Xinyu Jin , Tielei Tian , Huanlong Chen , Yuzhu Zhang , Tao Li , Yanjun Liu
{"title":"Effect of SiO2 content in magnesia flux pellets on softening-melting and dripping behavior of comprehensive burden structure","authors":"Xinyu Jin , Tielei Tian , Huanlong Chen , Yuzhu Zhang , Tao Li , Yanjun Liu","doi":"10.1016/j.powtec.2024.120021","DOIUrl":null,"url":null,"abstract":"<div><p>High-proportion pellet smelting is the current development direction of blast furnace burden structures in China. And that is an inevitable trend for the future steel industry to achieve pollution reduction and carbon reduction. This study focuses on the mixed burden of magnesia flux pellets with different SiO<sub>2</sub> contents, sinter, and lump ore. The influence of SiO<sub>2</sub> content on the softening-melting behavior of comprehensive burden and the high-temperature interaction between magnesia flux pellets and sinter were studied through droplet experiments and visual experiments. The results show that with increasing SiO<sub>2</sub> content, the T<sub>10</sub> of magnesia flux pellets gradually decreases, while the T<sub>10</sub> of the comprehensive burden shows no significant change. The T<sub>S</sub> of both shows a gradually decreasing trend with increasing SiO<sub>2</sub> content. However, due to the good matching of the melting range between sinter and magnesia flux pellets in the comprehensive burden, the trend of T<sub>S</sub> change in the comprehensive burden is relatively slow. The air permeability of the comprehensive burden has significantly improved compared with the single magnesia flux pellets; The interaction between magnesia flux pellets and sinter occurs through the liquid phase. The fayalite phase in the pellets reacts with the main high melting point substance Ca<sub>2</sub>SiO<sub>4</sub> in the sinter to generate a new low melting point kirschsteinite. With the increase of SiO<sub>2</sub> content, the content of kirschsteinite in the comprehensive burden increases. That is also the reason for the decrease in T<sub>S</sub> of the high silicon comprehensive burden; With the increase of SiO<sub>2</sub> content, the maximum pressure difference and characteristic values of magnesia flux pellets and comprehensive burden gradually increase. When the SiO<sub>2</sub> content exceeds 6%, the maximum pressure difference and characteristic value of a single pellet sharply increase, while the trend of the maximum pressure difference and characteristic value change of comprehensive burden is relatively gentle. Its characteristic values are below 980 kPa·°C. At this time, the air permeability of the comprehensive burden is significantly improved compared to the single magnesia flux pellets. In the case of SiO<sub>2</sub> content exceeding 6%, the addition of a sinter can effectively address the soft melting performance of high-silica magnesia flux pellets and enhance column air permeability. In addition, the high drop temperature of the high-silica comprehensive burden is due to the presence of a large amount of MgO in the magnesia wustite during the later stage of reduction, which increases the melting point. And the MgO content in the slag is relatively low. That causes a sharp increase in slag viscosity and makes it difficult to separate the slag from iron.</p></div>","PeriodicalId":407,"journal":{"name":"Powder Technology","volume":null,"pages":null},"PeriodicalIF":4.5000,"publicationDate":"2024-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Powder Technology","FirstCategoryId":"5","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S003259102400665X","RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"ENGINEERING, CHEMICAL","Score":null,"Total":0}
引用次数: 0
Abstract
High-proportion pellet smelting is the current development direction of blast furnace burden structures in China. And that is an inevitable trend for the future steel industry to achieve pollution reduction and carbon reduction. This study focuses on the mixed burden of magnesia flux pellets with different SiO2 contents, sinter, and lump ore. The influence of SiO2 content on the softening-melting behavior of comprehensive burden and the high-temperature interaction between magnesia flux pellets and sinter were studied through droplet experiments and visual experiments. The results show that with increasing SiO2 content, the T10 of magnesia flux pellets gradually decreases, while the T10 of the comprehensive burden shows no significant change. The TS of both shows a gradually decreasing trend with increasing SiO2 content. However, due to the good matching of the melting range between sinter and magnesia flux pellets in the comprehensive burden, the trend of TS change in the comprehensive burden is relatively slow. The air permeability of the comprehensive burden has significantly improved compared with the single magnesia flux pellets; The interaction between magnesia flux pellets and sinter occurs through the liquid phase. The fayalite phase in the pellets reacts with the main high melting point substance Ca2SiO4 in the sinter to generate a new low melting point kirschsteinite. With the increase of SiO2 content, the content of kirschsteinite in the comprehensive burden increases. That is also the reason for the decrease in TS of the high silicon comprehensive burden; With the increase of SiO2 content, the maximum pressure difference and characteristic values of magnesia flux pellets and comprehensive burden gradually increase. When the SiO2 content exceeds 6%, the maximum pressure difference and characteristic value of a single pellet sharply increase, while the trend of the maximum pressure difference and characteristic value change of comprehensive burden is relatively gentle. Its characteristic values are below 980 kPa·°C. At this time, the air permeability of the comprehensive burden is significantly improved compared to the single magnesia flux pellets. In the case of SiO2 content exceeding 6%, the addition of a sinter can effectively address the soft melting performance of high-silica magnesia flux pellets and enhance column air permeability. In addition, the high drop temperature of the high-silica comprehensive burden is due to the presence of a large amount of MgO in the magnesia wustite during the later stage of reduction, which increases the melting point. And the MgO content in the slag is relatively low. That causes a sharp increase in slag viscosity and makes it difficult to separate the slag from iron.
期刊介绍:
Powder Technology is an International Journal on the Science and Technology of Wet and Dry Particulate Systems. Powder Technology publishes papers on all aspects of the formation of particles and their characterisation and on the study of systems containing particulate solids. No limitation is imposed on the size of the particles, which may range from nanometre scale, as in pigments or aerosols, to that of mined or quarried materials. The following list of topics is not intended to be comprehensive, but rather to indicate typical subjects which fall within the scope of the journal's interests:
Formation and synthesis of particles by precipitation and other methods.
Modification of particles by agglomeration, coating, comminution and attrition.
Characterisation of the size, shape, surface area, pore structure and strength of particles and agglomerates (including the origins and effects of inter particle forces).
Packing, failure, flow and permeability of assemblies of particles.
Particle-particle interactions and suspension rheology.
Handling and processing operations such as slurry flow, fluidization, pneumatic conveying.
Interactions between particles and their environment, including delivery of particulate products to the body.
Applications of particle technology in production of pharmaceuticals, chemicals, foods, pigments, structural, and functional materials and in environmental and energy related matters.
For materials-oriented contributions we are looking for articles revealing the effect of particle/powder characteristics (size, morphology and composition, in that order) on material performance or functionality and, ideally, comparison to any industrial standard.