| 摘要 |
<p>This invention relates to an apparatus, method and product wherein fine particles of fly ash containing carbon are oxidized in a dry, bubbling fluid bed of previously introduced fine particles of the same fly ash so that the subsequently removed particles have reduced carbon content and are useful as pozzolan, suitable for use, without further processing, to replace a portion of the cement in concrete. The preferred conditions are a temperature of about 1300 DEG to 1800 DEG F., air velocity of between at least about 0.5, but not more than about 3 ft./sec., residence time of at least about 2 minutes but up to 100 minutes, volume ratio of air to fly ash of between about 1,000 and 1500, and an excess of oxygen between about 5% and 15%.</p> |
