Energy and Material Balance
Energy and Material in the Business Activity: Their Interrelationship Based on Recycling and Its Impact on the Environment
NSSMC uses iron ore mined overseas, coal as an iron ore reductant, and scrap generated by society as its main raw materials for steel production. By-product gases, such as coke oven gas generated by dry distillation of coal in the coke manufacturing process and blast furnace gas generated from blast furnaces, are fully utilized as fuel gas for steel heating furnaces or energy sources for power generation plants on the premises of steelworks.
In addition, NSSMC itself generates 84% of the electricity it uses at steelworks, 88% of which is from internally generated energy sources such as waste heat and by-product gases. 90% of water used for cooling and cleaning products and manufacturing equipment is repeatedly re-used.
When one ton of iron is produced, the amount of by-products generated exceeds 600 kg, but the steel slag, dust, and sludge are reused in-house as raw materials, or are used by society or other corporations as raw materials for cement, construction materials, and so forth. These efforts have resulted in the achievement of a very high recycling rate of approximately 99%.
We are also engaged in the recycling of various types of by-products generated by society or other industries by utilizing our steelmaking processes that are carried out at high temperature and high pressure. In recent years, we have been actively recycling waste plastics, waste tires, and other waste materials.
NSSMC’s share in Japan’s total energy
NSSMC’s share in Japan’s total final disposal
of industrial wastes (FY2013)
Resource Recycling Rate
Coke Dry Quenching (CDQ)
NSSMC recovers high-temperature waste heat and by-product gases generated in blast furnaces, coke ovens, converters, and so forth, and efficiently uses them as a source of self-generated electric power. The company uses CDQ and other facilities located in the steelworking facilities to generate 84% of the total electric power that it needs, and purchases the remaining 16% from outside. A total of 88% of the total electric power generated in the steelworking facilities is obtained from recovered waste heat and by-product gas.
Rotary Hearth Furnace (RHF)
This is a facility to recover iron and zinc, etc., and recycle them into resources. In these facilities, dust, sludge and other ferric oxide-rich by-products produced during the steelmaking process are mixed with coal or other reducing materials, and then continuously processed at a high-temperature.