还原回转窑中的粉末黏结特性及其固结机理  

Bonding Characteristics of Powder and Its Consolidation Mechanism in Rotary Kiln of Reduction

作　　者：黄柱成[1] 沈雪华 朱顺伟 钟荣海 汉合童 

机构地区：[1]中南大学资源加工与生物工程学院,湖南长沙410083

出　　处：《金属矿山》2018年第1期73-78,共6页Metal Mine

基　　金：国家自然科学基金项目(编号:51234008)

摘　　要：为了解决或延缓还原回转窑结圈问题,分析了粉末的黏结特性,包括粉末的软熔特性、固结强度,同时分析了还原回转窑中的粉末固结的原因与形成机理。研究结果表明:还原气氛越强、煤灰掺量越高,粉末的软熔温度越低,越容易形成液相固结;焙烧温度升高、煤灰的掺量增加,粉末固结强度提高,越易黏附固结在回转窑窑壁上;随着焙烧时间延长,粉末的固结强度先显著上升,再显著下降,然后又上升。焙烧温度升高、煤灰掺量增加,粉末固结强度增加的原因是促进了粉末中铁橄榄石和钙铁辉石等物质形成,产物使粉末黏结更紧密;焙烧时间造成粉末固结强度变化是固相固结和粉末还原过程晶形转变共同导致的结果:在焙烧初期,固相固结和还原同时进行,粉末固结强度上升;在还原焙烧中期,固相固结过程基本结束,还原膨胀效果显现,粉末的固结强度迅速下降;在焙烧后期,Fe2O3—Fe3O4—Fe O阶段基本结束,金属铁大量生成,粉末的体积收缩,其强度上升。To solve the problem of ring forming of reduction rotary kiln or prolong the time for ring forming, bonding char- acteristics of powder were analyzed ,including soft melting characteristics of powder and its consolidation strength. At the same time, the reasons and forming mechanism of powder consolidation in rotary kiln of reduction were also analyzed. The results showed that the stronger the reducing atmosphere and the higher the dosage of fly ash, the lower the soft melting temperature of powder, the easier the powder was to form liquid consolidation. The powder consolidation strength increased and became easier to consolidation in the rotary kiln wall with roasting temperature and ash content increasing. As the roasting time extended, pow- der considerably increased the bonding strength at first, then decreased significantly, and then rose again. The reason for powder consolidation strength increasing with temperature and ratio of coal ash increase, was that they promoted olivine and heden- bergite in powder to be formed, which made powder bonding closer. Powder consolidation strength change caused by roasting time was the common resuh of solid phase consolidation and powder morphology changes in reduction process as. At the begin- ning of roasting, solid phase consolidation and reduction simultaneously occurred, and powder consolidation strength rose;In the middle of the reduction roasting, after the solid consolidation process was basically ending, the reducing expansion effect ap- peared and powder consolidation strength drop rapidly;Late in the roasting and at basic end of Fe2O3-Fe3O4-FeO stage, metal- lic iron was generated in great quantities ,powder volume shrank, and it＇s strength rose.

关 键 词：粉末 黏结特性 还原回转窑结圈 固结强度 软熔特性 固结机理 

分 类 号：TD464[矿业工程—矿山机电] TF046[冶金工程—冶金物理化学]