ULCOS is a large European research project that aims toidentify and develop technology that could enable a drasticreduction in CO2 emissions from ore-based steel production.The IRonMAking flowsheeting model (IRMA) has madea vital contribution to one of the ULCOS subprojects, asIRMA models were used to evaluate the economics andCO2 reduction potential of a large number of alternativeironmaking routes.
IRMA is a software tool that allows for the use ofthermodynamic data relevant to iron- and steelmaking in aflowsheeting environment. It was developed by Corus to serveas a dedicated, flexible and accessible tool to evaluate andcompare a wide range of ironmaking routes.
IRMA can be used to calculate consumption figures, productquality and the occurrence and significance of emissions.IRMA can do this for a wide range of operating conditionsand raw material compositions.
IRMA is currently being used for benchmarking, design andpilot plant development of the ISARNA process, which wasdeveloped in the context of the ULCOS project. ISARNA isone of the four process routes that have been selected forfurther development within ULCOS.

Based on the balance equations of mass, partial mass,momentum and thermal energy, the pyrolysis processof non-coking coals using a counter-rotating twin screwreactor (TSR) is modelled by means of commercial CFDcode PhoenicsTM. In favour of good convergence of themathematical solution, a structured, cylindrical-polar gridis chosen. Variable filling and intermeshing degrees aretaken into account by blocking numerical cells in gasdomain and intermeshing domain instead of performingtwo-phase calculations in a body-fitted co-ordinate system.Viscous behaviour of the granular coals is expressed bymeans of a generalised Newtonian fluid and chemicaldecomposition is implemented with aid of distributedactivation energies.

Research conducted on biomass for Ulcos (“Ultra-Low CO2 Steelmaking” European Integrated Project)has progressively focused on charcoal supply fromtropical eucalyptus plantations. The sustainability of suchplantations is being investigated from the viewpoint oftheir carbon, water and nutrient budgets: they must allbe neutral or positive. Field research is producing resultsat the tree or stand level in several sites of Congo andBrazil, while a spatial model is developed to identifythe conditions of biomass neutrality at the scale of theforest ecosystem. The productivity of biomass has beenanalyzed through the description of practices along theAbstracts of technical articlesvarious supply-schemes that competitively feed the steelindustry in Brazil and the identification of bottlenecks forfurther expansion.

ULCORED is the concept suggested by SP 12 to meet thedemand of reduced CO2 emission using iron ore and gasbased direct reduction for steelmaking. The concept includesthe use of 100% oxygen, POX (partial oxidation) insteadof reformers, shifter for production of CO2 free reduction/excess gas and the reducing agent being either natural gas or syngas from coal/biomass.

The ULCORED coal based concept is simulated based onthe production of syngas using existing coal gasificationtechnology. The shifter gives the option to produce CO2-leanH2 from coal/biomass for in plant use. Large CO2 emissionsarise on site from the use of natural gas in heating ovens andfrom the use of electricity in EAF melting. In the case of thesecoal based systems, production of “excess gas” to be used asfuel gas in various processes will reduce the CO2 emissionfor the total site.

The Direct Reduction process can be carried out usingsyngas from biomass. Mathematical models of theintegrated process gasification plus direct reductionhave been used to evaluate flow rate, temperature andcomposition of the gas in the various steps of the wholeprocess. Fluidised bed gasification and operation withtechnological oxygen at high pressures is the proposedsolution to produce syngas. Best candidates for suchapplication are biomass from forest and wood industryand agricultural residues. Both of such type of biomassare present and distributed in many European areasin such amount to make industrially possible their use,taking into account the logistic requirements. A costbetween 30-60 Euros/t DRI is roughly estimated.
The characteristics of the syngas implies the adoptionof purification steps, before the use of the syngas inthe shaft furnace, using technologies permitting hot gascleaning, to save energy efficiency of the process.

Concevoir une nouvelle filière d'élaboration de l'acier fondée sur l'hydrogène semble prometteur si l'onconsidère les faibles émissions de CO2 qui en résulteraient. Dans le programme ULCOS, cette filière est wecomme une option à long terme, essentiellement conditionnée par l'émergence d'une économie de l'hydrogène.Pour anticiper son possible développement, on a décidé d'évaluer le procédé de réduction directe en four à cuvepar H2 pur et de déterminer ses conditions opératoires optimales grâce à une approche de modélisationmathématique, complétée par des expérimentations adaptées. Nous avons ainsi spécifiquement développé unmodèle mathématique, appelé REDUCTOR, qui simule le procédé et prédit ses performances. Ce modèle estfondé sur une description mathématique détaillée des phénomènes physico-chimiques et thermiques réels. Enparticulier, la cinétique de réduction est tirée d'essais expérimentaux en laboratoire. La version actuelle dumodèle ne tient compte que de la réaction par l'hydrogène mais une extension à la réduction par CO est prévuede manière à ce que ce modèle puisse aussi être utilisé pour simuler et optimiser les procédés de réductiondirecte existant actuellement. Les premiers résultats ont confirmé que la réduction par H2 était plus rapide quepar CO, ce qui permet d'envisager un réacteur sous Hz bien plus compact que les fours actuels des procédésMIDREX ou HYL.

The hydrodynamics in an electrolysis pilot-cell has beenmodelled with the aim of upscaling the direct iron productionprocess based on the alkaline electrolysis of an iron oxidesuspension. Two dispersed phase flow involved in this threephaseprocess have been evaluated: the solid and the gasphase hydrodynamics.The suspension flow characteristics areevaluated from existing litterature, and available correlationsare applied to the case under study. The minimum velocityrequired for transportation of finely ground iron oxide alongthe cathode surface is fairly low, in the laminar regime,corresponding to minimum pressure drop.The behaviour ofthe oxygen phase produced on the anode is evaluated in attwo scales. First, the trajectory of a single bubble sliding onthe anode is depicted, predicting possible rising or draggingof the bubbles as a function of its diameter. The gas-phasepattern is then studied from litterature results for gas-liquidflow in pipes. A separation of the gas phase from the liquidis predicted, the lightest phase being in contact with theupper part of the cell. Obtained results confirm the potentialof the selected design for transportation of particles and gasrecovery with low energy consumption.

In order to develop a new, efficient industrial process forproducing high quality iron and steel with significantly reducedcarbon dioxide emissions, we investigated the electrowinningof iron from an iron oxide ore in aqueous alkaline solutions.Hematite (Fe2O3) solid particles suspended in the concentratedaqueous sodium hydroxide (NaOH) solutions were transferredto the cathode (e.g., a rotating disk graphite electrode) andreduced to iron metal by applying a constant current; oxygenwas evolved on the anode (e.g., a nickel screen mesh). Currentefficiencies of above 90% with respect to iron depositionwere consistently obtained under the specific conditions in alaboratory cell, and the corresponding energy consumptionswere calculated to be around 3 kWh·kg-1 iron. The depositediron crystals were the oriented clusters of stacked six-fold twins ina tetrahedron-shape grew growing in a direction perpendicularto the cathode surface. Influences of rotation rates of the cathode,cathodic current densities, contents of the Fe2O3 particlesin electrolytes, and concentrations of NaOH solutions oncurrent efficiency and morphology of deposits were studied.

In the development of the electrolysis technique for iron,the cell-design step is crucial to ensure that the resultsobtained on smaller scale experiments are scaled-up toindustrial size. Design criteria, based on the theorem ofequipartitioned irreversibility, are proposed for the alkalineelectrowinning process. One of the specific features ofthe process is the treatment of a multiphase electrolyte, agenuine breakthrough for electroextraction processes. Eachof the unit-operations necessary to obtain the separation ofthe iron and oxygen from iron oxide are depicted togetherwith the corresponding physical limitations and availabletechnologies. Optimal solutions to obtain uniform andsteady variation of each of the involved phenomena canbe readily deduced from this approach and a cell-design isproposed.

Within the ULCOS project, a pilot cell for iron electrowinningis being designed. Electrical energy is used to transformiron ore particles (hematite) suspended in a sodiumhydroxide solution into iron metal and oxygen. The workdeveloped by Labein-Tecnalia is focused on the study ofthe fluid flow for different electrolytic cell configurationsto get knowledge of the interaction between the oxygenbubbles generated during the process and the electrolyteflow. The numerical algorithm used is the finite volume usedin the commercial Computational Fluid Dynamics codeFLUENT. The work developed is focused on vertical andhorizontal parallel plates configurations, to analyze theremoval of oxygen bubbles from the gap between anodeand cathode, and the access of iron ore particles to thecathode. A user subroutine has been developed for theCFD code to compute the mass flow rate of oxygen bubblesgenerated at the anode, as a function of the local currentdensity. A methodology has been developed to analyzethe accessibility of the iron ore particles to the cathode.The knowledge obtained from this work has helped for thedesign of the pilot cell within the ULCOS project.