- Steel decarbonisation is pivoting to DR + EAF & smelter route
- Deterioration in iron ore quality biggest challenge for DRI sector
- Low-CO2 emitting technologies progressing toward industrial maturity
Morning Brief: How best to decarbonise iron oxide reduction processes? That is a key question which lies at the core of global steel industry decarbonisation efforts.
In the European Union (EU), decarbonisation is a pressing concern not just for industry but also the authorities, as well as banks and financial institutions. Through the implementation of conducive policies, the authorities are pushing industry to make efforts to transition to a low-emissions future, while the banks are spearheading climate finance efforts, shoring up their own low-emissions credit profiles, while gradually withdrawing from fossil fuel-based industries and companies, says Christian Boehm, Global Head of Sales, DRI, Primetals Technologies, a global technology solutions provider.
The senior metallurgist updated BigMint with his perspectives on low-emissions iron production during a recent exclusive online interaction.
Excerpts from the interview:
As an iron oxide reductant, how does hydrogen compare with coke or carbon monoxide for conventional iron-making?
It is important to note that steel industry decarbonisation is pivoting to direct reduction processes coupled with the EAF or smelter, which promises to be an ideal route for low-carbon transition. This is true everywhere, whether in the EU, China, or the Middle East. This provides the most flexible route for gradual transition to low-emissions processes, as Midrex’s technology allows for the use of natural gas (NG) currently in DR reactors which have the potential to gradually switch to hydrogen (H2) as and when it is available in plenty and is also economical.
Now, to answer your question, I would compare H2 with carbon monoxide (CO) as an iron oxide reductant. While H2-based direct reduction is an endothermic process, the CO-based process is exothermic. This means that for H2-based processes, the sensible heat has to be increased in DR shaft furnaces, as well as the energy input. Moreover, H2-based DRI has much more smaller pores compared to iron ore reduced by CO, which means that the surface is bigger and the reactivity of the DRI is higher.
We know that the global average carbon footprint of the blast furnace route of steelmaking is around 1.8 tonnes of CO2 per tonne of crude steel, while DRI based on low-carbon fuels has a very low emissions factor of around 0.13 tonnes. A bit of carbon is typically added to the EAF or to the DRI to ensure proper metallurgical reactions in the EAF.
How is the DRI-EAF route of steelmaking prepared to address the challenge of deterioration in iron ore quality and the lack of availability of DR-grade ore?
From the point of view of Midrex vertical shaft furnaces, DRI produced from relatively low-quality iron ore generates a lot of slag in the EAF and there are operational issues related to handling of so much of slag in the EAF.
In recent years, technological solutions have emerged such as the electric smelter which can handle DRI produced from Fe 62-63% iron ore. It can be either round or rectangular. Primetals Technologies has a rectangular smelter for better distribution of electric power.
The smelter is designed to perform the final reduction of iron ore which is essential from the efficiency point of view. With the smelter, we can adjust the basicity of the slag in such a way that we can use it afterwards. The smelter is designed to handle a lot of slag and you can go for low-basicity slag in the smelter much like blast furnace slag, which can be further processed for road construction, etc.
In India, the overall quality of mined iron ore is decreasing and availability of lumpy ore is getting scarce. What are the technology choices for DRI producers using more of iron ore fines – a fluidised bed reactor, for example?
We need to make certain distinctions here, especially with regard to sinter feed. There is one DRI plant in Venezuela which uses sinter feed iron ore. The facility reduces iron ore in a combination of fluidised bed, with the DRI reactor and EAF further down the line.
The quality of sinter feed, in India and other parts of the world, remains a pressing concern. So, directly using fluidised bed with EAF may not be the solution due to technical problems mentioned earlier.
Maybe the solution in the future lies with Finored iron-making process in combination with fluidised bed and smelter for fines reduction.
With this in view, Primetals Technologies has teamed up with leading steelmaker POSCO, which is not the fluidised bed system of Finored but the Finex process, where iron ore fines are being reduced in sinter feed quality and then put together in a smelter.
This joint venture has started and in about two years’ time we will have a pilot plant, with 30-40 tonnes of production per hour, ideally suited to treating sinter fines of grain-sized quality.
In the Indian context, DRI producers have to deal with fines (blue dust) of concentrate quality. Concentrate fines size is too big for Finex or Finored. So, Primetals Technologies has developed the Hyphor technology for grain sizes of, let’s say, around 50 mm, which is in principle pellet or concentrate size.
In this process, we have a pilot plant (R&D) project in Austria. The pilot plant is complete now – in conjunction with voestalpine, which focuses on iron ore reduction and then going directly into the smelter.
To sum it up, Primetals Technologies has one small smelter pilot plant in Austria with a diameter of about 1.3 m, with one electrode, where the metallurgical processes in production are being investigated. We know exactly where to put the carbon or where to put the DRI.
The next step is 3-4 tonnes that Primetals Technologies is developing with voestalpine, and of course the 30-40 tonnes Hyrex that we are working together with POSCO.
Primetals Technologies is taking all these processes to industrial maturity across key markets worldwide. Importantly, these technologies have the innate capability to handle all sorts of iron ore, concentrate fines, low- and also medium-grade, as well as all grades of sinter feed.
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