Why iron ore is limestone? Chemistry
Iron ore to join the principle of limestoneIron ore used in iron ore, mainly hematite (the main component is iron oxide) and magnetite (the main component is iron oxide), iron ore also contains useless gangue, the main ingredient is Silica (SiO2). Iron, the reduced iron becomes liquid at high temperatures, and the particles with high melting point of silicon dioxide are mixed in the molten iron. In order to remove this impurity, the choice of limestone as a flux, limestone at high temperature decomposition into calcium oxide and carbon dioxide.
Limestone pyrolysis of CO2 can react with C to obtain CO for ironmaking CaO for the formation of slag
Analysis: Ironmaking process by adding limestone, with iron ore in the melting point of high gangue (silica) reaction, the formation of silicate and remove. Thereby reducing the impurity content in the pig iron.Because the iron when there will be sulfur dioxide and other harmful gases generated into the calcium carbonate can be neutralized to reduce the harmful gas escape
Calcium oxide reacts with silica at high temperature to produce calcium silicate with a lower melting point than that of molten iron. The density of liquid calcium silicate is smaller than that of hot metal and is not miscible with molten iron and floats on molten iron. Open the blast furnace on the slag mouth, liquid calcium silicate first flow out, solidification into blast furnace slag. In the past, this kind of blast furnace slag was discarded as a waste of ironworks. Both destroyed the field, but also pollute the environment. Now blast the blast furnace slag into cement, the past waste into today's building materials.
