초록

While any source of carbon dioxide may be used, the preferred source is exit gases from the kiln. The gases are conditioned by condensation of water and removal of ammonium compounds, such as sulfate and chloride. The conditioning condensate may be treated to recover useful byproduct salts.

대표청구항 ▼

[ I claim:] [1.]1. 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, u

[ I claim:] [1.]1. 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.