The Use of LD-Slag as a Fluxing Agent in the HIsarna Process

 
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The use of LD-slag as a fluxing agent
in the HIsarna Process
6
th
 International Slag Valorisation Symposium
Christiaan Zeilstra, Hans Hage, Johan van Boggelen,
Koen Meijer, Pieter Broersen (all: Tata Steel, IJmuiden, the Netherlands)
 
 
Mechelen, Belgium
 
4 April 2019
 
Together we make the difference
 
 
2
 
Content
 
1. 
 
What is 
HIsarna?
 
2.
Hot metal and slag chemistry
 
3.
Utilisation of LD-slag in HIsarna
 
4. 
 
Conclusions
 
 
HIsarna
Smelting reduction ironmaking process that
can achieve at least 20% reduction in CO
2
emission intensity without carbon capture
technology (more than 80% possible with
CCS).
Oxygen based, therefore high CO
2
concentrations
 
Game changer technology
Reduce CO
2
 and other emissions
No coking or ore agglomeration
Flexible raw materials use
 
3
 
1.1 HIsarna development
 
4
 
In 2004 several European steelmakers proactively started the ULCOS
project with the objective to achieve 50 % reduction of the CO
2
emissions of steelmaking
HIsarna is one of the four process development that originate from the
ULCOS project.
Since 2007 Tata Steel, Rio Tinto and ULCOS have been active developing
this coal-based smelting reduction process.
In 2010 a dedicated pilot plant was built at Tata Steel in IJmuiden (NL)
To date over 75 mln Euro has been invested in this new technology.
The HIsarna process offers a combination of 
environmental
 and
economical
 benefits.
 
1.2 HIsarna development
 
5
 
Iron ore
 
Coal
 
C
o
k
i
n
g
/
A
g
g
l
o
m
e
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I
r
o
n
m
a
k
i
n
g
 
Iron ore
 
Coal
 
I
r
o
n
m
a
k
i
n
g
 
Hot metal
 
Hot metal
 
Direct use of fine ores and coal
(no agglomeration and coking)
 
 
1.3 Comparison BF route - HIsarna
 
1.4. HIsarna – process layout
 
Iron ore is injected into the smelt cyclone,
together with oxygen.
Hot CO rich gas from the SRV is
combusted in the smelt cyclone,
increasing the temperature and causing
the iron to melt and partly pre-reduce.
The molten and partly reduced iron ore
will form a liquid film along the wall of the
cyclone after which it drops down into the
slag layer in the SRV.
Granular coal is injected in the slag layer.
This will fully reduce the iron ore to liquid
hot metal and carburise the hot metal
bath.
The reduction reaction produces CO gas.
This is partly combusted with oxygen in
the space between the top of the slag and
bottom of the cyclone, in order to
generate heat.
The splash and turbulence resulting from
the injection processes ensure part of this
heat is transported to the slag and metal
bath.
 
#
 
Smelt Cyclone
 
SRV
 
7
 
 
1.5 HIsarna – Benefits
 
 
Environmental benefits
Lower CO
2
 emissions
Lower emissions SO
X
, NO
X
, dioxines and fine dust
Minimizing the landfilling of slags and dusts through
recycling
 
Economic benefits
Ironmaking with low cost raw materials, non-coking coals
and low grade ores.
Recycling of waste oxides, slags and galvanised scrap
Lower steelmaking costs because of low Si, P in hot metal
Greenfield developments with much lower CAPEX
 
 
HIsarna offers a combination of 
environmental
 and 
economic
 benefits
 
HIsarna uses fluxes for getting the right slag
chemistry:
Limestone
 
- Pre-mix with iron ore
Dolomite
 
- Pre-mix with iron ore
Burnt lime
 
- ‘Finishing touch’
 
Replacing these fluxes with other sources of
CaO and MgO:
Reduce costs
Lower CO
2
 foot print
 
LD-slag is characterised by:
Calcined
Containing CaO: ~ 40 %wt
B2 basicity ratio: CaO/SiO
2
 ~ 3
Containing MgO: ~ 7 %wt
Containing Fe-units: ~ 18 %wt
P
2
O
5
: ~ 1.5 %wt
 
 
 
 
 
 
 
 
 
8
 
2.1 Hot metal and slag chemistry
 
FeOx level in different slags:
Blast Furnace: ~ 0.3 %wt
HIsarna: ~ 4-5 %wt
Steel convertor: ~ 20 %wt
 
FeOx level influences the partition of elements
- such as P and Mn – over hot metal and slag:
Blast furnace HM: P typically 0.05-0.10 %
HIsarna HM: P typically 0.02 %
Convertor (steel): P typically 0.007-0.02 %
(Note that P-levels depend on raw material input)
 
HIsarna slag is better capable of dealing with
increased P input than a blast furnace.
 
HIsarna is less effective in S removal than a
blast furnace, but this can be done before the
steelmaking step
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
9
 
2.2 Hot metal and slag chemistry
 
Factsage calculations were performed to assess the melting behaviour of
the iron ore in the smelt cyclone. Cases studied:
1.
100 % iron ore;
2.
95.8 % iron ore, 2.5 % limestone and 1.7 % dolomite;
3.
95 % iron ore and 5 % LD-slag.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
10
 
3.1 Effect of LD-slag on ore feed fluxing
 
Observations:
Fluxing of ore: better melting
Fluxing with convertor slag should be
similar/better as compared to
limestone/dolomite.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
A pilot plant trial was performed in order to assess the impact of fluxing
with LD-slag:
IJmuiden LD-slag was ground/screened to prepare ~ 2000 tons of iron ore /
LD-slag blend;
This blend was used during ~ 20 days of hot metal production
Hot metal and slag chemistry were compared with ‘regular’ fluxed iron ore
(limestone/dolomite)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
11
 
3.2 HIsarna plant trials using LD-slag
 
Table: Average HIsarna slag and metal compositions for test runs
with two different ore feed blends. Note the reported Fe
tot
 in the
slag is present as FeOx.
 
Observations:
1.
HIsarna process behaviour/control was
unchanged:
1.
Control of the smelt cyclone (iron ore
injection);
2.
Control of the final (tapped) slag
chemistry/basicity.
2.
Differences in hot metal and slag
compositions observed:
1.
Increased P and V levels in hot metal and
slag, originating from the LD-slag;
 
 
 
 
 
 
 
 
 
 
12
 
4. Conclusions / outlook
 
HIsarna is a break-through technology, offering
significant environmental and economic benefits.
 
Plant trials were performed:
Demonstrating capability of utilising/recycling LD-
slag in order to reclaim CaO, MgO and Fe units;
Observed that P levels in the hot metal went up, but
were still low compared to those of typical blast
furnace hot metal.
Lower P-levels will reduce costs of steelmaking;
Capability of taking increased P input.
 
Further study/testing to be done:
Better understand/optimise element partitioning
over hot metal and slag, e.g., P, Mn and V;
Effects of mineralogical phases of fluxes on melting
behaviour of iron ore in the smelt cyclone;
More general: investigate the differences between
HIsarna slag and blast furnace slag for cement
making applications.
 
Acknowledgements
 
HIsarna is being developed together with ArcelorMittal,
thyssenkrupp, voestalpine and Paul Wurth
.
This project has received funding from the European
Union’s Horizon 2020 research and innovation
programme under grant agreement No 654013.
 
13
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  1. Presentation title, change View >> Header & Footer The use of LD-slag as a fluxing agent in the HIsarna Process 6th International Slag Valorisation Symposium Christiaan Zeilstra, Hans Hage, Johan van Boggelen, Koen Meijer, Pieter Broersen (all: Tata Steel, IJmuiden, the Netherlands) Mechelen, Belgium Together we make the difference 4 April 2019 1

  2. Content 1. What is HIsarna? 2. Hot metal and slag chemistry 3. Utilisation of LD-slag in HIsarna 4. Conclusions 2

  3. 1.1 HIsarna development HIsarna Smelting reduction ironmaking process that can achieve at least 20% reduction in CO2 emission intensity without carbon capture technology (more than 80% possible with CCS). Oxygen based, therefore high CO2 concentrations Game changer technology Reduce CO2 and other emissions No coking or ore agglomeration Flexible raw materials use 3

  4. 1.2 HIsarna development In 2004 several European steelmakers proactively started the ULCOS project with the objective to achieve 50 % reduction of the CO2 emissions of steelmaking HIsarna is one of the four process development that originate from the ULCOS project. Since 2007 Tata Steel, Rio Tinto and ULCOS have been active developing this coal-based smelting reduction process. In 2010 a dedicated pilot plant was built at Tata Steel in IJmuiden (NL) To date over 75 mln Euro has been invested in this new technology. The HIsarna process offers a combination of environmental and economical benefits. 4

  5. 1.3 Comparison BF route - HIsarna Iron ore Hot metal Coal Coking/Agglomeration Ironmaking Iron ore Hot metal Direct use of fine ores and coal (no agglomeration and coking) Coal Ironmaking 5

  6. 1.4. HIsarna process layout Iron ore is injected into the smelt cyclone, together with oxygen. Hot CO rich gas from the SRV is combusted in the smelt cyclone, increasing the temperature and causing the iron to melt and partly pre-reduce. The molten and partly reduced iron ore will form a liquid film along the wall of the cyclone after which it drops down into the slag layer in the SRV. Granular coal is injected in the slag layer. This will fully reduce the iron ore to liquid hot metal and carburise the hot metal bath. The reduction reaction produces CO gas. This is partly combusted with oxygen in the space between the top of the slag and bottom of the cyclone, in order to generate heat. The splash and turbulence resulting from the injection processes ensure part of this heat is transported to the slag and metal bath. Smelt Cyclone SRV #

  7. 1.5 HIsarna Benefits HIsarna offers a combination of environmental and economic benefits Environmental benefits Lower CO2emissions Lower emissions SOX, NOX, dioxines and fine dust Minimizing the landfilling of slags and dusts through recycling Economic benefits Ironmaking with low cost raw materials, non-coking coals and low grade ores. Recycling of waste oxides, slags and galvanised scrap Lower steelmaking costs because of low Si, P in hot metal Greenfield developments with much lower CAPEX 7

  8. 2.1 Hot metal and slag chemistry HIsarna uses fluxes for getting the right slag chemistry: Limestone - Pre-mix with iron ore Dolomite - Pre-mix with iron ore Burnt lime - Finishing touch Replacing these fluxes with other sources of CaO and MgO: Reduce costs Lower CO2 foot print LD-slag is characterised by: Calcined Containing CaO: ~ 40 %wt B2 basicity ratio: CaO/SiO2 ~ 3 Containing MgO: ~ 7 %wt Containing Fe-units: ~ 18 %wt P2O5: ~ 1.5 %wt 8

  9. 2.2 Hot metal and slag chemistry FeOx level in different slags: Blast Furnace: ~ 0.3 %wt HIsarna: ~ 4-5 %wt Steel convertor: ~ 20 %wt FeOx level influences the partition of elements - such as P and Mn over hot metal and slag: Blast furnace HM: P typically 0.05-0.10 % HIsarna HM: P typically 0.02 % Convertor (steel): P typically 0.007-0.02 % (Note that P-levels depend on raw material input) HIsarna slag is better capable of dealing with increased P input than a blast furnace. HIsarna is less effective in S removal than a blast furnace, but this can be done before the steelmaking step 9

  10. 3.1 Effect of LD-slag on ore feed fluxing Factsage calculations were performed to assess the melting behaviour of the iron ore in the smelt cyclone. Cases studied: 1. 100 % iron ore; 2. 95.8 % iron ore, 2.5 % limestone and 1.7 % dolomite; 3. 95 % iron ore and 5 % LD-slag. 100 90 Observations: Fluxing of ore: better melting Fluxing with convertor slag should be similar/better as compared to limestone/dolomite. 80 70 Liquid phase [%] 60 50 40 30 20 10 0 1350 1400 1450 Temperature [ C] 1500 1550 1600 Pure ore Ore-Limestone-Dolomite Ore-Convertorslag 10

  11. 3.2 HIsarna plant trials using LD-slag A pilot plant trial was performed in order to assess the impact of fluxing with LD-slag: IJmuiden LD-slag was ground/screened to prepare ~ 2000 tons of iron ore / LD-slag blend; This blend was used during ~ 20 days of hot metal production Hot metal and slag chemistry were compared with regular fluxed iron ore (limestone/dolomite) Observations: 1. HIsarna process behaviour/control was unchanged: 1. Control of the smelt cyclone (iron ore injection); 2. Control of the final (tapped) slag chemistry/basicity. 2. Differences in hot metal and slag compositions observed: 1. Increased P and V levels in hot metal and slag, originating from the LD-slag; Limestone / dolomite blend %wt 1.16 Limestone / dolomite blend %wt 4.3 LD slag blend %wt 4.0 LD slag blend %wt 1.19 Hot Metal C Slag B2 [-] S P V Mn 0.082 0.016 0.0079 0.076 0.088 0.025 0.012 0.082 CaO SiO2 MgO Al2O3 38.6 33.2 5.5 12.7 38.2 32.0 5.2 12.5 Si < 0.01 < 0.01 Fetot P2O5 V2O5 3.5 0.11 0.064 3.7 0.22 0.14 Table: Average HIsarna slag and metal compositions for test runs with two different ore feed blends. Note the reported Fetot in the slag is present as FeOx. 11

  12. 4. Conclusions / outlook HIsarna is a break-through technology, offering significant environmental and economic benefits. Plant trials were performed: Demonstrating capability of utilising/recycling LD- slag in order to reclaim CaO, MgO and Fe units; Observed that P levels in the hot metal went up, but were still low compared to those of typical blast furnace hot metal. Lower P-levels will reduce costs of steelmaking; Capability of taking increased P input. Further study/testing to be done: Better understand/optimise element partitioning over hot metal and slag, e.g., P, Mn and V; Effects of mineralogical phases of fluxes on melting behaviour of iron ore in the smelt cyclone; More general: investigate the differences between HIsarna slag and blast furnace slag for cement making applications. 12

  13. Acknowledgements HIsarna is being developed together with ArcelorMittal, thyssenkrupp, voestalpine and Paul Wurth. This project has received funding from the European Union s Horizon 2020 research and innovation programme under grant agreement No 654013. 13

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