The effective calcium hydroxide content of pure calcium hydroxide is more than 95%, the impurity content is very small, the fineness is fine, widely used in the manufacture of bleaching powder, the preparation of dye dispersant, tap water disinfection, acid water and treatment, acid making agent, astringent and building materials, chemical industry, sugar industry, tanning, environmental protection sewage treatment, sludge conditioning, flue gas desulfurization, leather leaching, building materials raw materials, paint, etc. Nonferrous metal smelting, feed addition, calcium-based grease, dyes, refrigerants, etc. Pure calcium hydroxide is not as long as the effective calcium hydroxide content is up to standard, there are certain requirements for the content of some other elements and compounds, the specific indicators are as follows: calcium hydroxide (Ca(OH)2) content ≥ 95.0%; Moisture ≤1.0%; Iron (as Fe) content ≤ 0.01%; Magnesium and alkali metal content ≤1.0%; Hydrochloric acid insoluble matter content ≤0.05%; Arsenic content ≤0.0001%; Heavy metal (Pb) content ≤0.002%; Sulfide (SO4) content ≤0.20%; Chloride (CL) content 0.01%.