Patent ID: 7157064
Filing Date: 2007-01-02
Classification: B01D

Abstract:
1. A process for treating solid waste from flue gas treatment comprising the steps of: 1) obtaining a quantity of solid waste from flue gas treatment, wherein said solid waste is composed of compounds selected from the group consisting of fly ash, alkaline earth oxides, alkaline earth hydroxides, and alkaline earth carbonates; and wherein said waste also contains metals and halogen containing compounds; 2) adding water to said solid waste to create a first aqueous suspension having a pH of at least 10; 3) separating the first aqueous suspension of step 2) to produce a substantially particle free aqueous solution and collecting a first solid remnant; 4) creating a second aqueous suspension by addition of a sufficient amount of acid to lower the pH of the substantially particle free aqueous solution of step 3) to a value between 7 and 10, and precipitating metal compounds in the aqueous solution from step 3); 5) separating the second aqueous suspension of step 4) to produce a second substantially particle free aqueous solution and collecting a second solid remnant; 6) evaporating the water from the second aqueous solution obtained in step 5) to produce a solid containing alkaline earth halide salts; 7) collecting and drying the second solid remnant from 5) enriched in metal compounds; and 8) collecting the first solid remnant from step 3) for optional recycling.