In order to make corundum castables satisfy more severe service conditions in high temperature industries,colloidal alumina due to the same main component with corundum castables was introduced for a pure binding syst...In order to make corundum castables satisfy more severe service conditions in high temperature industries,colloidal alumina due to the same main component with corundum castables was introduced for a pure binding system.The influence of three dispersants(citric acid,FS10 and urea)on the flow ability of colloidal alumina bonded corundum castables was researched to choose a suitable dispersant for solving the shaping problem.In order to further understand the influence of dispersants on the flow ability and the mechanism,the rheological property and Zeta potential value of the colloidal aluminadispersant system and the matrix-colloidal alumina-urea-water system were tested.The results show the castables added with the urea have the best flow ability,and the appropriate addition of the urea is 0.5%.展开更多
In order to improve the flow ability and early-stage strength of colloidal alumina bonded corundum castables,the colloidal alumina with 20%of solid content was used as the binder,and tabular corundum aggregates and fi...In order to improve the flow ability and early-stage strength of colloidal alumina bonded corundum castables,the colloidal alumina with 20%of solid content was used as the binder,and tabular corundum aggregates and fines,and active alumina micropowder CL370 as the main starting materials.Influences of setting accelerating agents(magnesia fines and sodium meta-aluminate)on the linear change rate,the modulus of rupture and the microstructure of corundum castables after different heat-treatments were researched.The results show(1)cement bonded corundum castables have the highest modulus of rupture after 24 h of demolding,and colloidal alumina bonded corundum castables have the lowest one;both magnesia fines and sodium meta-aluminate can improve the strength after 24 h of demolding;(2)after firing at 1000℃for 3 h,the modulus of rupture of all specimens decreases,even lower than that after 24 h of demolding;(3)after firing at 1600℃for 3 h,the castable specimen added with 0.1 mass%magnesia fines has the highest modulus of rupture;the tabular phases appear interwovenly in the specimen;(4)taking the comprehensive properties into account,0.1 mass%of magnesia fines is appropriate,and the addition of sodium meta-aluminate shall be lower than 0.3%.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
Corundum - spinel purging plugs were optimized through adjusting the formulation and the particle size composition of starting materials to prolong the service life of purging plugs for a 60 t refining ladle in a stee...Corundum - spinel purging plugs were optimized through adjusting the formulation and the particle size composition of starting materials to prolong the service life of purging plugs for a 60 t refining ladle in a steel plant. Th.e optimized formulatioa is 30 mass% tabular corundum （6 - 3 mm ） , 20 mass% tabular corundum （3-1 ram）, 22 mass% tabular corundum （1 -0.5 ram） ＋ sintered spinel, 28% tabular corundum fines （0. 045 mm） ＋ fused spinel （0. 045 mm） ＋ bimodal α-Al2O3 micropowder ＋ Secar71 cement. The on-site results show that the plug can achieve an obviously long service life of 18 cycles, saving cost greatly.展开更多
The characteristics of hercynite including corystal structure, chemical compositions and physical properties, R ＆ D background of hercynite, synthesis problems of heronite, amt roles of hercynite in refractories were...The characteristics of hercynite including corystal structure, chemical compositions and physical properties, R ＆ D background of hercynite, synthesis problems of heronite, amt roles of hercynite in refractories were re-riewed. The application of hercynite in refractories was introduced with emphasis. The practical applications in cement rotary kiln showed the prepared magnesia her-cynite brick had better performance than the original magnesia chrome brick obviously.展开更多
Properties, section structure and service results of recycled MgO-C bricks and new MgO-C bricks for ladle slag line of Baosteel were analyzed and compared, and the measures of improving stability and quality of recycl...Properties, section structure and service results of recycled MgO-C bricks and new MgO-C bricks for ladle slag line of Baosteel were analyzed and compared, and the measures of improving stability and quality of recycled MgO-C bricks were summarized. The results show that： （1） High quality recycled MgO-C materials can be produced by scientific, meticulous and strict management for every process such as dismantling furnace, selection, removing impurity and slag, stacking and homogenization ; （2） Using high quality recycled materials and reasonable production technique, recycled MgO-C bricks with better properties and service efficiency than those of new MgO-C brick can be produced; （3） Service efficiency of recycled MgO - C bricks is good because of its high density, good oxidation resistance and reasonable structure.展开更多
文摘In order to make corundum castables satisfy more severe service conditions in high temperature industries,colloidal alumina due to the same main component with corundum castables was introduced for a pure binding system.The influence of three dispersants(citric acid,FS10 and urea)on the flow ability of colloidal alumina bonded corundum castables was researched to choose a suitable dispersant for solving the shaping problem.In order to further understand the influence of dispersants on the flow ability and the mechanism,the rheological property and Zeta potential value of the colloidal aluminadispersant system and the matrix-colloidal alumina-urea-water system were tested.The results show the castables added with the urea have the best flow ability,and the appropriate addition of the urea is 0.5%.
文摘In order to improve the flow ability and early-stage strength of colloidal alumina bonded corundum castables,the colloidal alumina with 20%of solid content was used as the binder,and tabular corundum aggregates and fines,and active alumina micropowder CL370 as the main starting materials.Influences of setting accelerating agents(magnesia fines and sodium meta-aluminate)on the linear change rate,the modulus of rupture and the microstructure of corundum castables after different heat-treatments were researched.The results show(1)cement bonded corundum castables have the highest modulus of rupture after 24 h of demolding,and colloidal alumina bonded corundum castables have the lowest one;both magnesia fines and sodium meta-aluminate can improve the strength after 24 h of demolding;(2)after firing at 1000℃for 3 h,the modulus of rupture of all specimens decreases,even lower than that after 24 h of demolding;(3)after firing at 1600℃for 3 h,the castable specimen added with 0.1 mass%magnesia fines has the highest modulus of rupture;the tabular phases appear interwovenly in the specimen;(4)taking the comprehensive properties into account,0.1 mass%of magnesia fines is appropriate,and the addition of sodium meta-aluminate shall be lower than 0.3%.
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.
文摘Corundum - spinel purging plugs were optimized through adjusting the formulation and the particle size composition of starting materials to prolong the service life of purging plugs for a 60 t refining ladle in a steel plant. Th.e optimized formulatioa is 30 mass% tabular corundum （6 - 3 mm ） , 20 mass% tabular corundum （3-1 ram）, 22 mass% tabular corundum （1 -0.5 ram） ＋ sintered spinel, 28% tabular corundum fines （0. 045 mm） ＋ fused spinel （0. 045 mm） ＋ bimodal α-Al2O3 micropowder ＋ Secar71 cement. The on-site results show that the plug can achieve an obviously long service life of 18 cycles, saving cost greatly.
文摘The characteristics of hercynite including corystal structure, chemical compositions and physical properties, R ＆ D background of hercynite, synthesis problems of heronite, amt roles of hercynite in refractories were re-riewed. The application of hercynite in refractories was introduced with emphasis. The practical applications in cement rotary kiln showed the prepared magnesia her-cynite brick had better performance than the original magnesia chrome brick obviously.
文摘Properties, section structure and service results of recycled MgO-C bricks and new MgO-C bricks for ladle slag line of Baosteel were analyzed and compared, and the measures of improving stability and quality of recycled MgO-C bricks were summarized. The results show that： （1） High quality recycled MgO-C materials can be produced by scientific, meticulous and strict management for every process such as dismantling furnace, selection, removing impurity and slag, stacking and homogenization ; （2） Using high quality recycled materials and reasonable production technique, recycled MgO-C bricks with better properties and service efficiency than those of new MgO-C brick can be produced; （3） Service efficiency of recycled MgO - C bricks is good because of its high density, good oxidation resistance and reasonable structure.
