Based on the relevant phase diagrams of ternary system in MgO - CaO - ZrO2 - SiO2 quarternary systems, the phase diagram of Fe - O system and the condensed phase stability area diagram of iron oxides, the corrosion re...Based on the relevant phase diagrams of ternary system in MgO - CaO - ZrO2 - SiO2 quarternary systems, the phase diagram of Fe - O system and the condensed phase stability area diagram of iron oxides, the corrosion resistance of MgO - CaO - ZrO2 refractories to silicate cement, and the forming conditions and prepar- ing measures of hercynite are analyzed.展开更多
Corrosion of burning urban domestic wastes to alkali-resistant bricks and spalling-resistant high alumina bricks was researched by static crucible method and SEM in order to choose refractories for cement rotary kilns...Corrosion of burning urban domestic wastes to alkali-resistant bricks and spalling-resistant high alumina bricks was researched by static crucible method and SEM in order to choose refractories for cement rotary kilns for collaboratively disposing wastes. The result indicates that the main corrosion mechanism is slag permeation and corrosion ; the emitted high temperature gases containing alkali, sulfur and chlorine during burning the wastes re- act with refractories forming low melting point sulfate, chloride and compound salts, which metamorphose the refractories, and the loose metamorphic layer is easy to spall under thermal stress. So, corrosion resistance and spaUing resistance shall be taken into account when choosing refractories for cement rotary kilns for collaboratively disposing wastes. It is suggested that decomposition furnaces should adopt spaUing resistant high alumina bricks and anti-coating SiC castables, and preheating equipment should adopt high strength alkali-resistant bricks and castables.展开更多
Modern cement rotary kiln is often large in size while rotating in high speed. Thermal condition within a rotary kiln is rather complex, exerting severe thermal and chemical attack on refractory of its kiln lining. In...Modern cement rotary kiln is often large in size while rotating in high speed. Thermal condition within a rotary kiln is rather complex, exerting severe thermal and chemical attack on refractory of its kiln lining. In the present paper, the cause that leads to refractory failure was analyzed; requirements for refractory to overcome such failure was discussed. Composites and properties of different refractories most often used as kiln lining were assessed, including magnesia - chrome bricks, magnesia spinel bricks, dolomite bricks, silicon carbide muUite bricks and castables etc. Recommendation was made for refractories with suitable composites and properties to be used as kiln lining in each specific zone to best counteract the severe thermal conditions. A cost-effective configura- tion was presented to assemble kiln lining for rotary kiln＇s different zones in line with the regulation at JC/ T 2196-2013 ＂Specifications of refractory for cement rotary kiln＂. Chromite-free refractories with property of high endurance to thermal attack and corrosion are required to be used in modern Pre-calcining cement rotary kilns.展开更多
Cement production is a highly energy-intensive process, and the rotary kiln is the most important part of the process. Having a comprehensive model of the kiln in order to reduce manufacturing costs, better performanc...Cement production is a highly energy-intensive process, and the rotary kiln is the most important part of the process. Having a comprehensive model of the kiln in order to reduce manufacturing costs, better performance can be created. In this paper, the influence processes in a simulated cement rotary kiln and operating parameters on the output of the study were to develop and validate the systems using the same batch. The followings were examined: solid phase, gas and coating temperature change in a rotary kiln.展开更多
This paper summarizes the current situation of China’s industrial hazardous waste treatment,the disposal technology and the characteristics of rotary kiln incineration system,analyzes the refractory lining design of ...This paper summarizes the current situation of China’s industrial hazardous waste treatment,the disposal technology and the characteristics of rotary kiln incineration system,analyzes the refractory lining design of rotary kiln incineration system in China,and puts forward optimization suggestions according to the process characteristics.展开更多
In order to improve the service performance and explore the damage mechanism of silicon carbide-mullite bricks for the transition zone of cement rotary kilns,the phase composition and the microstructure of a used bric...In order to improve the service performance and explore the damage mechanism of silicon carbide-mullite bricks for the transition zone of cement rotary kilns,the phase composition and the microstructure of a used brick in the transition zone of a cement rotary kiln were analyzed by XRD,SEM and EDS.The results show that the liquid and alkali vapor phases generated by the reaction between cement materials and the silicon carbide-mullite brick mostly enter the silicon carbide-mullite brick through the pores;meanwhile,Ca+and K+in the cement penetrate through the liquid maintaining a high chemical potential energy to dissolve Al2O3 and SiO2 at the top of the liquid phase thus enhancing the phase penetration;with the decreasing temperature,crystals such as gehlenite,potassium feldspar and potassium chloride are precipitated,which destroy the original structure and increase the difference of thermal expansion coefficient between the high temperature dense end and the metamorphic layer thus resulting in cracks,spalling,and rupture.展开更多
The chrome pollution from cement industry was introduced briefly,the research on chrome free basic refractories for cement kilns was reviewed,the production technologies of magnesia calcia,magnesium aluminate spinel,m...The chrome pollution from cement industry was introduced briefly,the research on chrome free basic refractories for cement kilns was reviewed,the production technologies of magnesia calcia,magnesium aluminate spinel,magnesia hercynite refractories,etc. were specified,the principles to improve thermal shock resistance and coating adhesiveness of refractories were analyzed,the measures to extend service life by improving production equipment and service conditions of refractories were put forward,the future of chrome free refractories was expected and some developing suggestions were given.展开更多
Destruction of industrial waste in cement rotary kilns (CRKs) is an alternative technology for the treatment of certain types of industrial waste (IW). In this paper, three typical types of industrial wastes were co-i...Destruction of industrial waste in cement rotary kilns (CRKs) is an alternative technology for the treatment of certain types of industrial waste (IW). In this paper, three typical types of industrial wastes were co-incinerated in the CRK at Beijing Cement Plant to determine the effects of waste disposal (especially solid waste disposal) on the quality of clinker and the concentration of pollutants in air emission. Experimental results show that (1) waste disposal does not affect the quality of clinker and fly ash, and fly ash after the IW disposal can still be used in the cement production, (2) heavy metals from IW are immobilized and stabilized in the clinker and cement, and (3) concentration of pollutants in air emission is far below than the permitted values in the China National Standard-Air Pollutants Emission Standard (GB 16297-1996).展开更多
There are many factors affecting the monolithic lining engineering of rotary kilns,resulting in the difficult quality control.In this paper,the key points of the whole lining engineering were discussed from the aspect...There are many factors affecting the monolithic lining engineering of rotary kilns,resulting in the difficult quality control.In this paper,the key points of the whole lining engineering were discussed from the aspects of lining structure design,personnel preparation,site construction management,maintenance and baking.展开更多
This paper presents the ways of comprehensive utilization of the natural magnesium containing resources and the trends of the MgO based refractories used in high temperature industries. In the first part, the uses and...This paper presents the ways of comprehensive utilization of the natural magnesium containing resources and the trends of the MgO based refractories used in high temperature industries. In the first part, the uses and productions of metal Mg, sorel cement, Mg (OH) 2 fire retardant, light magnesium carbonate, light magnesia and magnesium sulphate are described. In the second part, the developments of MgO based refractories used in steelmaking process, nonferrous metallurgy, cement rotary kiln and waste melting furnace are described from some applied theories, including corrosion resistant and slaking resistant MgO CaO materials, chrome free bricks such as MgO CaO ZrO 2 , MgO MgO Al 2 O 3 , MgO MgO·Al 2 O 3 ZrO 2 , MgO MgO·Al 2 O 3 2MgO ·TiO 2 and MgO FeO·Al 2 O 3 , and MgO containing monolithic refractories etc.展开更多
Based on the sandwich test, adherence mechanisms of cement clinker on various basic bricks were tackled by microstructural observations with help of cathodolumi-nescence technique. Doloma based bricks offer sufficient...Based on the sandwich test, adherence mechanisms of cement clinker on various basic bricks were tackled by microstructural observations with help of cathodolumi-nescence technique. Doloma based bricks offer sufficient lime to react with clinker, forming C3S rich layer and initializing superior adherence. However, clinker with low silica ratio leads to MgO agglomeration at the interface of doloma bricks, which reduces adherence strength. On magnesia spinel bricks , fine, crystalline spinel easily reacts with lime containing phases from clinker to form low-melting phases and belite zone, which shows high adherence performance. Lack of fine spinel in magnesia spinel bricks results in poor adherence.展开更多
Managers of cement plants are gradually becoming aware of the need for soft sensors in product quality assessment. Cement clinker quality parameters are mostly measured by offline laboratory analysis or by the use of ...Managers of cement plants are gradually becoming aware of the need for soft sensors in product quality assessment. Cement clinker quality parameters are mostly measured by offline laboratory analysis or by the use of online analyzers. The measurement delay and cost, associated with these methods, are a concern in the cement industry. In this study, a regression-based model was developed to predict the clinker quality parameters as a function of the raw meal quality and the kiln operating variables. This model has mean squared error, coefficient of determination, worst case relative error and variance account for (in external data) given as 8.96 × 10<sup>–7</sup>, 0.9999, 2.17% and above 97%, respectively. Thus, it is concluded that the developed model can provide real time estimates of the clinker quality parameters and capture wider ranges of real plant operating conditions from first principle-based cement rotary kiln models. Also, the model developed can be utilized online as soft sensor since they contain only variables that are easily measured online.展开更多
文摘Based on the relevant phase diagrams of ternary system in MgO - CaO - ZrO2 - SiO2 quarternary systems, the phase diagram of Fe - O system and the condensed phase stability area diagram of iron oxides, the corrosion resistance of MgO - CaO - ZrO2 refractories to silicate cement, and the forming conditions and prepar- ing measures of hercynite are analyzed.
文摘Corrosion of burning urban domestic wastes to alkali-resistant bricks and spalling-resistant high alumina bricks was researched by static crucible method and SEM in order to choose refractories for cement rotary kilns for collaboratively disposing wastes. The result indicates that the main corrosion mechanism is slag permeation and corrosion ; the emitted high temperature gases containing alkali, sulfur and chlorine during burning the wastes re- act with refractories forming low melting point sulfate, chloride and compound salts, which metamorphose the refractories, and the loose metamorphic layer is easy to spall under thermal stress. So, corrosion resistance and spaUing resistance shall be taken into account when choosing refractories for cement rotary kilns for collaboratively disposing wastes. It is suggested that decomposition furnaces should adopt spaUing resistant high alumina bricks and anti-coating SiC castables, and preheating equipment should adopt high strength alkali-resistant bricks and castables.
文摘Modern cement rotary kiln is often large in size while rotating in high speed. Thermal condition within a rotary kiln is rather complex, exerting severe thermal and chemical attack on refractory of its kiln lining. In the present paper, the cause that leads to refractory failure was analyzed; requirements for refractory to overcome such failure was discussed. Composites and properties of different refractories most often used as kiln lining were assessed, including magnesia - chrome bricks, magnesia spinel bricks, dolomite bricks, silicon carbide muUite bricks and castables etc. Recommendation was made for refractories with suitable composites and properties to be used as kiln lining in each specific zone to best counteract the severe thermal conditions. A cost-effective configura- tion was presented to assemble kiln lining for rotary kiln＇s different zones in line with the regulation at JC/ T 2196-2013 ＂Specifications of refractory for cement rotary kiln＂. Chromite-free refractories with property of high endurance to thermal attack and corrosion are required to be used in modern Pre-calcining cement rotary kilns.
文摘Cement production is a highly energy-intensive process, and the rotary kiln is the most important part of the process. Having a comprehensive model of the kiln in order to reduce manufacturing costs, better performance can be created. In this paper, the influence processes in a simulated cement rotary kiln and operating parameters on the output of the study were to develop and validate the systems using the same batch. The followings were examined: solid phase, gas and coating temperature change in a rotary kiln.
文摘This paper summarizes the current situation of China’s industrial hazardous waste treatment,the disposal technology and the characteristics of rotary kiln incineration system,analyzes the refractory lining design of rotary kiln incineration system in China,and puts forward optimization suggestions according to the process characteristics.
文摘In order to improve the service performance and explore the damage mechanism of silicon carbide-mullite bricks for the transition zone of cement rotary kilns,the phase composition and the microstructure of a used brick in the transition zone of a cement rotary kiln were analyzed by XRD,SEM and EDS.The results show that the liquid and alkali vapor phases generated by the reaction between cement materials and the silicon carbide-mullite brick mostly enter the silicon carbide-mullite brick through the pores;meanwhile,Ca+and K+in the cement penetrate through the liquid maintaining a high chemical potential energy to dissolve Al2O3 and SiO2 at the top of the liquid phase thus enhancing the phase penetration;with the decreasing temperature,crystals such as gehlenite,potassium feldspar and potassium chloride are precipitated,which destroy the original structure and increase the difference of thermal expansion coefficient between the high temperature dense end and the metamorphic layer thus resulting in cracks,spalling,and rupture.
基金funded by National 973 High Tech Project"Lowpower Preparation and High Efficient Applications of Cement " ( 2009CB623100 )the National 12th Five Years Scientific and Technological Projects "High Resistance to Corrosion Cast Aluminum Series Refractories Research" ( 2013BAE03B01 - 01B )
文摘The chrome pollution from cement industry was introduced briefly,the research on chrome free basic refractories for cement kilns was reviewed,the production technologies of magnesia calcia,magnesium aluminate spinel,magnesia hercynite refractories,etc. were specified,the principles to improve thermal shock resistance and coating adhesiveness of refractories were analyzed,the measures to extend service life by improving production equipment and service conditions of refractories were put forward,the future of chrome free refractories was expected and some developing suggestions were given.
文摘Destruction of industrial waste in cement rotary kilns (CRKs) is an alternative technology for the treatment of certain types of industrial waste (IW). In this paper, three typical types of industrial wastes were co-incinerated in the CRK at Beijing Cement Plant to determine the effects of waste disposal (especially solid waste disposal) on the quality of clinker and the concentration of pollutants in air emission. Experimental results show that (1) waste disposal does not affect the quality of clinker and fly ash, and fly ash after the IW disposal can still be used in the cement production, (2) heavy metals from IW are immobilized and stabilized in the clinker and cement, and (3) concentration of pollutants in air emission is far below than the permitted values in the China National Standard-Air Pollutants Emission Standard (GB 16297-1996).
文摘There are many factors affecting the monolithic lining engineering of rotary kilns,resulting in the difficult quality control.In this paper,the key points of the whole lining engineering were discussed from the aspects of lining structure design,personnel preparation,site construction management,maintenance and baking.
文摘This paper presents the ways of comprehensive utilization of the natural magnesium containing resources and the trends of the MgO based refractories used in high temperature industries. In the first part, the uses and productions of metal Mg, sorel cement, Mg (OH) 2 fire retardant, light magnesium carbonate, light magnesia and magnesium sulphate are described. In the second part, the developments of MgO based refractories used in steelmaking process, nonferrous metallurgy, cement rotary kiln and waste melting furnace are described from some applied theories, including corrosion resistant and slaking resistant MgO CaO materials, chrome free bricks such as MgO CaO ZrO 2 , MgO MgO Al 2 O 3 , MgO MgO·Al 2 O 3 ZrO 2 , MgO MgO·Al 2 O 3 2MgO ·TiO 2 and MgO FeO·Al 2 O 3 , and MgO containing monolithic refractories etc.
文摘Based on the sandwich test, adherence mechanisms of cement clinker on various basic bricks were tackled by microstructural observations with help of cathodolumi-nescence technique. Doloma based bricks offer sufficient lime to react with clinker, forming C3S rich layer and initializing superior adherence. However, clinker with low silica ratio leads to MgO agglomeration at the interface of doloma bricks, which reduces adherence strength. On magnesia spinel bricks , fine, crystalline spinel easily reacts with lime containing phases from clinker to form low-melting phases and belite zone, which shows high adherence performance. Lack of fine spinel in magnesia spinel bricks results in poor adherence.
文摘Managers of cement plants are gradually becoming aware of the need for soft sensors in product quality assessment. Cement clinker quality parameters are mostly measured by offline laboratory analysis or by the use of online analyzers. The measurement delay and cost, associated with these methods, are a concern in the cement industry. In this study, a regression-based model was developed to predict the clinker quality parameters as a function of the raw meal quality and the kiln operating variables. This model has mean squared error, coefficient of determination, worst case relative error and variance account for (in external data) given as 8.96 × 10<sup>–7</sup>, 0.9999, 2.17% and above 97%, respectively. Thus, it is concluded that the developed model can provide real time estimates of the clinker quality parameters and capture wider ranges of real plant operating conditions from first principle-based cement rotary kiln models. Also, the model developed can be utilized online as soft sensor since they contain only variables that are easily measured online.
