Steel making slag

                          Steel making slag Steel making slag is defined as the solid material resulting from the interaction of flux and impurities in the smelting and refining of steels. It is a by product of steel making. It is produced during the separation of the molten steel from impurities in steel making furnaces. The slag occurs during steel making in liquid state. It is a complex solution of silicates and oxides that solidifies during cooling. Steel making slag is mainly calcium alumino silicate. This compound contains elements like sulfur, selenium, carbon, cadmium, lead, copper, and mercury. Many of the residuals are encased within a glassy matrix. The matrix is soluble and releases calcium and manganese oxides, which can increase the pH of the dissolving fluid to 10 or 11. As slag is a coarse glass, it maintains high permeability (~4.5 x 10-2 cm/sec) regardless of how much water has passed through it. The permeability of the slag is reduced when it is compacted or grounded into smaller particles. Unlike lime, steel making slag does not absorb CO2 from the air and convert back to relatively insoluble limestone. This is an important property. Because of this property steel making slag, when left outside exposed to the atmosphere for years, achieves high levels of alkalinity upon dissolution. The neutralization potential (NP) of steel making slag is in the range of 45 % to 78 %. Most of the residuals are in the form of alumino silicates and iron oxides Steel making slag aggregates usually exhibit a tendency to expand. This is due to the presence of free lime and magnesium oxides which have not reacted with the silicate structures and which can hydrate and expand in humid environments. This potentially expansive nature (volume changes of up to...