Abstract: The present invention provides a method of reducing the detrimental environmental impact of an industrial plant which produced or produces a product selected from the group consisting of calcium oxide, also known as lime, and carbon dioxide gas, the method comprising the step of forming an environmentally less detrimental composition from such product which composition comprises predominantly calcium carbonate.

Abstract: A method of producing relatively pure calcium carbonate from a relatively impure source of calcium oxide, characterized in that the method comprises the steps ofslaking the calcium oxide source in water to produce an aqueous hydrated lime slurry;treating the slurry by the addition thereto of a water soluble source of anions which anions are capable of forming a salt with calcium ions which salt has a dissociation constant greater than the dissociation constant of calcium hydroxide;separating the solid content of the slurry from the liquid fraction content thereof to obtain a substantially solids-free solution of calcium ions and anions;intimately contacting the solids-free liquid fraction with carbon dioxide gas at a selected rate to maintain the temperature of the solution within a specific range and to lower the pH of the solution to a pre-set value conducive for the formation of a precipitate of calcium carbonate in which one of the crystalline forms, selected from the group consisting of calcite, vaterite