The role of steel in creating a net-zero carbon, circular materials economy

The UK Steel Industry, once world leading in terms of innovation, productivity and volume has been decimated in recent decades by new entrants to the saturated global linear economy.

These new entrants, located in developing nations, have access to more favourable operational costs and lower national environmental targets that have applied increasing pressure to the European and US steel producers, reducing profit margins and potential for reinvestment and growth. As the UK moves forward post-Brexit and post-COVID19, it is clear that there are vulnerabilities in many of these key areas that not only force dependence upon imports for our own infrastructure, defence and consumables, but reduce our ability to control quality and maximise profitability from the high value goods we export.

Due to its size, geography and history, the UK stands in a formidable position to lead the world in the transition to a true circular economy that must begin with the foundation industries as its nucleus.

Dr Richard Curry

The global environmental crisis together with the diminishing availability (sometimes politically driven) and escalating prices of mined elements that are key to modern technology, living standards and renewable energy production are quickly showing that we can no longer exploit our ‘consume and dispose’ habits that exemplify the linear economy to date. To ensure the continual existence of the human race where science, technology and living standards continue to improve from generation to generation, we must quickly transition to a truly circular economy where nothing is wasted, resources are cycled from generation to generation with minimal loss. This must be achieved on a foundation of carbon neutral energy to ensure sustainability and prevent environmental catastrophe.

Due to its size, geography and history, the UK stands in a formidable position to lead the world in the transition to a true circular economy that must begin with the foundation industries as its nucleus. This must also include, influence and shape the supply chain, higher tier manufacturing and tech industries to be truly circular in terms of future generations of society. However, this change will not be easy and will require a paradigm shift in thinking and attitude – focussing upon the domestic raw materials of the future that we currently call ‘waste’ and making changes to the way we design and manufacture products that will appear to be anathema to the current high efficiency, high productivity manufacturing processes.

As the UK emerges from the COVID19 pandemic, steel’s ubiquity, production volume and potential for recycling, places the industry in a primary position to lead the UK and rest of the world in a circular economy revolution. The SUSTAIN project, funded by UKRI, British Steel, Celsa, Liberty Steel, Sheffield Forge Masters and Tata together with support from the UK’s leading material research laboratories and trade bodies, was created to lead the UK through this transition. With focus upon the main challenges to sustainability such as the sequestration and reuse of waste heat and carbon emissions, reuse of hydrocarbon wastes and end of life consumer goods, digital innovation, harsh environment sensor and measurement techniques and late stage product differentiation, SUSTAIN aims to provide a national research platform to bring together the finest UK academics, RTO’s, SME’s and tech companies to overcome these challenges through the application of novel research to primary steel production and the greater supply chain.

Dr Richard Curry, third from left, with some of his SUSTAIN colleagues

The importance of steel to the UK

The UK consumes approximately 21m tonnes of steel annually. From government figures, 52% of this is used in building and infrastructure, 16% for the manufacture of mechanical equipment, 12% for automotive and a further 10% manufacturing metal products and components. The remaining 10% is split between other transport (5%), electrical equipment (3%) and domestic appliances (2%). This supports the UKs £90bn construction industry, £23bn transport industry (including aerospace), £18bn engineered goods industry and £13bn energy security industry, including renewables. Without steel, none of these industries would exist anywhere near the levels we have enjoyed or the level of growth seen over the last 50-100 years. Furthermore, many of the renewable energy technologies we are now relying upon to provide green, carbon free electricity production would not exist in a practical form that can be deployed reliably for a sustainable future.

How steel can drive the change

As mentioned earlier, steel is clearly the enabler of modern technology; modern living standards and can easily be seen to have driven the technology behind many of the key scientific discoveries over the last century. Without a stable, strong, versatile and cost effective material to build and form manufactured products, many of the ferrous and non-ferrous components of items we take for granted including automobiles, computers, smart-phones, buildings, etc. would not exist in the affordable, refined form we currently benefit from. This of course has implications both up and down the supply chain and includes the cost and volume of ore mining and mass transport of both raw materials and finished products to our homes or stores. The approximate 2bn tonnes of crude steel production mirrors this requirement for the material, which is second only to cement production globally. All other metallic and non-metallic materials such as aluminium, copper, titanium and plastics are several orders of magnitude lower in their annual production, have far worse carbon footprints per tonne and as a side would again be far more expensive and more difficult to extract and refine without steel.

Given that most modern consumer products are composites and contain ferrous based materials in key roles and considering overall volume of steel in domestic products and automobiles, the steel recycling process can be utilised to provide the sheer volume required to ensure profitability of resale of other materials.

Some of these materials are already recycled through the ferrous recycling process, however many valuable elements such as copper are not fully liberated causing huge issues to the recycling industry and prevent the true recycling of steel into new like-for-like products. This is unfortunately true for all recycled materials where the product differentiation potential and ultimately the value of the recycled material is limited. For example, most recycled steel from the UK is shipped to Turkey and other industrialised nations to produce low quality construction products such as rebar or used internally for small volumes of higher value ‘speciality steels’ for aerospace etc. that are inherently highly alloyed. High volume, high quality products such as automotive and packaging steels are off-limits due to contamination from extrinsic copper and other elements that are deleterious to the manufacture, forming and in-use properties of the resulting product.

Recycling vs Downcycling

Unfortunately when one considers modern recycling, the reality is that the materials involved are generally only utilised in the manufacture of low quality products. A car body, whether aluminium or steel is never truly recycled to manufacture another equivalent component. Similarly, food and drink packaging, high value construction and mechanical components are never recycled back to their original form; yet these products provide the overwhelming volume of global manufactured products, supporting the UK’s and other nations industrial sectors. This is perhaps not surprising given the connotations associated with the word ‘scrap’ which does not lend itself well to the concept of a highly valuable raw material capable of taking us into a waste-free, green future. Partly due to this stigmatisation and also the application of scraps to downcycled products has led to many if not all of the current scrap grades sold globally containing as much as, and sometimes more than 10% sterile wastes such as hydrated soil and oxides.

Many integrated steel plants will use a small (~15%) amount of ferrous scrap as part of the Basic Oxygen Steelmaking (BOS) process but require the significant dilution to retain the mechanical properties required for production, forming and use. The rest will feed the manufacture of a much smaller volume highly alloyed products sector and low-grade reinforcing bar produced by Electric Arc Furnace (EAF).

Without a suitable method of controlling the contaminants within scrap steel, the level of these deleterious elements will increase with each cycle of use making the steel more and more difficult to use, even when considering dilution via the BOS process. Current recovery systems are inefficient. As the amount of copper increases to achieve the technology demanded by consumers, the contamination by ineffective separation will rise quickly. It has been predicted that without such control, the copper level in scrap will exceed 1% (currently 0.2-0.4% Cu) by 2050, forcing the need for more virgin material to be mined and processed and resulting in the landfilling of ferrous scrap.

Given that the EAF has in recent years been touted as a potential green steelmaking solution by supporters around the globe, including the ill-fated Liberty Group’s Green Steel initiative, unless the fundamental issue of raw material chemistry control (and others including the increased N2 content of EAF produced steel) are resolved, net-zero carbon steelmaking becomes nothing more than a pipedream. The basis for the EAF momentum is the eliminated requirement for chemical reduction necessary for virgin production leaving only the requirement for high temperature melting which is 1/5th lower than the integrated Blast Furnace – BOS route in terms of CO2 emission, even when using a predominantly fossil fuel sourced electrical energy. Again, when considering a truly zero-carbon solution, the mining, transport and manufacturing of steelmaking consumables such as refractories and lime for slag will also have an impact upon the emission of CO2 even if green electricity were used in the process.

The SUSTAIN project is actively researching this very important issue to the circularity of steel: both in the investigation of pushing the envelope of coping with increasing contamination and reducing the contamination itself through advanced processing and on-line analysis of material. Such research will closely apply to all recycled materials, including other metals, glass and plastics. Beginning with steel, which applies to the highest volume of arising end of life products and the greatest number of alloys, again by orders of magnitude, the knowledge and methodology can be adopted by other materials industries, giving the ability for a truly circular materials sector to emerge.

Global potential for recycling

With many groups focussing upon the EAF and recycling of ferrous scraps to eliminate carbon emission, one has to consider the global potential of such a switch. According to the World Steel Organisation, global scrap arisings only contribute to 34% of the 2bn tonnes of steel produced annually. This is made up from 420 million obsolete scrap plus 200 millions of circular scrap (internal plant arising from waste) giving 620 million tonnes of scrap consumed. This is all of the globally available scrap and can only rise when more meta-based products reach the end of their life.

This differs from country to country and region to region with the oldest industrial nations obviously producing far more than developing or recently developed nations. Usage cycle times vary from a few weeks for packaging steels to 100 years for construction materials, with an overall 40 year average, meaning that there is potentially a several hundred year wait, requiring consistent production to reach equilibrium between scrap availability and usage through recycling. Even when this state is met, fluctuations in supply and inevitable production losses, there will still be a demand for virgin iron; although this could be met using green Hot Briquetted Iron (HBI) or Direct Reduced Iron (DRI) produced using H2. Using the UK, arguably the oldest industrialised nation, as an example: approximately 10.3m tonnes of scrap (in reality closer to 9m tonnes Fe due to contamination from sterile material) is generated annually (2019) but consumes 21m tonnes. Although this is far higher than the global average at close to 50%, the UK would still have a large deficit to overcome. This will eventually be resolved in the long term if scrap contamination is minimised today, resulting in self-sufficiency by 2200.

A short-term solution would be to begin importing scrap from other nations. If China or a large number of steelmaking nations began purchasing scrap in this way, the price would soar with knock-on effect to finished product creating a situation prohibitive to the product manufacturer and unaffordable to the end customer. Historically, the value of scrap has been limited by the cost of BOS route steel. Decarbonising will remove this limitation.

The situation is in fact worse than this as the 34% scrap is already in use and would ultimately result in no change in carbon emission globally.

Revisiting the UK, which currently only produces 7.2m tonnes of crude steel per annum, the availability of a domestically sourced scrap raw material could service the entire sovereign steel industry and potentially lead to growth of up to half the national annual need. The remaining steel could then be imported as required until the national scrap arisings reach equilibrium. A post-Brexit UK could easily initiate an export policy to isolate UK manufacture from any resulting price rises in the scrap open market that this would create. Europe is considering similar methods of retaining scrap with proposed carbon-border taxes providing a buffer between Europe and the global market, but the variation in sufficiency across the whole of Europe and the varying levels of industrial maturity through the 20th Century will recue the effectiveness of the strategy when comparing to the opportunity facing the UK.

Potential solutions

Realistically there is only one solution: the pre-treatment of scrap between supply chain and furnace to create a raw material that is fit for purpose, i.e. has a high differentiation potential for new products. This is, however, easier said than done.

Firstly, one would need to change the operation of a wealthy global industry that may not be so keen to invest and change its business model. Such a change would require significant investment in high throughput processing, the development of appropriate analysis and separation techniques which would add significant cost that domestic steel companies may also not be able to justify, especially if competing on the international market for a product that has been proven to produce low residual steel alloys. Such steel manufacturers would also need to develop strong relations with the scrap supplier or utilise costly analysis systems themselves to ensure that the supplied material matches the chemistry of the end product.

National policy would be beneficial for industrially developed nations with enough scrap to service the industry domestically however this may be difficult in many areas of the globe.

Another solution would be to develop a steel-as-a-service model, which would be in a similar vein to that of Rolls-Royce engines, where the material, not the components are owned by and are returned to the manufacturer at end of life. Difficulties may arise in the financial model of such a scheme and in deciding with whom the ownership lies, plus financial barriers such as the lower initial rates of return although the sheer volume of the material and time may resolve this. Similar issues will also be found in the recycling of other materials, however the much lower production volumes may present larger financial impediments although these may be resolved by the much higher value per tonne presented by other metals.

All of these solutions are currently being explored by the SUSTAIN programme in the UK, including the input from the UK’s leading academics and trade bodies to determine the best method of achieving a net-zero carbon, circular materials economy for the UK.

You can connect with Dr Richard Curry on LinkedIn, and read more about the SUSTAIN programme by visiting their website: www.sustainsteel.ac.uk

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