Coke Business

Providing high-quality coke for Japan. And for the world.

Business Outline

The coke business has been core to Nippon Coke & Engineering for more than 70 years dating back to the 1950s. We have established our place as Japan’s leading manufacturer handling the manufacture and supply of coke—a fuel that is essential for making the iron and refining the non-ferrous metals that provide the foundation for a variety of industries.
Our high-quality blast-furnace coke and foundry coke—made using advanced material blending and firing technologies based on our long experience—have earned high marks, and we have customers for it both in Japan and overseas.
When it comes to our coke manufacturing process, we have created an ecological manufacturing process that recycles the energy used. For instance, we use COG gas derived from coking coal to fuel the manufacturing process, while for the electrical power of our plants we use electricity we generate ourselves from recovering the exhaust heat generated when extinguishing the coke.

■ Conceptual Diagram of Our Ecological Manufacturing Process

Creating a recycling-oriented ecological manufacturing process that does everything possible to keep down its environmental load

Types of Coke

Blast furnace-coke

In addition to being used as the heat source for melting iron ore in an ironworks’ blast furnace, it plays an important role as a spacer that guarantees a path for the reducing gas, melted iron, and reducing agents that remove the oxygen from the iron ore.


Type of coke used for generating the high calorific volume that serves as the heat source for melting metals when casting automobile engines and wheels as well as industrial machinery.

General use-coke

Used for a variety of purposes based on the granularity and quality of the coke, including for refining non-ferrous metals, lime burning, alloy iron production, and the production of all types of chemical products.

Coke manufacturing process

Receive coking coal

Various brands of coal are procured from around the world. We have our own port facility where two large shipping vessels can dock at the same time. It can even accommodate vessels of up to the 150,000-ton class. Using a coal unloader, the shipment is separated by brand and taken to our coal yard.

Grinding and blending

The coal meant for coking is checked for quality on delivery at our own assay office. The coal that has cleared our stringent inspections is ground down to grain sizes suitable for manufacturing. We blend together various brands of coke to suit quality of the coke being asked for.

Coke ovens

The ground and blended coal is taken by unmanned larry car to the coke ovens. We have 200 coke ovens, which bake the materials to temperatures of up to around 1,200°C.


The ground and blended coal that has been baked for around 17 hours has now become red hot coke. It is removed using an extruder and taken to begin the quenching process.

Quenching (coke dry quenching, CDQ)

The bright red coke is quenched using recycled gases, with the calorific volumes generated converted into electric power. Every day, this generates enough power (approx. 900,000kW) sufficient to supply 20% of the electricity used by households around Kitakyushu City. It covers all of the electric power needs of the facility, and the excess electricity is sold to Nippon Steel’s Kyushu Works and other local companies.


After the manufactured coke has gone through a stringent quality-control check, it is stored at our coke yard. It will then be shipped to ironworks, non-ferrous metals companies, and automobile manufacturers around Japan, as well as customers located in the United States, Brazil, India, and other foreign countries.

Reuse in chemical products

Three-quarters of the coking coal is turned into coke. The remaining one-quarter goes through a gas formation process to be recovered and reused as chemical products including coke oven gas (COG) whose principal ingredient is hydrogen, diesel oil, and tar.

Coke has a unique role to play that makes it
essential to society

With its high calorific value and strength, in addition to being one of the two most important raw materials along with iron ore for producing iron, coke is also essential as a raw material for glass, for carbides, for zinc, and for refining the non-ferrous metals such as stainless steel. It provides a wide level of support to both manufacturing and everyday living.

Providing for both high quality and
reducing environmental impact

Our search for ever higher-quality coke production technology naturally is an important issue for us, as is our quest to lessen our environmental impact. We are pursuing a variety of initiatives connected to reusing energy and reducing CO2 in the production process.

Heat recovery from coke ovens and reuse

All coke ovens have CDQ system for heat recovery to quench the bright red coke from the coke oven. Recovered heat is changed to power and it covers all of the electric power needs of the facility, and the excess electricity is sold to Nippon Steel’s Kyushu Works.

Suppressing black smoke emissions through flue dust chambers

We have installed and put into operation flue dust chambers in order to suppress the black smoke released while operating our coke ovens (Kitakyushu Coking Works). This equipment operates by removing soot from the exhaust gases to clean it before returning it to the chimneys. Through this, it reduces the environmental impact on the surrounding area.

Improving productivity with formed coal briquette equipment

This equipment that we have installed and put into operation introduces caking additives to the low-grade coal that is the basic ingredient of coke and then molds it in a forming machine, blending it with the ingredient coal to fixed ratio (Kitakyushu Coking Works). Blending the coal briquette means we can anticipate a reduction in what it costs to produce coke of a uniform quality, and also will lead to efficient production efforts owing to increased production of coke and various by-products.