Research On Pulverization Of Sinter In Low-Temperature Reduction Based On Process Mineralogy

At present,due to the shortage of iron ore resources in China,the introduction of a large number of low grade,high aluminum,titanium-containing iron ores and composite block making technology in sinter raw materials leads to the serious reduction and pulverization of sinter at low temperature,thus affecting the smooth running of blast furnace.Based on the background of this study,the research group combined with the low-temperature reduction and pulverization performance of the on-site sintering ore,and through the analysis of the formation process of the ore phase structure,the influence mechanism of the ore phase structure on the low-temperature reduction and pulverization performance was explored.It was found that the two sinter(1#? 2#)were mainly composed of magnetite,hematite and calcium ferrite with good compressive strength,and had a good and similar drum index through the study of the phase structure of the sinter in the field.The microstructure of 1# sinter was more uniform,and the proportion of interlaced erosion and erosion structure was more than 90%.By contrast,the structure of 2# sinter was not uniform,the interlaced erosion structure accounted for 70%,and the granular structure and skeletal structure accounted for 30%.As a result of the large number of development and structural inhomogeneity of skeletal hematite and granular hematite,the resistance to low temperature reduction pulverization of sinter 2 # was obviously weaker than that of sinter 1 #.Through the study on the formation mechanism of sinter phase structure,it was found that the formation process of high alkalinity sinter was similar to that of magnetite type and hematite type made in the laboratory,and it was divided into nine stages and six structures with the change of temperature gradients: powder structure(900?)? cemented structure(1150?)? melting structure(1280?)? porphyry structure(1400?)? granular structure(1350?)? erosion structure(initial stage,1280?)? erosion structure(middle stage,1200?)? erosion structure(late stage,1100?)? granular structure(room temperature).Under the condition of sufficient reaction,the microstructure of hematite type sinter was better and better with the increase of basicity,and the microstructure of magnetite type sinter was getting worse with the increase of basicity.The structure of two kinds of sinter was the best at 1100?.The study on the mechanism of low temperature reduction pulverization based on the characteristics of mineral phase structure showed that the crystal development and essential characteristics of minerals were the most direct factors affecting the reduction and pulverization at low temperature,in which the hematite in the form of skeleton crystals can concentrated the phase transition stress at a point of explosion.More vitreous or olivine would be formed in the phase system of magnetite,which would reduce the fracture toughness of sinter and deteriorate the low temperature reduction and pulverization performance of sinter.The needle-shaped columnar calcium ferrate formed at 1100? in the cooling stage was beneficial to the improvement of the reduction and pulverization at low temperature because of its unique interleaved structure.The interaction between various microstructure in sinter was the indirect reason that affected the properties of reduction and pulverization at low temperature,the skeleton crystal structure and granular structure were the most prominent.Both of which were formed in the high temperature section(1350-1400?),and the bonding phase was vitreous.Due to the identity of the formation process,the two structures often appeaed in sinter at the same time,which resulted in the deterioration of low temperature pulverization performance.Figure 24;Table 19;Reference 69...