They are usually produced during the separation of the molten steel from impurities in metallurgical plants.
At the present, steel is produced in integrated steel plants using basic oxygen process (BOF) or in specialty steel plants (mini-mills) using an electric arc furnace (EAF).
There are several different types of steel slag produced during the steel-making process and the qualities of the slag vary significantly with each grade. Grades of steel can be classified as high, medium, and low, depending on the carbon content of the steel.
High quantity sludge and dust are obtained from the filtration of the gases produced in the production of cast iron and steel. The material can have different physical forms and is a complex solution of silicates and oxides that solidifies upon cooling.
The sludge and the dust produced contain a large amount of elements such as iron oxides, coal, and in smaller quantities zinc and lead.
Metallurgical sludge can be defined as non-metallic by-product consisting of compounds of silica, alumina, lime, magnesia, iron oxides and manganese oxides, developed during the refining of crude iron products to steel. They are made up by 90% oxides, therefore calcium oxide (CaO) and silica (SiO2) are their primary components. Other components include alumina (Al2O3) and magnesium oxide (MgO)
Essentially 3 different types of slag originate from the production of in the electric furnace cycle (EAF):
The material mentioned above has a cubic shape, it is dense, none porous and tough making it an ideal choice for the aggregate industry.
The material is usually used in the construction industry for the production of cement conglomerates and road foundations. Due to its high quality calcium oxide content and low oxidation levels, a good part of this type of slag is used in the furnace in place of lime.
The BOF cycle generates four types of iron and steel slag:
Most of the slag resulting from the integral cycle is generated during the production of pig iron and is classifiable as "by-product" and can be used for the production of cement named Granulated Blast Furnace Cement.
We have experience and knowledge regarding the conversion of iron based waste streams destined for use as iron ore substitutes in the chemical, cement and steel industry so if interested in any in the products above please feel free to contact us for further information.