ULCOS-Pilot testing of the low-CO 2 Blast Furnace process at the experimental BF in Luleå The ULCOS blast furnace process aims at reducing the CO 2 emission of the blast furnace by 50% in two steps: l Decrease of carbon consumption by recycling most of the top gas after CO 2 removal, which requires operating the blast furnace with pure oxygen; l Underground storage of CO2.

The ultralow CO 2 steelmaking blast furnace process (ULCOS-BF) aims at minimising the CO 2 emissions of the BF by at least 50%. This process is based on the replacement of hot blast by oxygen, the recycling of hot decarbonated top gas into the lower shaft and normal hearth tuyeres, and the capture of CO 2 and its storage in a geological trap (full CO 2 capture and storage process). The paper highlights the main technologies of this process and the expected benefits for CO 2 mitigation. The ULCOS-BF has been demonstrated during three campaigns of 7 weeks each by coupling the LKAB experimental BF in Luleå to a pilot vacuum pressure swing absorption unit for CO 2 removal. The concept, preparation and results of the campaigns are described. 1 Technological improvements in BF process and development of reducing agent rate in Europe 1 ß 2013 Tata Steel Nederland Technology BV Published by Maney on behalf of the Institute

Blast furnace (BF) coal injection became a routine practice among European BFs; roughly, 40% of total energy required for the process is covered by auxiliary reducing agents. Pulverized coal (PC) remains the most commonly used auxiliary reductant. The key trend is increasing PC injection rates; over 200 kg tHM À1 PC on an annual basis is no rarity any more. Despite numerous measures for intensifying the coal conversion in the raceway, [1] it is hardly possible to combust such a high amount of coal within a very short residence time of few tens of milliseconds. Recent computational fluid dynamics calculations showed that at PC injection rate of 240 kg tHM À1 , about 50% of the coal amount entering the raceway may leave it as so-called char. [2] Another theoretical study from 2011 calculated a maximum PC injection rate of 190-210 kg tHM À1 for some BFs, considering that no ash deposition nor change in the gas flow distribution due to unburnt coal fines trapped in the coke bed takes place. [3] The following types of coal residues appear depending on different conditions and stages of its formation (Figure 1): 1) devolatilized coal particles (after light gases and tar have been released); 2) pyrolyzed (partly or completely) particles (caused by the thermal decomposition of the organic matter); and 3) not completely gasified particles (residues). Char formation, transportation, and behavior outside the raceway may significantly affect the BF process both negatively with respect to process stability and positively by increasing the combustion efficiency by possible consumption of char. The knowledge on these phenomena was limited because the main efforts over the last few decades were focused on the complete conversion of PC within the raceway. A char morphology system was introduced for the characterization of char types. [4] However, few studies are devoted to the

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The solid flow inside a blast furnace is modelled using a standalone finite element program and a constitutive equation called hypo‐plastic, in order to better simulate the granular material behaviour. The parameters of this constitutive equation are calibrated using data obtained from simple soil mechanics tests on coke and sinter materials, such as triaxial and oedometric devices. Steady velocity, stress and void fraction fields are obtained after several iterations of the code. Knowledge of the solids velocity field makes it possible to determine the dead man profile, as well as its renewal kinetics. Burden trajectories and time lines are also computed. Knowledge of the stress field makes it possible to compute pressures acting on the burden as well as on the walls. Finally, knowledge of void fraction field makes it possible to determine gas paths. The solid flow model was validated on 2D and 3D small‐scale cold blast furnaces, but the simulations never required any tuning parameter. This code is in fact an invaluable tool to determine the effect of blast furnace profile on solid flow conditions, and reciprocally.