MATERIAL EFFICIENCY IN THE NORTH AMERICAN STEEL INDUSTRY

The North American steelmaking processes are complex and generate by-products. Material efficiency, as it relates to the steel industry, is described as the degree to which the steelmaking process is carried out in a manner which consumes, incorporates, or wastes more or less of a given material compared to permanent disposal. An example would be that making a still usable item out of thinner stock than a prior version, increases the material efficiency of the manufacturing process. Case-in-point, while it used to require 140 pounds of material to make 100 pounds of shipped steel, it now only takes 114 pounds.

For decades, a by-product of ironmaking was the generation of a product called blast furnace slag. Approximately 600 pounds of slag are generated per ton of hot metal produced. The slag is now recovered and reused for applications, including road building, railroad ballasts, fertilizer, glassmaking and other commercial uses. The recovery and reuse of these slags conserve tens of millions of tons per year of other natural resources.

Likewise, during the process of making coke, a material used in the ironmaking process, large quantities of gas are produced. These gasses are recovered, cleaned and reused so that we can save the valuable btu's which reduces our dependency on natural gas for reheating and other process energy requirements. Also, the same process captures off-gasses from the ironmaking process itself. And, once again, these gasses, once processed, are reused as fuel.