Cement raw meal with MSS and different heavy metals was blended to examine the fixation ratios, chemical species, and cement crystalline phases in clinkers. The results showed that blending MSS could decrease the fixa...Cement raw meal with MSS and different heavy metals was blended to examine the fixation ratios, chemical species, and cement crystalline phases in clinkers. The results showed that blending MSS could decrease the fixation ratio of Cr, Ni, Cu, and Zn in the produced clinker by 5% to 25%. And Cr, Cu, and Zn were mainly incorporated into clinkers as metal silicates, Ni was mainly solubilized in Mg O to form magnesium nickel oxides, and the transition phases were mainly metal aluminum oxides as indicated by X-ray diffraction. The reduction of fixation ratios was likely attributed to the presence of impure elements, such as sodium and phosphorus in MSS. In addition, high concentrations（eg, 1.7 wt%） of chlorine in MSS led to metal chloride formation that could vaporize Cu, Cr, Ni, and Zn. To summarize, introducing MSS would decrease the fixation ratios of heavy metals due to the presence of impure elements, such as sodium and phosphorus and chlorine.展开更多
Through the comparison of calcination conditions between cement preclinkering technology and cement precalcining technology,we studied the characteristics of temperature field distribution of cement preclinkering tech...Through the comparison of calcination conditions between cement preclinkering technology and cement precalcining technology,we studied the characteristics of temperature field distribution of cement preclinkering technology systems including cyclone preheater,preclinkering furnace,and rotary kiln.We used numericalsimulation method to obtain data of temperature field distribution.Some results are found by system study.The ratio of tailcoalof cement preclinkering technology is about 70%,and raw mealtemperature can reach 1070 ℃.Shorter L/D kiln type of preclinkering technology can obtain more stable calcining zone temperature.The highest solid temperature of cement preclinkering technology is higher than 80 ℃,and high temperature region（〉1450 ℃）length is 2 times,which is beneficialfor calcining clinker and higher clinker quality.So cement preclinkering technology can obtain more performance temperature filed,which improves both the solid-phase reaction and liquid-phase reaction.展开更多
Cement kiln co-processing techniques have been developed in the past 20 years in China,and more than 60 factories now use fermentation,screening,and gasification pre-treatment techniques to coprocess municipal solid w...Cement kiln co-processing techniques have been developed in the past 20 years in China,and more than 60 factories now use fermentation,screening,and gasification pre-treatment techniques to coprocess municipal solid waste(MSW).There three complete MSW pre-treatment techniques,coprocessing procedures,and environmental risk assessments have been described in few publications.In this study,we assessed the effectiveness of each technique.The results suggested that the pollutant content released by each pre-treatment technology was lower than the emission standard.To reveal the mechanisms of pollutant migration and enrichment,the substances in the kiln and kiln products are investigated.The input of co-processing materials(Co-M)produced by fermentation caused formation of polychlorinated dibenzo-p-dioxins and dibenzoftiran(PCDD/Fs)in the bypass flue gas(By-gas)in excess of the regulatory standard.The Co-M input produced by the screening and gasifier technologies caused the total organic carbon(TOC)concentration to exceed the standard.In addition,the NOx,TOC,and PCDD/Fs in the By-gas exceeded the regulatory standard.Raw meal was the primary chlorine and heavy metals input stream,and clinker(CK)and cement kiln dust(CKD)accounted for>90%of the total chlorine output stream.Flue gas and CKD were the primary volatile heavy metal(Hg)output streams.Greater than 70%of the semi-volatile heavy metals(Cd,Pb,T1 and Se)distributed in hot raw meal and bypass cement kiln dust.The low-volatility heavy metals were concentrated in the CK.These results indicated that co-processing techniques used in China still require improvement.展开更多
Hydration cracks of magnesia-spinel bricks in cement industry have been serious problems for both refractory producers and refractory users for a long time.When magnesia-spinel bricks are kept for more than 6months,th...Hydration cracks of magnesia-spinel bricks in cement industry have been serious problems for both refractory producers and refractory users for a long time.When magnesia-spinel bricks are kept for more than 6months,the bricks tend to have reaction with water or moisture and result in cracks and loss on their structural strength. Those bricks cannot be used anymore and cause substantial loss for the related parties. In 2013,the Siam Refractory Industry Co.,Ltd.,Thailand,successfully developed and applied a special nano-technology to create ＂Anti-Hydration Magnesia-Spinel Bricks ＂ for cement industry which can have the storage time more than two years even in high humidity areas. The cement producers can ensure that all bricks still have good properties as the new ones.展开更多
基金the National Major Science and Technology Project of Water Pollution Control and Management,China(No.2010ZX07319-001-02)
文摘Cement raw meal with MSS and different heavy metals was blended to examine the fixation ratios, chemical species, and cement crystalline phases in clinkers. The results showed that blending MSS could decrease the fixation ratio of Cr, Ni, Cu, and Zn in the produced clinker by 5% to 25%. And Cr, Cu, and Zn were mainly incorporated into clinkers as metal silicates, Ni was mainly solubilized in Mg O to form magnesium nickel oxides, and the transition phases were mainly metal aluminum oxides as indicated by X-ray diffraction. The reduction of fixation ratios was likely attributed to the presence of impure elements, such as sodium and phosphorus in MSS. In addition, high concentrations（eg, 1.7 wt%） of chlorine in MSS led to metal chloride formation that could vaporize Cu, Cr, Ni, and Zn. To summarize, introducing MSS would decrease the fixation ratios of heavy metals due to the presence of impure elements, such as sodium and phosphorus and chlorine.
基金Funded by the Major State Basic Research Perelopment Program of China(973 Program)(No.2009CB623102)the Key Fund Project of Sichuan Provincial Department of Education(No.14ZA0086)the Key Fund Project of Professional Scientific Research Innovation Team of Southwest University of Science and Technology(No.14tdfk01)
文摘Through the comparison of calcination conditions between cement preclinkering technology and cement precalcining technology,we studied the characteristics of temperature field distribution of cement preclinkering technology systems including cyclone preheater,preclinkering furnace,and rotary kiln.We used numericalsimulation method to obtain data of temperature field distribution.Some results are found by system study.The ratio of tailcoalof cement preclinkering technology is about 70%,and raw mealtemperature can reach 1070 ℃.Shorter L/D kiln type of preclinkering technology can obtain more stable calcining zone temperature.The highest solid temperature of cement preclinkering technology is higher than 80 ℃,and high temperature region（〉1450 ℃）length is 2 times,which is beneficialfor calcining clinker and higher clinker quality.So cement preclinkering technology can obtain more performance temperature filed,which improves both the solid-phase reaction and liquid-phase reaction.
基金This work was financially supported by the National Basic Research Program of China(2019YFC1906900)Chinese Central Public Welfare Research Project(2019YSKY-016).
文摘Cement kiln co-processing techniques have been developed in the past 20 years in China,and more than 60 factories now use fermentation,screening,and gasification pre-treatment techniques to coprocess municipal solid waste(MSW).There three complete MSW pre-treatment techniques,coprocessing procedures,and environmental risk assessments have been described in few publications.In this study,we assessed the effectiveness of each technique.The results suggested that the pollutant content released by each pre-treatment technology was lower than the emission standard.To reveal the mechanisms of pollutant migration and enrichment,the substances in the kiln and kiln products are investigated.The input of co-processing materials(Co-M)produced by fermentation caused formation of polychlorinated dibenzo-p-dioxins and dibenzoftiran(PCDD/Fs)in the bypass flue gas(By-gas)in excess of the regulatory standard.The Co-M input produced by the screening and gasifier technologies caused the total organic carbon(TOC)concentration to exceed the standard.In addition,the NOx,TOC,and PCDD/Fs in the By-gas exceeded the regulatory standard.Raw meal was the primary chlorine and heavy metals input stream,and clinker(CK)and cement kiln dust(CKD)accounted for>90%of the total chlorine output stream.Flue gas and CKD were the primary volatile heavy metal(Hg)output streams.Greater than 70%of the semi-volatile heavy metals(Cd,Pb,T1 and Se)distributed in hot raw meal and bypass cement kiln dust.The low-volatility heavy metals were concentrated in the CK.These results indicated that co-processing techniques used in China still require improvement.
文摘Hydration cracks of magnesia-spinel bricks in cement industry have been serious problems for both refractory producers and refractory users for a long time.When magnesia-spinel bricks are kept for more than 6months,the bricks tend to have reaction with water or moisture and result in cracks and loss on their structural strength. Those bricks cannot be used anymore and cause substantial loss for the related parties. In 2013,the Siam Refractory Industry Co.,Ltd.,Thailand,successfully developed and applied a special nano-technology to create ＂Anti-Hydration Magnesia-Spinel Bricks ＂ for cement industry which can have the storage time more than two years even in high humidity areas. The cement producers can ensure that all bricks still have good properties as the new ones.
