European Dioxin Inventory - Results

030301
Sinter plants

030301
Sinter plants

Process description
By sintering, the pelletisation of fine-grained, smeltable ores, iron ore in particular, to
compact lumps by heating nearly to the melting or softening point is understood. Melting
tendencies at the grain boundaries lead to a caking of the material.

Before the sintering, the various substances are first mixed and, if desired, granulated.
The iron ores are agglomerated on conveyor sinter installations, the conveyor belts
consist of a large number of waggons. These waggons that have been linked up as an
endless conveyor belt which can be as big as 4 m in width and 100 m in length. The fine
ore to be sintered is moistened and fed on to the circulating grid together with coke
slack and additions such as limestone, quick lime, olivine or dolomite. Burners above a
heat-resistant grate belt heat the material to the required temperature (1100-1200 °C).
This causes the fuel in the mixture to be ignited. The carbon burns with the aid of the air
sucked through the grid into the mixture, resulting in the flame front being moved through
the sintering bed. The sintering processes are completed once the flame front has passed
through the entire mixed layer and all fuel has been burnt.

Chlorine compounds can enter into the sinter installation by means of the additive cokes
slack as well by the ore from its natural chloride contents. Furthermore, returned
materials such as certain filter particles, scale and sludges from waste water treatment,
which are added to the materials to be sintered, which can also increase the chlorine
content of the substances used. This is reflected in the waste gases from sinter
installations which contain inorganic gaseous chlorine compounds.

Abatement technologies:
Cleaning of the flue gases generated during the process is done in different ways:
sometimes dedusting (cyclone or fabric filter) suffices; sometimes the flue gases are

73
European Dioxin Inventory - Results
030301
Sinter plants

cleaned by a wet scrubber. The way of cleaning depends on the circumstances and the
nature of the emissions (and on the substances to be sintered). With respect to the
reduction of dioxin emissions special abatement techniques are currently being tested in
Austria and Germany. The „Airfine“ technology used at the plant located in Linz, Austria
consists of a high performance wet scrubbing system ‹1 › leading to flue gas
concentrations between 0.2 and 0.5 ng I-TEQ/m³. In Bremen, Germany the flue gas is
split into parallel flows each being treated with adsorbent injection ‹2› as known from
abatement measures installed at municipal waste incinerators. Concentrations below 0.1
ng I-TEQ/m³ could be achieved occasionally.

Plant data/European situation

Most of the integrated steel works operated in Europe also have sinter plants (with a
few exceptions that use pelletising plants or produce steel only from scrap material). A
complete plant list could be obtained from the German Association of Steel Producers
(VDEH) ‹3 › ; according to these data 47 sintering bands are operated at 33 different
locations. Their total nominal capacity results to be nearly 125,000 kt/a (see 030301—
Table 2) with the real production typically being about 60 - 80 % of this value.

A small sintering plant located in Duisburg, Germany is not mentioned in the list because
it does use recycled materials from steel production (e.g. filter dust) or other iron
containing waste materials instead of iron ores; however, the sinter produced mainly
goes back into the iron and steel industry with a smaller fraction also being processed by
non-ferrous metal insdustries.
The plants located in Luxemburg are to be closed in the near future (or already have
been shut down).

Activity data
Activity data (shown in 030301—Table 2) were taken from the national inventories
(Belgium, Germany and United Kingdom) and from annual production statistics. The

74
 European Dioxin Inventory - Results
030301
Sinter plants

slight differences between the values reported for Belgium and UK are due to different
basic years.
Five countries do not have any sinter plants (Switzerland, Denmark, Greece, Irland and
Norway) and subsequently were not regarded in this chapter.

Emission factors
Emission factors for sinter plants as reported by the national dioxin inventories are
shown in 030301—Table 4. They had been gained either by special measurement
programs or by adoption of literature data. The PCDD/F emissions of sinter plants were
the subject of several scientific studies performed in the recent past. A broad range of
flue gas concentrations and emission factors was found depending on the operation
conditions of the sinter plants. In German publications two different emission factors are
presented one refering to hot crushing and sieving of the sinter material and the other
refering to stack emissions of the sintering process.

From these studies the following mean emission factors were derived to be used for
emission estimations:

Mean emission factors [µg I-TEQ/t]

arithm. mean of values for sintering process 7.01
estimate for hot sieving and crushing 1
overall estimate incl. fugitive emissions 10
030301—Table 1 Mean emission factors for sinter plants [µg I-TEQ/t]
It should be mentioned that a factor considerably above these values (nearly 100 µg I-
TEQ/t) was found at one occasion in Germany‹4 › .

Emission estimation
On the basis of the mean emission factors for the sintering process and hot sieving and
crushing standardised annual PCDD/F emissions were derived (030301—Table 4). The
sum of these two values gives the emissions of the overall process.

75
European Dioxin Inventory - Results
030301
Sinter plants

Conclusions/recommendations
Obviously sinter plants belong to the most important dioxin sources in Europe. Due to
measurement results from sinter plants the dioxin emissions are rather well known in
some European countries, e. g. Germany, The Netherlands, United Kingdom. By
contrast almost no information exists about the emissions from the facilities located in
other countries, the main producers being located in Belgium, Spain, France and Italy.

The annual PCDD/F emissions have been calculated provided that the measurement
results are valid for all plants in Europe. It should be stressed, that this assumption
cannot be verified by consideration and comparison of process conditions since it had
been shown that apparently similar processes may lead to very different emissions.
Hence the estimate given here may be associated with considerable uncertainty; thus it is
recommended to perform measurements on all or at least some additional plants in the
countries mentioned before.

76
 European Dioxin Inventory - Results
030301
Sinter plants

Country nominal national annual production

capacity Inventory ‹5›
A 3,400 2,720
B 14,146 10,630 9,828
CH nr
D 29,940 25,451 25,451
Dk nr
E 8,174 6,200
F 22,415 18,385
GR nr
I 18,570 12,800
IRL nr
L 5,700 4,600
N nr
NL 4,000 4,143
P 480 400
S 1,200 960
SF 2,400 1,920
UK 14,010 15,096 13,602
SUM 124,435 98,289
030301—Table 2 Activity rates related to annual sinter production [kt/a];
nr: not relevant

77
European Dioxin Inventory - Results
030301
Sinter plants

Flue gas conc. [ng I-TEQ/m³] Emission factors [µg/t] Remark

typ min max typ min max
A 0.20 2.50 2.35 lower EF correspods to plant with high performance wet scrubber "Airfine"
B 5.00 1.50 50.00 EF refers to data from S, NL and D
CH no sinter plant
D 0.08 0.11 0.62 0.88 0.89 refers to hot crushing and sieving
D 6.00 0.80 14.10 5.90 1.30 27.70 stack emission from sintering process; maximum concentration observed at one
DK no sinter plant
E 6.00 acc. to information obtained from TNO
F 18.00 10.00 100.00 EFs estimated from German results
GR no sinter plant
I no data obtained
IRL no sinter plant
L sinter plant to be closed down; emissions inofficially reported to be in the
"normal" range
N no sinter plant
NL 4.50 6.80 13.86 11.30 17.00
P
S 0.86 0.46 1.30 1.67 1.00 2.80 NTEQ; sinter plant to be closed down in 1995
SF
UK 0.60 3.40 3.29 1.20 9.00 Emission calculated from measured concentrations., spec. flew gas volumes and
7.01 chosen arithm. mean of values for sintering process
1 estimated for hot sieving/crushing
10 overall estimate incl. fugitive emissions
030301—Table 3 PCDD/F air emission factors for sinter plants from the national dioxin inventories

78
European Dioxin Inventory - Results
030301
Sinter plants

Country sintering hot overall

process sieving/crushing process
A 19.1 2.7 27.2
B 68.9 9.8 98.3
CH
D 178.4 25.5 254.5
Dk
E 43.5 6.2 62.0
F 128.9 18.4 183.9
GR
I 89.7 12.8 128.0
IRL
L 32.2 4.6 46.0
N
NL 29.0 4.1 41.4
P 2.8 0.4 4.0
S 6.7 1.0 9.6
SF 13.5 1.9 19.2
UK 95.3 13.6 136.0
SUM 708 101 1010
030301—Table 4 Comparison of PCDD/F air emission estimates [g I-TEQ/a] for sinter plants

79
European Dioxin Inventory - Results
030301
Sinter plants

References to 030301

1 Parzermair F., Gebort W. Muraurer F. (1994) : Emissionsminderung an

Sinteranlagen durch Gasreinigungstechnologie AIRFINE.. 37. Seminar, UTECH
BERLIN '94.

Theobald, W. (1995) : Ermittlung und Verminderung der Emissionen von

halogenierten Dioxinen und Furanen aus thermischen Prozessen; Untersuchung
der Emissionen polychlorierter Dibenzodioxine und -furane und von
Schwermetallen aus Anlagen der Stahlerzeugung. Umweltbundesamt, Berlin
(Ed.) 310

3 Data bank "plantfacts".VDEH, Düsseldorf

4 Bröker G., Bruckmann P., Geueke K.-J., Hiester E., Hoffmann , Radermacher
L., Gliwa H. (1995) : Abschlußbericht der Projektgruppe "Dioxinmeßprogramm
Nordrhein-Westfalen". Landesumweltamt Nordrhein-Westfalen (Ed.) 102 p.

5 Wirtschaftsvereinigung Stahl (Ed.): Statistisches Jahrbuch der Stahlindustrie

1995. Verlag Stahleisen GmbH, Düsseldorf, 360

80