The limestone absorb impurity from the ore and form a fluid slag which floats on the surface of the heavier molten iron.
石灰石吸咐了铁矿石中的杂质，形成浮在较重的铁水表面上的流动渣。
Material, such as gravel or slag, from which metal is extracted in mining.
矿渣诸如砂砾或矿渣等物质，可从中提取金属
Some come off in the form of gases, others collect as slag.
有的化成气体跑掉了，有的结成了熔渣。
