| As the main component of sulfur calcium aluminate clinker,the C/A ratio?CaO/Al2O3,molar ratio?was as low as 1.33..In contrast with traditional lime sintering process,the amount of lime's addition,sintering energy consumption and leaching residue of this process reduced obviously.And the alumina leaching rate of calcium sulphoaluminate?3CaO·3Al2O3·CaSO4?was higher than that of 12CaO·7Al2O3.Therefore,the synthesis of 3CaO·3Al2O3·CaSO4 was studied.The microstructure,phase composition and alumina leaching mechanism of 3CaO·3Al2O3·CaSO4 were further studied by means of XRD,SEM and Raman spectrum.The leaching property of the mechanical mixture between 3CaO·3Al2O3·CaSO4 and?-2CaO·SiO2,and the effect of temperature system on the quaternary system?CaO-Al2O3-SiO2-SO3?were investigated.The results show that:1)the compound of 3CaO·3Al2O3·CaSO4 was synthesized at 1375?for 120 min by analytically reagents of carbonate calcium,alumina and dihydrate calcium sulfate with the molar ratio of 3:3:1.The morphology of 3CaO·3Al2O3·CaSO4 is porous.The coexistence phase of multi crystal and single crystal exist in3CaO·3Al2O3·CaSO4 and grow along different directions.The alumina leaching rate of3CaO·3Al2O3·CaSO4 is 98.41%,which is better than that of 12CaO·7Al2O3 under the optimal condition(NC=80 g·L-1,NK=10 g·L-1,dissolution temperature 80?,dissolution time 10 min,liquid–solid ratio L/S=10).The aluminum and sulfur elements exist in the form of Al?OH?4-and SO42-in the leaching solution.The calcium element exists as CaCO3in the leaching residues,and the reaction is volume invariant liquid solid unreacted nuclear model.2)Under the conditions of C/A 1.33,A/S 2,sintering temperature 1 375?and holding time 30 min,the sulfur calcium aluminate clinker,whose phase components were 3CaO·3Al2O3·CaSO4 and?-2CaO·SiO2,were synthesized.When the sintering temperature is lower than 1 300?,little amount of calcium sulphoaluminate is generated,and?-2CaO·SiO2 is not formed.When sintering temperature is between 1 300?to 1400?,the phase composition of the slag does not change,but the amount of the phase of3CaO·3Al2O3·CaSO4 increased gradually.With the increase of sintering time,the crystallinity of 3CaO·3Al2O3·CaSO4 and?-2CaO·SiO2 phase increased,but the phase composition of the clinker was not affected.3)The alumina leaching rate of calcium aluminate clinker?C/A=1.33,A/S=2?synthesized at 1 375?for 30 min is 88.11%under the optimum leaching conditions of NC=70 g·L-1,NK=10 g·L-1,leaching temperature 80?,leaching time 10min,liquid–solid ratio 10. |
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