(154c) Capture and Utilization of CO2 in Steel Industry

Current Scenario:

CO₂ is required for GCP water treatment in steel making shops for reduction of TDS(total dissolved solid) from GCP(Gas cleaning plant) water. In this process metallic oxide is converted in to carbonate with help of CO₂ and precipitated out.

Limitation:

1. Presently CO₂ is purchased from suppliers which involve appreciable amount of cost and third-party dependency.
2. In house CO₂ utilization has a potential for reduction of GHG emission

Methodology:

Our company produces slag and part of it is converted to products used in building roads, fly ash bricks etc. and the balance is disposed as waste. Our company intends to utilize this slag waste by carbonization of slag to reduce the disposal costs and to produce value products. For slag carbonation, our company intends to use the CO2 in the stack emissions or any other gas source available within the plant. After diligent study of the gas network with the customer, it is determined to extract the feed gas for the CO2 recovery from the blast furnace and Steel making shop gas mixture network.

Fuel gas for CO2 recovery plant is tapped from the gas network. In this process, all impurities like SOX, NOX, and particulate matters are removed from blast furnace gas in pre-treatment section and after that gas is fed to absorber. In pre-treatment section, sodium bicarbonate is used as scrubbing solution. CO2 is adsorbed in amine (CDRMax solvent) in atmospheric and temperature condition from BF gas and CO2 free BF gas is again sent back to system. The solvent selectively absorbs CO2 from the gas mixture. Then CO2 is separated from rich amine solution in stripper at 80-1000C using steam in reboiler and solvent is regenerated as lean solvent. The generated CO2 is 96% pure on wet basis and more than 99% pure on dry basis.

Benefits:

1. CO₂ is separated out from Blast furnace gas and that CO₂ is utilized in GCP water treatment process
2. After CO₂ recovery from Blast furnace gas, rest part of the gas is again sent back to the system
3. Favourable to environment due to reduction of GHG emission, mitigation of climate change through CO₂ capture
4. 1^st of its kind to be used in any steel company worldwide
5. Saving of annual costs of 20 million INR.
6. It produces 5 tonnes per day (TPD) industrial plant for carbon capture and utilisation from blast furnace off-gas which helped in reducing freshwater consumption, developing sustainable supply chains, and imbibing circular economy.