Effect of bastnaesite as reductant on hematite reduction during in-situ suspension magnetization roasting of refractory iron ore under neutral atmosphere

The iron tailings of Bayan Obo mines are solid waste,which occupies land area and also causes environmental pollution;however,this waste can be recycled.In this study,based on the characteristics of iron minerals and fluorocarbonate contained in Bayan Obo iron tailings,clean magnetization roasting of iron minerals by bastnaesite from iron tailings during in-situ suspension magnetization roasting in a neutral atmosphere was explored.The results show that for iron tailings with a mass of 12 g,a N_(2) gas flow rate of 600 mL/min,and roasting for 5 min at 800℃,iron concentrate with a 60.44%iron grade at an iron recovery of 76.04%could be obtained.X-ray diffraction analysis showed that the weak magnetic hematite was reduced to strong magnetic magnetite in the neutral atmosphere,without additional reductant.The kinetics of the magnetization roasting of mineral mixtures(bastnaesite and hematite)in a neutral atmosphere showed that the optimal reaction mechanism function was the three-dimensional diffusion model with activation energy of 161.8838 kJ·mol^(-1);this indicates that the reaction was a heterogeneous,diffusion-controlled solid-state reaction.

Thermodynamic Analysis of Formation of Fluoride from Gangue in Bayan Obo Iron Concentrate Containing Fluorite

In order to fill up the deficiency of the theoretical basis about fluoride formation during Bayan Obo iron concentrate roasting process, the thermodynamic conditions of the interactivity between the components of the gangue and calcium fluorite were studied by means of thermodynamic calculation, DTA-TG thermal analysis and XRD characterization. The results revealed that KF, NaF and SiF4 （gaseous） could he,formed during the roasting process, and the tendency of the generation of KF is greater than that of NaF or SiF4 in standard state. Besides, the results of roasting experiments showed that the products of KCaCO3 F and KCaF3 formed in the temperature range of 800-1250 ℃and KF appears when the roasting temperature was higher than 1250 ℃ in K2O-CaF2 system. For the Na2O-CaF2 system, the product of NaF appears at temperature higher than 1050 ℃. The formation reaction of gaseous SiF4 with solid phase CaO · SiO2 in SiO2-CaF2 system took place＂only＇at temperature higher than 1 150 ℃. In the natural potash feldspar-CaF2-CaO system, the fluorination reaction products involved KF at temperature higher than 1 270 ℃ , while in the natural aegirine-CaF2-CaO system, NaF formed at terhperature higher than 980 ℃ during roasting process.

Iron recovery and rare earths enrichment from Bayan Obo tailings using Coal-Ca(OH)2-NaOH roasting followed by magnetic separation

The recovery of iron and enrichment of rare earths from Bayan Obo railings were investigated using Coal Ca（OH） 2 NaOH roasting followed by magnetic separation. The influences of roasting temperature, roasting time, coal content, milling time, Ca（OH）2 dosage and NaOH dosage on the iron and rare earths recovery were explored. The results showed that the magnetic concentrate containing 70.01 wt. % Fe with the iron recovery of 94.34G and the tailings of magnetic separation containing 11.46 wt. % rare earth oxides （REO） with the REO recovery of 98. 19% were obtained under the optimum conditions （i. e. , roasting temperature of 650℃, roasting time of 60 min, coal content of 2.0%, milling time of 5 min, and NaOH dosage of 2.0%）. The Ca（OH）2 dosage had no effect on the separation of iron and rare earths. According to the mineralogical and morphologic analysis, the iron and rare earths of Bayan Obo tailings could be utilized in subsequent ironmaking process and hydrometallurgy process.

白云鄂博西矿含铁岩选矿工艺试验研究

为实现白云鄂博西矿TFe品位13%~16%铁素资源(含铁岩)的回收利用,本文以含铁岩为研究对象,通过采用化学分析、X射线衍射仪、光学显微镜等检测手段研究其矿石性质,并在此基础上进行系统的选矿试验。研究结果表明:该含铁岩中TFe品位13.14%,可回收的主要金属矿物为磁铁矿,占全铁比例为52.28%。含铁岩需破碎至−3 mm时才能获得TFe品位20%以上的预选粗精矿,且通过阶段破碎-分级预选流程试验可获得尾矿抛除产率56.01%、粗精矿TFe品位20.62%、磁性铁品位14.80%、TFe回收率69.19%、磁性铁回收率94.27%的技术指标,推荐采用三段破碎-两级预选-高压辊磨超细碎抛尾的原则流程作为预选技术改造方案。将预选粗精矿细磨至−0.045 mm含量85.80%时,经过两次弱磁选后最终获得TFe品位65.10%、TFe回收率50.25%、磁性铁回收率93.03%的合格铁精矿。该研究结果可为含铁岩的高效回收利用提供科学依据。

Reaction characteristics of carbon-bearing pellets of Bayan Obo lean iron ores in a static magnetic field

The use of low-grade,refractory and composite paragenetic mineral resources is necessary for overcoming the shortage of iron ore resources in China.As a solution to the treatment of such iron ores,the direct reduction of carbon-bearing pellets can ensure complete iron removal and the effective enrichment of other high-value elements.Thus,this technology enjoys a broad application prospect.However,there are several problems with low-temperature reduction,such as low iron ore reaction efficiency,long reaction time,and high energy consumption.To improve the low-temperature carbothermic reduction efficiency of iron ores,a static magnetic field with magnetic induction intensity of 1.0 T was introduced.An isothermal reduction experiment was conducted at 1223 K to study the low-temperature self-reduction characteristics of carbon-bearing pellets of Bayan Obo lean iron ores in the static magnetic field.Also,the acting mechanism of the magnetic field was explored from the perspective of the reduction process,reaction efficiency,phase composition,microstructure changes,and dynamic behavior of iron ores.The results showed that the magnetic field can increase the low-temperature reduction rate of carbon-bearing pellets of Bayan Obo lean iron ores.Under the conditions of reduction temperature of 1223 K,magnetic induction intensity of 1.0 T,and reduction time of 60 min,the reduction degree was 92.42%,1.65 times that without a magnetic field.The magnetic field promoted the replacement of Ca^(2+)and Fe^(2+),so that the hard-to-reduce iron-bearing silicates were reduced in the order of Fe2SiO_(4)→(Ca,Na)FeSiO_(4)→FeO→Fe.The magnetic field enabled loose minerals,more pores and cracks,and changes in the growth morphology and distribution position of metallic iron.Compared with the case under the non-magnetic condition,the metallic iron precipitated from the slag phase in a foliated shape,separated from the matrix iron oxides,and grew up at the junction of the slag phase and coke.The magnetic field significantly increased the interfacial chemical reaction rate of the carbothermic reduction of iron ores and reduced the internal diffusion resistance of gas in the product layer.Specifically,the interfacial chemical reaction rate increased by 138%and the internal diffusion coefficient increased by 309%.Therefore,the effect of the magnetic field on the internal diffusion resistance was the main cause for strengthening the low-temperature reduction of iron ores.

白云鄂博某选厂选铁尾矿中稀土和萤石的综合回收试验研究

白云鄂博铁矿是世界上罕见的大型多金属矿床,多年来只作为铁矿和稀土矿进行开发,选别流程中稀土回收率较低,造成大量稀土资源和矿体中蕴含的萤石资源随着选铁尾矿排入到尾矿库中。为综合回收稀土和萤石资源,以白云鄂博某选厂选铁尾矿为研究对象,开展综合回收稀土和萤石的研究,采用的工艺流程为稀土浮选—萤石预选—萤石精选—强磁选。稀土浮选以水玻璃为抑制剂、SR为捕收剂、2#油为起泡剂,萤石预选以水玻璃为抑制剂、SF为捕收剂,萤石精选以酸性水玻璃为调整剂、SY为抑制剂、油酸钠为捕收剂,最终获得了REO品位50.54%、REO回收率92.32%的稀土精矿和CaF_(2)品位95.51%、回收率50.98%的萤石精矿。

白云鄂博矿床东矿段深部及白云向斜核部探矿的可行性探讨

白云鄂博东矿(铁矿石)已属于轻度危机矿山,解决白云鄂博东矿的资源接续问题已迫在眉睫。依据老地质资料和生产过程中的新发现,参考多位矿床成因研究专家的成果,笔者等认为在白云鄂博东矿体深部及白云向斜核部探矿是可行的。

内蒙古包头铁矿区土壤重金属污染特征及其评价

对位于内蒙古草原生态系统的包头尾矿库区和白云鄂博铁矿开采区土壤中重金属的污染状况进行了调查研究,旨在为治理草原矿区的土壤重金属污染提供理论依据.结果表明,包头尾矿库区周围不同方向的土壤都受到了重金属Pb、Cu、Zn和Mn的污染,单项污染指数法评价表明各重金属污染程度为Mn>Zn>Pb>Cu;内梅罗综合污染指数法评价表明,尾矿区东北、东南、西南、西北方向土壤重金属综合污染指数分别为2.43、10.2、1.88、1.64,主要受包头尾矿区常年主导风向西北风的影响,处于下风向的东南方位污染最为严重;除Cu外,尾矿库区各方位土壤重金属污染最严重为距尾矿库边缘50 m范围以内的区域.对于白云鄂博采矿区,单项污染指数评价表明,调查的6个区域内土壤也都受到了重金属Pb、Cu、Zn和Mn不同程度的污染;内梅罗综合污染指数评价表明,采矿区、排土场、场区外、城区外、铁路东侧和铁路西侧区域的土壤重金属综合污染指数分别为14.3、4.30、2.69、3.41、2.88、2.20,污染程度最严重的是采矿区内的土壤,另外铁路运输矿石也已经造成了沿线土壤的重金属污染.包头尾矿库区和白云鄂博采矿区的土壤具有相似的重金属污染特征,与尾矿砂中同种重金属浓度相对应,已经对当地草原生态系统的健康稳定构成了威胁.

白云鄂博稀土铁共生矿矿工肺内钍活度调查与评价的最新结果

目的弄清白云鄂博稀土铁矿在1983-2001年间长期吸入含钍稀土粉尘矿工肺内钍沉积量平均值、最高值及达到一个调查水平人数,并对其作出卫生评价。方法用静电负高压呼出气中钍射气子体收集测量系统,获得每名被测矿工肺内钍的沉积量。结果751名矿工1 270人次的测定结果表明,其肺内钍沉积量平均值为1.576 Bq,最高值为11.11 Bq;肺内钍沉积量达到1个调查水平者占被检总人次的22.91%。结论调查结果表明该矿接尘矿工肺内钍沉积量的平均值与最高值和1983-1994年的调查结果一致。但由于有一定数量的矿工肺内钍沉积量达到了一个调查水平,该矿防护措施仍需加强。