Study on polychlorinated dibenzo-p-dioxin/furan formation in iron ore sintering process

In order to understand and control the formation of dioxins and furans (PCDD/Fs) in iron ore sinter plants, a CFD model of iron ore sintering, combined with the kinetic models of 14 relevant chemical reactions and thermodynamic calculations of dioxin formation, has been developed to simulate the concentrations of the gaseous species, temperatures of the gas and solid, velocity of the gas, temperature zones, and residence time of the gas in each temperature zone. The predicted off-gas compositions, the velocities of the gas, and the trends for the gas temperature at the bottom of the bed have been compared with measured data from a sinter plant, and good agreement has been obtained. From the predicted temperature zones of the gas and solid, the predicted residence time of the gas in each zone, and thermodynamic conditions of PCDD/F formation, the PCDD/F formation in sinter plants has been discussed. The dioxins are formed in the critical temperature region of 250 °C to 450 °C below the combustion zone in the bed, are then carried downward with the gas, and are condensed close to the bottom of the sinter bed. Transported to the discharge end with the solid mixture, they are again released into the gas phase when the flame front approaches the bottom. The dioxins are also formed in the last wind boxes when the hot off-gases cool and reach the critical temperature range. These pathways on PCDD/F formation can explain the industrial observations well. The preceding information may assist in the effective control or elimination of dioxin formation in iron ore sinter plants.

[1]  W. Schlebusch,et al.  THE RHENISH-WESTPHALIAN TECHNICAL UNIVERSITY AACHEN∗: (Rheinisch-Westfälische Technische Hochschule Aachen - RWTH) , 1976 .

[2]  I. F. Macdonald,et al.  Flow through Porous Media-the Ergun Equation Revisited , 1979 .

[3]  W M Shaub,et al.  Dioxin formation in incinerators. , 1983, Environmental science & technology.

[4]  H. Vogg,et al.  Thermal behavior of PCDD/PCDF in fly ash from municipal incinerators , 1986 .

[5]  Shun Sato,et al.  Melting Model for Iron Ore Sintering , 1986 .

[6]  K. Kamei,et al.  Effect of Stacking Fault Precipitation on Hot Deformation of Austenitic Stainless Steel , 1986 .

[7]  H. Hagenmaier,et al.  Catalytic effects of fly ash from waste incineration facilities on the formation and decomposition of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans , 1987 .

[8]  H. Vogg,et al.  On formation conditions of PCDD/PCDF in fly ash from municipal waste incinerators , 1987 .

[9]  Michael Metzger,et al.  Recent Findings On the Formation and Decomposition of PCDD/PCDF in Municipal Solid Waste Incineration: , 1987 .

[10]  F. N. Fett,et al.  Thermisches Betriebsverhalten einer Bandsinteranlage , 1987 .

[11]  E. Streich,et al.  Modellmäßige Beschreibung des Temperaturfeldes eines Sinterprozesses , 1990 .

[12]  G. L. Moilanen,et al.  Simultaneous Control of PCDD/PCDF, HCI and NOX Emissions from Municipal Solid Waste Incinerators with Ammonia Injection , 1991 .

[13]  P. Spencer,et al.  Thermodynamic conditions for the formation of dioxin , 1992 .

[14]  A. Sigg,et al.  Dioxin removal in a wet scrubber and dry particulate remover , 1992 .

[15]  Christoffer Rappe,et al.  Influence of combustion parameters on the formation of polychlorinated dibenzo-p-dioxins, dibenzofurans, benzenes, and biphenyls and polyaromatic hydrocarbons in a pilot incinerator , 1993 .

[16]  J. Unsworth,et al.  Thermodynamic data for dioxins from molecular modelling computations: Prediction of equilibrium isomer composition , 1993 .

[17]  James D. Litster,et al.  An investigation of pre-ignition air flow in ferrous sintering , 1994 .

[18]  C Rappe,et al.  Influence of Postcombustion Temperature Profiles on the Formation of PCDDs, PCDFs, PCBzs, and PCBs in a Pilot Incinerator. , 1994, Environmental science & technology.

[19]  Barry Dellinger,et al.  The homogeneous, gas-phase formation of chlorinated and brominated dibenzo-p-dioxin from 2,4,6-trichloro- and 2,4,6-tribromophenols , 1995 .

[20]  J. Aguilar,et al.  Simulation of iron ore reduction in a fixed bed , 1995 .

[21]  R. Shekhar,et al.  Selective reduction of Indian nickeliferrous ore : single pellet experiments , 1995 .

[22]  E. Altwicker,et al.  Formation of polychlorinated dioxins, furans, benzenes, and phenols in the post-combustion region of a heterogeneous combustor: effect of bed material and post-combustion temperature. , 1995, Environmental science & technology.

[23]  A. Buekens,et al.  On the mechanisms of dioxin formation in combustion processes , 1995 .

[24]  A. Buekens,et al.  De novo synthesis of polychlorinated dibenzo-p-dioxins and dibenzofurans Proposal of a mechanistic scheme , 1996 .

[25]  W. J. Walker,et al.  A literature review of formation and release of PCDD/Fs from gas manufacturing: A previously unidentified source? , 1997 .

[26]  Nirupam Chakraborti,et al.  Dynamic process modelling of iron ore sintering , 1997 .

[27]  E. Dinjus,et al.  'De novo' testing of dusts, collected in successive fields of an electrostatic precipitator of a sintering Plant. (II) Effect of reaction temperature , 2000 .

[28]  N. Saito,et al.  Prediction for thermodynamic function of dioxins for gas phase using semi-empirical molecular orbital method with PM3 Hamiltonian. , 2000, Chemosphere.

[29]  Min-Kyun Kim,et al.  Comparison of PCDD/PCDFs composition in gas and solid phase emitted from sinter plants of POSCO in Korea , 2000 .

[30]  Yukio Tomita,et al.  Macroscopic Behaviors of Dioxins in the Iron Ore Sintering Plants , 2001 .

[31]  G Eriksson,et al.  Thermodynamic modeling of PCDD/Fs formation in thermal processes. , 2001, Environmental science & technology.

[32]  I. Hurtado,et al.  Predictions for isomer distributions of toxic dioxins and furans in selected industrial combustion processes. , 2002, Chemosphere.

[33]  Toshihiro Tanaka,et al.  Mechanism of Dioxins/Furans Formation at High Temperature in Combustion Processes , 2003 .