A company installs two new air classifiers and cyclones to produce marketable fly ash.
In 1942, the first major US repair using high-volume fly ash concrete was for a tunnel spillway at the Hoover Dam in Boulder City, Nev. The second major repair was for the Hungry Horse Dam in Columbia Falls, Mo., where fly ash concrete replaced about 35 percent of the existing cement. Since these two projects, fly ash, a by-product of burning pulverized coal, has developed into a necessity for high-quality concrete applications in the US. However, raw fly ash isn't always suitable for applications such as concrete. To use it, companies may first be required to classify it to a sufficient fineness to meet ASTM standards. When Phoenix Cement Co. [PCC], headquartered in Clarkdale, Ariz., built its newest fly ash beneficiation facility at the San Juan Generating Station in Waterflow, N. M., it needed to install a system to properly classify the fly ash generated by the power plant into a more marketable product.