烧结矿对高炉渣矿相结构及流动性能影响机理研究

The increasing content of iron ore with high Al2O3 and high TiO2 in sinter materials, has led to many problems of sinter, such as low temperature reduction degradation and poor flowability of blast furnace slag, which seriously affect the smooth operation of blast furnace. The microstructure of blast furnace slag and sinter will be quantitatively analyzed by using theoretical methords of process mineralogy. Based on polarized microscope, X-ray diffraction, electron probe, the chemical component and microstructure of mineral in the blast furnace slag and sinter will be analyzed. The genesis sequence of each mineral in blast furnace slag, and crystallization condition of high-melting mineral will be identified. The transformation law of minerals in sinter will be found. The quantitative relationship between microstructure of sinter and metallurgical property will be analyzed. The internal relationship between microstructure of blast furnace slag and flowability will be investigated. The migration rule of main elements in sinter materials and occurrence of main elements in sinter and blast furnace slag will be found out. The influence mechanism of sinter materials on metallurgical property of sinter and viscosity, melting temperature of blast furnace slag will be explored. The detailed analysis of basic reason, what affect the low temperature reduction degradation and flowability of blast furnace will be achieved. The study will provide a theoretical basis to enhance the production efficiency of blast furnace, improve the flowability of blast furnace slag and optimize sinter materials.

由于烧结原料中高铝及含钛型铁矿石的增加，导致烧结矿低温还原粉化严重、高炉渣粘稠性增加等问题，严重影响了高炉顺行。本课题以现场高炉渣及烧结矿为研究对象，运用工艺矿物学研究方法，采用透/反研究型偏光显微镜、X射线衍射仪、电子探针等测试手段，定量分析高炉渣及烧结矿的化学成分、矿物种类及含量、显微结构特征，查明高炉渣中每种矿物的生成顺序、高熔点矿物形成条件及烧结矿中矿物间相转变规律，厘清烧结矿矿相结构与冶金性能之间的定量关系及高炉渣矿相结构与流动性能的内在联系；查明烧结原料中主要元素的运移规律及其在烧结矿和高炉渣中的赋存状态，探讨烧结原料的化学成分和矿物种类对烧结矿冶金性能及高炉渣黏度与熔化性温度的影响机理，找出低温还原粉化及高炉流动性差的根本原因，旨在为提高高炉生产效率、改善高炉渣流动性能、保证高炉顺行及优化烧结原料提供理论依据。

本项目针对高炉冶炼过程中烧结矿低温还原粉化严重、高炉渣流动性差等问题，分别从唐钢、邯钢、承钢和攀钢现场调研取样，运用工艺矿物学的研究思路和方法，定量研究了含铁原料、烧结矿和高炉渣的化学成分、矿物组成、显微结构及冶金性能的关系；采用FactSage软件和相平衡理论，解析了四个钢厂的烧结成矿和高炉造渣过程中矿物相的析晶规律和形成条件；实验室内自制16种配料方案，分别设置9个温度梯度进行了144组烧结实验，查明了Mg、Al元素赋存运移规律，建立了烧结矿的化学成分、矿物生长特征、显微结构与低温还原粉化性能的关系，找出了影响高炉顺行的关键因素。.研究结果表明，唐钢和邯钢低钛型高炉渣结构较为均一，主要由含量高达95%以上的黄长石组成；承钢中钛型高炉渣主要矿物及含量为75～80%黄长石、10～15%钙钛矿和5～7%钛辉石等；攀钢高钛型高炉渣主要呈似斑状结构，基质为40～45%黄长石、40～45%钙钛矿和10～15%巴依石，斑晶为分布在金属铁周围的1～3%Ti[C,N]及其固溶体；集中在高炉终渣1500～1450℃降温段大量析出的钙钛矿、Ti[C,N]及其固溶体等矿物相是恶化攀钢高炉流动性的关键因素。.唐钢、邯钢和承钢烧结矿均由含量各占50%左右的金属相和粘结相组成，表现为他形磁铁矿、赤铁矿被针状铁酸钙、粒状硅酸二钙胶结形成的交织熔蚀结构；攀钢烧结矿表现为粒状结构，金属相主要为60～65%磁铁矿，突出特点是粘结相含量极少，尤其是有5～10％的网格状钙钛矿和骸晶状金属相生成；出现于成矿中期1280～1400℃升温段的骸晶状金属相，以及成矿后期1250～1150℃降温段的网格状钙钛矿，是恶化烧结矿低温粉化性能的关键因素。.在烧结原料成矿过程中，Mg主要赋存于磁铁矿晶格，抑制了烧结矿中骸晶状金属相生成；Al主要赋存于铁酸钙和玻璃质，致使铁酸钙形态由柱状向不利于低温还原粉化的板状发展；Mg、Al含量高易导致炉渣流动性能变坏的高熔点矿物生成。这些研究成果为优化烧结原料和工艺、改善高炉渣流动性能、提高高炉生产效率及保证高炉顺行提供了理论依据。