【作者】 朱忠平；

【导师】 姜涛； 李光辉；

【作者基本信息】 中南大学 ， 钢铁冶金， 2011， 博士

【摘要】 随着我国冶金工业的快速发展,铝土矿石和铁矿石的消耗量大幅度上升,国内铝土矿和铁矿的供需缺口越来越大,对外依存度日益提高,对国内高铁铝土矿的开发具有重要的现实意义。高铁三水铝石型铝土矿(以下简称为高铁铝土矿)是公认的难选难冶矿石,在我国储量很大。本论文以广西某高铁三水铝石型铝土矿为对象,开展了铁、铝、硅、钒、镓等综合利用新工艺的基础研究。采用光学显微镜、XRD、 SEM及电子探针等微观测试方法对高铁三水铝石型铝土矿工艺矿物学进行了详细研究,发现铁主要存在于针(赤)铁矿中,而铝主要存在于三水铝石中；针(赤)铁矿中含有铝元素,Al2O3含量的质量比从17%到39%不等,而三水铝石中也都含有铁元素,Fe2O3含量的质量比从15%～25%不等,这些嵌布粒度小于5μm、嵌入在铁矿内的Al2O3和嵌入在三水铝石内的Fe2O3,导致选矿方法无法将它们分离出来。采用热力学计算和绘图等方法研究了矿石中的铝、铁、硅等组份在不同气氛下焙烧时的物理化学行为。研究发现,在低于1500K的温度范围,在氧化性气氛下加热高铁铝土矿不能改变铝、铁、硅的赋存关系；Na2CO3或Na2SO4存在的条件下还原焙烧时,Al2O3和SiO2优先与钠盐反应生成铝硅酸钠,其次是硅酸钠,再次是铝酸钠；Na2SO4容易被还原为Na2SO3, Na2SO3性质不稳定易发生分解而生成Na2S和Na2SO4; Na2SO3与Al2O3和SiO2反应的规律与Na2SO4相同；Na2S不能直接与Al2O3.SiO2发生反应,但在FeO的参与作用下可与Al2O3. SiO2反应,其规律与Na2SO4的相同；钠盐存在时,在适宜的温度及还原气氛下,铁氧化物可还原成金属铁,而铝和硅转换成铝硅酸钠、硅酸钠或铝酸钠。在上述理论研究的基础上,开发了还原焙烧-磁选-浸出综合利用高铁三水铝石型铝土矿的新工艺。通过还原焙烧-磁选研究,获得了优化的焙烧和磁选工艺参数。在Na2SO4质量比15%、硼砂质量比2%、Na2CO3质量比25%、还原焙烧温度1050℃、还原焙烧时间60min、细磨至-0.074mm95.5%～96.0%,磁场强度975Gs的条件下,获得了TFe含量93.73%、Al2O3含量1.21%的磁性物和TFe含量6.73%、Al2O3含量40.56%的非磁性物(富铝渣)产品,铁回收率93.07%。机理研究表明,在钠盐还原焙烧中,硼砂具有助熔作用,碳酸钠以固相扩散反应为主,硫酸钠以液相反应为主,添加剂的添加促进了铁晶粒的长大和铝/铁的分离。化学分析及XRD物相分析表明,焙烧矿主要由金属铁、铝硅酸钠组成,其余还有少量未还原完全的铁氧富氏体及还原焙烧过程中生成的硫化亚铁；磁性物主要成分为金属铁；非磁性物主要成分为铝硅酸钠,其余还有少量硫化亚铁、硅酸亚铁和未分离完全的金属铁。进而研究了从富铝渣(非磁性物)中回收和分离铝、硅和钠的方法和工艺技术。研究发现,硫酸浸出可将富铝渣中的铝、硅、钠同时转入溶液。获得了浸出的最佳工艺条件：H2SO4浓度30%、浸出温度30℃、浸出时间30min、液固比10：1、搅拌速度200r/min。在此条件下,富铝渣中A12O3、 SiO2和Na2O浸出率分别达到89.37%、89.12%和96.46%。为从浸出液中分离铝、硅和钠,采用浓硫酸酸化首先分离出硅,再利用硫酸铝和硫酸钠溶解度的差别,采用蒸发结晶方法实现铝、钠的分离。获得了硫酸酸化分离SiO2的最佳条件是H2SO4浓度70%、浸出温度90℃、浸出时间120min、液固比10：1、搅拌速度500r/min。在此条件下,Si02分离率达到98.32%。查明了在还原焙烧-磁选-浸出过程中高铁三水铝石型铝土矿中镓和钒的走向。研究发现,镓几乎全部进入磁性物质中,可以在金属铁中得到回收；80%以上的钒进入非磁性物中,非磁性物经酸浸后,钒主要到浸出渣中,可以在浸出渣中加以回收。在工艺技术研究的基础上,推荐了还原焙烧—磁选—浸出法综合利用高铁三水铝石型铝土矿的新工艺流程,与已公开发表“先铁后铝”工艺相比,该流程具有工艺简单、投资成本低、废弃物排放少、综合回收利用率高的优点。本论文的研究为高铁三水铝石型铝土矿的综合利用提供了新的途径。更多还原

【Abstract】 With the rapid development of metallurgical industry in China, the consumption of the ore resources raises greatly. While the shortage of domestic bauxite and iron ores is becoming more and more severe, the amount of imported bauxite ores is increasing year by year; therefore, it is of a great significance to utilize domestic high iron bauxite ores. High iron gibbsite-type bauxite is a kind of refractory ores, and it has a large reserve in China and the rest of Southeast Asia countries. In this thesis, a basic research of a new process for the comprehensive utilization of iron, aluminum, silicon, vanadium, gallium etc. was carried out by using Guangxi high-iron gibbsite bauxite as raw materials.Measurement methods, including optical microscope, X-ray diffraction (XRD), Scanning electronic microscope (SEM) and electronic probe, etc. were used to study process mineralogy of the ore. Results obtained show that, iron element mainly occurs in goethide, and aluminum element mainly occurs in gibbsite, goethite contains aluminium and silicon elements, the content of A12O3within the goethide varies from17%to39%; and gibbsite also contains iron and silicon elements, the contents of Fe2O3within the gibbsite varies from15%to25%; the crystalline size of the aluminiferrouse minerals embedded in goethide and the ferrouse minerals embedded in gibbsite are less than5μm.Therefore, it is difficult to separate Fe, Al, Si from the ore by physical methods.The thermodynamics of CaO-Fe2O3-Al2O3-SiO2system indicates that it is impossible to separate aluminum, iron, silicon ingredients in oxidizing atmosphere. Reduction thermodynamics studies show that the sodium salts are capable of reacting with Al2O3and SiO2and forming sodium aluminosilicate, sodium silicate, sodium aluminate in turn; Na2SO4is easily reduced to Na2SO3, while unstable Na2SO3is easy to decompose into Na2S; the reaction of Na2SO3has the same regulation as Na2CO3and Na2SO4when reacting with Al2O3and SiO2; Na2S does not react directly with A12O3and SiO2, but it is capable of reacting with them in the presence of FeO. Based on the fundamental investigations, the new process of reduction roasting-magnetic separation-acid leaching for comprehensive utilization of high iron gibbsite-type bauxite ores was proposed and studied. The effect of the process parameters on the separation of iron, aluminum and silica was studied by reduction roasting and magnetic separation, the results show that aluminum and iron is capable of be separated under the condition of15%mass ratio Na2SO4,2%mass ratio borax,25%mass ratio Na2CO3, reduction roasting temperature of1050℃, reduction roasting time of60min, grinding pulp concentrate of50%, particle size of-0.074mm varies form95.5～96.0%and magnetic field intensity of975Gs; a magnetic product with TFe93.73%and Al2O31.21%, and a non-magnetic product with Al2O340.56%and TFe6.73%are obtained under above conditions; the magnetic separation recovery of iron reaches93.07%.Mechanism research shows that sodium salts promote the growth of metallic iron grain and enhance the separation of Al and Fe. Chemical analysis and XRD analysis show that the reduced pellet is mainly composed of metallic iron and sodium aluminosilicate, and main composition of the magnetic material is metallic iron, while main composition of nonmagnetic material (high-aluminium slag) is sodium aluminosilicate.The technologies recovering Al, Si and Na from nonmagnetic material were studied further. Sulfuric acid leaching is found to be one of effective methods. The optimum technological conditions of leaching high-aluminum slag in laboratory are obtained as H2SO4concentration30%, leaching temperature30℃, leaching time30min, liquid-solid ratio10:1, stirring speed200r/min. Under these conditions, the recovery of89.37%for Al2O3,89.12%for SiO2and96.46%for Na2O were achieved. The conditions of SiO2separation from the leaching solution is found to be H2SO4dosage70%, temperature90℃, time120min, liquid-solid ratio10:1, stirring speed500r/min, the recovery of SiO2is98.32%at the conditions.It has been found that gallium in high-iron bauxite goes into metallic iron, while more than80%of the vanadium goes into the nonmagnetic material and can be recycled from the leaching residue.On the basis of above investigations, a new process of comprehensive utilization of iron, aluminum, silicon, gallium and vanadium was first put forward. The process has many advantages such as short flowsheet, low investment cost, low waste disposal and high recovery efficiency over the process of First-Iron-then-Aluminium already published.The results provide a new way for the comprehensive utilization of high iron bauxite ores.更多还原