Steelmaking itself is not environment-friendly, but its byproducts can be, South Korean steel giant Posco said Monday, citing its application of slag and gases to the company’s conservation projects and businesses.

On average, in the process of making 1 metric ton of steel around 600-700 kilograms of byproduct is produced, mostly slag.

Slag, if the lime is separated, can be used as a fertilizer to improve the production of rice around 10-15 percent while preventing soil acidification and generating less methane, the company said in a statement explaining its green strategies for steelmaking byproducts.

Slag can also be recycled when used in cement and concrete production. Posco has developed eco-friendly slag cement that has a high level of chloride invasion resistance and reduces hydration heat.

The product, named PosMent, is appropriate for offshore concrete and was jointly developed by construction arm Posco Engineering & Construction and the Research Institute of Industrial Science and Technology, the company said.

By using a total of 10.69 million metric tons of slag for PosMent production, Posco estimates it has reduced 8.39 million metric tons of carbon dioxide when compared to greenhouse gases produced in the making of regular cement.

Slag -- a mixture of silica and calcium, magnesium and iron oxides -- can be used for the conservation of marine ecosystems, as its rich mineral components can accelerate the growth of marine plants and purify polluted water.

Posco developed Triton -- an artificial reef produced by steel slag -- to create a healthy environment for marine life, the company said. Last year, the company supplied 1,418 units of Triton for marine forest projects executed by the government and municipalities.

By Cho Chung-un (christory@heraldcorp.com)