【作者】 李建；

【导师】 朱德庆；

【作者基本信息】 中南大学 ， 矿物加工工程， 2004， 硕士

【摘要】 铬铁合金是制造不锈钢的重要原料，而冶炼铬铁合金的主要矿物原料为铬铁矿。目前天然铬铁矿块矿资源急剧减少，且价格急剧攀升，而粉矿价格低廉，但粉矿必须通过造块才能大量用于电炉冶炼铬铁合金。通过查阅国内外大量文献，在对不同铬铁矿造块方法进行综合分析对比的基础上，开展了铬铁矿球团烧结工艺及机理研究。 铬铁矿常规烧结试验研究表明：在焦粉用量8.0％，混合料水分8.0％，膨润土A添加3％，点火温度1100±50℃，点火时间2min，点火负压5000Pa，烧结负压10000Pa，冷却负压5000Pa，冷却时间3min，料层高度580mm的条件下，铬铁烧结矿成品率为73.16％，利用系数1.17 t·m^-2·h^-1，转鼓指数61.03％，固体燃耗115.80 kg·t^-1。采用常规烧结工艺，存在烧结矿成品率低，强度差，烧结利用系数低，固体燃耗高等问题。 铬铁矿球团烧结试验研究表明：在所有原料破碎到小于1mm，焦粉用量为7.5％，焦粉内外分加比例为60：40，混合料水分8.0％，膨润土用量为1％，干燥温度200—250℃，干燥时间3min，干燥负压4000Pa，点火温度1100±50℃，点火时间2min，点火负压4000Pa，烧结负压8000Pa，冷却负压4000Pa，冷却时间3min，料层高度580mm的条件下，铬铁烧结矿成品率为77.18％，利用系数1.47t·m^-2·h^-1，转鼓指数83.78％，固体燃耗107.32 kg·t^-1。球团烧结工艺可显著改善烧结矿产质量，成品率、转鼓指数、利用系数分别提高5.50％、37.28％、25.64％，固体燃耗下降7.32％。 采用光学显微镜、扫描电镜、电子探针等微观检测手段，对铬铁矿球团烧结工艺的固结机理进行了研究，结果表明：铬铁烧结矿主要由铁铬尖晶石、镁铬尖晶石、镁铝尖晶石、各种橄榄石矿物组成。烧结矿的固结以铁铬尖晶石、镁铬尖晶石、镁铝尖晶石再结晶固结为主，橄榄石等液相固结为辅。焦粉分加比例对烧结矿微观结构及矿物组成有显著影响：a、焦粉全部外加到球团表面，球团内外结构不一致，欠烧，强度差；b、焦粉内外分加比例为60：40，球团结构均匀，呈中孔厚壁结构，孔隙适中，强度好；c、焦粉全部加入球团内部，球团内出现大孔薄壁结构，孔隙多，烧结矿强度差。 原料的粒度对球团烧结矿固结有重要影响，当所有原料（包括返矿）粒度＜1mm时，球团烧结矿结构最均匀，各种尖晶石与橄榄石胶结良好所以强度最高。 球团烧结矿宏观结构为葡萄状团块。 球团烧结工艺是强化铬铁矿烧结、提高烧结矿产质量、节省固体燃耗的重要技术方案，为强化电炉冶炼CrFe合金供应优质炉料提供技术支持，有重要的理论价值和现实意义。更多还原

【Abstract】 Chromite is main raw material for smelting ferrochromium which can be used to make stainless steel products. And ore feed of smelting ferrochromium is chromite. At present resources of natural chromite lump is decreasing rapidly and its price is going higher than before. But the price of chromite fines is cheap. Agglomeration is one necessary process to utilize. So by comparing with conventional sintering, chromite pellet sintering technology (PST) and its agglomeration mechanism have been studied.The investigation on conventional sintering of chromite shows that the rate of finished sinter, the productivity, tumbler index and fuel comsuption are 73.16%, 1.17 t-m-2h-1, 61.03%, 115.80 kg-t -1 respectively under fuel content of 8.0%, moisture content of 8.0%, bentonite addition of 3%, ignition temperature of 1100 + 50 C, ignition time of 2min, ignition pressure of 5000Pa, sintering pressure of 10000Pa, cooling pressure of 5000Pa, cooling time of 3min and bed depth of 580mm.The investigation on pellet sintering of chromite shows that the rate of finished sinter reaches 77.18% and the productivity reaches 1.47 t-m. -2h-1 and tumbler index reaches 83.78% and fuel comsuption reaches 107.32 kg-t-1 under all feed size of -lmm,fuel content of 7.5%, 60% coke added into pellet inside, bentonite addition of 1%, moisturecontent of 8.0%, drying temperature of 200-250 C, drying time of 3min, drying pressure of 4000Pa, ignition temperature of 1100 + 50 C, ignition time of 2min, ignition pressure of 5000Pa, sintering pressure of lOOOOPa, cooling pressure of 5000Pa, cooling time of 3min and bed of 580mm. The quality and productivity of sinter are improved by using PST. The rate of finished sinter, tumbler index, productivity are increased by 5.50%, 37.28%, 25.64% respectively and meanwhile fuel consumption is decreased by 7.32%.The solidification mechanism of pellet sintering was studied by using microscope, SEM, EPMA. Results show that sinter of chromite consist of Fe-Cr spinel, Mg-Cr spinel, Mg-Al spinel spinel and olivine. The agglomeration of sinter mainly depends on recrystallization of spinels and liquid phase of olivine plays an assistant role as well. The micro-structure and composition of sinter was affected remarkablely by divided coke addition. There is big different between outer structure and inner, and strength of pellet is poor under 100% coke adhered at the surface of pellet. Pellets have good structure and strengthen under 60% coke added into inside pellet and 40% coke adhered at the surface of pellet. The big pore appeared and poor strengthen under 100% coke added into inside pellet. Besides, the agglomeration of pellet was affected obviously by size of balling feed. The structure of sinter is reasonable and has good connection of chromite and olivine andpowerful strength when all feed size is under lmm(including returns).The macroscopical structure of sinter is recemose.PST is important process that can strength chromite sintering and improve the quality and productivity of sinter. PST can give technical support for smelting ferrochromium by electric arc furnace.更多还原