Technology shears cost of grinding fly ash to match silica fume performance

Sources: CP staff; IgniteIP, New York

By Don Marsh

A New York investor announced at World of Concrete (January 18–21, Las Vegas) technology economizing the grinding of fly ash, or secondary grinding of portland cement, to 3- or 1-micron median particle sizes. With $30–75/ton processing plus $20–100/ton raw feed (fly ash, Type I/II portland cement) costs, the technology can yield premium binding agents whose performance properties in concrete and grouts match those of ultra-fine high-reactivity metakaolin or silica fume—typically commanding $300–$700/ton.

“Historically, the industry has not seen a lot of fine grinding of pozzolans because the energy input was greater than the price finished materials could bring,” said IgniteIP Managing Director Brandon Williams. The company is promoting its process and equipment—in configurations starting at 2,000 tons/year—to cement or pozzolan producers and marketers, toll blenders, and larger concrete operators through Flyanic LLC, Newark, N.J.

Flyanic holds rights to a stirred media grinding process under license with developer New Jersey Institute of Technology (NJIT). In contrast to large, horizontal ball grinding mills for cement clinker, the stirred media method consists of a cylindrical vessel, vertical agitation shaft and tiny grinding balls similar to BBs or buckshot. The technology is especially conducive to extracting greater binding capability from Class F fly ash, as stirred media fracture spherical particles to shard- and flake-like shapes that increase reactive area with minimal added water demand in the concrete mix.   —  212/580-7373;