Technical Article
Electric Arc Furnace operating at Outokumpu ’ s mill in Calvert , USA
Association CO 2
Emissions Report ). By contrast , Outokumpu uses 95 % recycled material ( nickel content excluded ) and is aiming to go even further . It has also started to recycle the waste – unused slag , tailing sand from mining operations , as well as sludge , dust and scales from production . The metals from these waste streams are extracted and can be re-used in stainless steel production . The waste can also be recycled in road construction , refractory and concrete production , as well as water treatment . Other stainless steel producers boosting their recycling operations include BUTTING ( which is working with Cronimet Envirotec to recycle materials , waste and cutting residue ) and Stalatube , which guarantees that a minimum 75 % of stainless steel raw materials are recycled . This uptick in recycling activity is driving sales ofelectric arc furnaces ( EAFs ), in which electricity replaces fossil fuels ( see below ).
Carbon capture and storage ( CCS ) is another way of dealing with CO 2
. The steel industry has been using it for several years , and several new projects are in the offing . In the stainless steel industry , Outokumpu is leading the way by exploring with QPower the potential of carbon capture utilization ( CCU ) to re-use the company ’ s emissions as raw materials to make new products such as e-fuels .
Ferrochrome , the fundamental ingredient of stainless steel . By FocalPoint – Own work , CC BY-SA 4.0 , https :// commons . wikimedia . org / w / index . php ? curid = 3150871
Biocoke can replace fossil-coke in the steel making process . Image : Envigas
Decarbonization
Three promising paths towards decarbonization are electrification , biocoke and ( possibly ) the use of hydrogen as a reductant .
Electrification
Both carbon steel and stainless steel mills are switching from coke-fuelled blast furnaces to EAFs , which produce lower CO 2 emissions than blast furnaces . They are not new , having originated in the 19th century . They are the preferred type of furnace in mini-mills , but integrated mills are turning to them as they can smelt scrap consuming less energy than traditional blast furnaces . They are also more efficient , as they can be switched on and off to accommodate fluctuations in demand . Naturally , the CO 2 reduction will be greater if the electricity is renewably resourced : it is no coincidence that green-steel projects are largely concentrated in countries where most electricity comes from fossil-free sources such as renewables and nuclear . Outokumpu , being the only producer in the world to mine its own chromite , is well placed to refine it into ferrochrome in a more sustainable manner , using low-carbon electricity there as well as with its operations locally .
The ore is crushed , then , using centrifugal forces , is concentrated into chromite . The concentrate is injected into a more efficient type of EAF , the submerged arc furnace ( SAF ). Into this melt , carbon is added solely as a reductant , not as a heat source , along with other materials . One of the waste products of this process is carbon monoxide , which is either sold ( for instance , to chemical plants ) or re-used as fuels to fire up the furnaces . Some carbon-steel mills are building their own renewable power plants , including US producer EVRAZ , Panatère in Switzerland and SSAB in Italy . Among stainless-steel producers , Outukumpu is partnering with Fortum to explore the use of Small Modular Reactors ( SMR ) in Finland , while Aperam is exploring how to use hydro-electricity , photovoltaics , wind power and charcoal biomass from the company ’ s forests in Brazil . Last year India ’ s Jindal Stainless announced it would instal two rooftop solar plants and use wind and solar energy to power its mill in Jajpur . It has just launched a green-hydrogen electrolyzer , fuelled by solar panels , at its facility in Hisar , Haryana , India , which incorporates energy storage .
Biocoke
Biocoke can replace fossil coke as a reductant . Outokumpu is currently studying the implementation of a facility that converts biomass in a pyrolysis process into biocarbon which , in a second process , can be processed and pelletized into biocoke .
Hydrogen reduction
In Europe , carbon steel manufacture is being transformed by a revolutionary technology , H-DRI ( hydrogen used to make direct-reduced iron ), which cuts
Solar panels provide electricity to power JSL ’ s stainless-steel mills and to make green hydrogen for energy storage .
CO 2 emissions by about 95 %. Iron ore is reacted with hydrogen to produce DRI , which is then blended with scrap steel in an electric arc furnace ( EAF ) to create liquid steel . The main waste product in this process is no longer CO 2 but water . Several steel makers in Europe and Asia are constructing mills that will deploy H-DRI , including SSAB , H 2
Green Steel , Salzgitter , Metso , POSCO , Nippon and LKAB . However , the extent of future market penetration is uncertain : DRI manufacture is expensive and heavily dependent on subsidies . In fact , many of these producers continue to use natural gas as well as the more expensive hydrogen .
Can hydrogen be applied in a similar process to make stainless steel ? Using hydrogen as a reductant can cut emissions , but because of various practical problems this method has been discussed over several decades without yet being applied . Stefan Erdmann of Outokumpu doubts if it is feasible ; instead , the company is working on a new process to achieve chromite reduction . Some success has been achieved in the laboratory and the technology – still a closely guarded secret – awaits scaling up .
Nickel and Titanium
The nickel and titanium industries face the challenge of adopting more sustainable mining and processing methods . Nickel is processed at very high temperatures , but highpressure acid leaching offers a less energy-intensive alternative . Bioleaching promises to negate the need for higher temperatures altogether .
As for titanium , alternatives are being sought to the Kroll method , which requires high temperatures ( 1,300 ° C ) and corrosive chlorides to form the titanium metal sponge . IperionX proposes its Hydrogen Assisted Metallothermic Reduction ( HAMR ) technology , which is simpler , faster and requires lower temperatures , and its Hydrogen Sintering and Phase Transformation ( HSPT ) technology . These replace the traditional refining and forging steps . The pilot phase is complete and commercial production will begin in Virginia 2024 using 100 % Ti metal scrap . Meanwhile , Rio Tinto has started its BlueSmelting demonstration plant at its metallurgical compete in Sorel-Tracy , Quebec , using ilmenite reduction technology that could reduce CO 2 emissions by 95 % compared to conventional coal burning .
Diagram showing how biomass is converted into biocarbon . Image : Envigas .
The Future
Decarbonization in the carbon- and stainless-steel industries is likely to take a long time and will be costly . But Stefan Erdmann of Outokumpu is confident of ultimate success . “ The stainless-steel industry ,” he reflects , “ has reached a stage where we have to show ingenuity and question everything we think we know .” Given the challenges , it is essential to win hearts and minds . Erdmann thinks the best way to achieve this is through education . Outokumpu and Stalatube both supply documentation detailing the carbon footprint of their products , to support and inform customer in their product choices in respect to sustainability . EU legislation will go further : a law that is expected to pass soon will oblige European companies , from 2029 , to prove they are taking action to protect the environment and human rights throughout their supply chain . This will have a significant impact on all steel production .
The author ' s thanks to Stefan Erdmann , Chief Technology Officer of Outokumpu , for his kind help in the preparation of this article .
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