“It ultimately boils down to one question: do the costs compensate for the benefits?”
Published on 04 July 2018
Steel is easy to recycle without losing its strength. If it were up to the steel industry, new lightweight electric cars would be made of steel recycled from end-of-life vehicles. “The technology is in place.”
Pieter Kuiper is a senior engineer at ARN. He is looking for ways to further fine-tune shredder technology and increase the recyclability of cars. Pieter is interested in hearing what the steel industry needs to make high-quality automotive steel from automotive scrap. To find the answer, he asked Nico Langerak, Department Manager of Applications & Engineering at Tata Steel Europe, a number of probing questions.
Kuiper: Why does Tata Steel need scrap to produce steel?
Langerak: “In IJmuiden, we primarily produce new steel from crude iron, which in turn is made from iron ore and coal. We need scrap for this primary process. Adding scrap to liquid crude iron enables us to keep the temperature in the convertors manageable. Depending on the quality of the steel we are producing, we use 15% to 25% scrap per batch. This is mostly pure scrap, such as train rails, turnings, demolition scrap and basic materials for steel processing companies. We use around one-and-a-half million tons of scrap each year, half of which we purchase externally.”
Can steel from end-of-life vehicles be used to produce new automotive steel?
“On the detail level, every part of a car body is made from a different type of steel. Yet, in terms of chemical composition, all of these types seem to be rather similar and contain few alloy elements. So, in principle, you can simply throw them all together and melt them down again, resulting in a clean batch that can be reprocessed. Car scrap is also steel, but has two problems: zinc and, to a lesser degree, copper. As you know, most car parts are galvanised. When reused, zinc evaporates during the steel production process and ends up in our water purification system as sediment. This sediment contains a lot of iron. So, we put it back into the furnace. But it also causes problems here because it evaporates and ends up in the furnace gas dust. That is why we prefer not to use automotive scrap. There are enough other types of scrap that can be used to make new car plates.”
But aren’t there ways to separate zinc?
“Galvanised scrap is usually sent to a scrap smelter, an electric arc furnace. But we don’t use this technique. In IJmuiden, we developed the HIsarna method. HIsarna is primarily a process for producing iron to which scrap can be added if desired. The technology eliminates several pre-processing steps and places less stringent demands on the quality of the raw materials. This enables us to use scrap containing zinc to produce crude iron. We capture the vaporised zinc as vapour, salvage it and can then sell it to the zinc industry. Although we developed HIsarna to produce less CO2 in order to save energy and reduce particulate matter emissions, we discovered along the way that this process makes it easy to recycle scrap.
Have you already tested the method with shredder scrap?
“Yes, once, and there were no problems. To achieve a recycling loop for zinc, we are now launching a European project.”
Automotive scrap contains not only zinc, but also copper from electric wiring. So, this makes it primarily a matter of downcycling. What would ARN have to do to step things up a level?
“The materials would have to be separated better at the source. We prefer not to have any copper in our scrap. Copper does not evaporate and makes the steel too brittle to roll and process further. Why not remove the wiring separately? This brings you closer to upcycling and increases the value of car scrap. After all, our ultimate common goal is a circular economy.”
At present, it is still too costly to manually remove copper. And it’s not possible to approach recycling without considering the economic aspects. How does the steel industry deal with this?
“We’re able to separate all elements. But this requires extra efforts and extra money. You can be as idealistic as you want about sustainability, but what it ultimately boils down to is the question: do the costs compensate for the benefits? There is a manufacturer in the United States that uses electric arc furnaces to turn scrap into car plate steel. But apart from large quantities of pure scrap, this requires such a tremendous amount of electricity that this example is hardly followed elsewhere. After all, where can you find inexpensive, clean energy to stay competitive these days? It’s not like you can build a coal plant next to your plant. You simply can’t get away with that in the Netherlands.”
Recycling is only a small aspect of sustainability efforts. It seems more worthwhile to make changes to the use phase, i.e. produce lighter and electric cars. What’s your take on this?
“We’re steel makers. As far as the CO2 impact of production is concerned, steel is a significantly better product than carbon fibre or aluminium. These lightweight materials are now being used to lower CO2 emissions during the use phase of automobiles. But if all cars are to be electric in the future, the CO2 emissions from the tailpipe no longer matter. What becomes important then is how you make cars and legislation aimed at car production and recycling in order to keep CO2 emissions manageable. We’re also a member of WorldAutoSteel. As the steel industry, we want to develop a car that meets the needs of the future. We are already able to make lightweight steel bodies that are half as expensive as bodies made of other materials. We can build cars with a body that lasts at least thirty years and is safer than ever. But is that the answer? We see that the world is starting to focus on other possibilities than what is technically possible at this time. Perhaps we need to build cars that can be recycled faster and more easily. If you consider a scenario in which we share self-driving cars, our cars will be moving more than they will be parked. This means that the rotating parts will wear out more quickly. If a car only needs to last for two years, why bother to galvanise it? Without any alloys, it’s much easier to scrap and less expensive to recycle.”
So, it’s not a matter of either-or but of both?
“Until a few years ago, safety was first priority in the automotive industry. Partly as a result of this, the strength of our steel has increased nearly tenfold in thirty years. We’re now ready for the third generation of high-strength steel. But the world keeps on turning. The environment has pushed aside safety as top priority. The car industry now primarily engages in dialogue with environmental experts. HIsarna is our answer to the challenge of reducing the CO2 footprint of steel. We are now able to reduce the emissions of CO2 and particulate matter by 20% to 80%. So, we are able to greenify the steel industry to a revolutionary degree. Automobile manufacturers consider HIsarna as an interesting development because they will be held accountable in the future for the entire cycle - from material production to recycling. It won’t be long until the first manufacturer claims to be fully sustainable. If a model is 100% recyclable, it can have a high residual value. That is not only attractive for consumers, but also for the entire sector.”
Is it conceivable that iron ore will no longer be needed in the future to make steel for cars?
“The demand for steel is so great that there’s no way around it at this time. But I can imagine that there will come a time when steel is such a large part of the cycle that you can produce more and more steel through recycling. And, who knows, by the end of this century, iron more may no longer be necessary and we’ll be making car plates from automotive scrap - provided the car as we know it today still exists.”