The applications of calcium hydroxide (commonly known as slaked lime or hydrated lime) can be summarized into the following six major areas:
Construction and Building Materials
· Traditional materials: Used to produce lime mortar and milk of lime for masonry and plastering; also a key raw material in cement production.
· Modern materials: Used in the production of aerated concrete, silicate bricks, calcium-based coatings, and tile adhesives.
· Soil stabilization: Used in roadbed engineering and the improvement of expansive soils to enhance load-bearing capacity and stability.
Agriculture
· Soil improvement: Neutralizes acidic soil, raises pH levels, and replenishes calcium.
· Pesticide preparation: Used to formulate Bordeaux mixture (a fungicide) and for whitewashing tree trunks to prevent pest infestations and frost damage.
· Feed additive: Serves as a calcium supplement to promote skeletal development in animals.
Environmental Protection and Wastewater Treatment
· Wastewater treatment: Neutralizes acidic wastewater, precipitates heavy metal ions (such as lead and cadmium), and removes phosphates and fluorides.
· Flue gas desulfurization: Removes sulfur dioxide (SO₂) from flue gases in coal-fired power plants and steel mills, achieving efficiencies of over 90%.
· Waste treatment: Neutralizes landfill leachate and immobilizes heavy metals in incineration fly ash.
Industry and Chemical Manufacturing
· Chemical raw materials: Used to produce bleaching powder, light calcium carbonate, calcium-based greases, etc.
· Metallurgy: Acts as a flux and pH regulator in the production of iron, steel, aluminum, and copper.
· Petrochemicals: Used as a lubricant additive or to adjust the pH of drilling mud.
· Sugar refining: Neutralizes acidity in syrup and precipitates impurities.
· Rubber/Plastics: Used as a filler to improve processing characteristics.
· Papermaking: Used in pulp bleaching and alkali recovery processes.
Food and Pharmaceuticals
· Food processing: Serves as a processing aid in the production of tofu and century eggs, and in the clarification of sugar juice.
· Pharmaceuticals: Used in dental root canal therapy and as a raw material for antacids and calcium supplements.
Other Emerging Fields
· New energy: Used as an electrolyte additive for lead-acid batteries and in the field of new energy materials. · Other uses: Leather dehairing, laboratory reagents, disinfectants, etc.
It is worth noting that, in recent years, high-specific-surface-area calcium hydroxide has attracted increasing attention in fields such as environmental desulfurization, new energy materials, and high-end petrochemical additives, owing to its superior reactivity.