节点文献
高磷硫菱铁矿选冶联合新技术及理论研究
【作者】 柏少军；
【导师】 文书明；
【作者基本信息】 昆明理工大学 ， 矿物加工工程， 2011， 博士
【摘要】 中国铁矿资源丰而不富,钢铁工业持续高速的增长造成国内铁矿石供求矛盾日益突出。目前,我国钢铁工业所需的铁矿石自给率远不足50%。国内铁矿石资源严重短缺,必须扩大开发利用新的铁矿资源。在此背景下,我国储量近100亿t的高磷难选铁矿石的开发利用被提上日程。本论文以惠民原生矿石为原料,在系统的矿石工艺矿物学研究和大量试验研究的基础之上创造性地提出了“反浮选脱硫磷—钠盐催化还原焙烧—磁絮凝强化分选”的选冶联合新工艺,并获得良好的技术指标。该高效选冶技术的应用将对我国类似铁矿石的开发和利用具有一定的指导意义。矿石工艺矿物学研究结果表明,原矿铁品位30%左右,含磷约1%,含硫约1.4%。铁主要以菱铁矿的形式存在,其中含少量的磁铁矿,但有23.40%的铁以硅酸盐的形式存在；矿石中有害元素磷主要以胶磷矿的形式存在,硫主要以黄铁矿的形式存在。该矿石中矿物组成复杂、铁品位低、铁矿物嵌布粒度细、磷、硫含量高,这给高效回收利用该铁矿资源带来相当大的难度。在矿石工艺矿物学研究的基础上,首先进行了矿石可选性试验。结果表明,单一的选矿或单一的冶金方法都不是处理该矿石的有效方法,而有效地脱除硫磷杂质是开发利用该矿石的关键。为此,本论文创造性地提出了反浮选脱硫磷的新工艺。通过大量的试验研究,反浮选脱硫磷工艺在小型试验中获得含磷仅为0.27%、含硫0.34%、铁回收率为80.93%的分选指标。随后进行了1t/d规模的连选试验,并取得了与小型试验结果基本上一致的工艺指标。反浮选脱硫磷的新工艺虽能获得令人满意的工艺指标,但浮选系统中的药剂种类多,用量偏大。为简化反浮选脱硫磷工艺的药剂制度,进行了优化试验研究。脱磷优化试验研究结果表明,通过降低19.71个百分点的脱磷率,能大幅度地减少脱磷药剂的用量（矿浆pH调整剂用量由9000g/t减少到2500g/t、淀粉用量减少25.68%、捕收剂用量减少54.08%）,同时节省了调整剂SIS和水玻璃。针对优化试验中脱硫—脱磷联合流程中药剂的相互干扰,提出了“碱法优先脱硫的异步脱硫磷流程”,实现了单一脱硫流程和单一脱磷流程的有机联合,并获得了含磷0.48%、含硫0.38%、铁回收率为80.06%的分选指标。还原焙烧过程中的物相演变规律试验研究中考察了试验过程中各种工艺参数对铁精矿指标的影响。其优选的工艺参数为：还原温度1050℃,还原时间150min,M煤：M矿样为1：5、MNa2CO3：M矿为1：20,并采用XRD技术分析了还原温度和还原时间对铁矿物相变的影响。分析结果表明,菱铁矿的还原过程为菱铁矿-磁铁矿-金属铁的逐级还原过程,并伴有铁橄榄石的生成,提高还原温度及延长还原时间有利于金属铁矿相的增强。钠盐催化还原矿的磁选特性研究表明,当磨矿细度为-45μm粒级含量占90.45%、磁场强度为232kA/m时,磁选管分选的精矿品位为65.85%,含磷0.21%,铁回收率74.21%；鼓形湿式弱磁选机分选的铁回收率仅为68.55%。因此,如何有效地强化细粒级及微细粒级磁性矿物的回收将是改善弱磁选工艺指标的关键。还原焙烧及钠盐催化的理论研究中,进行了还原焙烧热力学计算和冶金动力学分析。热力学计算结果表明,菱铁矿磁化还原焙烧为吸热过程,1050℃时,其等压热效应为68856.67J/mol。采用SEM和EDAX技术分析了钠盐催化还原矿石的外观形貌和成分。分析结果表明,Na2CO3的添加能促进金属铁的重建和发育,铁粒的粒径随Na2CO3的添加量的增加而粗化。钠盐催化还原矿石的XRD分析结果表明,添加适量的Na2CO3 （MNa2co3:M矿为1：20-1：10）能强化菱磁铁矿的还原,还原矿中金属铁（Fe）衍射峰值明显增强,铁橄榄石（Fe2Si04）的峰值明显降低,但不添加Na2CO3或添加过量的Na2CO3将不利于菱铁矿的还原。同时,通过焙烧过程中胶磷矿形态变化的热力学计算表明,钠盐催化还原矿石中的胶磷矿并没有被还原成P2,提高磁性铁矿物与胶磷矿的解离度是制备合格铁精矿的有效途径。针对常规磁选设备不利于细粒级及微细粒级磁性铁矿物回收的问题,本论文提出了“磁絮凝强化分选”的新工艺。在自制的磁絮凝分选柱中考察了分选过程中各种工艺参数对铁精矿指标的影响。在最佳工艺参数下（磨矿细度-45μm占88.7%、切向水流量3L/min,搅拌强度250r/min）,一次磁絮凝分选所获得的铁精矿品位为66.32%、含磷0.21%、含硫0.28%、铁回收率74.26%。与鼓形湿式弱磁选机分选指标相比,铁回收率提高近6个百分点。磁絮凝分选有效地强化了细粒级及微细粒级磁性铁矿物的回收。针对惠民高磷、高硫、含铁贫的原生矿石,采用了全新的“反浮选脱硫磷—钠盐催化还原焙烧—磁絮凝强化分选”的选冶联合新工艺进行处理,所研发的新工艺的最终指标为：铁品位67%左右、含磷0.21%、含硫0.28%,综合回收率为60%,从而为下一步惠民原生矿石资源的开发利用奠定了重要的理论与试验基础。
【Abstract】 China has abundant reserves of iron ore in the world. However, the available iron ore resources tend to be poor-graded, fine-disseminated and mixed with impurity. With the continuous and rapid development of iron and steel industry, the contradiction between supply and demand of domestic iron ore has become more and more serious. At present, the domestic supply of iron ore is no more than 50%. For heavy shortage of iron ore reserves in China, exploiting new iron reserves is needed timely. On this background, the exploitation and utilization of approximately 10 billion tons of refractory high-phosphorus iron ore is proposed.Huimin primary iron ore was used as materials in the present study. Based on the investigation on properties of mineralogy and extensive experimental research, a novel dressing-metallurgy combination flowsheet consisting of removing sulfur and phorsphors by reverse flotation--odium-salt-added catalyst reductive roasting—magnetic flocculation was adopted for treating this ore, in order that the extreme difficulties might be overcome of exploitation of this iron ore. What’s more, the application of this creative technology would play an important role in the beneficiation and exploitation of similar refractory iron ore.Mineralogy analysis of run-of-mine indicated that it contains about 30% iron. The contents of P and S in the ore reached 1% and 1.4% respectively. The iron minerals were mainly siderite and small amounts of magnetite, additional 23.40% of iron minerals occurs as silicate.The phosphorous mainly occured as collophanite, while the sulfur occurs as pyrite. Because of its complex minerals composition, poor iron-content, fine-grained dissemination and high content of phosphorous and sulfur, the research on dressing and metallurgy process of this iron ore should be faced with considerable difficulties.Following tentative experiment was conducted, which indicated that a single mineral processing or a single metallurgy methods was never effective in dealing with the iron ore, and removal of sulphur and phosphorous impurities effectively would be key to exploitation and utilization of the ore. Therefore, a novel process of desulfurization and dephosphorization by reverse flotation was creatively put forward in this paper, which aimed at removal of the sulphur and phosphorous as much as possible on condition of guarantee of iron recovery. Through a great deal of laboratory experiment, a product with 0.27% phosphorous and 0.34% sulfur and iron recovery 80.93% was obtained by the combined process of desulfurization-dep hosphorization. Basing on the bench-scale test, a continuous test at 1d/t scale was carried out, which resulted a consistent technical indexes compared with those of bench-scale test. Satisfactory separation indexes were obtained by the novel process of desulfurization and dephosphorization by reverse flotation. However, large dosage and numerous types of reagents were the characteristic of the flotation system.Therefore, optimization experiments were carried out for simplification of the reagent system in reserve flotation. As a result, Dephosphorization agent was greatly reduced through decreasing the desorption rate of phosphorus by 19.77 percents(doseage of pulp pH adjustment agent was reduced from 9000g/t to 2500g/t, and 25.68% of starch and 54.08% of collectors were saved), meanwhile, the regulator SIS and sodium silicate were no longer used. Considering the mutual disruption of reagents used in desulphurization and dephosphorization, an asynchronous process of desulphurization and dephosphorizatio, with alkaline desulphurization preference was applied creatively. The process yielded a product of 0.48% for phosphorus content,0.38% for sulphur content and 80.06% for iron recovery.In this papar, the effects of altering parameters on indexes of the iron concentrate during the reduction roasting were studied. The optimized parameters were identified, that was 1050℃for reduction temperature,150min for reduction duration,1:5 for Mcoal:More and 1:20 for MNa2CO3:More 1:20. In order to identify the pattern of phase transitions of iron minerals with altering the reduction temperatures and reduction durations, SEM and EDAX analyses were employed. The results indicated the siderite was deoxidized according to the theory of Gradual Dcoxidizing, with the order of siderite-magnetite-metallic iron accompanied by the production of fayalite. Both increasing reduction temperature and extenting reduction duration were benefit for enhancement of the metallic iron phase.Fowlling the magnetic separation research of sodium-salt-added catalyst reductive roasting, a concentrate with 65.85% Fe, at a recovery of 74.21% and phosphorous content 0.21% was obtained on the condition of 90.45% below -45μm of grinding fineness and 232kA/m of magnetic field intensity. But only 68.55% of iron recovery could be obtained by wet drum type weak magnetic separation. Therefore, enhancement of the recovery of fine particles of magnetic minerals effectively would be principal to improve the indexes of low intensity magnetic separation.Study on mechanism of sodium-salt-added catalyst reductive roasting was conducted, in which the kinetics of thermodynamic calculations and metallurgical analysis were performed. Thermodynamic calculations showed that the magnetic roasting process of siderite is endothermic process. Speciafically, when the reduce temperature was 1050℃, the isobaric thermal effect of siderite was 68856.67J/mol. In order to observe morphology appearance and analyse mineral composition, SEM and EDAX analyses of sodium-salt-added catalyst reductive roasting sample were employed. The results showed that addition of Na2CO3 would promote reconstruction and development of metallic iron. What’s more, the more Na2CO3 was added, the larger iron particless sizes assembled. The results of XRD pattern of reductive roasting sample indicated it was hopeful to promote the reduction of siderite and magnetite when appropriate ratio of Na2CO3(MNa2CO3:More 1:20～1:10) was added to the test samples before reductive roasting. It was observed obviously in the XRD pattern that diffraction peak of metallic iron is increased markedly and diffraction peak of fayalite was significantly reduced. While no addition of Na2CO3 or excess addition of Na2CO3 would be harmful to reductive of siderite and magnetite. At the same time, thermodynamic calculations of collophanite morphological changes showed that the collophanite had not transformed to P2 during reductive roasting. Consequently, improving the degree of dissociation of iron and apatite would be an efficient way to acquire qualified concentrate.As traditional equipments were not good at recovering fine particles of magnetic iron minerals, a novel separation technology was applied in the present study, involving fine-grinding and then magnetic flocculation. The effects of parameters of flocculation on indexes of the iron concentrate were investigated through a self-made separation column and the optimum parameters were identified (grinding fineness was 88.7% below -45μm, tangential flow was 3L/min, stirring intensity was 250r/min,). Under the optimum conditions, the grade and recovery rate of the iron concentrate produced by single flocculation reached 66.32% and 74.26% respectively. Meanwhile, the contents of phosphorus and sulphur substantially declined to 0.21% and 0.28% separately. Compared to separation indexes by wet drum type weak magnetic separation, nearly 6% increase of iron recovery rate was obtained. It implied that the magnetic flocculation was capable to effectively recover fine particles of magnetic iron minerals.In summary, an innovative technology was conducted for processing the Huimin raw ores which were characterized of high contents of phosphorus and sulphur but a deficiency of iron. The technology consisted of reserve flotation for the desorptions of phosphorus and sulphur, sodium salt reduction roasting and magnetic flocculation in sequence, yielding a concentrate of 67% for iron grade,0.21% for phosphorus content,0.28% for sulphur content with a comprehensive recovery rate of about 60%. Undoubtedly, the progress made in this dissertation might supply a good base for exploitation of Huimin primary iron ore resources.