Aiming at alkaline problem of bauxite residue,this work focused variation of alkaline characteristics in bauxite residue through phosphogypsum treatment.The results demonstrated that the pH of bauxite residue reduced ...Aiming at alkaline problem of bauxite residue,this work focused variation of alkaline characteristics in bauxite residue through phosphogypsum treatment.The results demonstrated that the pH of bauxite residue reduced from initial 10.83 to 8.70 when 1.50 wt%phosphogypsum was added for 91 d.The removal rates of free alkali and exchangeable sodium were 97.94%and 75.87%,respectively.Meanwhile,significant positive correlations(P<0.05)existed between pH and free alkali,exchangeable sodium.The effect of free alkali composition was CO3^2–>OH^–>AlO2^–>HCO3^–.In addition,alkaline phase decreased from 52.81%to 48.58%and gypsum stably presented in bauxite residue which continuously provided Ca^2+to inhibit dissolution of combined alkali.Furthermore,phosphogypsum promoted formation of macroaggregate structure,increased Ca^2+,decreased Na+and Al^3+on the surface of bauxite residue significantly,ultimately promoting soil formation in bauxite residue.展开更多
Chrame containing refractories are a kind of traditional material for the lining of alkali recovery furnaces, but the formation of hexavalent chrome compounds will give rise to detrimental effect on environment and hu...Chrame containing refractories are a kind of traditional material for the lining of alkali recovery furnaces, but the formation of hexavalent chrome compounds will give rise to detrimental effect on environment and human＇s health. With the gradual awakening of people＇s comciousness about environment protection, it is urgent to prepare environmental-friendly materials for alkali recovery jurnaces with high quality and long life. In this paper, alumina-rich MgAl2O4 spinel （ AR90 ） was used to replace chromite. The physical properties of dried （110 ℃ for 24 h） or fired （1 300 ℃ for 3 h） AR90 and chromite were studied, respectively. The alkali vapor method was used to determine the alkali resistance of the two materials. The results show that： （1） after drying at 110 ℃ for 24 h, AR90 specimens show higher apparent porosity and slightly lower bulk density than chromite specimens; after firing at 1 300 ℃ for 3 h, AR90 has significantly higher apparent porosity as well as higher bulk density; （2） after the alkali attack, the AR90 specimens sintered at 1 300 ℃ exhibit smaller strength change and much higher compressive strength than the chromite specimens; meanwhile, the permeability degree of alkali salt in chromite specimens is more serious than that in AR90 specimens, which indicates that AR90 possesses better alkali resistance.展开更多
Soap-free P(MMA-EA-MAA) particles with narrow size distribution were synthesized by seeded emulsion polymerization of methyl methacrylate (MMA), ethyl acrylate (EA) and methacrylic acid (MAA), and large voids inside t...Soap-free P(MMA-EA-MAA) particles with narrow size distribution were synthesized by seeded emulsion polymerization of methyl methacrylate (MMA), ethyl acrylate (EA) and methacrylic acid (MAA), and large voids inside the particles were generated by alkali posttreatment in the presence of 2-butanone. Results indicated that the size of void and the particle volume were related with the amount of 2-butanone. The generation mechanism of voids was proposed.展开更多
The influences on the brightness, viscosity and Kappa of the straw pulp under the different oxygen-alkali bleaching conditions have been studied in this paper.
基金Projects(41877511,41842020)supported by the National Natural Science Foundation of China
文摘Aiming at alkaline problem of bauxite residue,this work focused variation of alkaline characteristics in bauxite residue through phosphogypsum treatment.The results demonstrated that the pH of bauxite residue reduced from initial 10.83 to 8.70 when 1.50 wt%phosphogypsum was added for 91 d.The removal rates of free alkali and exchangeable sodium were 97.94%and 75.87%,respectively.Meanwhile,significant positive correlations(P<0.05)existed between pH and free alkali,exchangeable sodium.The effect of free alkali composition was CO3^2–>OH^–>AlO2^–>HCO3^–.In addition,alkaline phase decreased from 52.81%to 48.58%and gypsum stably presented in bauxite residue which continuously provided Ca^2+to inhibit dissolution of combined alkali.Furthermore,phosphogypsum promoted formation of macroaggregate structure,increased Ca^2+,decreased Na+and Al^3+on the surface of bauxite residue significantly,ultimately promoting soil formation in bauxite residue.
文摘Chrame containing refractories are a kind of traditional material for the lining of alkali recovery furnaces, but the formation of hexavalent chrome compounds will give rise to detrimental effect on environment and human＇s health. With the gradual awakening of people＇s comciousness about environment protection, it is urgent to prepare environmental-friendly materials for alkali recovery jurnaces with high quality and long life. In this paper, alumina-rich MgAl2O4 spinel （ AR90 ） was used to replace chromite. The physical properties of dried （110 ℃ for 24 h） or fired （1 300 ℃ for 3 h） AR90 and chromite were studied, respectively. The alkali vapor method was used to determine the alkali resistance of the two materials. The results show that： （1） after drying at 110 ℃ for 24 h, AR90 specimens show higher apparent porosity and slightly lower bulk density than chromite specimens; after firing at 1 300 ℃ for 3 h, AR90 has significantly higher apparent porosity as well as higher bulk density; （2） after the alkali attack, the AR90 specimens sintered at 1 300 ℃ exhibit smaller strength change and much higher compressive strength than the chromite specimens; meanwhile, the permeability degree of alkali salt in chromite specimens is more serious than that in AR90 specimens, which indicates that AR90 possesses better alkali resistance.
基金the National 863 Project of China(grant No.2001AA242041)for financial support
文摘Soap-free P(MMA-EA-MAA) particles with narrow size distribution were synthesized by seeded emulsion polymerization of methyl methacrylate (MMA), ethyl acrylate (EA) and methacrylic acid (MAA), and large voids inside the particles were generated by alkali posttreatment in the presence of 2-butanone. Results indicated that the size of void and the particle volume were related with the amount of 2-butanone. The generation mechanism of voids was proposed.
文摘The influences on the brightness, viscosity and Kappa of the straw pulp under the different oxygen-alkali bleaching conditions have been studied in this paper.
