The CAER has developed several beneficiation technologies that can produce high-quality, consistent products from ash.
FastFloat™ incorporates beneficiation technologies commonly applied in coal preparation and mineral processing. The process allows total utilization of CCBs and is being implemented in stages in order to expedite commercial development.
. . . deals with bottom ash and incorporates sizing and density separation. Bottom ash is recovered from ponds or from boilers and is screened to remove oversize (>3/8 inch) material. The coarse ash is hydraulically classified to efficiently reject fines (<100 mesh or 150 Ám). The ash is then separated by density using concentrating spirals to produce a lightweight aggregate suitable for use in the manufacturing of concrete masonry units and a variety of other applications.
This technology was first demonstrated in 1997 and is in commercial operation at three plants in the U.S., producing approximately 200,000 tons per year (tpy) of lightweight aggregate.
A fourth plant is also in operation where the bulk density of the bottom ash precludes use as lightweight aggregate. In this application, construction fill sand is being produced. While construction fill sand is not as high-valued as lightweight aggregate, over 250,000 tons have been marketed to date, reducing disposal costs incurred by the host utility and extending the life or their ash storage facility.
. . . adds selective density separation to recover coarse carbon (>100 mesh) and froth flotation to recover fine carbon (< 100 mesh) from fly ash to produce a supplemental fuel. A mobile, pilot-scale processing plant was constructed and operated by CAER to demonstrate this phase of the technology. The demonstration produced over 500 lbs. of fine carbon with a heating value of 4360 Btu/lb. Combustion testing and economic analyses confirmed the technical and economic viability of recovering these products as supplemental fuel.
. . . incorporates thickening and filtration to produce a high-quality pozzolan. This phase was selected by the US DOE as part of the Clean Coal Power Initiative and was implemented at Kentucky Utilities' Ghent Power Plant in Ghent, Kentucky, in collaboration with Cemex, Inc. Pilot-scale evaluations were carried out at a feed rate of 2.5 tph and larger quantities (several tons) of high-quality pozzolan were generated for testing.
. . . The final phase of the FastFloat™ technology is to
process a slip-stream of the flotation tailings through a secondary
classifier to produce a mineral-grade filler suitable for use in
This process represents the next step in coal combustion by-product utilization, addressing the entire CCB stream and a wide array of quality issues. The process generates pozzolan that can be used at higher Portland cement replacement levels in concrete, while producing better strength and durability than what is available from unprocessed ash.
|Animated (Flash) Movies*||Web pages with Graphics|
|Video (wmv format, 53MB)||Narration Document (PDF)|
|FastFloat Video Narration|
The research that CAER conducts is important in order to find new technologies that allow for the more efficient utilization of CCBs as well as decrease the costs of CCB storage; improve CCB environmental issues such as leaching and land remediation; and in finding ways to use CCBs in new products used in the construction and transportation industries.