Resource Circulation
The primary components of granulated slag, calcium oxide and silicon dioxide, can serve as substitutes for cement clinker1). This substitution reduces the GHGs produced during the calcination of traditional cement raw materials like limestone, highlighting its role as an eco-friendly material. POSCO, in partnership with RIST and POSCO E&C, has developed and disseminated PosMent2), a product that enhances the granulated slag content up to 58% compared to conventional slag cement. This innovation significantly aids in GHG reduction and by-product recycling
Additionally, granulated slag serves as a key raw material for silicate fertilizer, which is abundant in silica, a crucial nutrient for rice plant growth. This nutrient significantly strengthens rice stalks, increasing their resilience by over threefold, thereby enhancing both yield and quality of the rice. Moreover, studies conducted in collaboration with specialized institutions have demonstrated that the trace iron ions (Fe3+) present in the slag inhibit the activity of methanogenic bacteria, leading to an approximate 14% reduction in GHG (methane) emissions during rice cultivation
2) PosMent is a type of slag cement developed by POSCO, which enhances product performance by incorporating an activator and increasing the granulated slag content to up to 58%.
Steelmaking slag, rich in iron, undergoes crushing and magnetic separation to extract iron, which is then used as a substitute for scrap metal. The residual steelmaking slag, mainly composed of lime and silicon dioxide, serves as an alternative to natural aggregate in construction materials.
Especially in projects where slag is used as aggregate for site formation, the potential generation of leachate upon contact with water necessitates adherence to the slag management guidelines set forth by the Korea Iron & Steel Association.
In partnership with specialized firms, we have developed a technology to completely substitute natural aggregate with steelmaking slag in the production of asphalt concrete (ascon) for concrete road construction. Using steelmaking slag in ascon not only prevents deforestation but also provides more than twice the strength of conventional ascon. Additionally, it is highly effective in reducing fine dust and noise, leading to plans for expanded application.
Dust and sludge generated from environmental facilities like dust collectors and water treatment facilities are reused as raw materials in ironmaking and steelmaking processes, either in their original form or processed into pellets or briquettes due to their high iron content.
We are actively developing recycling technologies and identifying potential users to increase the recycling rate of unutilized by-products that would otherwise be landfilled or incinerated. For designated waste such as waste acid and waste alkali, which are challenging to recycle, we manage the entire process, from discharge to disposal, in compliance with the Waste Management Act.
