褐铁矿对烧结矿铁酸钙形貌及微区组成的影响

Effect of limonite on morphology and micro-area composition of sinter calcium ferrite

为了探究褐铁矿配比变化对烧结矿铁酸钙形貌及微区组成的影响,明确褐铁矿配比增加时烧结矿的转鼓强度性能变化趋势,利用FactSage 7.1热力学模拟软件计算了不同褐铁矿配比条件下混合矿的黏附粉含量及其液相生成性能,同时采用矿相显微镜结合OIA自动矿相系统和EPMA电子探针依据铁酸钙微观形貌特征不同的原理对烧结矿矿物学特征及铁酸钙微区组成进行了研究。结果表明,烧结矿黏结相主要由铁酸钙和硅酸盐组成,铁酸钙形貌以针柱状为主,纤维状为辅,纤维状铁酸钙主要形成于铁酸钙形成初期,具有SiO_(2)组分含量高和w(Fe_(2)O_(3))/w(CaO)低的特点,随着铁酸钙黏结相的发展,Fe_(2)O_(3)组分含量增加,w(Fe_(2)O_(3))/w(CaO)提高,促进了铁酸钙晶粒的发展长大,形成针柱状。当褐铁矿配比由33%增加到50%时,由于粗粒度LB矿配比增加21%,导致黏附粉质量分数降低2.16%,热力学理论模拟计算单位质量黏附粉产生液相量降低0.25%,w(Fe_(2)O_(3))/w(CaO)降低0.3,表明褐铁矿配比增加不利于烧结矿铁酸钙的形成发展;热力学模拟计算结果与实际烧结结果相吻合,实际烧结矿中铁酸钙总量降低7.75%,其中针柱状铁酸钙质量分数降低9.78%,针柱状铁酸钙中w(Fe_(2)O_(3))/w(CaO)降低0.68,一定程度上弱化了针柱状铁酸钙晶粒的发展,铁酸钙形貌多为细碎纤维状,铁酸钙连晶发展受限,最终导致烧结矿转鼓强度受到不利影响。

In order to explore the influence of limonite ratio change on the morphology and micro-area composition of sinter calcium ferrite,and to clarify the change trend of drum strength performance of sinter when the limonite ratio increases,the FactSage 7.1 thermodynamic simulation software was used to calculate the adhesion powder content and liquid phase formation performance of mixed ore under different limonite ratio conditions.At the same time,the mineralogical characteristics of sinter and the micro-area composition of calcium ferrite were investigated by using the mineral phase microscope combined with OIA automatic mineral phase system and EPMA electron probe according to the different micro-morphological characteristics of calcium ferrite.The results show that the binder phase of sinter is mainly composed of calcium ferrite and silicate.The morphology of calcium ferrite is mainly needle columnar,supplemented by fibrous.The fibrous calcium ferrite is mainly formed in the early stage of the formation of calcium ferrite,which has the characteristics of high content of SiO_(2) and low w(Fe2O3)/w(CaO).With the development of the binder phase of calcium ferrite,the content of Fe2O3 component increases and w(Fe2O3)/w(CaO)increases,which promotes the development and growth of calcium ferrite grains and forms needle columnar.When the proportion of limonite increases from 33%to 50%,the content of adhesion powder decreases by 2.16%due to the increase of 21%of the proportion of coarse-grained LB ore.Thermodynamic theory simulation shows that the amount of liquid phase produced by unit mass adhesion powder decreases by 0.25%and w(Fe2O3)/w(CaO)decreases by 0.3,indicating that the increase of limonite ratio is not conducive to the formation and development of calcium ferrite in sinter.The thermodynamic simulation results are consistent with the actual sintering results.The total amount of calcium ferrite in the actual sinter is reduced by 7.75%,of which the content of needle columnar calcium ferrite is reduced by 9.78%.The w(Fe2O3)/w(CaO)in needle columnar calcium ferrite is reduced by 0.68,which weakens the development of needle columnar calcium ferrite grains to a certain extent.The morphology of calcium ferrite is mostly fine fibrous calcium ferrite,and the development of calcium ferrite is limited,which eventually leads to the adverse effect on the drum strength of sinter.