ENVIRONMENTAL ASPECT OF INDUSTRIAL TECHNOLOGIES FOR RECYCLING
OF FE- AND ZN-CONTAINING SLUDGE AND DUST OJSC NOVOLIPETSK STEEL
Speaker:Ivan Kurunov Doctor of Technical Sciences 2011
Slide 2
The production of one ton of steel requires spending almost 20
GJ of energy and is accopmpanied by the emission of 1.7 t of 2 into
the atmosphere. In addition 20-25 kg of sludges and dust are
generated, containing up to 60% of iron in the form of oxides and
up to 2.5% of zink. 2 In blast furnace iron production 5-15 kg of
sludges is generated, where, apart from iron and carbon (25-30%),
up to 1.5% of zink is contained. The recycling of this
technologically generated raw material will be a solution to one of
the most important environmental and economical tasks.
Slide 3
We reviewed four industrial process routes for recycling of
iron and zink containing sludges and dusts with the obtaining of
iron as a final product and commodity output with high content of
zink. For all the routes 2 through out emission was calculated at
the recycling of BOF and BF iron and zink containing sludges for
iron producer of an integrated type in the amount of 600 thousand
t/y. 3 The first stage for all these technologies is usually a
pelletizing of the sludges by the method of hard extrusion which
makes able to obtain sturdy cylindrical briquettes 20-30 mm in
diameter and 40-80 mm in length.
Slide 4
4
Slide 5
5
Slide 6
6 Melting briquettes in a blast furnace (DK Recycling
process)
Slide 7
7 Metallization of briquettes in a ring chamber furnace with
rotating floor (Fastmet, Rediron) and the use of the received DRI
in blast furnace process
Slide 8
8 Metallization of briquettes by Waeltz process and the use of
the resulting DRI in blast furnace process
Slide 9
9 Melting of briquettes in OxyCup cupola
Slide 10
10 The method for calculation of through out consumption of
fuel and emission of 2 At the calculation of through out
consumption of fuel and emission of 2 the following fuel
consumption figures were taken into account: coke production,
sinter production, pellets calcination, production of DRI out of
sludges, oxygen production, iron production in a blast furnace,
ironmaking in a cupola. Consumption of fuel and oxygen in blast
furnace process for different variants was evaluated by computer
simulation model with the application of a balance mathematical
model of a blast furnace process, constructed with the use the
operational line of A. Rist. The fuel consumption in OxyCup process
was assumed according to the published data.
Slide 11
11 Consumption of carbon and emission of 2 in ironmaking
according to the variants, kg/t Points of carbon consumption, kg/t
of hot metal Blast furnace burden components Process OXYCUP Sinter
and pellet Briquettes and pellets DRI (Fastmet), sinter, pellets
DRI (Waeltz) sinter, pellets Sinter Production output 6514 Pellet
production 2,51513 Production DRI * 71393 Briquette composition
108262,5 DRI composition 4,5 Coke** 315277285 263 Natural gas
562850 Oxygen content in the blast*** 11,59939 Carbon consumed
451,0428,0446,5768,5564,5 Emission of 2 16541569167428182070 *
Heating up to 1300 , direct iron reduction, overall heat losses.
**Less carbon, which was transfered into iron. *** Assuming 1787
kkal/m 3 2 or /m 3 2.
Slide 12
12 CONCLUSION Of all industrially used technologies for
recycling of iron and zink containing sludges and dusts the minimum
fuel consumption per ton of iron, made using them, and the minimum
2 emission is provided by: the blast furnace process recycling of
briquettes from these sludges and blast furnace processing of DRI
which was produced by metallization of such briquettes by Fastmet
or Rediron processes. Through out emission of 2 in OXYCUP process
and in BF process with the use of DRI, produced by Waeltz process,
1.3 and 1.8 times higher, than during the melting of the briquettes
in the blast furnace.