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

One of the primary causes that limit the blast furnace productivity is the resistance exerted to the gas flow in the cohesive zone by the ferrous burden. Use of nut coke (10-40 mm) together with ferrous burden proves beneficial for decreasing this resistance. In present study, effect of nut coke addition on the olivine fluxed iron ore pellet bed is investigated under simulated blast furnace conditions. Nut coke mixing degree (replacement ratio of regular coke) was varied from 0 to 40 wt% to investigate the physicochemical characteristics of the pellet bed. Three distinct stages of bed contraction are observed and the principal phenomena governing these stages are indirect reduction, softening and melting. It is observed that nut coke mixing enhances the reduction kinetics, lowers softening, limits sintering and promotes iron carburisation to affects all three stages. In the second stage, the temperature and displacement range is reduced by 60°C and 24%, respectively upon 40 wt% nut coke mixing. Addition of nut coke exponentially increases the gas permeability (represented by pressure drop and S-value). A higher degree of carburisation achieved on the pellet shell (iron) is suggested to be the principal reason for decrease in the pellet melting temperature. The pellets softening temperature increases by approximately 4°C, melting and dripping temperature drops by 11°C and 12°C, respectively, for every 10 wt% nut coke addition. Consequently, the nut coke addition shortens the softening, melting and dripping temperature ranges, which shows improved properties of the cohesive zone.

An off-line simulation model of the blast furnace hearth is developed based on mass balances for iron and slag, expression of the liquids outflow rates and logical conditions for the start and the end of the outflow of liquids. The dynamic model divides the furnace hearth into two regions of sizes that may change during the tapping process. It provides a description of the time evolution of the liquid levels and predicts the duration and the periods of iron-or slag-only flow in the beginning of the taps. The values of some model parameters are estimated on the basis of measurements in a reference blast furnace, while others are fixed. A sensitivity analysis of the model is provided, revealing the role of some key parameters. The model is demonstrated to describe the overall drainage behavior of the reference furnace reasonably well, and the presence of pools with different liquid levels can also be deduced from the real data. Finally, some recommendations for future work are suggested.