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Development of new methodologies for industrial CO2-free steel production by electrowinning

Periodic Reporting for period 4 - SIDERWIN (Development of new methodologies for industrial CO2-free steel production by electrowinning)

Berichtszeitraum: 2022-04-01 bis 2023-03-31

SIDERWIN activities focused on using the electrolysis process using renewable energies to transform any iron oxide, including those inside the by-products from other metallurgies, into steel plate. The objective is to work towards the decarbonation of steel production by 2050. The CO2 reduction is directly addressed by SIDERWIN project and by the end of the project, the partners managed to produce a first 1.25M2 of intact iron plate. From a technical standpoint, the project has fullfilled its main objective. In addition, the SIDERWIN project aimed to study the use of alternative raw materials for the production of iron. The project has established the process for hematite concentrate however, the pilot activities are still underway.

The mill scales which have been identified as the most promising alternative raw material to be used in the developed process, has been further examined in labscale by NTUA. Unfortunately, alternative iron oxides were not actually tested on the pilot, due to performance constraints and to avoid damaging the pilot that was not optimized to be fed with alternative raw materials. Therefore, further studies will be carried out in a follow-up project in order to finalize the already available preliminary results.

The potential of the SIDERWIN technology in terms of economic viability in its current stage of development is promising, especially compared to H-DRI technology. The economic results show that the SIDERWIN technology could become profitable by the time it will become technically and commercially viable – around 2030 at the earliest.
During the first period, the project focused on the specifications of the pilot, CFD simulations to design an optimal prototype cell and development of the process parameters as well as designing the overall system. Regarding the use of alternative raw materials, the period was centered on the characterization of bauxite residue samples from the Bayer Process.

During the second period, the development of the numerical 3D CFD model has been achieved and successfully applied to design the cell while finalizing the design of the overall system and the sub-components (3D and 2D drawings) in order plan the erection of the pilot in the building that has been built specifically to host the pilot. Laboratory trials on bauxite residues and other alternative materials were pushed further in order to assess the current efficiency (70% à 130°C).

During the 3rd period, the efforts were focused on 2 main items: finalizing the design of the equipment and the commissioning of the pilot. After the basic design, we focused on the detailed design of each sub-component such as the P&ID, the instrument and motor list, the valve list and so on. During the first phase of the commissioning, many experiments have been conducted in order to define the best materials for the cell, as well as the best electrolysis parameters.

During the fourth period, a huge effort has been put towards the safe operation of the pilot with the completion of an ATEX and HAZOP analysis. Several trials on the cell to produce iron plates have been carried out. Changes were made to the initial process design and parameters to enhance gas management and improve the quality of the iron plates. These modifications involved reducing the cathode size, decreasing the flow rate of the electrolyte, and lowering the concentration of hematite. In the last year, a total of six trials have been carried out with the graphite mini-cathode, resulting in the production of intact iron plates for the first time. Overall, these adjustments have proven to be effective in optimizing the gas management system and enhancing the quality of the final product.

Finally, an exploitation roadmap has been defined with the partners and some of this exploitation work will also be performed within the scope of a follow-up EU project as well as more complex studies on raw materials which are promising but couldn't be fully finalized.

SIDERWIN is highly promising as during the fourth and final period, the project managed to produce a first 1.25M2 of intact iron plate after the adjustments of the initial cell design and process parameters. A data driven predictive model, and an optimization tool have been developed.

Whilst the technology is currently working, and optimisations are still needed, current cost estimates and revenue projections show that with further research and the right exploitation of available flexibility in its production process this is a promising sustainable way of producing steel.
Progress toward Objective 1: Development of an electrochemical processing route for primary steel production.
The assembling of the pilot and the commissioning of the individual equipment have been done accordingly to the final drawings.

Progress toward Objective 2: Industrially feasible new processing route
The four key components of the ΣIDERWIN cell, namely vertical extension, continuous supply of reactant, gas collection and metal harvesting, have been manufactured and implemented on the pilot. Commissionning of those elements have been done one by one. The ΣIDERWIN prototype cell incorporates the components of the imagined final cell consistently with a TRL5 corresponding to industrially feasible technologies. Operation of the cell is conducted with a closed loop electrolyte circulation which represents a radical improvement in safety and working conditions compared to the conventional electrowinning technology.

Progress toward Objective 3: Iron metal production from renewable energy
The laboratory results in WP3 on the influence of interruption on the efficiency of the deposition process have shown that provided that cathodic protection is maintained during interruption, there is no significant loss of efficiency. It confirms the interest of the process for flexible operation.

Progress toward Objective 4: Raw material efficiency during steel production
The experimental electrochemical studies of Bauxite Residues have shown that a current efficiency higher than 60% could be reached. However, longer duration experiments have been conducted and shown a rapid decrease of efficiency over time. A review of solid residues has enlarged the possible sources beyond red mud, with akageneite from nickel metallurgy, jarosite from zinc metallurgy, slags from copper metallurgy and with scales from steel.

Progress toward Objective 5: Close to market research
The economic value of the flexibility of the ΣIDERWIN processing route has been studied and show highly promising financial gains by simplifying the generation fleet. Particularly, Demand Side Response participation could reduce the reliance of the energy system on gas plant with extremely low load factors and ΣIDERWIN could be a substitute for this equipment.

Besides, revisiting the iron metal production is an ambitious and significant opportunity for the industrial sector to contribute to the transition toward a low-carbon and competitive economy by 2050. The preliminary assessment performed WP7 establishes the strong potential for reducing emissions of the steel sector through electrification, using the ΣIDERWIN technology, with a reduction of 16% of the carbon footprint of steel coil in the most conservative, short-term scenario, and an 82% reduction potential for ΣIDERWIN coupled with Induction Furnace in a decarbonised electricity mix.
3D design of the basic layout of the equipment