to put food back into the oven to bake again

烧饼凉了，回炉烤一下更酥脆。

noun · to melt down or remelt metals for reprocessing

这些废旧金属需要回炉重新铸造。

verb · to return to education or training to improve one's skills or knowledge

为了适应新的岗位要求，他决定回炉深造。