The interfacial reactions of Cr2O3- Al2O3 refractory materials with smelting reduction ironmaking slag were investigated by thermodynamic modeling. The calculation results indicated that different spinel phases were p...The interfacial reactions of Cr2O3- Al2O3 refractory materials with smelting reduction ironmaking slag were investigated by thermodynamic modeling. The calculation results indicated that different spinel phases were produced after the interactions between the slag and three types of refractory materials（ 10Cr2O3- 90Al2O3,50Cr2O3- 50Al2O3 and 90Cr2O3- 10Al2O3） at 1 500℃. Increased contents of Al2O3 and Cr2O3in the remained liquid slag after interaction implied the dissolution of refractory. Thermodynamic modeling predicted that the process of dissolution might lead to much deeper penetration into the refractory materials by the present compositional slag. Accordingly,corrosion testing was also conducted to validate the thermodynamic prediction.展开更多
Chrome oxide free refractories have significant economic benefits for the development of gasification technology.Spinel based and SiC based refractories are corroded by coal slag at 1500℃under reducing atmosphere.Mor...Chrome oxide free refractories have significant economic benefits for the development of gasification technology.Spinel based and SiC based refractories are corroded by coal slag at 1500℃under reducing atmosphere.Moreover,interactions between refractory materials and molten slag are also predicted by thermodynamic calculations under the same conditions.The results indicate that spinel based refractories are corroded by dissolution of molten slag,while SiC based refractories are corroded by oxidation of CO and FeO.Both of the spinel and SiC based refractories show good corrosion resistance against coal slag by the present experimental tests.Finally,preliminary developed spinel-SiC composite materials are prepared and corroded by coal slag as well,the research of which shows great potential to be used in slagging gasifiers.展开更多
Water, oxygen and coal are converted into CO, H2, methane in the coal slurry gasifier. Under the condition of high temperature and high pressure, high chromecontaining refractories are used as hot face lining. The col...Water, oxygen and coal are converted into CO, H2, methane in the coal slurry gasifier. Under the condition of high temperature and high pressure, high chromecontaining refractories are used as hot face lining. The collapse of refractories from corrosion and spalling is mainly attributed to liquid deslagging. Refractories for coal slurry gasifier, destruction mechanism and solutions are analyzed.展开更多
Pure Cr2O3 refractories and high Cr2O3 bearing refractories are difficult to sinter in oxidizing atmosphere, but they can be sintered easily in carbon embedded conditions. In the latter case it is attributed to the fo...Pure Cr2O3 refractories and high Cr2O3 bearing refractories are difficult to sinter in oxidizing atmosphere, but they can be sintered easily in carbon embedded conditions. In the latter case it is attributed to the formation of liquid CrO in reducing atmosphere. The thermodynamic calculation shows that the Cr2O3 is reduced by CO at 1 550 ℃ to chromium carbides, which disproves the existence of liquid CrO. This is confirmed by further sintering experiment of the Cr2O3 refractories. Effect of atmosphere on sintering of high Cr2O3 bearing refractories and measures to accelerate the sintering process are discussed based on the experiment and thermodynamic calculation.展开更多
Six kinds of Cr2O3 - Al2 O3 fused grains （the mass percent of Cr203 was 15%, 40%, 50%, 60%, 85% and 99%, respectively ） were prepared using chrome green and Al203 powder as starting materials by electro-fnsion, n...Six kinds of Cr2O3 - Al2 O3 fused grains （the mass percent of Cr203 was 15%, 40%, 50%, 60%, 85% and 99%, respectively ） were prepared using chrome green and Al203 powder as starting materials by electro-fnsion, named as CR15, CR40, CR50, CR60, CR85, and CR99, respectively. The corrosion resistance of the six kinds of Cr2O3- Al2O3.fused grains （4-1 ram） was studied using rotary slag corrosion method. The results show that： （ 1 ） the corrosion resistance of the fused grains increases with the Cr203 content and the grain size increasing; （2）the grains of CR99 and CR85 with higher Cr2O3 content are corroded at the slag surJace layer, because FeO and Al2O3. in the slag corrode the grains ; FeO reacts with Cr2O3 in the aggregates.forming （Fe, Cr ）3O4 ,spinel firstly, and the spinel reacts with other phases forming composite spinel; when FeO is fidly consumed, Al2 O3 penetrated into the grains reacts with Cr2O3 Jorming Al2O3 - Cr2O3 solid solution on the grains surface; （3） for CR60, the corrosion exists both in the slag surface layer and in the penetration layer; in the penetration layer, CaO and SiO2 react with Al2O3 in Al2O3 - Cr2O3 solid solution forming anorthite , gehlenite ,and glass phase; the grains of CR50, CR40 and CRI5 have the same corrosion mechanism with CR60 in the penetration layer.展开更多
Cr2O3 can be sintered well at 1500℃ in carbonembedded condition or H2 atmosphere. But the high chrome bearing refractories can not reach densification when sintered at 1 700℃ .for 10 h in weak reducing atmosphere fo...Cr2O3 can be sintered well at 1500℃ in carbonembedded condition or H2 atmosphere. But the high chrome bearing refractories can not reach densification when sintered at 1 700℃ .for 10 h in weak reducing atmosphere formed by the combustion of fuel, and its ap- parent porosity is about 18%. The high chrome bearing refractories are mainly used in coal gasifiers. The temperature in the furnace is about 1 500℃ and the products are H2 and CO, which are just the sintering conditions of the dense chrome refractories with apparent porosity less than 10%. The high chrome bearing refractories used in coal gasifiers may be sintered again and then shrink, destroying the gasifier lining. The thermodynamic calculation shows that it is safe about the high chrome bearing refractories used in gasifiers. It is also explained that the high chrome bearing refractories can＇t be sintered densely in weak reducing atmosphere formed by the combustion of fuel. The new sintering technologies can be used to improve the bulk density of the high chrome bearing refractories.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
基金supported by Preliminary Research Project for National Basic Research Program of China ( 2012CB724607 )
文摘The interfacial reactions of Cr2O3- Al2O3 refractory materials with smelting reduction ironmaking slag were investigated by thermodynamic modeling. The calculation results indicated that different spinel phases were produced after the interactions between the slag and three types of refractory materials（ 10Cr2O3- 90Al2O3,50Cr2O3- 50Al2O3 and 90Cr2O3- 10Al2O3） at 1 500℃. Increased contents of Al2O3 and Cr2O3in the remained liquid slag after interaction implied the dissolution of refractory. Thermodynamic modeling predicted that the process of dissolution might lead to much deeper penetration into the refractory materials by the present compositional slag. Accordingly,corrosion testing was also conducted to validate the thermodynamic prediction.
基金This work was supported by the National Natural Science Foundation of China(U1604252).
文摘Chrome oxide free refractories have significant economic benefits for the development of gasification technology.Spinel based and SiC based refractories are corroded by coal slag at 1500℃under reducing atmosphere.Moreover,interactions between refractory materials and molten slag are also predicted by thermodynamic calculations under the same conditions.The results indicate that spinel based refractories are corroded by dissolution of molten slag,while SiC based refractories are corroded by oxidation of CO and FeO.Both of the spinel and SiC based refractories show good corrosion resistance against coal slag by the present experimental tests.Finally,preliminary developed spinel-SiC composite materials are prepared and corroded by coal slag as well,the research of which shows great potential to be used in slagging gasifiers.
文摘Water, oxygen and coal are converted into CO, H2, methane in the coal slurry gasifier. Under the condition of high temperature and high pressure, high chromecontaining refractories are used as hot face lining. The collapse of refractories from corrosion and spalling is mainly attributed to liquid deslagging. Refractories for coal slurry gasifier, destruction mechanism and solutions are analyzed.
文摘Pure Cr2O3 refractories and high Cr2O3 bearing refractories are difficult to sinter in oxidizing atmosphere, but they can be sintered easily in carbon embedded conditions. In the latter case it is attributed to the formation of liquid CrO in reducing atmosphere. The thermodynamic calculation shows that the Cr2O3 is reduced by CO at 1 550 ℃ to chromium carbides, which disproves the existence of liquid CrO. This is confirmed by further sintering experiment of the Cr2O3 refractories. Effect of atmosphere on sintering of high Cr2O3 bearing refractories and measures to accelerate the sintering process are discussed based on the experiment and thermodynamic calculation.
文摘Six kinds of Cr2O3 - Al2 O3 fused grains （the mass percent of Cr203 was 15%, 40%, 50%, 60%, 85% and 99%, respectively ） were prepared using chrome green and Al203 powder as starting materials by electro-fnsion, named as CR15, CR40, CR50, CR60, CR85, and CR99, respectively. The corrosion resistance of the six kinds of Cr2O3- Al2O3.fused grains （4-1 ram） was studied using rotary slag corrosion method. The results show that： （ 1 ） the corrosion resistance of the fused grains increases with the Cr203 content and the grain size increasing; （2）the grains of CR99 and CR85 with higher Cr2O3 content are corroded at the slag surJace layer, because FeO and Al2O3. in the slag corrode the grains ; FeO reacts with Cr2O3 in the aggregates.forming （Fe, Cr ）3O4 ,spinel firstly, and the spinel reacts with other phases forming composite spinel; when FeO is fidly consumed, Al2 O3 penetrated into the grains reacts with Cr2O3 Jorming Al2O3 - Cr2O3 solid solution on the grains surface; （3） for CR60, the corrosion exists both in the slag surface layer and in the penetration layer; in the penetration layer, CaO and SiO2 react with Al2O3 in Al2O3 - Cr2O3 solid solution forming anorthite , gehlenite ,and glass phase; the grains of CR50, CR40 and CRI5 have the same corrosion mechanism with CR60 in the penetration layer.
文摘Cr2O3 can be sintered well at 1500℃ in carbonembedded condition or H2 atmosphere. But the high chrome bearing refractories can not reach densification when sintered at 1 700℃ .for 10 h in weak reducing atmosphere formed by the combustion of fuel, and its ap- parent porosity is about 18%. The high chrome bearing refractories are mainly used in coal gasifiers. The temperature in the furnace is about 1 500℃ and the products are H2 and CO, which are just the sintering conditions of the dense chrome refractories with apparent porosity less than 10%. The high chrome bearing refractories used in coal gasifiers may be sintered again and then shrink, destroying the gasifier lining. The thermodynamic calculation shows that it is safe about the high chrome bearing refractories used in gasifiers. It is also explained that the high chrome bearing refractories can＇t be sintered densely in weak reducing atmosphere formed by the combustion of fuel. The new sintering technologies can be used to improve the bulk density of the high chrome bearing refractories.
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.
