Annex 16 Complementary information to source category 2a Iron Ore Sintering
Overview of recent revisions
A literature survey on source group 2 was conducted based on the information submitted by Toolkit expert panel members, and new data collected and assessed based on the examination of 71 reports and scientific articles. This survey resulted in the identification of possible new/revised emission factors for PCDD/PCDF and possible new emission factors for PCBs and HCB.
The assessment of recent scientific findings led to new proposals regarding emission factors for PCDD/PCDF releases, along with the revision of class definition and description. Changes to emission factors were made where significant differences were found between factors derived from recent scientific literature and those included in the Toolkit. In many instances, the literature review also enhanced the level of confidence associated with current dioxin emission factors.
The majority of PCDD/PCDF emission factors for source category 2a Iron Ore Sintering were confirmed; in the case of residues in classes 2 and 3, higher emission factors were proposed. New emission factors are also proposed for PCBs and HCB air emissions:
Table III.16.1 PCB emission factors for source category 2a Iron Ore Sintering
2a Iron Ore Sintering Emission Factors (µg TEQ/t sinter produced) Classification Air Water Land Product Residue 1 High waste recycling including oil contaminated materials, no or limited air pollution control system 1 2 Low waste use, well controlled plant 0.2 3 High technology emission reduction 0.05
Table III.16.2 HCB emission factors for source category 2a Iron Ore Sintering
2a Iron Ore Sintering Emission Factors (µg/t sinter produced) Classification Air Water Land Product Residue 1 High waste recycling including oil contaminated materials, no or limited air pollution control system 1,000 2 Low waste use, well controlled plant 1,000 3 High technology emission reduction 300
For PCB and HCB, default emission factors provided in the above tables are assigned:
- A medium level of confidence for class 2 (PCB) and class 3 (HCB), as emission factors are based on a low data range and not on expert judgment but are not derived from a broad geographical coverage;
- A low level of confidence for class 1 (PCB and HCB), class 2 (HCB) and class 3 (PCB), as emission factors are based on extrapolations and expert judgment.
Derivation of emission factors
Release to Air
Iron ore sinter plants have been identified as a major source of PCDD/PCDF to air in some countries. The highest emissions are expected from plants which have not made comprehensive attempts to reduce PCDD/PCDF emissions and use waste materials such as cutting oils, dust from the ESP, etc (class 1). The emission factor for this class – 20 μg TEQ/t – comes from two inventory studies using a gas volume of 2,000 Nm³ per ton of sinter and a concentration of 10 ng TEQ/Nm³ (HMIP 1995, SCEP 1994). At one plant in Germany, an emission factor of nearly 100 μg TEQ/t sinter has been determined; respective stack emissions were 43 ng TEQ/m³ (LUA 1997). This emission factor was confirmed through the highest value observed in the European Union after the year 2000 which is 16 µg TEQ/t (BREF 2012).
For plants with low waste use, the class 2 emission factor is 5 μg TEQ/t based on studies from Belgium, Sweden, the Netherlands, and Germany (LUA 1997). This emission factor was confirmed by several publications. In the 2011 version of the iron and steel BREF (BREF 2012), the majority of values ranges from 2 to 6 µg TEQ/t (more than 12 plants). The CORINAIR database considers an emission factor of 1.8 µg TEQ/t where ESPs are used. Between 2002 and 2004, measurements have been achieved on three sinter plants using ESPs in the UK showing emission factors with a mean value of 2.2 µg TEQ/t (Aries et al. 2006).
For highest technology plants, where PCDD/PCDF emissions were addressed and major changes to technology and plant operation were realized, a class 3 emission factor of 0.3 µg TEQ/t is proposed. Improvements may include measures to reduce gas flows and multistage scrubbing with effluent treatment. The emission factor of 0.3 μg TEQ/t is based on a reduced gas flow of 1,500 Nm³/t and a concentration of 0.2 ng TEQ/Nm³ (Smit et al. 1999, HMIP 1995). This emission factor is confirmed by the lowest emission factor (0.15 µg TEQ/t) observed in the European Union, during the data collection process which was achieved for the iron and steel BREF (BREF 2012). Data collected in Taiwan from 4 plants show emission factors ranging from 0.18 to 0.89 µg TEQ/t (Wang et al. 2009) whereas data collected in Japan provide a mean value of 0.27 µg TEQ/t (Iwata et al. 2008). Concentration measured in one Korean sinter plant was 0.45 ng TEQ/Nm³ (Kim et al. 2005), which corresponds to an emission factor of 0.9 µg TEQ/t (assuming a gas flow of 2,000 Nm³/t of sinter). Where wet scrubbers are used in conjunction with an ESP, the mean PCDD/PCDF concentration from 9 measurements is 0.31 ng TEQ/Nm³ (Guerriero et al. 2006), which, assuming a gas flow of 2,000 Nm³ /t, corresponds to an emission factor of 0.62 µgTEQ/t.
Air emission data related to PCBs and HCB have also been identified in the literature. The European BREF document gives a PCB emission factor range of 0.025 to 0.18 µg TEQ/ t (BREF 2012). Measurements carried out in Korea showed PCB concentrations of 0.018 ng TEQ/Nm³ (Kim et al. 2005). Assuming a gas flow of 2000 Nm³/t, such concentration corresponds to an emission factor of 0.04 µg TEQ/t. Thirdly, measurements achieved in two Polish sinter plants gave similar results: 0.048 and 0.056 µg TEQ/t (Grochowalski et al. 2007). Hence, an emission factor of 0.05 µg TEQ/t is proposed for class 3 and an emission factor of 0.2 µg TEQ/t for class 2. According to these references, the PCB share in the total TEQ is ranging from 4 to 9%. Therefore, an emission factor of 1 µg TEQ/t is proposed for class 1. HCB data are provided by three references. Two Japanese studies have synthesized HCB measurement results and propose emission factors of 430 µg/t and 150 µg/t respectively (Ota et al. 2005, Sakai et al. 2009). Measurements were also carried out in Poland and HCB emission factors could be derived. Those are ranging from 640 to 1,730 µg/t (Grochowalski et al. 2007). Assuming that class 3 APC devices are the most efficient for HCB removal and that class 1 and 2 APC devices have similar removal efficiencies towards HCB emissions, an emission factor of 300 µg/t is proposed for class 3 and an emission factor of 1,000 µg/t for class 2 and class 1.
Release to Water
A release to water may occur if there is a wet scrubber used in the process with an effluent discharge. No emission factor could be developed for this release route. Any liquid discharge should be noted, along with its quantity and any treatment.
Release to Land
No release to land is expected. Dumping of residues to land should be noted.
Release in Products
The product of this process is sinter, which is fed to the blast furnace. PCDD/PCDF present in the sinter will enter the blast furnace and are likely to be destroyed. Therefore no release in product can be assessed.
Release in Residues
The main residue is expected to be in the form of dust collected in dust control devices. Some of it may be recycled to the process, or may be removed from the process as a waste. As de-dusting devices are more sophisticated in the case of classes 2 and 3, the corresponding emission factors should be higher than class 1.
Class 1 emission factor is derived from measurements carried out before 2005 when de-dusting systems were far from BAT. UK data on the amounts of PCDD/PCDF in dust from sinter plant ESPs give a range from 29 to 90 ng I-TEQ/kg. Only a small amount of sinter dust is disposed of (e.g., in the UK, 700 t/a from a sinter production of 15.1 million tons of sinter – about 0.05 kg dust per ton of sinter). Data from Germany measured in 1993/94 were in the range of 196 to 488 ng I-TEQ/kg (EC 1999). An emission factor of 0.003 is therefore proposed for class 1. The iron and steel BREF developed within the EU gives an emission factor range for residues ranging from 0.14 to 3.21 µg TEQ/t (BREF 2012). Besides, measurements carried out in Korea in 2008 gave emission factors ranging from 0.14 to 3.21 µg TEQ/t (Jin et al. 2009). These references lead to Toolkit emission factors of 1 and 2 µg TEQ/t for classes 2 and 3 respectively.