Metals such as Steel and Iron are extracted from ores. These ores contain impurities such as silicates. To remove them, quicklime is added to the ores, and the mixture is melted at high temperatures. The silicates bond with the lime to form a liquid called slag, which is immiscible with the molten metal. This slag, which is full of impurities, can be easily drained out, leaving behind the purified metal.