Desulfurizer calcium desulfurization uses the chemical and physical stability of calcium sulfate to achieve the purpose of desulfurization. The raw materials are limestone, lime, etc. First of all, SO2 is dissolved:


SO2+H_2=H_2SO_3, H_2SO_3=HSO_3-+H+, HSO_3-=H++ SO32-


Dissolve limestone:


CaO+H2O=Ca(OH)2, Ca(OH)2=Ca 2++2OH-,


SO2 that is absorbed and dissolved by chemical reaction between the two solutions:


Ca2++ SO32 - = CaSO3, CaSO3+ (1/2) H_2O = CaSO3 /(1/2) H_2O.


Oxidation of liquids:


HSO 3-+(1/2)O 2=H++ SO42-, Ca 2++ SO42-=CaSO4_, CaSO4+2H 2 O 2=CaSO4.2H 2_


The final product is CaSO4.2H 2O_ (gypsum), which is a water-insoluble stabilizer and can be used in building materials and raw materials for cement production.


The above method is commonly referred to as the chemical mechanism of limestone-gypsum flue gas desulfurization (FGD).