高磷鲕状赤铁矿气基还原及脱磷剂对除磷效果影响

Effect of gas-based reduction of high-phosphorus oolitic hematite and dephosphorization agent on phosphorus removal effect

针对目前高磷鲕状赤铁矿因其矿物组成复杂多样、嵌布粒度细小、SiO_(2)和Al_(2)O_(3)等杂质成分以及磷含量高而无法被有效利用的现状,采用气基直接还原及脱磷剂-磁选工艺研究各工艺参数对还原产物及磁选铁精矿品位及磷含量指标的影响。以氢气为还原剂,配加脱磷剂,对铁品位为46.75%、磷元素质量分数为0.92%的国外某地区的高磷鲕状赤铁矿进行试验研究。试验中,脱磷剂不仅能破坏鲕状结构、抑制含磷矿物的还原,而且对还原过程中铁颗粒的生长起促进作用。在还原温度为1 050℃、保温时间为90 min、碱度为1.2以及H_(2)流量为200 mL/min的条件下,通过化学成分分析、粒度分析、微观结构分析(包括偏光显微分析和扫描电镜分析),研究脱磷剂种类和用量以及还原产物粒度和磁场强度等不同工艺参数对该矿提铁除磷效果的影响。结果表明,铁精矿在配加脱磷剂后,铁品位和铁回收率均有提高同时磷含量也大幅降低;4种常用脱磷剂CaCO_(3)、Na_(2)CO_(3)、Na_(2)SO_(4)、SiC中,脱磷剂Na_(2)SO_(4)在提高铁品位和除磷方面效果较佳,脱磷剂Na_(2)CO_(3)在提高铁回收率方面效果较佳;当还原矿粉粒度小于0.074 mm、磁场强度为1 000 Gs、Na_(2)SO_(4)与Na_(2)CO_(3)的质量比为9∶7、总质量分数为16%时,磷质量分数降至0.23%,铁回收率为82.35%。为高磷鲕状赤铁矿除磷提供了一定的理论指导。

Aiming at the current situation that high-phosphorus oolitic hematite can not be effectively utilized due to its complex and diversified mineral composition,fine embedded particle size,impurity components such as SiO_(2) and Al_(2)O_(3),and high phosphorus content,the gas-based direct reduction and dephosphorization agent-magnetic separation process was used to study the influence of each process parameter on the reduction product and the magnetic separation of the iron ore concentrates with grade and phosphorus content indexes.Using hydrogen as the reducing agent and dephosphorizing agent,experimental research on high-phosphorus oolitic hematite ore with iron grade of 46.75%and mass percent of phosphorus of 0.92%in a foreign region were conducted.In the test,the dephosphorizing agent not only destroys the oolitic structure and inhibits the reduction of phosphorus-containing minerals,but also promotes the growth of iron particles in the reduction process.Under the conditions of reduction temperature of 1050℃,holding time of 90 min,alkalinity of 1.2 and H_(2) flow rate of 200 mL/min,the effects of the type and dosage of dephosphorizing agent and different process parameters,such as the particle size of the reduction products and the intensity of the magnetic field,on the effect of iron and phosphorus removal in this ore were investigated by means of chemical composition analysis,particle size analysis and microstructural analysis,including polarized light microscopy and scanning electron microscopy analysis.The results show that the iron grade and iron recovery rate of iron concentrate are improved and the phosphorus content is also greatly reduced after adding dephosphorization agent.Among the four commonly used dephosphorization agents CaCO_(3),Na_(2)CO_(3),Na_(2)SO_(4) and SiC,the dephosphorization agent Na_(2)SO_(4) has a better effect on improving iron grade and phosphorus removal,and the dephosphorization agent Na_(2)CO_(3) has a better effect on improving iron recovery.When the particle size of the reduced ore powder is less than 0.074 mm,the magnetic field strength is 1000 Gs,the mass ratio of Na_(2)SO_(4) to Na_(2)CO_(3) is 9∶7,and the total mass percent is 16%,the phosphorus content is reduced to 0.23%,and the iron recovery rate is 82.35%.Some theoretical guidance for phosphorus removal from high phosphorus oolitic hematite are provided.