Direct phase transformation of flue gas desulfurization gypsum in hot salt solution at atmospheric pres-sure was investigated.The effects of temperature,salt species,salt concentration,solids content,pH and modifier w...Direct phase transformation of flue gas desulfurization gypsum in hot salt solution at atmospheric pres-sure was investigated.The effects of temperature,salt species,salt concentration,solids content,pH and modifier were examined.The crystals obtained under different conditions and solubility of calcium sulfate in contact with solid gypsum were also determined.α-Calcium sulfate hemihydrate crystals of stubby columnar shape and regular pentahedral sides were obtained under the following conditions：salt concentration 20%-30%,operation tempera-ture 95-100 °C,solids mass content in the slurry 10%-30% and neutral pH.Thermodynamic analysis revealed that phase transformation of calcium sulfate dihydrate to α-calcium sulfate hemihydrate occurs because of the difference in solubilities between the two solid gypsum phases in this system.展开更多
Plaster is a binder which, compared with other materials as lime and cement Portland, can be considered much less aggressive to the environment. While, in the process of production, Portland cement and lime emits CO2,...Plaster is a binder which, compared with other materials as lime and cement Portland, can be considered much less aggressive to the environment. While, in the process of production, Portland cement and lime emits CO2, plaster emits molecules of water in the atmosphere. While the production of lime and cement Portland requires high temperature, plaster needs only 150~C. In spite of these environmental advantages, plaster is relatively little used in Brazil and in the rest of South America. An effort has been made to increase the consumption of this material in housing. In this work, a constructive system was developed using plaster blocks. This rationalized system looks for to reduce the manpower considerably, the times of execution and, consequently, the final costs of the construction. The basic components are three types of main blocks, and from these main blocks, sub-blocks are obtained, so that all the dimensions of the construction are achieved. All the dimensions of blocks, sub-blocks and construction are multiples of the base-unit, 10 cm, basic principle of the modular coordination. So, waste of material is avoided. The blocks developed and the constructions way are presented.展开更多
基金Supported by the National High Technology Research and Development Program of China（2006AA06Z385） the Science Foundation of Wuhan University of Science and Technology（2008RC06）
文摘Direct phase transformation of flue gas desulfurization gypsum in hot salt solution at atmospheric pres-sure was investigated.The effects of temperature,salt species,salt concentration,solids content,pH and modifier were examined.The crystals obtained under different conditions and solubility of calcium sulfate in contact with solid gypsum were also determined.α-Calcium sulfate hemihydrate crystals of stubby columnar shape and regular pentahedral sides were obtained under the following conditions：salt concentration 20%-30%,operation tempera-ture 95-100 °C,solids mass content in the slurry 10%-30% and neutral pH.Thermodynamic analysis revealed that phase transformation of calcium sulfate dihydrate to α-calcium sulfate hemihydrate occurs because of the difference in solubilities between the two solid gypsum phases in this system.
文摘Plaster is a binder which, compared with other materials as lime and cement Portland, can be considered much less aggressive to the environment. While, in the process of production, Portland cement and lime emits CO2, plaster emits molecules of water in the atmosphere. While the production of lime and cement Portland requires high temperature, plaster needs only 150~C. In spite of these environmental advantages, plaster is relatively little used in Brazil and in the rest of South America. An effort has been made to increase the consumption of this material in housing. In this work, a constructive system was developed using plaster blocks. This rationalized system looks for to reduce the manpower considerably, the times of execution and, consequently, the final costs of the construction. The basic components are three types of main blocks, and from these main blocks, sub-blocks are obtained, so that all the dimensions of the construction are achieved. All the dimensions of blocks, sub-blocks and construction are multiples of the base-unit, 10 cm, basic principle of the modular coordination. So, waste of material is avoided. The blocks developed and the constructions way are presented.
