The recycling rate is the proportion of a material that is recovered and recycled. If 90% of steel cans are recovered and recycled after they have been used, then the end-of-life recycling rate for steel cans would be 90%.
In a previous post ‘Unrecovered or unrecoverable? The fate of end-of-life steel’ I pointed out the need for clarity as to whether the recycling rate for end-of-life scrap is being calculated before or after the exclusion of ‘unrecoverable’ end-of-life steel. (It should be calculated before!)
And we need to be careful how we treat ‘hibernating’ scrap. If steel that reached the end of its life-in-use in previous years is recovered and recycled later, that will affect the apparent recycling rate in the later year. But there’s more…
We also need to pay attention to whether the recycling rate is being calculated for all potentially available scrap, or for just some categories of scrap. Approximately half of all scrap is end-of-life scrap, and half is home and manufacturing scrap (pre-consumer). Pre-consumer scrap is a valuable commodity that is relatively easy to recover and collect, so close to 100% of it is recycled as standard practice. But worldsteel estimates an end-of-life steel recycling rate of 85%, which would imply an overall steel recycling rate of around 92%1 for both pre- and post-consumer scrap. As a crude comparison, if steelmakers did not recycle any end-of-life scrap at all, they would still be able to claim a recycling rate of around 46%2 based on the recycling of pre-consumer scrap alone.
Then we need to be careful about assuming that the only use of scrap is for the production of crude steel. In fact the Bureau of International Recycling (BIR) estimates that around 70 Mt of scrap is used each year by iron and steel foundries. That needs to be included when we try to calculate the iron and steel recycling rate. And we need to make sure we are not missing end-of-life steel that is recycled in the informal sector as well, potentially beyond the reach of official statistics.
What about steel which is salvaged and re-used? That will not count as being recycled for steelmaking – but it needs to be considered if we are thinking about circularity, and the potential to increase the recycling rate.
All of this is just to count the scrap that is collected and recycled in a given year. But we also going to need to know how much is not collected and recycled, to calculate the proportion that is recycled. That is a much tougher proposition – and will have to be the subject of another post!
And one final point in relation to the recycling rate and circularity. Even a 100% recycling rate would not mean that steelmaking is a circular process. It would mean that we are recovering and recycling all the available scrap. But we’ve noted already that there are yield losses when scrap is smelted. Those losses may represent 5% of the metallic content of the scrap- and ore-based metallic inputs, or more. Other losses include metals in sludge and dust, and from corrosion or wear and tear for products in use.
A more complete picture of circularity needs to consider all such losses from the steel cycle, and not just those relating to scrap recovery.
Footnotes
- Total recycled scrap estimated to be 625 Mt, of which 50% (312.5 Mt) is estimated to be pre-consumer and 50% end-of-life. If the EOL recycling rate is 85% that implies there was 368 Mt of end of end-of-life steel potentially available for recycling, making a total scrap availability of 312.5 Mt + 368 Mt = 680 Mt. The overall recycling rate would be 625/680 = 92%. ↩︎
- Using the same estimates for scrap availability as above, but assuming that none of the available end-of-life scrap is recycled. Recycling rate = 312.5/ 680 = 46%. ↩︎