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ITP Steel: Steel Industry Technology Roadmap -- Chapter Two: Process Development
Steel Technology Roadmap
Chapter 2: Process Development
7
Steelmaking is a dynamic, ever-changing industry. The manufacture of steel involves many processes that
consume raw or recycled materials from around the world, producing thousands of products and by-products (see
Figure 2-1). Over the past 150 years, steelmaking processes have improved dramatically. Some processes, such
as the Bessemer process, flourished initially but were then replaced completely. Other processes, such as the
blast furnace, electric arc furnace, and hot strip mill, have evolved continuously over the decades and are likely
to remain a part of steelmaking in the future. Currently, the two major steelmaking routes use either the basic
oxygen furnace (BOF) or the electric arc furnace (EAF) or some combination of the two.
Advances in steelmaking, including the EAF and BOF processes, have historically evolved in response to factors
such as industrial expansion, world wars, technological innovation, competition and sheer creativity. Global
competition requires that North American steelmakers be low cost providers to the market, and it is this rule of
economic survival that will drive innovation. The plan for that innovation is outlined in the Technology
Roadmap. This chapter describes, process by process, the technical advances required for competitive advantage.
2.1 Cokemaking
Metallurgical coke is an important part of the integrated iron and steelmaking process because it provides the
carbon and heat required to chemically reduce iron ore in blast furnaces to molten pig iron (hot
metal). Because of its strength, coke also supports the column of materials in the blast furnace, and its shape
provides permeability for gases to penetrate the material bed.
Despite the importance of metallurgical coke, naturally aging coke plants, tightening environmental regulations
(which create higher production costs), and shutdowns threaten to reduce production capacity in North America.
This gap between demand and reduced capacity is projected to exceed more than 12 million tons annually over
the next 20 years, according to studies by World Steel Dynamics and CRU International.
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Process Development Chapter 2: Process Development
Steel Technology Roadmap
8
Figure 2-1. Overview of Steelmaking Processes Steel Technology Roadmap
Chapter 2: Process Development
9
This gap also presents a challenge for coke manufacturers to explore new and emerging technologies that
improve environmental controls at existing facilities and lend themselves to application at new ones. The need
to improve controls will become more urgent as the demand for steel grows at an anticipated 2% annually over
the next 10 years.
Metallurgical coke is usually produced by baking coal (coking) in a battery of large coke ovens, multiple vertical
chambers separated by heating flues. A blend of metallurgical coals is charged into ports (holes) on the top of
the ovens and is then heated at high temperature in the absence of air (to prevent combustion).
After hours of static heating at a high temperature during which the coal passes through a plastic stage, the
volatiles are driven from the coal to form coke. When coking is completed, a pusher machine on one end of an
oven removes the oven door and rams the hot coke out of an opened door at the other end and into a mobile
container car. The hot coke is then quenched, either dry or with water.
As the coal turns into coke, the volatile content is recovered in the by-product plant where it is made into a
variety of chemicals including tar, light oil, ammonia, and others. Until the 1950s, the value of these by-
products exceeded that of the coke. However, the advent of petroleum refining has driven the price of these
chemicals to such low levels that today the coke oven by-product plant is merely a very costly pollution control
device.
Trends and Drivers. The entire cokemaking process, which has changed very little over its more than 100-year
history, is subject to strict environmental regulations. These regulations and changes in steelmaking force higher
production costs or shutdowns, pressuring the steel industry to improve the cokemaking process. Aging
facilities, primarily in developed countries, also need to be replaced, and combined with tightening of
environmental regulations, these factors are reducing the amount of coke produced. Studies by World Steel
Dynamics and CRU International forecast a worldwide shortage of metallurgical coke by the year 2005. For
example, the United States and Canada currently produce 22 million short tons of metallurgical coke each year.
Normal aging of facilities will require the replacement of at least 12 million tons over the next 20 years.
Technological Challenges. Cokemaking is subject to government regulations to control emissions during
charging, coking, discharging (pushing), and quenching. The primary concern over emissions focuses on the
doors at either end of the ovens and on the oven charging ports atop the battery because improperly sealed doors
and charging port lids allow gases to escape.
By-product processing presents additional environmental control issues for cokemakers. Throughout the
cokemaking process, organic compounds are recovered as gas, tar, oil, and other liquid products for reuse or
conversion into by-products for sale or internal use. Some of the recovered compounds, characterized as
carcinogenic, are also classified as health hazards and therefore require special processing. In addition, the value
of cokemaking by-products has decreased significantly and are generally uneconomical to recover.
New and Emerging Technologies. The need to improve environmental controls for existing cokemaking
facilities and to find more cost-effective methods of producing high quality metallurgical coke has prompted
several new and emerging technologies. Chapter 2: Process Development
Steel Technology Roadmap
10
Cokemaking
<
Sealed, continuous coking process
<
Cost-effective coke quenching and dust collection
systems
<
New cokemaking processes to produce valuable,
environmentally friendly by-products
<
Ways to extend life of existing coke plants.
<
Improved process control
<
Ability to use noncoking coals and low value
carbonaceous material
<
Improved refractory repair technology
<
Particulate and sulfur control
<
Methods to produce stronger coke
<
Upgraded value of coke oven by-products
<
Improved form coke manufacturing processes
<
Development of comprehensive economic
models incorporating coal and batter operating
parameters
R

&

D

Needs
New technologies include the following:
The European Jumbo Coking Reactor has reconfigured batteries for larger individual batch process
ovens. Recent studies have indicated that capital costs for the technology, also referred to as the Single
Chamber System, were significantly greater than conventional technology, and therefore, interest in
utilizing the technology is minimal.
Non-recovery cokemaking is a proven technology derived from the Jewell-Thompson beehive oven
design. Beehive ovens operate under negative pressure, eliminating by-products by incinerating the off-
gases. The technology also includes waste heat boilers, which transfer heat from the waste products of
combustion to high-pressure steam for plant use and for conversion into electricity.
The Coal Technology Corporation is using a formcoke process that produces coke briquettes from non-
coking coals and waste coals. The process is currently referred to as the Antaeus Continuous Coke
process, named for the Australian company which purchased the patent rights.
The Japanese SCOPE21 project, still in its early stages of development, is using a formcoke process that
combines briquetted formcoke and improvements in existing batteries. With this technology,
cokemaking is performed in three sections: coal pretreatment, carbonization, and coke upgrading. The
project is being developed as part of an eight-year research program.
Emerging technologies include the following:
The Ukrainian State Research Institute for Carbochemistry is testing a continuous cokemaking process
using a vertical shaft structure and a piston to push metallurgical coke blends through the heated zones.
A pilot unit is said to exist at Kharkov.
A Calderon Cokemaking Technology under development in the United States involves continuously
producing coke from metallurgical coal and cleaning and cracking of the gases under completely sealed
conditions. The cleaned gases are used as a syngas.
Research and Development Needs and
Opportunities. The process of converting coal to
coke produces by-product gases and liquids.
These materials must be contained and handled in
an environmentally safe manner. For those that
contain valuable constituents, the components
must be separated and safely proces