At the end of the last century, the approximate 55 million tons of blast furnace hot metal produced in the United States annually requires about 23 million tons of coke. By 2015, it is anticipated that many of the smaller, older furnaces will be shut down while productivity in the larger furnaces increases. Most likely, no new blast furnaces will be built in the United States.

It has been estimated that by 2015 blast furnace production will decrease to 42 to 46 million tons, which will require only 14 to 18 million tons of coke (Fruehan 1996). Iron from scrap, direct reduced iron, and smelter metal will make up the remainder of the required iron units. Coal, oxygen, and, in some cases, natural gas injection will increase, possibly supplying up to 50% of total furnace requirements. Specific productivity in the blast furnace should also increase. The current and projected future performance of the blast furnace is given in Table 1 (Productivity is with up to 5-10% reduced iron or scrap. Higher productions are possible with higher rates of scrap or DRI).

The major drivers for technological developments related to the blast furnace are to reduce its reliance an coke and to extend campaign life to reduce capital costs of repairs. These goals will be achieved through increased coal and natural gas injection. The other major concern related to the coke plant/blast furnace is the high capital cost. However, since few if any will be built, the cost issue must eventually be solved with a more radical process such as direct smelting. Other developments related to the blast furnace, such as gas recirculation and the oxygen blast furnace, are not high priority.

The blast furnaces remaining in operation will need to improve their efficiency. One of the key factors to an energy-efficient blast furnace operation is maintaining stability, which in turn is affected by consistent taphole performance. Consistent performance of the taphole clay is required for stable taphole operation, and key to maintaining the clay performance is its resistance to erosion and curing properties.

Technical barriers to replacing more coke with injected coal are:

• The practical limit and limiting process for coal injection are not known precisely. The major challenge in injecting more coal lies in the strength of the pellets. Pellets will be reduced with a gas of higher reducing power, higher heating rate, and longer residence time. The specifications of iron ore quality must be reevaluated for the new practice. Furthermore, any new DRI product for the blast furnace must have sufficient physical strength for the same reasons.
• Since less coke is charged into the furnace, coke must be stronger. There is concern as to whether current coke production methods can economically yield a coke of sufficient strength.
• The lack of an economical process to produce partially reduced (50 to 75%) pellets or sinter is a barrier to significantly increasing productivity.
• Technology developments have outpaced modeling capabilities. There is no comprehensive blast furnace
• model (including fluid flow and kinetics) or accompanying lower-cost sensors.
• There is a lack of effective uses of process gas and sequestration of CO

New and Emerging Technologies. New and emerging blast furnace technologies include the injection of coal and natural gas to displace coke, improved refractories, and new control technologies. The Japanese may have developed a blast furnace model that includes fluid flow and kinetics. It may also be possible to develop other attractive fuels, for example wood wastes or plastics.

Blast furnace R&D needs are primarily based on incremental improvements around current operating practices. One key need for improving this process is the development of a comprehensive model of the blast furnace, including fluid flow and kinetics and low-cost sensors to measure gas composition, temperature, and bed permeability. Such a model could help steelmakers optimize in-plant coke oven and blast furnace off-gas utilization, as well as evaluate recent tuyere injection developments.

Another blast furnace need is for improved raw material development. This includes new types of iron ore pellets more suitable for blast furnaces with high levels of coal injection. In addition, a process is needed to economically produce partially reduced pellets or sinter of sufficiently high physical strength.

More specifically, the Blast furnace R&D needs focus on the following areas: