Pick any two reports on ferrous scrap, and the chances are that they will use three different words to describe ‘home’ and ‘internal’ scrap. If they use the terms home or internal scrap at all they will probably use them to refer to the same thing. Take the following examples:

Home Scrap

• “Waste steel that is generated from within the steel mill, through edge trimming and rejects. It normally is sent directly back to the furnace” (The Association for Iron and Steel Technology)
• “Excess steel that is generated at a mill and often routed back to the furnace” (Recycling Today)
• “Scrap generated within a steel production facility and captured prior to exiting the facility [… ] (Note: Scrap generated by a downstream process in the same facility may be classified as ‘new scrap.’)” (Determination of Steel Recycling Rates in the US)
• “Also known as internal scrap, [home scrap] is the scrap generated within the steel mill during the production process (comes from trimming, cut-offs, etc.)”. (Circular Steel: a system perspective on recycled content targets)
• “Scrap steel generated due to the imperfect yields of steelmaking, rolling and finishing processes within a site. Synonyms include return scrap, internal scrap and semi-manufacturing scrap” (Iron and Steel Technology Roadmap: towards more sustainable steelmaking, IEA, 2020)

Internal Scrap:

• “Internal scrap is the scrap accruing in the production of steel. It is recycled directly in steelworks and foundries” (Scrap Bonus: external costs and fair competition in the global value chains of steelmaking)
• “Also known as revert or home scrap. [Internal scrap] refers to the reject metal within the steel plant which gets generated during steel making, steel casting and steel finishing activities within the steel plant” (worldofsteel)

In contrast, the ISO 20915 standard defines home and internal scrap as two distinct categories – see ‘What is Scrap’. So why does ISO 20915 make a distinction, and why might it matter?

The answer is that two terms are needed because they serve different purposes.

If a steelmaker needs to control the quantity of scrap in the charge for the blast furnace, it needs to count all kinds of scrap in the measurement, irrespective of the point in the steelmaking process at which it was generated. That will include any scrap generated before the steelmaker measures how much crude steel it has produced.

However, a steelmaker might also want to make claims about the recycled content of its steel. If scrap generated during the production of the steel itself is counted as scrap, then the greater the reject rate in the production process, the higher the scrap content. Inefficient production would support claims of high recycled content, which could be considered highly misleading. The same issue needs to be addressed when calculating steel sector recycling rates – the inclusion of scrap generated during the production of steel itself would artificially inflate the figures. The authors of the report ‘Determination of Steel Recycling Rates in the US’ are careful to exlude it from their calculations, for that reason.

The inclusion of scrap generated during the production of crude steel would similarly distort the calculation of the carbon footprint for steel products, a factor addressed by worldsteel in its treatment of scrap in its assessment of life cycle inventory for steel.

In other situations, consistency is key. The quantity of scrap used as an input can be crucial when it comes to comparing the performance of different steelmakers in reducing greenhouse gas emissions. That is why the ResponsibleSteel production standard takes account of the recycled content of the steel in evaluating greenhouse gas emission performance. It is essential in that case for the same rules for counting scrap to be applied when setting the performance levels as are then used for assessing their achievement.

In summary, there are a number of situations when a clear distinction is needed between scrap generated on site in the production of crude steel and then returned to the same process, as distinct from scrap also generated on site but downstream of the crude steel production process itself. In some cases both kinds of scrap may count towards the scrap total, in others not.

The question then is what terms to use for the different categories. The ISO 20915 standard chose to apply the term ‘internal scrap’ to the scrap generated during the production of crude steel, and the term ‘home scrap’ to the scrap generated on site, but downstream. The report, ‘Determination of Steel Recycling Rates in the US’ makes the same distinction but chooses to call scrap generated during the production of crude steel ‘home scrap’, and scrap generated in downstream processing at the same site or separate downstream sites, ‘new scrap’. The words may not matter so much, but we do need consistency, so we all know what we are talking about.

At OneWorldStandards we believe in the value of international standards. If there is an international standard that defines terms appropriately, then the preferred option should be to adopt that terminology.

That is why we have used the terms internal, home, manufacturing and end-of-life scrap as defined in ISO 20915 as the basis for our discussions – and we call on others to do the same.