碱度对白云鄂博矿球团矿还原膨胀性能的影响

高比例球团矿冶炼是高炉炼铁发展的趋势。由于化学成分、矿物组成和结构的差异，不同企业生产或所用的球团矿还原膨胀的原因各不相同且相对复杂。面向保障矿产资源安全供给的国家重大战略需求，选择白云鄂博铁精矿球团矿作为研究对象，根据球团矿铁氧化物还原理论，从热力学方面深入研究碱度对球团矿还原膨胀性能的影响机理，并结合XRD结果来探究钙结合相在球团矿生产中的变化规律以及对球团矿还原膨胀的影响，找到满足高炉冶炼对球团矿还原膨胀率要求的合理碱度，从而提高白云鄂博铁精矿球团矿在包钢冶炼生产中的比例。完善特殊矿球团矿还原膨胀理论，为复杂共生矿高效冶炼提供理论支撑。研究结果表明，随着碱度的提高，球团矿的膨胀率呈现出先升高后降低的规律，碱度为0.8时，其膨胀率最大，达到75.743%,其外形如同花瓣开花，无法维持原来的球型。综合不同碱度球团矿含铁品位的高低和还原膨胀的大小，得到制备球团矿的最优碱度为1.4。随着碱度的提高，成品球的液相生成量先降低后升高，碱度为0.8时液相生成量最少。球团矿膨胀率先增加是因为球团矿的结晶度提高，晶粒粗大，晶体结构逐渐趋向有序，为铁晶须的生长奠定了基础；膨胀率后减小是因为生成了铁酸...

Influence of basicity on reduction swelling properties of pellets prepared from Bayan Obo iron ore

High-proportion pellet smelting is the development trend of blast furnace ironmaking. Due to the differences in chemical composition, mineral composition and structure, the reasons for the reduction and swelling of pellets produced or used by different enterprises are different and relatively complex. Facing the major national strategic needs of ensuring the safe supply of mineral resources. Pellets prepared from Bayan Obo iron ore concentrate were selected as the research object. According to the iron oxide reduction theory of pellets, the influence mechanism of basicity on the reduction swelling performance of pellets was studied from the perspective of thermodynamics. The XRD results were combined to investigate the change law of calcium-binding phase in pellet production and the influence on the reduction swelling of pellet. A reasonable basicity that meets the requirement of reducing swelling rate of flux pellets in blast furnace ironmaking was found. Increase the proportion of Bayan Obo iron concentrate pellets in iron and steel smelting production. Improve the reduction and swelling theory of special ore pellets to provide theoretical support for the efficient smelting of complex intergrowth ores. The results show that with the increase of basicity, the swelling rate of pellets first increased and then decreased. When the basicity was 0.8, the swelling rate was the largest, reaching 75.743%. Its shape was like an open petal, and it could not maintain its original spherical shape. The optimum basicity of the pellets prepared is 1.4 by synthesizing the iron grades of pellets with different basicity and the reduction swelling rate. With the increase of basicity, the amount of liquid phase generated of pellets first decreasing and then increasing. The amount of liquid phase generated at an basicity of 0.8 was the least. The reason for the increase in the swelling rate of the pellets is that the crystallinity of the pellets increases, the grains are coarse, and the crystal structure gradually tends to be ordered, which lays the foundation for the growth of iron whiskers; The reason for the decrease in swelling rate is because of the generation of calcium ferrite. Calcium ferrite has excellent binder phase properties and good reducibility,which improves the strength of the pellets,enhances the ability to resist swelling stress, and promotes the uniform swelling of the pellets. The volume swelling caused by the crystal transformation of Fe₂O₃→Fe₃O₄ is reduced.