Macroscopic Behaviors of Dioxins in the Iron Ore Sintering Plants.

Kasai, Eiki; Aono, Teruhiko; Tomita, Yukio; Takasaki, Makoto; Shiraishi, Norihisa; Kitano, Shinji

doi:10.2355/isijinternational.41.86

Cited by 37 publications

(31 citation statements)

References 4 publications

(4 reference statements)

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“…Plant observations 7) confirmed that dioxin concentration at wind-box increases with increase in wind-box temperature, and that an increase of Cl concentration of raw mixture leads to larger emissions. The sintering pot tests 8) have showed the importance of Cl 9,10) and Cu 11) contents in the raw mixture and the coke properties.…”

Section: Introductionsupporting

confidence: 54%

Observation of Behavior of Dioxins and Some Relating Elements in Iron Ore Sintering Bed by Quenching Pot Test

2005

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Understanding of the formation mechanism of dioxins in the sintering bed is of importance in developing countermeasures to reduce the emission of dioxins from sintering plants. This research has clarified the behavior and the possible mechanism of dioxin formation and the relation to Cl and Cu components in the sintering bed by conducting a series of quenching tests utilizing sintering pots.The progress of flame front was quenched by terminating the air supply, then introducing N 2 gas in the reverse direction when the sintering process progressed halfway through the test pots, specifically to the position of the thermocouples. The primary specimens were obtained from the raw mixture zone situated beneath the combustion interface for chemical analysis.Concentrations of dioxins, Cl and Cu were found at the depth of 10-20 mm beneath the combustion interface in raw mixture zone. This was considered to be the site of dioxin synthesis. Slight increase of dioxins in the wet zone was related to dioxin vaporizing from the site of the synthesis, then to be trapped in this zone. Significant amounts of dioxins escaping into the outlet gas at and after burn through point could be explained by both the releasing of trapped dioxins and the acceleration of the synthesizing process attributable to the increased concentration of Cl and Cu.KEY WORDS: agglomeration; copper; chlorine; dioxins; iron ore sintering; sintering bed.series of experiment, which was conducted to examine the influence of the use of Ore C containing a higher Cu content. The type and quantity of additives were varied according to the purpose of experiment. As the base condition of the experiment, 200 mg/kg NaCl was added to a raw mixture, so as to accelerate the dioxin formation during sintering to a detective extent. The chemical composition of the sintered product aimed for 5.1 mass% as SiO 2 , 9.5 mass% as CaO, and 1.9 mass% as Al 2 O 3 .The sintering pot was 300 mm in diameter and 600 mm in height. To quench the sintering at a specified position, a thermocouple was inserted into the bed at 400 mm from the top of the bed. Upward N 2 gas flow was applied to stop the combustion of coke and cool the bed when quenching (Fig. 1). Procedure of Sintering and QuenchingThe raw mixture was mixed for 60 s and granulated with adding water for 180 s in a drum-type mixer of 1 m in diameter. The moisture content was set at 6.5 mass%. The granulated mixture was charged into a pot to form a bed with 560 mm in thickness. The average mass of charges weighed 66 kg. After ignition at 1 100°C for 90 s, the sintering process was conducted under a constant suction pressure of 12 kPa.The quench technique applied in the present study was basically follows after Soma et al. 14) Quenching proceeded as follows: when the thermocouple gave the maximum bedtemperature, the main blower was stopped and simultaneously N 2 gas was introduced from the bottom of the pot. For experimental series 1 and 2, the flow rate of the N 2 gas was set at 0.3 Nm/s. It required 2 h to cool the bed. For se...

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Section: Introductionsupporting

confidence: 54%

Observation of Behavior of Dioxins and Some Relating Elements in Iron Ore Sintering Bed by Quenching Pot Test

2005

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“…In addition, the carbon active site could then react with HCl to form covalent C-Cl bonds (Takeda et al, 2006). Here, HCl could be formed during the combustion process since the Cl content was originally containing in the cokes (Kasai et al, 2001a). Yet, it is true that HCl might be converted to Cl 2 under the temperature range between 340 and 400°C via the Deacon reaction.…”

Section: Possible De Novo Synthesis Pathways Of Organic Chlorine Compmentioning

confidence: 99%

“…The above pattern is similar to that of PCDD/F emissions from municipal waste incinerators. The de novo synthesis has been considered as an important formation pathway of PCDD/Fs during the iron ore sintering process according to the results obtained from several field and laboratory investigations (Kasai et al, 2001a(Kasai et al, , 2001bXhrouet et al, 2001;Cieplik et al, 2003;Kuzuhara et al, 2003;Suzuki et al, 2004;Kasama et al, 2006;Tsubouchi et al, 2006). For example, a series of laboratory sinter-pot studies have identified that the de novo synthesis could be occurred in the drying zone of the sinter bed (Cieplik et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

“…For example, PCDD/Fs emitted from the sintering process contributed to 19.6%, 1134%, 8.4% and 30.7% of the total annual PCDD/F emissions in Europe (Quaß et al, 2000), United Kingdom (Anderson and Fisher, 2002), Japan (Japan Ministry of the Environment, 2005) and Taiwan (Taiwan Environmental Protection Administration, 2008), respectively. Kasai and his colleagues (Kasai et al, 2001a) have investigated that the PCDD/Fs congener profiles of exhaust gases of windboxes. They found that the concentration of PCDFs were 10 times in magnitude higher than PCDDs.…”

Section: Introductionmentioning

confidence: 99%

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Identification the Content of the Windbox Dust Related to the Formation of PCDD/Fs during the Iron Ore Sintering Process

Kuo

Chen

Yang³

et al. 2011

Aerosol Air Qual. Res.

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This study measured the contents of the ionic and elemental constituents, and the chemical compounds containing in windbox (WB) dusts collected from a commercial iron ore sintering plant, then the results were used to identify possible PCDD/Fs formation pathways in the WB. We found that the abundance in both KCl and NaCl may provide a suitable condition for de novo synthesis of PCDD/Fs in the WB. Al, Fe, K, Ca, and Pb were the top five contents in WB16 dusts, but the co-existence of the above five metal contents warrants the need for further investigation on their roles in PCDD/F formation processes in the future. Although a low concentration of Cu was detected, it might be of importance to PCDD/Fs formation inside the WB. A total of 29 chemical compounds were identified. Among them, several oxygenated organic compound might be associated with PCDD/F formations at the beginning stage, but the roles of aromatic oxygenates on the formation of PCDD/Fs required further investigation. Finally, possible de novo synthesis pathways of PCDD/Fs were proposed based on the above findings. However, the above pathways are required further laboratory studies for validation before possible formation suppression approaches can be determined.

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“…Some emissions limits in GB28662-2012 are more stringent than the standards of other developed countries. [8][9][10] Currently processing methods for SO 2 in the sintering process are mainly based on the calcium method, such as wet limestone/gypsum technology, circulating fluidized bed (CFB), spray drying adsorption (SDA), maximized emission reduction of sintering (MEROS), etc. All these techniques belong to the end-of-pipe treatment process and significant progresses have been made in the treatment of SO 2 in the sintering process, but some problems do exist, for instance, high investment cost, high running expense, large occupation of land and secondary pollution, etc.…”

Section: )mentioning

confidence: 99%

Lower SO<sub>2</sub> Emissions in the Sintering Process Utilizing the Difference of Sulphur Contents of Iron Ores

Qie

Zhang

et al. 2017

ISIJ Int.

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The current treatment of sintering flue gas pollutants is mainly focused on the end-of-pipe treatment, but some problems still exist. It will be more simple and efficient to start from the source to control the pollutants elements. In this paper, the iron ores are classified into two parts utilizing the difference of sulphur contents of iron ores and their adding ratio, "High Sulphur" iron ores and "Low Sulphur" iron ores. Both parts of the iron ores are located inside or outside of the tested pellet, respectively, by granulating with other sintering materials. The experiment results of SO 2 emissions reduction are similar in the tubular electric furnace experiment and the sinter-pot test. The sinter-pot test performed in this study reveals that about 41.02% and 34.20% of SO 2 are reduced, respectively, through the method in which the "High Sulphur" iron ores are located inside and outside of the tested pellet compared with the traditional method. The falling strength and tumbler strength of sinter decrease by 3.04% and 1.51% when the "High Sulphur" iron ores are located inside of the tested pellet, respectively. While the falling strength and tumbler strength increase by 5.44% and 0.08% when the "Low Sulphur" iron ores are located inside of the tested pellet, respectively. Reduction index (RI) decreases by 1.38% and 4.96%, respectively, while the characteristic value (S) decreases by 19.89% and 70.50%, respectively. The reducibility of sinter decreases, but the softening-melting properties of sinter improve obviously. Compared with the traditional method, the methods introduced in this article have some advantages from the perspective of SO 2 emissions reduction and the improvement of the softening-melting properties of sinter. In general, the method in which "High Sulphur" iron ores are located outside of the pellet would be more preferable than that of located inside.

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Macroscopic Behaviors of Dioxins in the Iron Ore Sintering Plants.

Cited by 37 publications

References 4 publications

Observation of Behavior of Dioxins and Some Relating Elements in Iron Ore Sintering Bed by Quenching Pot Test

Observation of Behavior of Dioxins and Some Relating Elements in Iron Ore Sintering Bed by Quenching Pot Test

Identification the Content of the Windbox Dust Related to the Formation of PCDD/Fs during the Iron Ore Sintering Process

Lower SO<sub>2</sub> Emissions in the Sintering Process Utilizing the Difference of Sulphur Contents of Iron Ores

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