B Innovative Iron-making Process and Energy Conservation Technology Used in the Iron and Steel Industry

## (A) Innovative Iron-making Process

Iron is an indispensable metal in daily life, used in various kinds of products ranging from building frames, ships, and automobiles to office supplies such as staples. To extract iron, oxygen must be removed from iron oxide in the iron ore. The process requires maintaining a temperature over approximately a thousand degrees for a long time. During the first oil crisis, the iron and steel industry was one of the industries hardest hit in Japan. By actively adopting energy conservation technology, it was able to overcome the crisis, and in the aftermath, it has kept up its steady effort in technological development.

However, in order to reduce carbon dioxide emissions more drastically, the industry must approach technological development with a long-term perspective. It needs to develop (1) technology to separate/capture carbon dioxide from the gas emitted from shaft furnaces, also known as blast furnaces at iron works, and (2) technology to use hydrogen reductant to replace some of the cokes. Specifically, with a view to commercialization in 2030-50, Japan will pursue development of a new type of absorbing solution that can efficiently separate carbon dioxide from gas emitted from shaft furnaces, which has high concentrations of carbon dioxide, and development of technology to regenerate absorbing solution. Japan will also promote the development of technology to use catalysts to change the property of gaseous by-products from coke production and technology to reduce iron ore utilizing increased hydrogen as a reductant. The goal is to reduce about 30% of carbon dioxide emissions from the iron-making process by combining the use of these technologies.

## (B) Energy Conservation Technology

The iron and steel industry in Japan boasts the highest level of energy efficiency in the world. This is attributed to the widespread use of equipment to recover exhaust energy, in addition to superior production technology and operation techniques.

For example, the top-pressure recovery turbine (TRT) utilizes gas recovered from the blast furnace to generate electricity. In the blast furnace, iron oxide in the iron ore is reduced to iron, which is the most important process in iron making. The high-temperature, high-pressure gas, which is generated secondarily from the process, rises up to the top of the furnace. Rather than releasing it into the atmosphere, the gas is recovered at the top of the furnace and the exhaust energy is used to operate a turbine to generate electricity.

When coal is baked in a coke oven to generate coke, hot coke at a temperature of approximately $ 1200\ °C $ is quenched in an enclosed coke dry quenching system (CDQ) using inert gases such as nitrogen. The heat absorbed by the inert gas is then used to power a steam boiler to generate electricity. Similar to TRT, CDQ is an effective means for utilizing exhaust energy.

Figure 3-2-5 CO₂ Reduction Potential of Energy Efficient Technologies in Iron and Steel Industry (Forecast for 2030)

Note: 1. Centrally Planned Asia includes China, Mongolia, North Korea, and Vietnam.

2. SP= sinter plant, ME=main exhaust, WH=waste heat, SC=sinter cooling, HS=hot stove, BOFG=basic oxygen furnace gas, CC=continuous casting, TRT=top pressure recovery turbine, CDQ=coke dry quenching