| As the main raw materials of blast furnace(BF),the metallurgical properties of sinter have important effects on the technical indices of BF ironmaking process.Recently,in order to decrease the cost of raw materials,more kinds of ores have been used in sintering plant,and the chemical compositions of sinter change in a wider range.The improvement in the qualities of sinter has advantages in increasing the utilization of gas and reducing CO2 emission.Therefore,the fluidity of calcium ferrite bonding phase in a wider range was investigated based on Fe2O3-CaO-SiO2 phase diagram.Then,the fluidity of bonding phase may be predicted based on the liquidus temperature and percentage of liquid.Consequently the research results can give guidance for sintering mixing raw materials.First the relation between fluidity index and composition of liquid phase,liquidus temperature,and percentage of liquid was investigated based on the binary Fe2O3-CaO phase diagram.Then,the fluidity indexes of certain content of Fe2O3,CaO and certain basicity have been detected in Fe2O3-CaO-SiO2 ternary phase diagram.Finally,mechanism can be analyzed combined with isothermal section of tertiary phase diagram.The goal of the fifth chapter is to verify the results of basic research in the former chapters.The experimental results between the actual iron ores and chemical reagents are consistent.The main findings in this thesis could be summarized as follows:(1)The composition of liquid phase has the greatest influence on the fluidity.The fluidity can be predicted by the amount of liquids and liquidus temperature if the two points have the same composition of liquid phase.The fluidity is proportional to the amount of liquid phase,and is inversely proportional to the temperature of melting temperature.With the increase of the content of Fe2O3,the fluidity index of liquid shows a decreasing trend.When the contents of Fe2O3 increase from 72.4%to 83.6%,the indexes of fluidity decrease from 7.9 to 5.9.(2)In Fe2O3-CaO-SiO2 ternary system,in case of Fe2O3=70%,when the SiO2 content increases from 0 to 10%,the fluidity decreases from 9.29 to 7.33.(3)Whether the materials are chemical reagent or iron ores,although the samples that the content of CaO is 8%and the content of SiO2 increase from 0 to 10%have not been melted after roasted,a certain amount of liquid phase can be observed by microscopic observation.The region where the liquid phase located drawn by the phase diagram is the same as the result by the conversion of the component point ratio of the energy spectrum analysis.The reasons why the samples after melted don’t reflect fluidity are as follows:a)amounts of liquids are not enough;b)reaction is not balanced.In the region which is full of liquids with the content of CaO is 25%,with the increase of SiO2 content,the fluidity of the Fe2O3-CaO-SiO2 shows a decreasing trend from 7.71 to 6.21.The increase of the ionic group of silica acid leads to the increase of viscosity and the weakening of the fluidity.(4)With the increase of the content of Fe2O3 and the decrease of the content of SiO2,the fluidity of Fe2O3-CaO-SiO2 becomes worse.There is a large range between the maximum and the minimum.At R=1.0,the fluidity index decreased from 11.97 to 1,and at R=4.0,the fluidity index decreased from 5.9 to 1.When the basicity of the iron ore is set to 4,the fluidity becomes better with the increase of content of SiO2 in the ore.The fluidity index of Gaohui is highest(6.55)due to its highest SiO2 content.Similarly,the fluidity index of Baka is lowest(1.86)due to its lowest SiO2 content. |
PDF Full Text Request