POSCO expands use of slag as fertilizers

POSCO has been carrying out various activities to promote the use of slag, a steelmaking byproduct, the company said Wednesday.

Slag — a mixture of silica and calcium, magnesium and iron oxides — can be used as a fertilizer that can assist in fortifying disease resistance in rice because of its mineral components.

It can also be used to assist in the growth of marine plants and to purify polluted water. Around 600 to 700 kilograms of byproducts, mostly slag, are formed in the process of making 1 metric ton of steel, according to the company.

POSCO Chairman Choi Jeongwoo and 50 employees participated in a volunteer event in Gwangyang,

South Jeolla Province, to demonstrate how leftover slag can be used as fertilizer. “Steelmaking slag is beneficial not only for rice health and growth, but also from economic and environmental perspectives,” Choi said. “It can contribute to increasing farm incomes, improving soil quality and reducing greenhouse gas emissions.”

Slag when used as a fertilizer can improve the production of rice by around 10 percent to 15 percent while preventing soil acidification.

Iron eluted from steelmaking slag also reduces the amount of methane emitted from paddy fields by about the same percentage. POSCO said that processed slag used as fertilizer could reduce greenhouse gas emissions by 1.1 million metric tons to 1.5 million metric tons annually.

Earlier on Oct. 13, Choi addressed POSCO’s efforts to reduce greenhouse gas and promote cooperation with the agriculture and fishery sectors at the 10th Steelie Awards ceremony hosted by worldsteel in Monterrey, Mexico.

By introducing examples of fertilizer from recycled slag and sea forests with artificial reefs, the company received positive feedback from the worldsteel executive committee.

To promote “Life Cycle Assessment,” POSCO has been pursuing “eco-friendly” businesses with the byproducts from its steel works to minimize waste discharge and reduce carbon emissions.

Its trading arm POSCO International has been exporting recycled slag to share the company’s “eco-friendly” vision.

Courtesy of POSCO POSCO Chairman Choi Jeong-woo, second from right, and employees use steelmaking byproduct, slag, which has been processed to make fertilizer, in paddy fields in Gwangyang, South Jeolla Province, Wednesday.