Lime pretreated phosphogypsum（PG） was calcined at 500 ℃ to produce anhydrate gypsum cement. Due to the slow hydration of anhydrate gypsum, additives, K2SO4 and hemihydrate gypsum were selected to accelerate the hyd...Lime pretreated phosphogypsum（PG） was calcined at 500 ℃ to produce anhydrate gypsum cement. Due to the slow hydration of anhydrate gypsum, additives, K2SO4 and hemihydrate gypsum were selected to accelerate the hydration of anhydrate. The hydration characteristics, the resistance to hydrodynamic water, and the mineralogical studies were investigated. The experimental results suggest that activated by K2SO4 and hemihydrate, anhydrate PG hydrates much more rapidly than that in the presence of only K2SO4 or in the absence of additives. The binder has proper setting time, good strength development, and relatively better resistance to water. The hardened binder has hydrated products of rod or stick like shaped dihydrate gypsum crystals.展开更多
Phosphogypsum（PG） calcined at 500 ℃ was activated by K2SO4 and salt lime with loose structure as seed crystal. To determine the effect of activation, hydration of the anhydrate PG activated was investigated by exam...Phosphogypsum（PG） calcined at 500 ℃ was activated by K2SO4 and salt lime with loose structure as seed crystal. To determine the effect of activation, hydration of the anhydrate PG activated was investigated by examination of the setting time, the proportion of hydrated anhydrate PG, the microstructure of the hardenite and the resistance to water. Results show that activated anhydrate PG hydrates much more rapidly than that in the absence of activators. The activated anhydrate PG has proper setting time and hydrated proportion. The resistance to water was greatly improved. SEM photos show that the set activated PG has hydrated products of rod-like and closely connected crystals. The different addition of activator leads to different compact structure.展开更多
In this work,phosphogypsum(PG) with a small amount of lime was thermally pretreated at 450 ℃ to produce anhydrate gypsum for the purpose of searching new ways for utilization of waste PG. Additives,K2SO4 and one sele...In this work,phosphogypsum(PG) with a small amount of lime was thermally pretreated at 450 ℃ to produce anhydrate gypsum for the purpose of searching new ways for utilization of waste PG. Additives,K2SO4 and one selected seed crystal(SC),were used as activator for anhydrate PG. The hydration characteristics of the anhydrate PG binders were investigated by determination of the setting time,the ratio of hydrated anhydrate PG,the compressive strength development,and the microstructure of the hardenite. The resistance to water was studied by measuring mass loss of binders exposed to hydrodynamic water. Results suggest that activated by K2SO4 and SC,anhydrate PG hydrates much more rapidly than that without additives. The anhydrate PG binder with K2SO4 and SC has proper setting time and good strength developments. SEM photos show that the set binders have hydrated products of rodlike and regularly shaped crystals. Those crystals connected closely,and the hardenite has a compact structure,which is beneficial to the obtainment of good properties.展开更多
基金Funded by the National Natural Science Foundation of China (No. 50802019)
文摘Lime pretreated phosphogypsum（PG） was calcined at 500 ℃ to produce anhydrate gypsum cement. Due to the slow hydration of anhydrate gypsum, additives, K2SO4 and hemihydrate gypsum were selected to accelerate the hydration of anhydrate. The hydration characteristics, the resistance to hydrodynamic water, and the mineralogical studies were investigated. The experimental results suggest that activated by K2SO4 and hemihydrate, anhydrate PG hydrates much more rapidly than that in the presence of only K2SO4 or in the absence of additives. The binder has proper setting time, good strength development, and relatively better resistance to water. The hardened binder has hydrated products of rod or stick like shaped dihydrate gypsum crystals.
基金Funded by the National Natural Science Foundation of China(No.50802019)
文摘Phosphogypsum（PG） calcined at 500 ℃ was activated by K2SO4 and salt lime with loose structure as seed crystal. To determine the effect of activation, hydration of the anhydrate PG activated was investigated by examination of the setting time, the proportion of hydrated anhydrate PG, the microstructure of the hardenite and the resistance to water. Results show that activated anhydrate PG hydrates much more rapidly than that in the absence of activators. The activated anhydrate PG has proper setting time and hydrated proportion. The resistance to water was greatly improved. SEM photos show that the set activated PG has hydrated products of rod-like and closely connected crystals. The different addition of activator leads to different compact structure.
基金support provided by the National Natural Science Foundation of China (Project NO.50802019)the Introduction of Research Personnel Foundation of Guizhou University(Project No.2008019)
文摘In this work,phosphogypsum(PG) with a small amount of lime was thermally pretreated at 450 ℃ to produce anhydrate gypsum for the purpose of searching new ways for utilization of waste PG. Additives,K2SO4 and one selected seed crystal(SC),were used as activator for anhydrate PG. The hydration characteristics of the anhydrate PG binders were investigated by determination of the setting time,the ratio of hydrated anhydrate PG,the compressive strength development,and the microstructure of the hardenite. The resistance to water was studied by measuring mass loss of binders exposed to hydrodynamic water. Results suggest that activated by K2SO4 and SC,anhydrate PG hydrates much more rapidly than that without additives. The anhydrate PG binder with K2SO4 and SC has proper setting time and good strength developments. SEM photos show that the set binders have hydrated products of rodlike and regularly shaped crystals. Those crystals connected closely,and the hardenite has a compact structure,which is beneficial to the obtainment of good properties.
