FIELD: chemistry.
SUBSTANCE: invention relates to a hydrated lime composition, preparation thereof and use in cleaning flue gases. The powdered lime composition, which contains calcium hydroxide particles having BET surface area of 25 m2/g or higher and total pore volume BJH on nitrogen desorption equal to or higher than 0.1 cm3/g also contains an alkali metal in amount of 0.2-3.5% of the total weight of the composition. The method of preparing said composition, involving slaking CaO with size of 10 mm or less, water in an amount which is sufficient for formation of calcium hydroxide with residual moisture content of 15-35 wt %, drying to obtain a powdered lime composition, also involves, during and/or after slaking, addition of an alkali metal compound to CaO particles into water for slaking and/or into calcium hydroxide, in an amount which is sufficient to provide said content of alkali metal. The method of preparing said composition, involving mixing CaO and/or Ca(OH)2 with water in an amount which is sufficient to obtain lime milk with content of solid substance equal to 10-50 wt %, separating water from the lime milk, drying to obtain a powdered lime composition, also involves addition, during or after mixing, of an alkali metal compound to CaO and/or Ca(OH)2, into water for mixing and/or lime milk, in an amount which is sufficient to provide said content of alkali metal in the composition. Said composition can be used to clean flue gases. The invention is developed in subclaims.
EFFECT: high SO2 trapping capacity while maintaining HCl trapping capacity.
14 cl, 6 ex, 5 tbl, 2 dwg
