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Carbon-Negative Ironmaking Using Fast Pyrolysis Bio-Oil Gasification
Brian Jamieson, Jake Wilkins, Grace Connors, Subodh Adhikari, Victor Silva, Peter Reinhardt
1
Charm Industrial
2575 Marin St, San Francisco, CA, USA, 94124
Phone: (415) 869-8822
Email: brian.jamieson@charmindustrial.com
ABSTRACT
This paper details initial investigations of fast pyrolysis bio-oil (bio-oil, or FPBO) as a reducing agent for a potential Direct
Reduced Ironmaking (DRI) process. Using an entrained flow gasifier, FPBO was gasified producing syngas that was passed
through a heated pellet bed for 90 minutes. Pellets were reduced, achieving partial metallization. These results are promising
given that the system did not contain a gas looping system which would raise the gas reducing power. Process design
considerations are noted, as are major challenges with this alternative reductant.
Keywords: DRI, Biomass, Carbon Dioxide Removal, Circular Economy, Fast Pyrolysis, Gasification
INTRODUCTION
Charm Industrial (Charm) is a leading Carbon Dioxide Removal (CDR) company. Charm utilizes waste agricultural and
forestry residues as a feedstock to produce fast pyrolysis bio-oil (bio-oil, or FPBO) which can be sequestered underground.
Sequestered bio-oil polymerizes and solidifies over time, yielding 1000+ year carbon dioxide removals. This activity is
currently being supported through voluntary carbon removal buyers. Carbon dioxide removals are a requirement to achieve
net-zero emissions, and to achieve Charm’s mission of restoring the atmosphere to 280 ppm (preindustrial CO
2
levels). While
significant reductions in current fossil fuel emissions are required to achieve net zero emissions goals, so too are carbon
removals, noted as a requirement by the Intergovernmental Panel on Climate Change (IPCC) to limit global warming to 1.5°C
1
.
The need for carbon removal technologies as a component of a global warming mitigation strategy for 2°C warming is
visualized in Figure 1.
Figure 1: The role of carbon dioxide removal in climate change mitigation; copied from UNEP (2017)
2
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© 2024 by the Association for Iron & Steel Technology.
AISTech 2024 — Proceedings of the Iron & Steel Technology Conference
6–9 May 2024, Columbus, Ohio., USA
DOI: 10.33313/388/039
Charm Industrial is focused on bio-oil production because it offers significant benefits related to transportation when compared
to other sources of biogenic carbon. Unlike biomass or biochar, bio-oil is dense and readily transportable, reducing
transportation costs and associated emissions. Table 1 provides some exemplary ranges of carbon content and bulk density for
materials with biogenic carbon content.
Table 1: Comparison of Some Biogenic Carbon Sources. Note that there are a wide range of compositions available in the
literature stemming from specific input materials through processing method.
Material Dry Bio-Oil Corn Stover Wood Chips Biochar
wt%C 50-66% 3 44-48% 3 45-50% 4 62-92% 5
Bulk Density
(kg/m3) 1200 6 40-80 7 112-340 8 250-600 9
C Mass Density
(kgc / m3) 600-792 18-38 50-170 155-552
To address shipping concerns associated with biomass transportation, Charm Industrial is developing a decentralized model
for pyrolysis. Charm’s fleet of pyrolyzers will travel to the biomass instead of bringing the biomass to pyrolysis equipment.
Figure 2 shows an example of one of Charm’s early pyrolyzers in Kansas, producing bio-oil near the biomass source.
Construction of a fleet of pyrolyzers reduces CAPEX risk associated with a single, large plant: the individual pyrolyzers can
begin producing immediately, and individual pyrolyzers are no longer held captive to local biomass prices. Combined with
bio-oil shipping benefits, the use of a fleet of biomass to bio-oil pyrolyzers improves bio-oil production economics.
Figure 2: Charm’s first containerized pyrolyzer deployed in Kansas in 2022.
Produced bio-oil can be shipped to a sequestration site for permanent carbon removal. While this pathway fulfills a market
demand for CDR, it is an inefficient use of the high carbon and energy values in bio-oil. A dry bio-oil is comparable to some
coals in terms of energy value, approaching 30 MJ/kg. Charm’s vision is to utilize bio-oil as a reductant and heat source for
ironmaking, further backed by traditional gaseous CO2 capture. The captured CO2 can then be sequestered, fulfilling demand
for negative carbon emissions, while the iron produced can be sold as a fossil free and carbon neutral iron. Combined, this is a
pathway for carbon negative ironmaking, offering iron units, CO2 avoidance, and CO2 removal.
Ironmaking with carbon removal is important as it not only avoids CO2 emissions associated with traditional fossil fuel sources,
but also removes CO2 linked to embedded emissions. For comparison, while hydrogen-based ironmaking may substantially
reduce total process emissions by today’s standards there remain value chain emissions associated with Scope 2 energy sources
(e.g. electricity) and Scope 3 inputs (e.g. iron ore) that are unaddressed.
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© 2024 by the Association for Iron & Steel Technology.
BACKGROUND ON THE PROPERTIES OF BIO-OIL
Understanding Biomass Processing
Iron cannot be produced from bio-oil without a sufficient supply available, and in order to achieve this supply chain, a process
from biomass source to iron plant must be considered. There are 4 components in a typical biomass processing system with
pyrolysis: input biomass, output biogas (gas phase); biochar (solid phase); and bio-oil (liquid phase). One of the first major
decisions a pyrolyzer operator must consider is selection of slow or fast pyrolysis technology. Slow pyrolysis is typically
conducted in a temperature range of 300-700°C with low heating rates, yielding a high ratio of biochar relative to bio-oil and
syngas10. Fast pyrolysis uses higher temperature (600-1000°C) with heating rates of 10-10,000°C/min. Charm uses fast
pyrolysis, and expects to see biomass converted to 50-60% liquid fraction, 20-30% solid fraction, and 10-30% gas phase.
Syngas can supplement pyrolyzer heat demands, and biochar is envisioned as a soil amendment to maintain sustainable soils.
Ultimate Analysis of Bio-Oil
Not all bio-oils are alike, and this will impact the ability to maintain a stable ironmaking process. Literature is available
discussing attempts at gasification of bio-oils that have produced poor syngas compositions for ironmaking purposes. These
bio-oils generally contain high amounts of water, reducing the energy value of the bio-oil. Targeting deliberately dry oil through
processes such as fractionation improves the bio-oil quality and results in a better syngas composition.
Pyrolysis oil can contain virtually any combination of CHON elements, owing to changes in biomass feedstock and pyrolysis
reactor design. Even for comparable pyrolysis reactors, downstream gas tailoring equipment can selectively condense water
vapor and pyrolysis tars which yields separate streams of water rich and hydrocarbon rich compounds. Table 2 shows some
example bio-oils: from literature, to purchasable product, to some Charm Industrial oil.
Table 2: Demonstration of Various Bio-oils from Literature and Charm Industrial’s Experience
Bio-Oil (Dry Basis)
Literature 1 11
Literature 2
Error! Bookmark not
defined.
Commercial 1 Charm Industrial
wt%C 57.4 61.4 70.4 66.0
wt%H 6.6 6.6 7.8 7.2
wt%O (by bal.) 35.6 31.8 20.0 26.5
wt%N <0.1 0.8 1.69 0.8
wt%S 0.0046 0.0622 0.0492 0.0242
wt%H2O 21.1 23.5 9.1 8.6
Metallurgical Benefits of Bio-Oil versus Biochar
Biomass feedstocks to ironmaking may contain higher levels of some ironmaking contaminant species that must be considered.
Biochar is frequently discussed as a drop-in coal replacement for the ironmaking industry. Biochar typically offers a higher
carbon content than bio-oil per unit mass (but a lower volume density). However metallurgical grade biochar requires very
clean and ash free feedstocks, as ash tends to significantly segregate to the solid phase during biomass pyrolysis.
LeijenhorstError! Bookmark not defined. performed extensive work assessing the transfer of various elemental species from biomass
to bio-oil. The results show that pyrolysis acts as a purification step for bio-oil, where most of these elements separate to the
char. The results indicate that, relative to the feedstock biomass:
• Alkalis (Na, K) see transfer rates of 1-5%, typically <3%,
• Alkali earth metals (Ca, Mg) see transfer rates of 1-5%, typically <2%,
• Sulfur (S) transfer rates are higher, <50%, and
• Phosphorus (P) transfer rates are 1-6%, typically <2%.
The results indicate that, aside from sulfur, the process of pyrolyzing biomass results in significantly lower concentrations of
contaminant species for ironmaking. While sulfur shows comparably high transfer to the bio-oil, it is still 50% of the sulfur
content of biomass and equivalent to sulfur content in biochar for the same feedstock. These results indicate that bio-oil can be
used more extensively in ironmaking applications before risks of contaminant addition arise.
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© 2024 by the Association for Iron & Steel Technology.
Low ash contents of the bio-oil also support the gasifier design, as unlike coal, ash contents in bio-oil are very low. Charm’s
aggregate data across a range of commercial and in house trials indicates total ash content averaging <0.2wt%. In some cases,
bio-oil ash contents can reach ~1.25wt% though these values are limited to specific bio-oils from specific vendors. This
indicates a high degree of connection between biomass feedstock and pyrolysis process, and that ultimately ash content is
manageable when procuring bio-oil for ironmaking applications.
Bio-Oil Gasification
The final stage before a traditional ironmaking process is assumed is the gasification of bio-oil to syngas. Gasification is a
process that can convert any carbonaceous raw material into syngas
12
. Oxygen is used to react with the carbon bearing material
and cause partial oxidation, generating heat and maintaining a steady state reactor at elevated temperatures and pressures. Steam
can also be used as an oxidant, though this lowers the reactor temperature which may impact syngas quality. Often gasification
is paired with catalysts to maximize tar destruction and support conversion of the carbon source to other gasses (such as
hydrogen). There are a range of gasification technologies and carbon fuels available, Charm is focused on entrained flow
gasification of bio-oil. More details on Charm’s entrained flow gasifier are provided later.
IRONMAKING PROCESS DESIGN CONSIDERATIONS
Commercially Similar Plant Concepts for Reference
Commercializing an ironmaking pathway using a novel reducing agent like bio-oil will come with its own challenges, ignoring
the construction of a traditional ironmaking facility. One method of de-risking this pathway is to focus on adding novel
equipment to already commercial technologies. In this case, both Tenova HYL
13
and Midrex MxCoL
14
processes can use
gasification and syngas instead of traditional natural gas.
At a very high-level view, both the Tenova HYL and Midrex MxCoL process designs couple a hydrocarbon gasifier (typically
coal) to a DRI shaft reactor. Ultimately the route does not require coal and can work with any syngas that has been tailored for
the process, including Coke Oven Gas and syngas from natural gas gasification (opposed to reformation). The MXCOL process
is notably different than MIDREX natural gas processes as it does not use a natural gas reformer.
The general flow of the process route is that:
1. Hydrocarbons (coal, coke oven gas, refinery bottoms, etc.) are gasified into crude syngas,
2. The syngas is cleaned and conditioned, removing particulate and raising the ratio of H
2
:CO,
3. The new syngas can be merged with cleaned process top gas,
4. The reducing gas is heated in a gas heater before entering the DRI shaft,
5. Reducing gasses interact with iron oxide in the shaft to produce iron, exiting through the reactor top,
The top gasses are scrubbed, quenched, and CO2 is removed from the circuit. This gas enters step 3 above. Process flows of
these systems are shown in Figure 3.
Figure 3: ENERGIRON ZR
13
(left) and MxCoL
14
(right) Flowsheet Examples; these figures are copied from their respective
sources.
Top gas recycling has 2 major benefits compared to a once through system:
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© 2024 by the Association for Iron & Steel Technology.
1. Unspent reducing gasses (CO & H
2
) in the top gas, limited by the thermodynamic equilibrium of the ironmaking
process, can be recovered and reintroduced to the reactor improving energy efficiency of the process, and
2. The cleaned top gas is rich in reducing gasses and when blended with fresh syngas raises the amount of reductants in
the reactor inlet gas, improving process kinetics and reactor productivity for a given gas flow.
Benefit 1 is why DRI processes can approach the theoretical minimum energy required for ironmaking, whereas a once-through
blast furnace cannot. These considerations are important for bio-oil based ironmaking as it minimizes the demand for bio-oil
energy and allows for some hydrocarbon feedstock flexibility compared to a traditional natural gas DRI. The presence of a
carbon capture unit in the process by default is advantageous for a process seeking to capture biogenic CO
2
emissions.
Steam Bio-Oil Reforming
Charm Industrial’s proposed process for DRI production using bio-oil would take the name Steam Bio-oil Reforming. A process
route similar in principle to what is listed above would be followed. Gasification of bio-oil yields a syngas rich in reductants
for the ironmaking process. There are some key distinctions compared to what is known in the literature:
• The use of a low ash feedstock is expected to allow for direct injection of gasifier syngas to the process loop, reducing
CAPEX demands associated with gas cleaning and conditioning,
• H
2
:CO ratios are lower than typical for DRI processes, impacting productivity and shaft heat balance,
• The relatively low heating value of bio-oil compared to natural gas necessitates very high oxygen enrichment of
oxidant streams to maximize the available heat energy of bio-oil and syngas for combustion, and
• The need for ironmaking coupled with carbon dioxide removal necessitates the use of two amine carbon capture plants
in the reference design: one for the process loop and one for the steam boiler.
Figure 4 provides a conceptual representation of the process flows in a high performing SBR scheme. With respect to carbon
negative ironmaking, carbon capture rates are estimated over 95% for the looped gas system, and with appropriate sequestration
infrastructure will allow for the facility to produce iron, abate its entire Scope 1, 2, and 3 emissions, and provide surplus CDR
credits for sale. A first approach LCA has been completed to provide support for these claims
15
.
Figure 4: Conceptual Block Flow for Charm’s Steam Bio-Oil Reforming Process
Bio-Oil Gasifier Construction
Validating bio-oil gasification has been a core goal of Charm Industrial for some time - it is the least technically developed
aspect of Charm’s proposed ironmaking operation. While bio-oil is the primary energy feedstock for this process, it is the
syngas produced from bio-oil that provides reductants for the ironmaking process, and fuel gas for the process gas heater. To
maintain the process as “fossil free ironmaking”, syngas is proposed as the sole source of heat for the process. Syngas is
335
© 2024 by the Association for Iron & Steel Technology.
generated via entrained flow gasification, which allows for high efficiency bio-oil to syngas conversion, including low levels
of tar and particulate. Figure 5 shows a schematic representation of the mini-pilot SBR, and Figure 6 the constructed gasifier.
Figure 5: Charm Industrial’s First Gasifier & Syngas Cleanup Process. From left to right: gasifier, scrubber, condenser, and
flare.
Figure 6: Constructed Mini-Pilot Gasifier in San Francisco (~7 kg/hr bio-oil). The image was taken during the California
wildfires of 2020.
Steady State Modeling
As part of understanding process viability, a coupled technoeconomic assessment (TEA) and process flow model was created
using iterative calculations in Google Sheets. By coupling the TEA and process flows, it is possible to predict the economic
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© 2024 by the Association for Iron & Steel Technology.
and technical behavior of some aspects of the SBR process route, such as decreases in bio-oil demand for heating applications
with increasing oxy-enrichment.
The process model incorporated here is focused upon the movement of gasses (CO, CO2, H2, H2O, N2, and CH4) in the system.
The model is representative of an engineering study between FEL1 and FEL2, and indicates that using a bio-oil comparable to
Charm Industrial’s current dry product would result in:
• Bio-oil consumption per tonne of DRI around 0.76 tFPBO per tDRI,
o Reduction demands are around 0.39 tFPBO per tDRI, and
o Heating demands, including gas heating and steam boiling for amine carbon capture, are 0.37 t/t,
• Reducing gas flow per tonne of DRI is estimated around 1650 Nm3/tDRI.
The model was designed and corroborated based on the work of Buergler & Di Donato16 and Bechara et al.17. When using a
clean and dry syngas composed predominantly of CO and H2, the results are in line with industry expectations of roughly 10
GJNG/tonneDRI. The addition of multiple carbon capture units causes a significant increase in energy demands, as does the use of
bio-oil with some water content. This modeling exercise clearly revealed that in order to maximize the value of bio-oil for
heating applications it is important to maximize oxycombustion opportunities; the result is a significant demand for oxygen.
Most factors of this models dynamically scale, such as cost of oxygen production as a function of oxygen plant size, or the
OPEX of carbon capture as a function of CO2 concentration in flue streams. This provides a powerful technoeconomic
assessment tool for SBR. A high level discussion on process economics is noted later.
Detailed Modeling & Kinetics with ASPEN PLUS
While the technoeconomic model offers good insights into the SBR process, it lacks in comparison to a true chemical process
model. The use of ASPEN PLUS to model the process provides additional learnings and confidence in Charm’s proposed
process route. To date, advanced chemical process modeling has:
• Improved Charm’s understanding of amine carbon capture systems, including the incorporation of potential losses of
reducing gasses and amine solvent,
• Improved CAPEX estimates beyond simple index engineering, and
• Allowed for improved kinetic modeling in the model, by incorporating the framework of Bechara et al.17
ASPEN PLUS also allows for a ready investigation of alternative technologies that may support the ironmaking process. For
example, Pressure Swing Adsorption (PSA) based carbon capture technology can reduce steam generation demands, thus
reducing the need to use bio-oil for heat, by utilizing electricity to drive carbon capture. This change can improve the process
flow sheet and reduce overall CAPEX. ASPEN PLUS further allows for the coupling of bio-oil gasification and DRI models,
providing a complete understanding of the SBR process.
EXPERIMENTAL WORK
Gasification Trials at Charm Industrial
Charm’s gasifier has been used on multiple occasions to demonstrate bio-oil conversion to syngas. Two major campaigns were
conducted with different oils that show some results of gasification. Table 3 shows the relative range of bio-oil compositions
tested, while Table 4 shows the range of outputs measured. These results provide some indication of the gasification properties
of bio-oil for the given gasifier design. Heavy ends are bio-oils approaching tar, low in water content and rich in carbon. Light
ends are bio-oil compounds rich in water and with a tendency to segregate to the top of a given tote or container. Maximum
generally refers to a high-quality gasification product, and minimum to a relatively low-quality.
Table 3: Typical Tested Range of Bio-oils for Gasification (note that oxygen is minimized when other species are maximized).
Heav
y
Ends Li
g
ht Ends
wt% Minimu
m
Maximu
m
wt% Minimu
m
Maximu
m
C 60 68 C 20 50
H 6 10 H 6 10
O 19.9 34 O 37.9 74
N
0 2
N
0 2
S 0 0.1 S 0 0.1
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© 2024 by the Association for Iron & Steel Technology.
Table 4: Syngas Composition Ranges Measured during Heavy & Light Ends Gasification Trials (note that oxygen is
minimized when other species are maximized).
Heav
y
Ends Li
g
ht Ends
mol% Minimu
m
Maximu
m
mol% Minimu
m
Maximu
m
H2O 0.5 25 H2O 10 40
CO 40 60 CO 20 45
CO2 5 15 CO2 10 30
CH4 0.5 5 CH4 0.5 15
H2 22 35 H2 10 20
O2 0 3 O2 0 3
N
2 0 5
N
2 0 5
The results indicate that dry oils produce higher quality syngas, and that gasifying water should be avoided (within reason to
control tar and particulate). It is notable that some of the heavy ends trials resulted in higher fractions of tar and particulate –
indicating some need for steam injection to control tar and particulate.
The original trials were carried out in a refractory lined gasifier built by Charm Industrial that supported variable nozzle feeds.
This provided an opportunity to modify atomization of the bio-oil spray in the gasifier. Additional work was carried out at low
temperatures to explore nozzle atomization performance. Figure 7 is a still image taken from high-speed camera video showing
bio-oil droplet sizes from atomization.
Figure 7: Bio-oil Spray Atomization Rig (left) and Size Distribution of some Droplets (right).
Results of these trials indicated that an average droplet size below 40 µm was achievable, characterized by the Sauter Mean
Diameter (D[3,2])18. This measure was chosen as it relates to droplet reactivity and the conversion of heavier hydrocarbon
compounds in the bio-oil to permanent gasses. This work supports the current nozzle used in the gasifier, and reveals some
controlling conversion mechanisms that may allow for even smaller droplet size. Bio-oil droplet size is important to ensure
complete decomposition of the bio-oil droplets to permanent gasses, thus reducing the presence of tar and particulate.
Ultimately Charm seeks to control the degree of partial oxidation and gasifier design to maximize the conversion of bio-oil to
a syngas rich in permanent reducing gasses (CO and H2), without producing significant amounts of oxidized gasses (CO2 and
H2O). The ratio of CO+H2 over CO2+H2O is known as reducing power. Controlling reactor temperature and total conversion is
a difficult balancing act in a gasifier.
Ironmaking Metallization Results
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© 2024 by the Association for Iron & Steel Technology.
An electrically heated tube furnace was connected to the gasifier to maintain a bed of DRI pellets at ~900ºC. The gasifier outlet
was routed to the tube furnace to expose the pellets to gasifier gas. The system was not configured for gas looping, resulting in
a lower reducing power than is expected in a looped system. Nonetheless the results were promising. Figure 8 shows the tube
furnace setup and connection to the gasifier. Pressure drop was balanced across the pellet bed and bypass lines to manage gas
flow across the pellet bed.
Figure 8: Tube Furnace Containing Pellets to Assess as-is Reduction Potential of Bio-Oil Syngas
The product syngas was measured by using Continuous Gas Analyzers (CGA) on either side of the furnace. Tars and
particulates were scrubbed from the gas stream so that they could be measured - this data was sent to a lab for analysis. Syngas
flowed over the pellet bed for a period of 90 minutes. Table 5 shows an example syngas composition observed towards the end
of a 90-minute reduction trial, where the ratio of H2/H2O approached equilibrium, but the CO/CO2 ratio remained high.
Table 5: Bio-oil syngas measurement before and after the tube furnace. High N2 is caused by a sight glass purge stream on
the reformer.
Measured Species Furnace Entrance Furnace Exi
t
CO (vol%) 56.4 49.5
CO2 (vol%) 9.8 13.1
H2 (vol%) 28.5 26.9
H2O (vol%) 4.0 9.9
N
2 (vol%) 1.3 1.5
CH4 (vol%) 2.6 2.3
Tars (m
g
/Nm3) 220 420
Particulate (m
g
/Nm3) 25,260 3,370
The overall average reducing power, defined as (CO+H2) over (CO2+H2O), was 6 at the furnace inlet. The product DRI was
~78% metallized and is shown in the following figure. Ongoing experimentation is underway to ensure that the tar and
particulates in the gas stream do not cause pore clogging of the DRI. A system using syngas from bottles (free from tar and
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© 2024 by the Association for Iron & Steel Technology.
particulate) is being used to validate results from the gasifier trials. Figure 9 shows an example of unreduced and reduced
pellets used in Charm’s system.
Figure 9: Unreduced iron oxide pellet (left) compared to partially metallized DRI from the trial.
A kinetic model of iron oxide pellet reduction is being prepared to better understand gas shifting requirements (e.g. CO to H2)
that would improve the overall kinetics of reduction. Ideally only a minimum amount of gas shift will be required to improve
reduction of the DRI pellets, such that external cleanup and conditioning equipment is not required in the process.
Future Opportunities
Two of the largest perceived technical challenges with the SBR setup are management of the H2:CO ratio, and of tars and
particulates without a catalyst. Both challenges can be approached with the use of steam in the gasifier in place of oxygen,
though this will reduce gasification temperatures, impacting syngas quality. Balancing the complex reactions within an
entrained flow gasifier is a known challenge subject to many tradeoffs. Work is underway at Charm Industrial to understand
these modifications and incorporate favorable results into the overall process design.
ECONOMIC CONSIDERATIONS OF SBR
SBR Internal Rate of Return
The technoeconomic assessment mentioned above was used to provide CAPEX, OPEX, and income estimates. Using an index
engineering approach, CAPEX data for ironmaking plants
19
, carbon capture
20,21,22
, oxygen plants
23
, and various other pieces of
data provided a prediction of plant cost. For a 2 million tonne per year SBR plant, IRR approaches 15% without any premium
on the sales price of iron (e.g. a green iron premium, or fossil free iron premium). This is positive for the SBR business case.
DRI Pellet Pricing
There is public concern about the lack of available supply of DRI pellets in the coming years. Current annual DRI pellet supply
is estimated around 120 million tonnes per year, however announced DRI projects are expected to raise demand by 10s of
millions of tonnes beyond supply growth expectations
24
. Figure 10 below shows a view of this supply-demand imbalance. The
expected result is an increase in the cost of DRI pellets which would impact the SBR process (and all DRI processes). This
would not impact SBR process competitiveness compared to other DRI technologies, however, may pose a challenge compared
to ironmaking technologies that do not use DRI pellet feed.
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© 2024 by the Association for Iron & Steel Technology.
Figure 10: Projected Iron Ore Pellet Market Deficits of Traded Market Pellets
The Cost of Carbon
SBR shows promising economic results. However, like most alternative feedstocks for ironmaking, it is dependent on an
associated carbon price. By coupling ironmaking with Carbon Dioxide Removal, it is possible to produce fossil free iron near
market prices for iron so long as a buyer is available to pay for CO
2
removals. The model assumes the market value of carbon
removal approaches $100/tonne by 2050 which effectively becomes a price floor for CDR from SBR. The reason for this floor
is that the combined cost of carbon capture system CAPEX, OPEX, and downstream transportation and sequestration yields a
cost of carbon capture approaching $100/tonne, thus CDR cannot be sold for less than this cost. Opportunities to improve the
economic model through process gas heater electric heating and pressure swing adsorption (PSA) based carbon capture are
being investigated.
CONCLUSIONS
Bio-oil has been demonstrated as an effective reducing agent of iron ore in a pilot scale DRI reactor. Using entrained flow
gasification technology, carbon rich bio-oil can be converted to syngas with a high degree of carbon conversion, resulting in
syngas with high reducing power. Small pilot plant trials have shown reasonable levels of metallization in reduced DRI samples,
without gas quality improvements that will come from top gas looping. Improvements of the reactor and bio-oil conversion
process are underway.
FUTURE WORK
There are many opportunities for improvement of Charm’s ironmaking pathway as the company works towards a scaleup
program for this ironmaking pathway. Some are mentioned below.
• Modifying the ratio of oxygen and steam to the gasifier is expected to reduce tar and particulate while providing an in
situ technique for gas conditioning.
• There are notable deviations in bio-oil composition based on biomass feedstock and reactor selection. While it is likely
that a specific line of technology and feedstock can be utilized to achieve product consistency, some amount of bio-
oil upgrading may be required to achieve consistency. This is being investigated.
• The use of partial oxidation entrained flow gasification significantly simplifies gasifier design, but comes with the
tradeoff of creating combustion products in the reducing gas stream. More work is underway to understand optimal
combustion in the gasifier, where temperatures are high for good gasification but oxygen injection is minimized so
that the reducing power of the syngas stream is not compromised.
• Charm is working on pilot plant development to upscale its equipment to >100 kg/hr DRI production based on findings
from the above work.
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© 2024 by the Association for Iron & Steel Technology.
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