Release Date: April 6, 2000

An advanced iron making technology demonstrated in the U.S. Department of Energy's Clean Coal Technology Program stands out for its potential to provide major environmental and financial benefits to the United States steel industry.

The Energy Department has profiled the project in a topical report entitled Blast Furnace Granular Coal Injection System Demonstration Project. The report describes the federal government's partnership demonstration project with Bethlehem Steel Corporation, which tested a new method for reducing the heavy use of coke fueling systems at steel making plants throughout the country.

Conventional iron making requires coke to provide a gas mixture, primarily carbon monoxide with some hydrogen, that reduces iron ore to molten iron. Coke, as it is prepared from coal, generates significant airborne toxic impurities along with nitrogen- and sulfur-based pollutants.

The topical report discusses the demonstration of the British Steel and CPC-Macawber Blast Furnace Granular Coal Injection Process at Bethlehem Steel's Burns Harbor Plant in Burns Harbor, Indiana. The technology is installed on blast furnaces C and D. Each of these units has a production capacity of 7,000 net tons of hot metal per day.

DOE selected the Bethlehem Steel project in the third round of the Clean Coal Technology Demonstration Program and awarded the cooperative agreement in November 1990. Construction began in September 1993 and was completed in January 1995. Test operations commenced in November 1995 and were completed in November 1998.

"The major conclusion of this project," the topical report states, "is that the injection of granular coal into a large blast furnace works very well and can reduce coke requirements on almost a pound-for-pound basis."

A blast furnace smelts iron ores to produce pig iron, the primary ingredient in steel production. Other raw materials consumed in the smelting process include coke, the primary fuel and reducing agent; limestone, which acts to flux the earthy constituents in the iron-bearing ore and coke ash to form a slag; and hot air and oxygen, which support combustion of the coke.

The slag, containing most of the impurities from the raw materials, is skimmed from the molten pig iron and used as aggregate for road fill or cement manufacture. Thus the sulfur introduced by the direct injection of coal in the Blast Furnace Granular Coal Injection process becomes a constituent of a useful by-product.

Conventional iron-making requires the use of coke, which is made from coal by a process that can release significant emissions of airborne toxic impurities along with nitrogen- and sulfur-based pollutants. Standard coke ovens emit a variety of pollutants from different locations in the coking process. In a typical coke battery, there may be leaks from doors, lids, and offtake pipes.

Additional emissions occur when coal is fed into the oven at the beginning of a new coking cycle and at the end of the cycle when the coke is pushed from the oven into a car and quenched with water. These emissions are particulate matter and raw coke oven gases that contain coal tar, methane, ammonia, hydrogen cyanide, hydrogen sulfide, carbonyl sulfide, and various hydrocarbons.

By replacing a significant fraction of the coke fed to the blast furnace with coal, the Blast Furnace Granular Coal Injection process results in a marked reduction in the quantity of pollutants emitted from coke-making facilities.

In the demonstration project, two high-capacity blast furnaces, Units C and D at Bethlehem Steel's Burns Harbor Plant, were retrofitted with Blast Furnace Granular Coal Injection technology. Each unit has a production capacity of 7,000 net tons of hot metal per day. The two units use about 2,800 tons of coal per day during full operation. Tests were conducted on eastern bituminous coals with sulfur content of 0.8% to 2.8% and a western sub-bituminous coal with sulfur content of 0.4% to 0.9%.

The demonstration project performed injection tests of both pulverized and granular coal. Pulverized coal, with a particle size similar to face powder, costs more to grind down to a fine powdered form. Granular coal's size compares more to granulated sugar. Researchers found the granular coal easier to handle in pneumatic conveying systems.

Since the gas leaving the blast furnaces is cleaned before being burned as fuel, injected coal does not result in an increase in pollution from the blast furnace. The report concluded that the Blast Furnace Granular Coal Injection technology can be applied to essentially all U.S. blast furnaces and can use a wide range of commercially available coals.

For more details on this project see Topical Report Number 15 titled, Blast Furnace Granular Coal Injection System Demonstration Project, and the project's Final Report, titled, Blast Furnace Granular Coal Injection System, Final Report Volume 2, Project Performance and Economics (DE-FC-91MC27362) which are available on the Clean Coal Compendium.