"Sintering plants serve for recycling of dusts, scrap and abrasion from other processes of the metallurgical plant to recover the iron for further use in the blast furnace. But this reasonable waste management method is accompanied by the problem of introducing traces of chlorine and organic compounds responsible for the generation of PCDD/F (dioxin) within these plants."We have asked it at the Hoogovens iron and steel plants in The Netherlands: NO scrap recycling is done in sintering plants! Only the dust from the blast furnaces is recycled that way. Sintering is the reaction of iron ORE with coke and some other stuff (e.g. lime) to form hard pellets that can withstand the high static pressure of the blast furnace. Scrap metal has no use there, it is used in steel furnaces and reclamation plants. In fact no external industrial sources of chlorine are introduced, neither in the sintering process, nor in blast furnaces.Source: Greenpeace report 'Achieving Zero Dioxin' - July 1994 [1].
Maximum chlorine content and measured/estimated dioxin release:
All figures expressed in µg I-TEQ
to air per ton produced or incinerated.
| chlorine input and dioxin output of different processes | ||||
|---|---|---|---|---|
| Process | max.%
chlorine in 'fuel' |
dioxin release | rem | |
| min | max | |||
| Incineration of hospital waste: | 7 | 800 | 5000 | 1 |
| Incineration of copper cable: | 20 | 3.7 | 2280 | 5 |
| Incineration of wood (with PCP): | 1 | 25 | 500 | 6 |
| Incineration of solid chemical waste: | 6 | 3.6 | 310 | 1 |
| Incineration of municipal waste: | 0.5 | 7 | 277 | 1 |
| Incineration of liq/gas. chemical waste: | 5 | 4.4 | 222 | 1 |
| Incineration of wood (painted): | 1 | 5 | 100 | 6 |
| Incineration of chlorinated waste: | 69 | 2.7 | 93 | 1 |
| Cremation: | 0.15 | 53 | 1 | |
| Recycling of copper/brass/bronze: | ? | 5 | 35 | 1 |
| Recycling of aluminiumscrap (dirty): | ? | 1.7 | 35 | 1 |
| Incineration of wood (clean, dry): | 1 | 13 | 28.5 | 6 |
| High temp. processes (glass, cement): | ? | 0.3 | 8.7 | 7 |
| Sintering processes: | ? | 1 | 8 | 3 |
| Diesel motor of seaships (heavy fuel): | 0.000011 | 3.2 | 6.5 | 2 |
| Secundary steel (scrap recycling): | ? | 4.4 | 6 | 1 |
| Incineration of waste lubricating oil: | ? | 5 | 1 | |
| Recycling of lead: | ? | 5 | 1 | |
| Incineration of sludge (municipal): | 0.1 | 5 | 1 | |
| PVC at a warehouse fire: | 57 | 4 | 1 | |
| Incineration of sludge (industrial): | ? | 3.2 | 4 | 1 |
| Incineration of electromotors: | ? | 3.3 | 1 | |
| Incineration of clean wood (stove): | 1 | 1 | 3.3 | 1 |
| Incineration of VCM production waste: | 69 | 2.7 | 8 | |
| Incineration of coal: | ? | 0.35 | 1.6 | 1 |
| Carmotor on leaded gasoline: | 0.000048 | 1.2 | 1 | |
| Incineration of biogas: | ? | 1.1 | 1 | |
| Dieselmotor Rhine barge (gasoil): | 0.000001 | 1 | 2 | |
| Production of coke: | ? | 0.3 | 1 | |
| Primary iron/steel production: | ? | 0.13 | 4 | |
| Production of VCM: | 57 | 0.1 | 1 | |
| Thermic groundcleaning: | ? | 0.07 | 1 | |
| Carmotor, unleaded gasoline, no catalist: | 0.000001 | 0.06 | 1 | |
| Asphalt mixing installations: | ? | 0.05 | 1 | |
| Dieselmotor trucks: | 0.000001 | 0.03 | 1 | |
| Carmotor, unleaded gasoline, with catalist: | 0.000001 | 0.01 | 1 | |
Remarks:
There is an enormous difference in amount of chlorine: from near zero
to 69% of the incinerated material. As you can see, there is no correlation
between the chlorine content of the 'fuel' and the amount of dioxin released.
An incidental fire with lots of PVC gives less dioxin per ton as the fuel
use of a seaship, although PVC contains at least 500,000 times more chlorine!
There are even enormous differences in releases of dioxin from incineration
of the same type of waste: municipal waste gives amounts ranging from 7
to 277 µg per ton incinerated, due to differences in incinerators
and circumstances.
The incineration of hospital waste gave the highest dioxin emission
per ton. This was due to the lack of quality of the incinerators. All individual
incinerators at hospitals are closed now and the waste is incinerated at
one central facility which satisfies all strict rules on dioxin release
(less than 0.1 ng I-TEQ/m3 off-gas), and
should be below 1 µg per ton now.
The incineration of copper cable is now forbidden. Instead of incineration,
cable is stripped.
There were no measurements on the use of pitch (the heaviest part of
crude oil) as an energy source at refinaries. This makes it impossible
to make comparisons between 100% oil based and partly salt based plastics
in dioxin releases during production. Neither were there measurements at
paper production and recycling plants, 'because they use no chlorine'.
That is not a guarantee not to form dioxins, see Chlorine
and paper bleaching.
The total amount of dioxins released to air is the most important source
of dioxins in the environment. But with building new incinerators and renovation
of existing ones, and the measures, taken in the metal industry, dioxin
releases will firmly go down.
The American Society of Mechanical Engineers conducted a study [6] of all available evidence about tests at different incinerators all over the world. 72 municipal incinerator facilities showed no relationship between chlorine input and dioxin output, even when near all chlorine input was omitted or the chlorine/PVC input was augmented to a fivefold. Neither could a change in composition of the dioxins ('the fingerprint') been detected. Eight facilities displayed decreasing dioxin concentrations with increasing chlorine and ten facilities displayed an increase. With other words, the chlorine content is not important for dioxin output. That is in fact normal, because in general only one millionth of the average chlorine input is needed to form all the dioxin found. What is important, is the conditions which makes dioxin. For the complete abstract and summary of this report, see The ASME Research Report summary.
To understand why there is no correlation between chlorine input and dioxin output, you have to know how dioxin is formed. That was investigated in a lot of experiments at different universities. Dioxin and a lot of other unpleasant materials are formed as a result of incomplete burning of any organic material. This happens mainly when the temperature is too low, especially between 200 and 600 °C. In incinerators, if there is enough air and the burning temperature is above 950 °C and the residence time is long enough, all dioxin and other organic stuff is effectively destroyed. What rests, is some fly ash, which contains carbon, chlorine (in form of salt) and trace metals. When the off-gases are cooling down, dioxin and other stuff are formed again, especially on the surface of the fly ash particles. The amount of dioxin relates directly to, in descending order:
An investigation of the German Firebrigades, on a lot of incidental
fires, revealed that with all fires some very small amounts of dioxin are
released. Even in the case of big fires with 'chlorine-free' materials
like polyethylene and polypropylene, small quantities of dioxin are found
in the soot. The concentrations found are about one quarter of those found
in soot from PVC-fires, but no quantities of soot are known, so no quantitative
comparations can be made.
Is dioxin release from incidental fires a threat for health? No, the
German firemen themselves were tested for dioxin in their blood. The average
was not higher than the average dioxin level of the general German population.
Is dioxin release from incidental fires an environmental problem? No,
even in the worst cases measured, the amounts of dioxin in soot were so
low, that you have to eat hundreds grams of soot (!) to reach the (WHO)
daily allowable dose. Just by washing off the soot from vegetables and
fruits or pealing them, the possible problem was over. In all cases (even
from measurements, conducted by Greenpeace!) the dioxin content of upper
soil was below the directives of the German UBA for industrial areas and
in most cases for urban areas and agricultural use.
Higher amounts of dioxin were found in partly burned rests of fires,
but not more than found in ashes of open fireplaces... These could easely
been destroyed by burning in well equiped incinerators.
You are at level two of the Chlorophiles pages.
Created: April 8, 1996.
Last update: September 8, 2001.
Dioxin and PAH emissions compared
The ASME Research Report summary of incinerators
For any comment on sources of dioxins or other Chlorophiles pages:
chlorophiles@pandora.be
