A by-product of steel production process is steel slag – waste product depositing on the surface of the furnace. The molten, liquid slag is poured into the slag chamber and using specialized equipment is received from the steel plant and transported outside to cool.
The next step prior to waste processing is to deliver the cooled slag to the point of its processing, i.e. to the production line. In order to receive and transport the molten slag from the current production we use specialized equipment, operated by properly trained staff. At every stage of production it is of great importance to use a half-century’s experience in the slag business in order to provide safe and efficient operations.
Slag processing line consists of a series of belt conveyors, magnetic separators, and double-deck vibrating screens. In Poland, we are currently operating 3 efficient slag processing lines, whose design is the result of over 50 years of experience of our experts in the USA steel plants. The waste which is processed by the production line cannot exceed the size of 300 mm, therefore the slag and large size scrap is initially broken into smaller pieces using a pile driver.
Steel slag is a post-metallurgical waste, consisting of 4% – 11% of metallic constituents, which following the recovery may be reused as input scrap in the steelmaking process. Delivery of the steel slag to the slag processing line initiates the process of separation of magnetic materials (scrap) and non-magnetic (aggregates).
The magnetic material is sorted into appropriate scrap classes according to its size and the percentage of iron content. Afterwards, it is placed on a suitable conveyor belt and stored in the form of small prism-shaped heaps. The result of magnetic separation is steel skull scrap and pig iron scrap, devoid of foreign impurities and constituting a valuable input material for the steel industry.
A similar procedure is employed for the non-magnetic material (slag remaining after separation of the metal), which is subjected to crushing, and the resulting aggregate is afterwards sorted by size into several grain fractions. The result is pure material with appropriate grain fraction to be used in construction of roads of all categories, embankments and general construction.
The resulting product, in the case of slag from current production, still needs ageing in the landfill for at least 6 months in order for it to be safely used in road construction and civil
engineering construction. However, the aggregate produced from the dump slag can be used straight away.