【作者】 韩志国；

【导师】 黄柱成；

【作者基本信息】 中南大学 ， 矿物加工工程， 2005， 硕士

【摘要】 磁铁精矿是我国主要的铁矿资源,我国北方的一些烧结厂以磁铁精矿为主要烧结原料。近几年我国铁精矿进行了降硅提铁,许多烧结厂在以磁铁精矿为主的烧结原料中配加了国外优质赤铁矿,进行高铁低硅烧结。在新的原料条件下研究其成矿机理及进行改善烧结矿产质量的工艺研究是很有意义的。 本文结合赤铁矿,以细磁铁精矿为主要研究对象,分析了其原料特点,研究和考察了铁矿颗粒间的固相固结、单一铁矿烧结反应性能、磁铁矿配加赤铁矿的烧结反应行为和混合料颗粒的烧结行为等,并进行了提高细磨磁铁精矿烧结产质量的烧结试验研究。研究结果表明: （1） 在氧化气氛下磁铁精矿颗粒间固相固结比较快,以氧化再结晶和再结晶的方式固结。铁矿的粒度细、颗粒间接触点多,有利于质点扩散与固结;FeO含量也影响磁铁矿颗粒间固相固结,磁铁精矿氧化放热,有利于质点的扩散,促进颗粒固结:磁铁矿与SiO₂生成低熔点化合物,可以加强颗粒间的粘结;赤铁矿颗粒间在1200℃以下一直保持原有形态,颗粒间不存在固相固结。超过1280℃能观察到晶体颗粒明显长大,小晶粒之间可形成初期的连接桥。 （2） 赤铁矿烧结时,烧结初期液相是CaO-Fe₂O₃系。赤铁矿颗粒被铁酸钙包围并逐渐被融蚀,最后形成赤铁矿与铁酸钙相互交织的结构;细磨高铁低硅磁铁精矿烧结时其成矿机理与赤铁矿不同,铁酸钙生成量较少,主要矿物是磁铁矿的氧化再结晶和磁铁矿的再结晶;在磁铁矿氧化后生成铁酸钙,与磁铁矿和赤铁矿交融在一起;磁铁矿容易固溶Ca²⁺和Mg²⁺,生成含钙镁的铁矿物,结构致密。 （3） 混合料中的粗粒子,澳矿被铁酸钙液相包围为团块提供骨架支撑作用的,返矿在团块焙烧过程中优先软融并快速与其他矿物发生矿化反应,石灰石分解后快速与其它矿物发生矿化反应而形成液相,白云石在混合料中矿化需要较高的焙烧温度和较长的焙烧时间。白云石分解后被磁铁矿包围,形成镁铁矿与方镁石交代互融的结构。更多还原

【Abstract】 Magnetite is main iron resource in China. Magnetite is chief sintering raw material in some sintering plants in the north of China. In recent years, the technique of improving iron and decreasing silicon has been implemented to iron concentrate in China. Many sintering plants have adopted the technique of high-iron and low-silicon, and mainly used magnetite as sintering raw materials with addition of sane high-quality hematite overseas. It is very important to study metallogenic mechanics and technical conditions of improving production and quality of sintered ores.Solid phase consolidation of iron ore particles, sintering reactivity of single iron ore, sintering reactivity behavior of magnetite with addition of hematite and sintering behavior of particles were studied on the basis of characteristics of fine magnetite mixture and hematite. Besides, effects of improving production and quality of sintered ores dominated fine grinding magnetite were tested. Results are as follows:（1）Solid phase consolidation rate of magnetite particles which are consolidated by crystallization and oxidization crystallization is faster under oxidization atmosphere. Iron ore particle size is fine and the particles are contacted with each other, which is good for diffusion and bonding. Content of FeO is also a factor of affecting solid consolidation. Oxidization heat of magnetite is advantageous for diffusion of mass point and accelerates particles bonding. In addition, magnetite and SiO₂ will form low-melting compound when magnetite is not oxidized completely, which will strengthen particles bonding .So SiO₂ content is also a factor of affecting particles consolidation. Hematite particles keep original shapes and do not contact with each other at 1200℃.Crystal particles grow up and form initial attachment bridges, when temperature is over 1280℃.（2）Early sintering liquid phase is CaO-Fe₂O₃ system when hematite is sintered.Hematite particles are enclosed and ablated gradually, at last formed interlaced texture between hematite and calcium ferrite. Sintering mechanics of fine grinding high-iron and low-silicon magnetite is different from that of hematite. Formation of calcium ferrite is little and main consolidation shapes are magnetite oxidization recrystallization and magnetite recrystallization. Magnetite is oxidized to form calcium ferrite, which is blended with magnetite and hematite. Magnetite easily consolidates with Ca2+ and Mg2+,then forms iron ores containing calcium and magnesium.（3）Coarse particles in mixture （e.g. Australian ore）enclosed by liquid phase calcium ferrite can provide framework for the briquette. Some large particles are prior to soft melt or form low melting point minerals during roasting process （e.g. returning ores）. Limestone mineralizes with other minerals to forme fluid phase quickly after decomposed. Dolomite mineralization needs higher roasting temperature and longer roasting time in the mixture. It is enclosed by magnetite after decomposed, and formed interlaced texture between magnoferrite and periclase.（4） Studies on improving the yield and quality of the fine grinding magnetite sintering in the sintering cup assay have been performed in this paper. The results indicate that: the mixture of full concentrate sintering is weak in permeability, and the sintering utilization index is low. Adding the compound binder F and catalyst J can improve the sintering quality. The dosage of compound binder F, from 0% to 1.0%, has obvious effects on granulation of the mixture. The granularity composition of-lmm is low and permeability index is improved in the mixture. The vertical sintering velocity is improved from 16.95 mm/min to 21.05 mm/min, and the utilization index is obviously improved from 1.352 t/（m2.h） to 1.729 t/（m2.h）, which shows adding catalyst J has obvious effects on improving tumble index and utilization index. Especially, the catalyst had obvious effect on reducing the solid fuel consumption.When the fine grinding magnetite is mainly sintered with some addition ofhematite, the sintering yield and quality are both better than those of sintering by full concentrate. On the base of that, it was studied that the effects of alkalinity, MgO and the quantity of calcined limes on the sintering yield and quality. The alkalinity has obvious effect on the tumble index of sintering. When the alkalinity is improved form 1.6 to 2.0, the tumble index is obviously increased from 57.60% to 69.60%. MgO content in the sintering ores decreased from 2.3% to 1.4%, and the sintering utilization index increased from 1.629 t/（m2h） to 2.031 t/（m2.h）, but the tumble index has no obvious change. Calcined limes can effectively improve the granulation effect of the mixture, and the material bed permeability is markedly improved, the vertical sintering velocity is instinctly accelerated, the utilization index increases, moreover, the tumble index is improved a little.更多还原