Within steel mills, steel dust forms after electric arc furnaces melt scrap metal. In the United States alone, over one million tons are generated every year. And 40% of that ends up in landfills, creating safe storage issues and squandering the opportunity to produce a staggering amount of valuable zinc and iron rich material. SDR has found the way to a better outcome. From the 120,000 tons of steel dust that arrive at its plant yearly, over 24,000 tons of zinc and nearly 65,000 tons of iron rich material are captured. A great deal of that zinc is then reused by steel producers to galvanize new steel, while the iron rich material is used as an ingredient in cement and asphalt plants and as iron units in steel mills.
The heart of the SDR plant is its Waeltz Kiln. To increase the recycling capacity for hazardous steel dust at the plant, we were asked to serve as the design-build contractor for a new, second kiln line. That line includes a new kiln, two heat exchangers, settling chamber, and bag house.
The new kiln was massive: 180 feet long and 13.5 feet in diameter. It was manufactured offsite, then installed on extensive, deep foundations that we constructed adjacent to the existing kiln, which radiated temperatures in excess of 3,500 degrees Fahrenheit throughout construction. Because of the extreme size, weight, and dynamic loading of the kiln, precision in the construction of the foundations, concrete piers, and structural steel was crucial. In addition, the project required a new electrical power system and expanding other control, instrumentation, and monitoring systems, each of which were ultimately connected to existing systems at the plant.