Iron ore
In cast iron sulfur promotes the formation of white iron. As little as 0.5% can counteract the effects of slow cooling and a high silicon content . White cast iron is more brittle, but also harder. It is generally avoided, because it is difficult to work, except in China where high sulfur cast iron, some as high as 0.57%, made with coal and coke, was used to make bells and chimes . According to , good foundry iron should have less than 0.15% sulfur. In the rest of the world a high sulfur cast iron can be used for making castings, but will make poor wrought iron.
Technological and industrial history of the United States
Although steel is an alloy of iron and a small amount of carbon, historically steel and iron-making were intended for different products given the high costs of steel over wrought iron. The main difficulty with making steel is that its higher melting point than pig or cast iron was not easily achievable in large-scale production until methods that introduced air or oxygen to oxidize the carbon in the molten pig iron were developed, allowing the direct conversion of molten pig iron to molten steel.