The aqueous solution of lime milk is often referred to as limewater (forming lime milk or lime slurry in large quantities), which is alkaline. It absorbs carbon dioxide and water from the air, leading to deterioration, and is commonly described as hygroscopic. It is generally used in construction or for the improvement of acidic soil. Lime milk is typically produced by adding water to calcium oxide: CaO + H₂O = Ca(OH)₂, which is an exothermic reaction. Calcium oxide dissolves in water to form calcium hydroxide, but its solubility is not very high, often resulting in a suspension of calcium hydroxide (meaning undissolved calcium hydroxide remains in the aqueous solution), which is lime milk. As a widely available and easily prepared industrial raw material, lime milk plays an important role in industrial production. For example, in the metallurgical industry, lime milk is added as a dissolution additive during the production of alumina; in the chemical industry, it serves as an important raw material for producing propylene oxide, calcium propionate, nylon, and other products, and is also used in desulfurization systems; in the sugar industry, it acts as an indispensable and inexpensive clarifying agent; in the construction and building materials industry, it is also an essential raw material; and in the environmental protection sector, it can be used to treat industrial wastewater.