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
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
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
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
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.