Patent ID: 6331207
Filing Date: 2001-12-18
Classification: C04B

Abstract:
A method for treating cement kiln dust for return to the cement-making process, such method consisting of:a. mixing kiln dust with water such that the ratio of dust to water is greater than 1:5;b. treating the mixture with carbon dioxide;c. controlling the amount of carbonation, using pH of the slurry, to maximize retention of calcium in the kiln dust solids and to maximize dissolution and removal of alkalies and sulfate;d. separating the resulting slurry into moist solids and brine;e. washing the solids with water to remove interstitial brine;f. recycling the wash water to the process;g. returning the solids to the cement-making process as kiln feed; andh. treating the separated brine for recovery of byproduct alkalies by direct use of the brine; by concentration of the brine by evaporation or reverse osmosis; or by recovery of salts by precipitation, evaporation, or crystallization.