Messung von Phasen im Sinter und die Auswirkung bestimmter Phasen auf den Koksverbrauch im Hochofen

Beppler, E.; Gerstenberg, Bernhard; Janhsen, Urban

doi:10.1002/srin.198700236

Cited by 4 publications

(6 citation statements)

References 2 publications

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“…8) Concentration gradient of alkali in coke lump was reported to be responsible for stress abrasion of alkali-rich layer of coke. 14) In other study, up to 5 % variation of alkalis in coke did not indicate any adverse impact on the coke strength (CSR). 15) Potassium adsorption by carbonaceous materials such as coke could vary in many ways depending on the nature of the carbon phase as well as the treatment temperature.…”

Section: Introductionmentioning

confidence: 77%

Degradation Behaviour of a High CSR Coke in an Experimental Blast Furnace: Effect of Carbon Structure and Alkali Reactions

et al. 2005

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A high CSR coke was tested in the LKAB's Experimental Blast Furnace (EBF) at Luleå. The evolution of physical and chemical properties of the centre-line coke samples were analysed by Light Optical Microscopy (LOM), BET N 2 absorption and SEM/XRF/XRD. Alkali distribution in the EBF cokes was examined by XRF/SEM and EDS. Thermo Gravimetric Analysis (TGA) was used to measure isothermal and nonisothermal CO 2 reactivity of the cokes. The crystalline order of carbon and the concentration of alkalis were found to increase as the coke descended through thermal reserve zone to the cohesive zone of the EBF. The crystallite height (L c ) of EBF coke carbon displayed a linear correlation with the measured EBF temperatures demonstrating the strong effect of temperature on carbon structure of coke in the EBF. Alkali concentration of the coke was increased as it descended into the EBF, and was uniformly distributed throughout the coke matrix. The CO 2 reactivity of lower zone cokes was found to increase when compared to the reactivity of the upper zones cokes, and was related to the catalytic effect of increased alkalis concentration. The deterioration of coke quality particularly coke strength and abrasion propensity were related to coke graphitisation, alkalization and reactivity. Coke graphitisation is shown to have a strong influence on the coke degradation behaviour in the EBF.KEY WORDS: coke; CSR; abrasion; graphitisation, XRD; gasification; TGA reactivity; alkali.experimental blast furnace. Even though the EBF tests are time consuming, tedious and highly expensive, the information generated is of great value in terms of their reliability suitability due to simulation of more realistic conditions of a blast furnace process.Coke degradation in a blast furnace occurs due to chemical, mechanical and thermal effects. At higher flame temperature, cracking of coke is mainly attributed to thermal stress while at lower temperatures, the degradation behaviour is influenced by coke reactivity which is dependent on other coke properties. The coke reactivity can be influenced by its three major properties namely porosity, carbon structure and constituent minerals. Coke pore structure is modified by growth and/or coalescence of pores, which is often related to fluidity and swelling characteristics of parent coals, 5) and modifies the available carbon surface area for gas reactions. Coke displays graphitisation behaviour particularly at temperatures exceeding 1 200°C, which is influenced by the catalytic effect of minerals such as iron, and is believed to weaken the abrasion resistance.6) Iron in coke is also believed to catalyze gasification reactions 7) which could have different implications on coke behavior in the EBF. The influence of other minerals particularly those containing alkali on the coke degradation is less certain. The main aim of this study is to investigate the effect of alkalis on coke behaviour in the experimental blast furnace. Therefore, it is imperative to discuss further various aspects of alkalis influence on...

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Section: Introductionmentioning

confidence: 77%

Degradation Behaviour of a High CSR Coke in an Experimental Blast Furnace: Effect of Carbon Structure and Alkali Reactions

et al. 2005

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“…Despite several studies indicating a possible relationship between alkali content and coke strength, there are uncertainties regarding the extent of their impact and their role on the mechanisms of coke weakening [150]. For example, the concentration gradient of alkali in coke lump was reported to be responsible for stress abrasion of the alkali-rich layer of coke [22] but other studies contradict this finding by concluding that up to 5% variation of alkalis in coke did not indicate any adverse impact on the coke strength (CSR) [18,116]. The influence of alkalis on coke gasification in a blast furnace also raises the concerns about the suitability and interpretation of the conventional CSR test results [153,[155][156][157] due to its inability to account for the effect of recirculating alkalis.…”

Section: Lkab Experimental Blast Furnacementioning

confidence: 99%

“…This innovation would require a new dimension for coke quality, namely the development of a higher reactivity coke (to decrease the thermal reserve zone temperature) which is stronger (to minimize fines production within the furnace). This is a significant R&D task, since traditionally highstrength cokes have lower reactivity and vice versa [22][23][24]. In the low-temperature operation, the major reactions such as reduction of iron ore and gasification of carbon materials must occur at a higher kinetic rate in order to compensate for the lower temperature of operation [44].…”

Section: Compact Blast Furnace Process (Low-temperature Operations)mentioning

confidence: 99%

Minerals and iron-making reactions in blast furnaces

Gupta

French

Sakurovs

et al. 2008

Progress in Energy and Combustion Science

109

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“…Silicon monoxide is usually assumed to form from coke ash and ash from injectants as a result of any of the following reactions [5][6][7][8]10,12,13,[15][16][17]19,20,[22][23][24] : SiO 2 (in ash)ϩCO (g)ϭSiO (g)ϩCO 2 Usually reaction (2) is given as the dominating reaction 5,6,12,13,[15][16][17]20,[22][23][24] Some sources also give reaction (1) as the dominating reaction. 7,8,10) The difference between reactions (1) and (2) is Boudouard's reaction: C (graphite, coke or coal powder)ϩCO 2 (g)ϭ2CO (g)... (5) If reaction (1) occurs, the CO 2 gas formed will react with carbon (from coke or injectants) according to reaction (3) resulting in the net reaction (2).…”

Section: Theoretical Considerationsmentioning

confidence: 99%

“…7,8,10) The difference between reactions (1) and (2) is Boudouard's reaction: C (graphite, coke or coal powder)ϩCO 2 (g)ϭ2CO (g)... (5) If reaction (1) occurs, the CO 2 gas formed will react with carbon (from coke or injectants) according to reaction (3) resulting in the net reaction (2). Most of the coke in the blast furnace process is consumed in the raceway.…”

Section: Theoretical Considerationsmentioning

confidence: 99%