The effect of sinter basicity on softening-melting behaviors of mixed burden made from chromium-bearing vanadium-titanium magnetite(Cr-V-Ti magnetite) was investigated and the function mechanism was simultaneously ana...The effect of sinter basicity on softening-melting behaviors of mixed burden made from chromium-bearing vanadium-titanium magnetite(Cr-V-Ti magnetite) was investigated and the function mechanism was simultaneously analyzed.The results show that with increasing sinter basicity from 1.71 to 2.36,the softening interval tends to increase from 149.3 ℃ to 181.7 ℃while the melting interval tends to decrease from 178.0 ℃ to 136.7 ℃.The location of cohesive zone moves downwards firstly and then ascends slightly,but the cohesive zone becomes thinner.The softening-melting characteristic value becomes small,which indicates that the permeability of burden column is improved.The dripping ratio of mixed burden tends to increase firstly and then decrease,which comes to the highest value of 74.50%when the sinter basicity is 2.13.The content and the recovery of V and Cr in dripping iron are all increased.The generation amount of components with high melting point in slag becomes little with the increase of sinter basicity,which could improve the permeability of mixed burden.Taking softening-melting behaviors of mixed burden and recovery of valuable elements into account,the proper sinter basicity is no less than 2.13 for smelting mixed burden made from Cr-V-Ti magnetite in blast furnace.展开更多
Selective laser melting(SLM)technology is the prevailing method of manufacturing components with complex geometries.However,the cost of the additive manufacturing(AM)fine powder is relatively high,which significantly ...Selective laser melting(SLM)technology is the prevailing method of manufacturing components with complex geometries.However,the cost of the additive manufacturing(AM)fine powder is relatively high,which significantly limits the development of the SLM.In this study,the 316L fine powder and coarse powder with a mass ratio of 80:20,70:30 and 60:40 were mixed using a ball milling and the samples with a relative density greater than 97%were prepared by SLM.The results show that the intricate temperature gradients and surface tension gradients in SLM will produce Marangoni flow,forming a typical molten pool morphology,cellular and strip subgrain structures.And as the proportion of coarse powder increases,the scanning track morphology changes from smooth to undulating;the morphology of the molten pool and subgrain structure are weakened.Meanwhile,the unmelted particles appear on the surface of the SLM sample.On the premise of an introducing appropriate amount of large particle size powder(20%),the SLM samples still have good mechanical properties(662 MPa,47%).展开更多
In order to reasonably utilize the abundant resources of high-phosphorus iron ore and ilmenite in China, the technology of top-blown smelting reduction with oxygen enrichment was used to smelt the mixed ore of high-ph...In order to reasonably utilize the abundant resources of high-phosphorus iron ore and ilmenite in China, the technology of top-blown smelting reduction with oxygen enrichment was used to smelt the mixed ore of high-phosphorus iron and ilmenite. The effect, which is related to basicity, reduction temperature, carbon-oxygen ratio and time of ventilated oxygen to iron recovery, dephosphorization rate, content of iron, phosphorus, sulfur and titanium in pig iron, was investigated in the experiment. The results show that an ideal outcome can be gained in condition of 6：4 ration on Mengqiao concentrate and Huimin iron ore, temperature of 1 500℃, basicity of 1.3, 1.0 on molar ration of carbon to oxygen, time of 10 min on blowing-oxygen. The outcome is that there is no foamy slag in generation, a good separation of slag and iron, iron recovery with 91.41%, content of phosphorus with 0.27% and tilanium content less than 0.001%, The atmosphere of strong oxidizing in the upper of reduction container and high potential of oxygen in the composition of slag in this technique bring phosphorus, titanium and silicon into slag, which ensures less content of impurity in pig iron.展开更多
基金Project(51574067)supported by the National Natural Science Fundation of ChinaProjects(2012AA062302,2012AA062304)supported by the National High Technology Research and Development Program of ChinaProject(N110202001)supported by the Fundamental Research Funds for the Central Universities of China
文摘The effect of sinter basicity on softening-melting behaviors of mixed burden made from chromium-bearing vanadium-titanium magnetite(Cr-V-Ti magnetite) was investigated and the function mechanism was simultaneously analyzed.The results show that with increasing sinter basicity from 1.71 to 2.36,the softening interval tends to increase from 149.3 ℃ to 181.7 ℃while the melting interval tends to decrease from 178.0 ℃ to 136.7 ℃.The location of cohesive zone moves downwards firstly and then ascends slightly,but the cohesive zone becomes thinner.The softening-melting characteristic value becomes small,which indicates that the permeability of burden column is improved.The dripping ratio of mixed burden tends to increase firstly and then decrease,which comes to the highest value of 74.50%when the sinter basicity is 2.13.The content and the recovery of V and Cr in dripping iron are all increased.The generation amount of components with high melting point in slag becomes little with the increase of sinter basicity,which could improve the permeability of mixed burden.Taking softening-melting behaviors of mixed burden and recovery of valuable elements into account,the proper sinter basicity is no less than 2.13 for smelting mixed burden made from Cr-V-Ti magnetite in blast furnace.
基金Projects(51671152,51304153,51504191,51874225)supported by the National Natural Science Foundation of ChinaProject(14JK512)supported by the Natural Science Foundation of Shaanxi Educational Committee,China+1 种基金Project(18JC019)supported by Shaanxi Provincial Department of Education Industrialization Project,ChinaProject(14JK1512)supported by Shaanxi Provincial Department of Education Natural Science Special Project,China
文摘Selective laser melting(SLM)technology is the prevailing method of manufacturing components with complex geometries.However,the cost of the additive manufacturing(AM)fine powder is relatively high,which significantly limits the development of the SLM.In this study,the 316L fine powder and coarse powder with a mass ratio of 80:20,70:30 and 60:40 were mixed using a ball milling and the samples with a relative density greater than 97%were prepared by SLM.The results show that the intricate temperature gradients and surface tension gradients in SLM will produce Marangoni flow,forming a typical molten pool morphology,cellular and strip subgrain structures.And as the proportion of coarse powder increases,the scanning track morphology changes from smooth to undulating;the morphology of the molten pool and subgrain structure are weakened.Meanwhile,the unmelted particles appear on the surface of the SLM sample.On the premise of an introducing appropriate amount of large particle size powder(20%),the SLM samples still have good mechanical properties(662 MPa,47%).
基金Project(51064015) supported by the National Natural Science Foundation of ChinaProject(ZD2010001) supported by the Key Project of Yunnan Province Education of China
文摘In order to reasonably utilize the abundant resources of high-phosphorus iron ore and ilmenite in China, the technology of top-blown smelting reduction with oxygen enrichment was used to smelt the mixed ore of high-phosphorus iron and ilmenite. The effect, which is related to basicity, reduction temperature, carbon-oxygen ratio and time of ventilated oxygen to iron recovery, dephosphorization rate, content of iron, phosphorus, sulfur and titanium in pig iron, was investigated in the experiment. The results show that an ideal outcome can be gained in condition of 6：4 ration on Mengqiao concentrate and Huimin iron ore, temperature of 1 500℃, basicity of 1.3, 1.0 on molar ration of carbon to oxygen, time of 10 min on blowing-oxygen. The outcome is that there is no foamy slag in generation, a good separation of slag and iron, iron recovery with 91.41%, content of phosphorus with 0.27% and tilanium content less than 0.001%, The atmosphere of strong oxidizing in the upper of reduction container and high potential of oxygen in the composition of slag in this technique bring phosphorus, titanium and silicon into slag, which ensures less content of impurity in pig iron.
