Metallic scrap can be generated all along the production flow sheet. It may be generated in large solidified shapes – such as cylinders of steel that has solidified in a ladle or pot, irregular sheets from spillages or pouring, end-crops and other parts of slabs, blooms, billets rods, wire coil and off-specification materials. Larger pieces of material must be processed into manageable sizes for the type of handling system and furnace utilised for re-melting. This material is normally has a very high metallic content. If the steelmill produces a limited number of grades it may not be worth segregating this material into different types. However if there are a wide range of steel qualities produced – particularly if there are any ‘special’ grades produced it may be worthwhile segregating some materials in order to maximise value and/or minimise contamination.
Most of this scrap will be free from coatings but at steel plants with galvanising and or coating lines any scrap from these areas should ideally be segregated and used in suitable heats.
Metal Recovered from Slag
A number of magnetic fractions can be recovered from iron and steel slags. The iron that is recovered from de-sulphurisation slags has a high sulphur content and should be kept separate. Since sulphur is difficult to remove at the steelmaking stage this material should be recycled via the Blast Furnace or used for steel grades that accept higher sulphur contents.
The metal recovered from steel making slag will be of a similar composition to the grades of steel produced. If special grades are produced it may be worth evaluating the segregation of the slag from those heats.
The material recovered magnetically can be upgraded to high metallic contents suitable for recycling to the steelmaking stage or even as ladle coolant material. The magnetic fractions with high iron oxide and low metal contents should be recycled to the Blast Furnace or Sinter plant according to grade and sizing (>60%Fe and > 6mm to the BF, <6mm to the SP).