NOVELTY - Use of a water-soluble copolymer consisting of methacrylic acid monomers and/or its salts, optionally acrylic acid monomers and/or its salts and monomers (I) for preparing an aqueous suspension of calcium hydroxide from powdered calcium hydroxide, is claimed.    USE - The water-soluble copolymer is useful for preparing an aqueous suspension of calcium hydroxide from powdered calcium hydroxide, where the aqueous suspension of calcium hydroxide is useful: for treating industrial flue gases, preferably for the desulfurization of flue gas or for the treatment of domestic wastewater, preferably drinking or industrial wastewater (all claimed); as a chemical neutralization agent; in household or industrial waste incineration plants to generate the sulfur and other impurities including acid molecules (sulfur dioxide, sulfur trioxide, sulfuric acid, hydrochloric acid and hydrofluoric acid) or pollutants (mercury and heavy metals); as mine effluent neutralizers for neutralizing acidity and/or separating heavy metals in solution before the discharge of fluids into the natural environment or into a lagoon; for water decarbonation processes and a process for temporarily reducing water hardness (partial or total elimination of alkaline earth metal bicarbonates); for the treatment of aggregates used in the bituminous coated material production process; for the production of aerated concrete type construction materials; in the treatment of contaminated soils to neutralize the acidity of these soils, to immobilize pollutants by neutralization or flocculation and to avoid the driving of such pollutants into the groundwater; in the treatment of soils in agriculture to correct the pH of these soils, improve the soils by providing a source of calcium or of calcium and magnesium in the case of dolomitic lime and to make these soils less impermeable by flocculation of clays; in the treatment of surface waters, lakes, ponds and rivers to adjust the pH of the water to reduce the impact of the acidification of these waters, preferably acidification of rain or animal origin in the case of fish farming; for the production of food for livestock or poultry; in the paper industry such as papermaking pulp; for refining sugar; and for the production of precipitated calcium carbonate, where the industrial flue gases are obtained from energy-producing plants.    ADVANTAGE - The water-soluble copolymer easily prepares the concentrated and stable aqueous suspension of calcium hydroxide with good rheology properties and without sedimentation during the storage of suspension with agitation.    DETAILED DESCRIPTION - Use of a water-soluble copolymer consisting of methacrylic acid monomers and/or its salts, optionally acrylic acid monomers and/or its salts and monomers of formula (R-X-R1) (I) for preparing an aqueous suspension of calcium hydroxide from powdered calcium hydroxide, is claimed.    R = polymerizable unsaturated group, preferably acrylate, methacrylate, methacrylurethane, vinyl or allyl;    R1 = H or 1-4C-alkyl;    X = structure with n units of ethylene oxide and m units of propylene oxide arranged randomly or regularly; and    m, n = non-zero integers or 1-150.    INDEPENDENT CLAIMS are included for:    (1) an aqueous suspension of calcium hydroxide comprising a water-soluble copolymer consisting of methacrylic acid monomers and/or its salts, optionally acrylic acid monomers and/or its salts and monomers (I); and    (2) preparing the aqueous suspension of calcium hydroxide comprising subjecting the suspension to a homogeneous shearing.