A New Method For Determination Of Assimilation Of Iron Ore:Principle Of Resistance Change

Optimization of ore blending based on high-temperature characteristics of iron ore powder sintering is of great significance for achieving cost reduction and efficiency increase in sintering production.The assimilation of iron ore powder is characterized by the difficulty of producing liquid phase in the sintering process of iron ore powder?represented by the lowest assimilation temperature?,which is a very important high-temperature characteristic index.The sintering temperature can be effectively reduced and fuel consumption can be reduced by reducing the lowest assimilation temperature of sintered mixture through the assimilation complementarity of iron ore.At present,a lot of research work has been carried out on the detection of the minimum assimilation temperature of iron ore powder,and good research results have been obtained in the field of optimal sintering and ore blending.However,the existing detection method?observation method?needs to carry out repeated experiments,and the detection efficiency is not high.In this paper,according to the characteristics that assimilation reaction changes from solid phase to liquid phase,A new method?resistance method?is proposed to determine the assimilation reaction by measuring the changes in the electrical conductivity of the contact surface materials before and after the assimilation reaction,so as to provide data support and theoretical guidance for the optimization of ore blending based on the lowest assimilation temperature of iron ore.The optimal experimental conditions for the determination of the lowest assimilation temperature of iron ore powder by resistance method and the analysis of the detection process were explored.Results show that under the condition of the CaO chip 20 mm diameter,iron ore powder should be added 0.5 g,the electrode should be buried depth is 2 mm,heating rate should be controlled at 1?/s.According to the change of resistance value,the detection process can be divided into three phases:declining phase,abrupt phase and stable phase.The macroscopic morphology and microphase composition of the reaction interface between iron ore powder and CaO at different reaction temperatures were analyzed and he accuracy of resistance method in detecting the lowest assimilation temperature of iron ore powder is proved.The results show that in the unassimilated sample,the iron Ore powder and CaO interface position has obvious dividing line,only A small number of tiny particles iron Ore powder with CaO in the solid phase reaction;In the assimilated sample,iron ore powder and CaO reaction is relatively obvious,the boundary between the contact surface into a jagged,the reaction to form the layer thickness of about 0.3 mm calcium ferrite;In the over-assimilated sample,CaO spread to all of the iron ore powder,and iron ore powder after reaction is no longer a granular but fusion as a whole.The lowest assimilation temperature of iron ores commonly used in two steel plants in China were tested by resistance method and observation method respectively,the results show that the resistance method is consistent with the observation method;The ratio of sintering materials and technological parameters were adjusted according to the test results of sintering site reference resistance method and both the drum index and the yield of sinter have been effectively improved.The law of the influence of chemical composition on the minimum assimilation temperature of iron ore powder was explored through the resistance method,and compared with the existing research conclusions at the same time.The results show that the influence of MgO content,Al₂O₃content,SiO₂ content and LOI content obtained by the resistance method on the lowest assimilation temperature is basically consistent with the existing research conclusions,which further proves the accuracy and effectiveness of the resistance method in detecting the lowest assimilation temperature of iron ore.