太陽光を利用した二水セッコウの脱水

抄録

　This study explored using solar energy instead of fossil fuels to dehydrate gypsum dihydrate (CaSO₄・2H₂O)in waste gypsum board into gypsum hemihydrate (CaSO₄・1/2H₂O). We investigated the conditions for heating a graphite crucible filled with gypsum using 40×40 cm and 60×60 cm Fresnel lenses, which collect sunlight. For both Fresnel lenses, the crucible temperature reached 160℃, the typical dehydration point of gypsum dihydrate. When the diameter of focusing range was changed from 1 cm to 8 cm, no significant differences in the temperature rise of the crucible were observed. The time taken to reach the theoretical dehydration level was 15 minutes for the 40 cm Fresnel lens and 10 minutes for the 60 cm Fresnel lens. The irradiation efficiencies of the 40 cm and 60 cm Fresnel lenses were 4.2% and 2.8% respectively. These values improved to 9.6% when ALC, a material with low thermal conductivity, was placed beneath the crucible. The dehydration rate and irradiation efficiency were lower for the waste gypsum board than for the reagent dihydrate gypsum. These findings confirm the feasibility of using solar energy to dehydrate gypsum dihydrate.