EUROPEAN COMMISSION
JOINT RESEARCH CENTRE
Institute for Prospective Technological Studies
Sustainable Production and Consumption Unit
European IPPC Bureau
Seville, 26 May 2011
Proposals for new NFM BAT conclusions for Ferro-Alloys
production
9.4
Best available techniques for Ferro-Alloys
Key environmental issues for the production of ferro-alloys are: dust and fume,
CO and CO2 gas, SO2, energy recovery, waste water, residues such as filter dust,
sludge and slag.
Air
BAT Process control: see Sections 2.5.1, 2.5.2, 2.6.1.
Raw materials storage and handling
Transport of raw materials such as char coal, coke and coal
< 3 mg dust/Nm3 measured, always < 20 mg dust/Nm3.
(Where are these data from?)
Displaced air cleaning
Handling, storage and transport of very fine powders can create problems
The BAT-AEL for dust is < 1 to 20 mg/Nm3.
Burden preparation (crushing,weighing, mixing, blending) and conveying
BAT is to minimise dust emissions by appropriate measures and, where relevant,
to extract emissions with subsequent purification by means of dry dedusting.
I.
Wet grinding, filtering, pelletising
(measured at the homogenization of charge mix for themetallothermic reduction
process showed emissions concentration values of 0.2 mg dust/Nm3. [255])
The BAT-AEL for dust is < 1 to 20 mg/Nm3.
Pretreatment stages such as coke and raw material drying, prereduction and
preheating, drying and degreasing of secondary raw materials
Raw material drying in rotary drums or kiln furnaces
Shaft furnace for coke drying
BAT-AEL for FF 5 mg/Nm3
Rotary kiln
???
DC Plasma process
BAT for the drying and degreasing of raw materials is to apply a rotary kiln,
afterburner for VOC
BAT-AEL for dust 5 mg/Nm3 and VOC 20 mg/Nm3?
Sintering plant
BAT for sinter plants is to reduce dust emissions by applying the following
techniques individually:
I.
wet scrubber
II.
FF
The BAT-AEL for dust is <4 to 10 mg/Nm3, determined as daily mean value.
Smelting processes
BAT for process gas cleaning from closed EAFs is to apply individually or in
combination
I.
II.
III.
wet scrubber
dry cleaning systems
any other technique with the same removal efficiency
For cleaned process gas, the residual dust concentration associated with BAT is 10 –
50 mg/Nm3, determined as the average over the sampling period (spot measurement,
for at least half an hour).
BAT for charging, open EAFs, is to prevent or reduce diffuse emissions by
applying the following techniques
I.
Fume collection enclosure
What about the preference of semi-continuous charging over batch charging? [526]
II.
hoods
Optimising the capture efficiency for diffuse dust emissions and fumes with
subsequent cleaning
The BAT-AEL is???
BAT for the off-gas from semi-closed or open EAFs, ladles, oxygen blown
converters, crucibles, or other furnaces is optimising the capture efficiency, and
applying fine dust abatement by means of FF or other techniques with the same
removal efficiency.
The BAT-AEL for dust is < 1 – 5 mg/Nm3, determined as a daily mean value.
BAT for SO2 emissions from molybdenite roasting is to apply desulphurisation in
single or double contact plants.
The BAT-AEL is a conversion efficiency of 98 – 99%. (Crosscheck with SO2 section
in chapter 2)
Do we have example plants? What are the residual SO2 concentrations?
We have SADACI, Ghent, Belgium with conversion rate between 99 and 99.4 %
BAT for Dioxins , HCN, vaporised metals such as Hg, Cd, Pb?? PAH?
If dusts from steel mills are recovered it is quite likely that HM can be emitted. Two stage bag
filter with injection of activated carbon or a 3 stage venture scrubber or wet ESP with
subsequent mercury removal with selenium filter can be applied. Try to get further
information.
SO2: Depends on the sulphur content of the input materials. Are any requirements necessary?
Dioxins: very low concentration values are reported. Nevertheless industry proposes very
high values (see Excel spread sheet). Is there any BAT for dioxins or only prevention?
Decide if something is needed in the material selection and pretreatment stage for dioxins
and Hg in particular.
Post furnace operations
BAT for tapping (oxygen lancing, drilling, vaporised slugs if tapping guns are
used), melt refining and casting from all exposed metal and slag furnaces is to
prevent or reduce diffuse emissions by applying the following techniques
I.
complete fume collection enclosures
II.
casting spout capture hoods
III.
cast house canopy hoods
IV.
vortex capture hood if applicable
Optimising the capture efficiency for diffuse dust emisissions and fumes with
subsequent cleaning.
The BAT-AEL for dust is < 1 – 10 mg/Nm3, determined as a daily mean value.
BAT is to minimise dust emissions from size reduction, screening and packaging
of alloys to extract emissions by applying one of the following techniques with
subsequent purification by means of dry dedusting.
I.
totally enclosed systems
II.
crushers with capture hoods
The BAT-AEL for dust is < 1 – 10 mg/Nm3, determined as a daily mean value.
(values < 3 mg/Nm3 have been measured. [255] enclosed systems!)
Handling, storage and transport of very fine powders can create problems:
Densification of silica powder
Water
Water consumption and discharge
BAT is to minimise the water consumption from the smelting process by the use
of closed loop water cooling systems for the cooling of furnace devices and by the
use of treated waste water for metal and slag granulation and cooling.
(Quenching of off-gas?)
BAT is to minimise the waste water discharge from wet scrubbers, cooling
systems and granulation processes by applying the following techniques in
combination:
I
II.
III.
IV.
the removal of cyanide and fluoride
the reduction of Cr6+ to Cr3+, precipitation of metal hydroxides together
with oxidation of cyanides
removal of solids by sedimentation, flocculation and/or filtration
in the case of molybdenite roasting ion exchangers
The BAT AELs for waste water after treatment is:
• Suspended solids < 20 – 40 mg/l
In Section 9.2.4 are no data for waste water after treatment. Only emission factors for the
treated scrubbing water from plasma dust process and the roasting of molybdenite. Where
are the data from Section 9.4.2 from?
Production residues such as wastes and by-products
Minimising slag treatment emissions
Slag granulation and water spraying to reduce dust emissions
See tables 9.31 and 9.32 in Section 9.4.3 of the draft of the NFM BREF.
BAT is to prevent waste generation by applying the following techniques
individually or in combination (see Sections…..):
I.
appropriate collection and storage to facilitate a specific treatment
II. on-site recycling of dust and sludge from gas treatment and pretreatment
processes, dust from crushing, raw material and product transport and
handling, secondary dedusting and mill scale from continuous casting
back to the ferro-alloy making processes with due regard for the effect of
emissions from the plant where they are recycled
III. on-site recycling of ferro-alloy slag and ferro alloy fines in various
applications
IV. use of MnO rich slag as raw material for the production of silicomaganese or other metallurgical applications , use of FeV and FeCr-slags
i.e. in the steel industry
V. slag treatment where market conditions allow for the external use of slag
(e.g. as an aggregate in materials or for construction, sandblasting,
production of refractory castables or refractories)
VI. use of filter dusts and sludge for external recovery of alloys in the nonferrous metals industry, e.g. ISP or waelz kiln
VII. use of a settling tank for sludge with the subsequent recycling of coarse
fraction in the sinter/blast furnace or cement industry when grain size
distribution allows for a reasonable separation.
Ferro-alloy production residues which can neither be avoided nor recycled
should be managed in a controlled manner.
Energy
BAT for the production of HC FeCr, HC FeMn and SiMn is to apply closed
furnaces and to collect, clean and buffer CO rich off gas for subsequent use as a
fuel or raw material where prerequisites are given individually or in
combination for
I.
coke drying
II.
sintering
III.
preheating of burden
IV.
V.
VI.
VII.
heating of ladles
production of electrical energy
heat and steam production
use as a raw material in the chemical industry
BAT for the production of FeSi, Si-metal, and FeNi is to apply semi-closed
electric arc furnaces where prerequisites are given and reduce/minimise thermal
energy consumption by applying the following techniques individually or in
combination:
I.
process integrated re-use of sensible heat as far as possible from the off-gas
II.
using sensible heat for internal and external heating networks if there is a
demand from a third party (the cooperation and agreement of a third party
may not be within the control of the operator, and therefore not be within the
scope of an IPPC permit).
(What about oxygen blowing converters, crucibles, plasma dust process or other
furnaces? Is there any energy recovery, or CO recovery??)
BAT is to reduce energy consumption by covering ladles with a lid during
transport where prerequisites are given.
Noise
??
EAF can be quite loud, see iron and steel BREF requirements