Surely everyone knows what scrap is? Well, kind of. But we’re going to need to get technical…

I want to focus on iron and steel scrap, so when I say ‘scrap’ that is what I am talking about. But already we have to think about stuff that might be mixed up with iron and steel scrap but which is not iron or steel. Some of that stuff is potentially useful – other metals, for example. Some of it is not useful: lumps of concrete, remnants of plastic, soil, water and such like. And some – radioactive material, say – is particularly problematic.

When we start to talk about the quantity of scrap being collected, traded or recycled, we need to be careful about what we are measuring, and if we are weighing it what we are weighing.

Just to be clear, steel scrap is not the same thing as recycled steel – it shouldn’t need saying, but scrap is not recycled steel until it has been recycled – see ‘No such thing as scrap? Really?’.

But even with these basics in place, there is a bewildering range of terms and specifications for iron and steel scrap: post-consumer scrap and pre-consumer scrap; internal or external scrap; home, new, prompt, industrial, fabrication or manufacturing scrap; old, obsolete or end-of-life scrap…

And that’s before we get to the possible commercial specifications for scrap content. The Institute of Scrap Recycling Industries (ISRI) defines well over 100 specifications for ‘ferrous’ scrap, not including stainless steel scrap (which are categorised as non-ferrous). In Europe, the EU-27 Steel Scrap Specification defines a more manageable 11 grades, as well as stringent specifications for cleanliness and non-ferrous residual elements.

If are going to talk about scrap, or categories of scrap, we are going to need to know what we are talking about, and whether we are talking about the same thing. That’s what standards are for – and, as luck would have it, there’s an international standard to define the terminology of scrap.

For the purposes of this discussion I am more interested in the categorisation of iron and steel scrap in the context of recycling, green claims and the determination of greenhouse gas emissions, than in the context of commercial specifications and grades, so my focus is on definitions of pre- and post-consumer scrap, recycled content, and such like. Nonetheless, it is worth bearing in mind that efforts to increase the quantity of scrap for recycling will be constrained by the ability to meet commercial specifications for cleanliness and purity.

The ISO standard 20915: 2018 Life cycle inventory calculation methodology for steel products summarised in the figure above provides a framework for a consistent terminology for the steel sector, based on the following definitions:

3.3 scrap iron and steel material in metallic form that is recovered in multiple life cycle stages, including steel production processes, the manufacturing processes of final products (3.2) and the end of life of final products, and is recycled as a raw material for steel production 3.4 internal scrap scrap (3.3) from a crude steel making unit process that is then recycled within the same unit process [e.g. basic oxygen furnace (BOF) or electric arc furnace (EAF)] 3.5 home scrap scrap (3.3) from a downstream steel production process within the steelworks (e.g. rolling, coating) that is returned to steel making processes (e.g. BOF or EAF) 3.6 manufacturing scrap scrap (3.3) from the manufacturing processes of final products (3.2), such as automobiles and buildings 3.7 end of life scrap scrap (3.3) from after the end of life of final products (3.2) 3.8 external scrap scrap (3.3) provided from outside of the steelworks, including manufacturing scrap (3.6) and end of life scrap (3.7)

Some details of the ISO 20915 classification are worth noting:

• there is a clear distinction between internal and home scrap
• all kinds of scrap – including internal scrap as well as home scrap – can be counted towards the total quantity of scrap used to make steel
• the distinction between home scrap and manufacturing scrap comes down to home scrap being generated through steel product processing on site, while manufacturing scrap is generated off site through further processing prior to a product’s transformation into a ‘final product’¹. Some processing could take place either on- or off-site: what matters is where the process takes place, not the nature of the process itself.
• external scrap includes all scrap generated off site. But internal scrap does not include all scrap generated on site, because it does not include home scrap: external is external to the steelmaking site; internal is internal to the steelmaking process at the site.
• external, home and internal scrap are all defined in relation to steelworks. If you are a manufacturer, the scrap you generate at your own site will be categorised as external scrap because it is external to steelmaking.

Some elements of the ISO 20915 terminology may be contested, but it at least provides a clear, consistent basis for discussion, with the benefit of formalisation in an international standard. Based on this terminology we can try to classify the variety of terms used by steelmakers, and in the research literature to describe scrap as follows:

Origin of scrap	ISO 20915 terminology	Other terms	May also be referred to as	Pre- or Post-consumer
Steelmaking and integrated steelmaking/ manufacturing sites	Internal scrap Home scrap	Often referred to interchangably as: internal, home, own, mill, in-house, circulating, runaround, revert2…	Own, in-house, internal2	Pre-consumer3
Downstream manufacturing sites	Manufacturing scrap	New, prompt, industrial, process, fabrication, mill…	External, 3rd party, traded, purchased	Pre-consumer
Final products in use	End-of-life scrap	Old, obsolete…	External, 3rd party, traded, purchased	Post-consumer

Translating between ISO 20915 terminology and the terms used by businesses and researchers will not always be exact, precisely because the terms used by different parties may not be clearly defined or may be defined differently, but it provides a starting point for answering the kinds of questions about steel recycling, recycled content and claims about green house gas emissions raised in the post, ‘Can scrap save the planet?’.

But before we get there, we need to look at our four categories of scrap in a bit more detail. First up, when does end-of-life steel become end-of-life scrap?

Footnotes

1. The definitions of steel- and final products in the standard are problematic. The standard defines steel products as being produced at a ‘steelworks’ (without defining that term), and final products as products that ‘require no additional transformation prior to… use’. The standard does not give a term for (steel) products that are manufactured outside of a ‘steelworks’ and traded prior to the production of a final product. The ‘manufacturing processes of final products’ needs to be understood to include the manufacturing of such intermediate products.? ↩︎
2. It is often unclear whether these terms are being used to refer to what the ISO standard defines as ‘internal’ scrap, or ‘home’ scrap, or both – see, for example Recycling Rates of Metals: a status report, which uses the term ‘home scrap’ to cover what ISO 20915 would split into home and internal scrap. ↩︎
3. Both internal and home scrap are included in this table as examples of ‘pre-consumer’ scrap. However, it should be noted that the ISO standard 14021: 1999 on environmental labels and declarations specifies that internal scrap (as defined in ISO: 20915) should not be counted as ‘pre-consumer material’ for the purpose of making claims about recycled content. We’ll come back to this in another post. ↩︎