How does steel major POSCO aim to achieve carbon neutrality by 2050? BigMint explores

• Company's current emissions intensity is 2.02 tCO2/tcs
  
  
• Reducing hot metal ratio in BOFs, new EAF short-term goals
  
  
• H2-based DRI project designated as 'National Strategic Technology'
  
  

Morning Brief: South Korean steel major POSCO has set a net-zero carbon emissions target for 2050. It was the seventh largest steel producer in the world in 2023, according to the World Steel Association (worldsteel), with production of over 38 million tonnes (mnt) from its two key facilities of Gwangyang and Pohang in South Korea and overseas subsidiaries.

POSCO is considered one of the most technologically advanced steel manufacturing companies in the world with an array of high-quality products and export presence in as many as 53 countries. However, the company is wholly reliant on the traditional blast furnace-based technology that accounts for high carbon emissions.

Emissions profile

As per the company's recent disclosures, direct emissions (scopes 1 & 2, as per the GHG Protocol) from its Pohang and Gwangyang Steelworks in 2023 stood at around 72 mnt, which was a slight increase from 70-odd mnt in 2022 but considerably lower than over 78 mnt in 2021. These figures only include the company's South Korean facilities and not its consolidated carbon footprint.

The steelmaker's emissions intensity from production, however, reflects a marginal improvement from 2.05 tCO2/tcs in 2021 and 2022 to 2.02 tCO2/tcs in 2023. According to worldsteel, the global average emissions intensity of the BF-based route in 2.32 tCO2/tcs.

Technology roadmap

In the short- to mid-term, POSCO plans to reduce carbon emissions by expanding the use of low-carbon fuel and raw materials, operating at a low HMR (hot metal ratio), and introducing EAF-smelter using the current facilities through low-carbon "bridge technology". In the long-term, it aims to achieve carbon neutrality by gradually implementing hydrogen reduction ironmaking technology - HyREX.

Bridge technologies

Raw materials: Switching the BF raw material from sintered ore to pellets can reduce the fossil fuel used in sintered ore production. If HBI (hot briquetted iron) is fed into the blast furnace, it reduces the amount of coking coal required for reduction. Generally, using 100 kg of HBI per tonne of molten iron production reduces CO2 emissions by 100 kg compared to sintered ore. POSCO is planning an HBI production project in iron ore-rich Australia to ensure stable supply.

Low HMR operating technologies: Technologies that enable the extensive use of steel scrap instead of molten iron, like 'Melted Scrap Charging Method' or 'OTBB Converter Technology' (oxygen top bottom blowing) are collectively referred to as 'Low HMR Operation Technology' by POSCO.

'Melted Scrap Charging Method' increases the scrap ratio used in the converter by pre-melting the scrap in an EAF. POSCO plans to operate a large EAF with an annual production capacity of 2.5 mnt starting in 2026. This technology, which combines BF molten iron with EAF steel in the BOF, aims to simultaneously reduce carbon emissions and produce high-grade steel. Producing 2.5 mnt of steel in the EAF is expected to reduce carbon emissions by up to 3.5 mnt.

Since the converter does not receive external heat, it relies on the heat generated by the oxidation reactions of impurities in the molten iron. Increasing the amount of steel scrap lowers the temperature of the molten iron. This challenge is addressed by OTBB Converter Technology, which introduces additional heat sources by blowing oxygen from both the top and bottom of the converter to increase the use of steel scrap.

CO2 injection in coke oven: This technology separates and captures high-purity CO2 from high-temperature gases generated in BFs, converters, and FINEX melting furnaces and then injects it into the coke oven to be used as a heat source for byproduct gas power generation.

In January 2024, demonstration results at Pohang Steelworks revealed that injecting CO2 at a medium purity level of 65-70% into the coke oven is economically feasible, as it does not require additional energy for further purification. Additionally, the calorific value of the coke oven gas (COG) increased by approximately 7%. Expanding this application to Pohang and Gwangyang Steelworks is expected to reduce CO2 emissions by 320,000 t annually.

Long-term vision: HyREX

The fluidised bed H2-DRI production technology has been developed by POSCO as a long-term alternative to BF-BOF steelmaking technologies and HyREX has been designated as a National Strategic Technology.

HyREX is based on the fluidised bed reduction furnace technology of the already commercialised FINEX process. This differs significantly in terms of raw materials and equipment technology from the shaft furnace method. The shaft furnace uses pellets but HyREX can use fine iron ore directly, making raw material procurement easier and production costs more economical.

Fluidised bed reduction furnace technology offers superior temperature control compared to the shaft furnace, according to POSCO. The company's FINEX process, based on the fluidised bed reduction furnace, already incorporates hydrogen injection and DRI manufacturing technology, which are key components of hydrogen reduction ironmaking.

By April 2024, POSCO had completed and successfully tested a 1-tonne per hour electric smelting furnace (ESF) pilot facility at Pohang. This laid the foundation for the development of core technologies essential to the electric smelting furnace and the commercialisation of HyREX.

POSCO plans to develop and commercialise the core technology by 2030. By 2050, it aims to gradually transition existing blast furnace facilities to HyREX facilities, achieving carbon neutrality.

Nirmalya Deb