Steelmaking not only produces steel but a range of material, which is either essential in the steelmaking process or is an unintended result of the production process.
For example, slag is essential in the steel production process as it removes impurities from the steel, allowing it to meet the purity levels and have the properties that our customers demand.
Iron oxide, another steelmaking co-product, either in the form of scales or dust and sludge, on the other hand, results from the processing of the steel in rolling mills or gas cleaning systems.
No matter at what stage of the steelmaking process the co-products are produced, they typically have a value, and they can either be fed back into the steelmaking process or they can serve as useful materials in applications in other industries.
The use of steel industry co-products has many benefits and their use should be encouraged to:
- Prevent landfill waste – using the materials reduces the need for landfills and saves landfilling costs.
- Increase resource efficiency – when materials such as dust and scales are fed back into the process, it allows the industry to make more with less.
- Reduce CO2 emissions – the use of granulated blast furnace slag as replacement for clinker allows the saving of about 10% of CO2 emissions during cement making. In principle, all co-products that substitute the production process of another material will save the energy and CO2 emissions associated with the avoided production.
- Preserve virgin materials – steelmaking slags used for road construction replaces sand and gravel that would otherwise need to be excavated. This comes in addition to the raw materials savings from the use of scrap steel on site.
- Create value – steelmaking slag used for artificial reefs helps to maintain healthy seas, upgrading co-products to ensure desired properties give them a higher value and ensures more sophisticated uses.
- Generate revenue – co-products that can be sold to other industries as input material generate value for the steelmaker and reduce costs, e.g. for landfilling. Examples include the production of sulphur and tar in the coke making process.
Considering all of the above, it is crucial that policies are in place that enable the sustainable use of co-products. Steelmakers also have a role to play to maximise their use.
The role of policymakers
- Improve the public perception of industrial co-products – e.g. by clearly differentiating them from waste in legislation
- Ensure that the same requirements apply to both co-products and virgin materials – testing regimes for specific applications should impose the same requirements on all alternative materials no matter their origin
- Allow for more flexibility in the permitting process, for example, to enable research into new applications of industrial co-products - this would encourage innovative solutions for new uses
- Give preference to the use of co-products - provided they fulfil all the requirements for that specific use
The role of steelmakers
Steelmakers need to consider co-products as part of their product portfolio and make sure they produce them in a way that ensures both the properties and quality are consistent and suitable for future use.
The steel industry needs to continuously look to improve the properties of its co-products and try to find new or increasingly beneficial uses. The more precision within the process, the more value will be created.
Many companies are already doing this, but further efforts would have a positive impact on the willingness of potential customers to consider co-products as viable alternatives for their input materials.
With ever greater focus on resource efficiency and circular economy, it will become even more important to do more with less and encourage the full use of industrial co-products.
With joint efforts by policymakers and the steel industry, and an openness of potential customers to consider co-products, we can all make a real difference to the environment.
Head, Environment and Climate Change
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