Rare Earths, Niobium and Tantalum Minerals in Bayan Obo Ore Deposit and Discussion on Their Genesis

Bayan Obo ore deposit is endowed with and lie hidden in the Proterozoic strata. The localities and occurfences of the minerals in the ore deposit were described. It is obviously that some minerals are strata minerals and some are post-strata minerals. The rare earths, niobium and tantalum minerals are exactly the post-strata minerals. In these minerals the hydrothermal metasomatic phenomena distinctly reveal their metallogenic characteristics. According to tectonic movement, magma activity, mineral paragenesis, hydrothermal metasomatism, geological age and lasting time-scale of metallogenesis, and some other factors, it is supposed that genesis of rare-earths, niobium and tantalum minerals in Bayan Obo ore deposit are closely related with hydrothermal metallogenic solution which is differentiated from silica acid and carbonic acid magma and derived from deep seated source, and then intruded into Proterozoic strata and metasomatized. It is recognized that the metallogenesis of Bayan Obo ore deposit is undergoing a long geological period and many episodes.     

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

The recovery of iron and enrichment of rare earths from Bayan Obo tailings were investigated using CoalCa(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 94.34% 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°C,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.     

Recovery Behavior of Rare Earth from Bayan Obo Complex Iron Ore

A novel process is presented for recovering rare earth from Bayan Obo complex iron ore. The iron ore was reduced and melting separated to produce iron nugget and rare-earth-rich slag. In order to investigate the influence of cooling rate on mineral components, especially the enrichment behavior of RE-containing mineral, the slag was remelted at 1673 K (1400 °C) and the liquid slags were cooled using three types of cooling conditions, water quenching, air cooling, and furnace cooling. Subsequently, the slags were leached by hydrochloric acid to evaluate the relations between leaching efficiency of rare earth and cooling conditions. The results indicated that the slags under different cooling conditions mainly contained fluorite, cefluosil, and cuspidine. The rare-earth mineral is more fully crystallized when the cooling rate of the liquid slag was decreased. The proportion of Ce (III) to Ce (IV) increases with the increase of heating time and decrease of cooling rate. It has been found that the influence of cooling rate on the leaching rate of the rare earth is slight. From water quenching to furnace cooling, the leaching rate of rare earth increases from 97.00 pct to 99.48 pct. After being filtered, filtrate can be used to produce rare-earth chloride. Leached residue, with CaF₂ of 64.45 pct and ThO₂ of 0.05 pct, can be used to recover CaF₂ and extract nuclear source material.     

电感耦合等离子体质谱法测定白云鄂博矿石中15种稀土元素总量及其分量

白云鄂博矿物为典型的晶格型矿物,含有铌、锆、钛等难溶金属的矿物,常规酸溶法处理难以将其溶解完全。采用氢氧化钠和过氧化钠碱熔融分解白云鄂博矿石样品,热水浸取,碱分离后,用盐酸和过氧化氢破坏滤纸和溶解沉淀,以1%盐酸为测定介质,通过控制基体质量浓度不大于0.5 g/L和采用Cs内标进行校正以消除基体效应,建立了电感耦合等离子体质谱法(ICP-MS)测定白云鄂博矿石中包括镧、铈、镨、钕、钐、铕、钆、铽、镝、钬、铒、铥、镱、镥、钇在内的15种稀土元素含量及其总量的方法。实验表明,各稀土元素在质量浓度为5.00~100.0 ng/mL(以氧化物计,下同)范围内和稀土元素与内标元素的强度比呈良好的线性关系,相关系数均不小于0.999 6。方法检出限为0.010~0.034 ng/mL,定量限为0.030~0.10 ng/mL。按照实验方法对白云鄂博矿石样品中稀土元素总量及其分量进行测定,测定结果与电感耦合等离子体原子发射光谱法或X射线荧光光谱法基本一致;相对标准偏差(RSD,n=6)在1.0%~4.9%之间,加标回收率在95%~105%之间。将实验方法应用于稀土矿石成分分析标准物质中稀土元素总量及其分量的测定,结果与认定值基本一致。     

电感耦合等离子体质谱法测定白云鄂博矿石中15种稀土元素总量及其分量

白云鄂博矿物为典型的晶格型矿物,含有铌、锆、钛等难溶金属的矿物,常规酸溶法处理难以将其溶解完全。采用氢氧化钠和过氧化钠碱熔融分解白云鄂博矿石样品,热水浸取,碱分离后,用盐酸和过氧化氢破坏滤纸和溶解沉淀,以1%盐酸为测定介质,通过控制基体质量浓度不大于0.5 g/L和采用Cs内标进行校正以消除基体效应,建立了电感耦合等离子体质谱法(ICP-MS)测定白云鄂博矿石中包括镧、铈、镨、钕、钐、铕、钆、铽、镝、钬、铒、铥、镱、镥、钇在内的15种稀土元素含量及其总量的方法。实验表明,各稀土元素在质量浓度为5.00~100.0 ng/mL(以氧化物计,下同)范围内和稀土元素与内标元素的强度比呈良好的线性关系,相关系数均不小于0.999 6。方法检出限为0.010~0.034 ng/mL,定量限为0.030~0.10 ng/mL。按照实验方法对白云鄂博矿石样品中稀土元素总量及其分量进行测定,测定结果与电感耦合等离子体原子发射光谱法或X射线荧光光谱法基本一致;相对标准偏差(RSD,n=6)在1.0%~4.9%之间,加标回收率在95%~105%之间。将实验方法应用于稀土矿石成分分析标准物质中稀土元素总量及其分量的测定,结果与认定值基本一致。     

白云鄂博高品位混合稀土精矿特性分析

随着稀土选矿技术的日趋进步,白云鄂博稀土精矿的品位提升至65％以上,且可进行大规模的生产应用.以白云鄂博高品位混合型稀土精矿为研究对象,采用XRD、EDS、SEM、AMICS等表征手段对高品位稀土精矿进行系统研究.研究结果表明,高品位精矿中REO品位为67.96％,轻稀土元素占稀土总量的98.65％,属典型富铈低钇型轻...     

Phase change,micro-structure and reaction mechanism during high temperature roasting of high grade rare earth concentrate

The deposit of Bayan Obo in Inner Mongolia is the world's largest rare earth element(abbreviated as REE)resource.The exploration of the theory of mineral formation of Bayan Obo is an important foundation for mineralogical research,and is the scientific basis for mining,industrial beneficiation,smelting and extraction,and processing and utilization.With the rapid development of science and technology,the demand for the utilization of rare earth elements is increasing,and the separation process between rare earth elements needs to be developed.The purpose of this paper is to provide high temperature experimental information for the formation and application of rare earth minerals.To this end,the mineral evolution of high-grade rare earth concentrates with increasing temperature and the migration of rare earths at different stages and their reaction mechanisms were studied.According to thermogravimetric analysis and differential scanning calorimetry(TG-DSC),calcination was carried out at different temperature ranges,and the calcined products were characterized by X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FT-IR),scanning electron micro scope and energy dispers ive spectrometer(SEM-EDS)and other analytical techniques.The re sults are shown in this process,the ra re earth phase is first converted into rare earth oxide and rare earth oxyfluoride.As the temperature increases,Ca_5(PO_4)_3 F and a large number of self-shaped spherical Ca-RE-OF and Ca-RE-PO_4 particles are formed,and the separation of La and Ce elements is discovered.Acco rding to the phase diagram analysis,the production of Ca_5(PO_4)_3 F is due to the reaction of monazite and fluorite,and the phases CeF_2 and Ce F_3 are formed during the reaction.When it reaches 1500℃,barium ferrite is produced and a new substance containing Ba~(2+)is formed.     

Geochemical Characteristics of a Carbonatite Dyke Rich in Rare Earths from Bayan Obo, China

Since the discovery of the carbonatitedykes at Bayan Oho of inner Mongolia, Chi..[l], more and more evidence from geologicaland geochemical investigations reveal that theore-hosted dolomite marble of the Bayan OboRE-Nb-Fe giant mineral deposit is similar tocarbonatite in origin['~7]. Although it is notfully clear at present whether there is a realpetrogenetic linkage between the formation ofthe ore deposit and the intrusion of the carbonatite dykes, there is no doubt that the studiesof the …     

Rare earth extraction and separation from mixed bastnaesite-monazite concentrate by stepwise carbochlorination-chemical vapor transport

A stepwise carbochlorination-chemical vapor transport (SC-CVT) process is proposed for the rare earth extraction and separation from a mixed bastnaesite-monazite concentrate based on thermodynamic and kinetic analysis using carbon as reductant, chlorine gas as chlorination agent, SiCl₄ as defluorination agent, and AlCl₃ as vapor complex former. Between 500 °C and 800 °C, apparent activation energy of the carbochlorination within 2 hours changed from 22 to 16 kJ/mol roughly for the initial half hour and final 1 hour, respectively, in the absence of SiCl₄; but these values reduced to 15 and 2.1 kJ/mole under 2 kPa of SiCl₄ gas. The rare earth chloride yield for 2 hours was 56 to 88 mol pct in the absence of SiCl₄ and 92 to 99 mol pct in the presence of SiCl₄; but carbochlorination at above 1000 °C yielded a large amount of acid-insoluble residue. This, together with the negligible equilibrium vapor pressure of ThCl₄ at below 600 °C, suggests that carbochlorination of the mixed concentrate at temperatures as low as 500 °C in the (Cl₂ + SiCl₄) atmosphere is suitable for rare earth extraction and thorium-free volatile by-product release, which is different from the conventional Goldschmidt process at 1000 °C to 1200 °C. The CVT reaction of the carbochlorination product was performed at 800 °C for 0.5 hours in the (Cl₂ + SiCl₄ + AlCl₃) atmosphere and then at 1000 °C for 6 hours in the (Cl₂ + AlCl₃) atmosphere along different temperature gradients, leading to complete thorium removal and efficient rare earth separation, respectively. Their combination allows an efficient and environmentally conscious extraction and separation of rare earth elements from the mixed concentrate.     

Rare earth extraction from bastnaesite concentrate by stepwise carbochlorination-chemical vapor transport-oxidation

A stepwise carbochlorination-chemical vapor transport-oxidation process is developed for the green rare earth extraction from a bastnaesite concentrate using carbon as reductant, chlorine gas as chlorination agent, SiCl₄ gas as defluorination agent, AlCl₃ as vapor complex former, and (O₂+H₂O) mixed gas as oxidant. Between 500 °C and 800 °C, the apparent activation energy of the carbochlorination within 2 hours changed from 17 to 10 kJ/mole roughly for the initial 20 minutes and final 1.5 hours, respectively, in the absence of SiCl₄, but these values reduced to 15 and 5.9 kJ/mole under 10 kPa of SiCl₄ gas, while the rare earth chloride conversion for 2 hours was 43 to 81 mol pct in the absence of SiCl₄ and 55 to 99 mol pct under 10 kPa of SiCl₄ gas. After carbochlorination at 550 °C for 2 hours in the (Cl₂+SiCl₄) atmosphere for efficient rare earth extraction and thorium-free volatile by-product release, throium was removed by chemical vapor transport at 800 °C for 0.5 hours in the (Cl₂+SiCl₄+AlCl₃) atmosphere and alkaline earths were separated from rare earths by oxidation at 700 °C to 1000 °C in the (O₂+H₂O) atmosphere for 0.5 hours, followed by water leaching at room temperature. Their combination allows a clean and efficient rare earth extraction from the concentrate.     

镁钙铵系浸取剂对离子吸附型稀土矿区土壤生态影响初探

离子吸附型稀土矿富含宝贵的中重稀土战略资源,工业开采过程产生的氨氮污染问题长期备受关注。分别以硫酸镁、氯化钙和硫酸铵柱浸模拟离子吸附型稀土矿浸取尾矿,以中黄13大豆为供试作物,开展了室外盆栽试验,探究其对离子吸附型稀土矿区土壤的生态影响。结果表明,与采用铵浸尾矿种植相比,采用镁浸或钙浸尾矿种植的豆苗株高相当或更高,叶片的叶绿素含量更高或相当,根系生长正常,主根明显,侧根茂盛,且地径明显更粗,这可能与镁、钙等能直接参与叶绿素合成、加速糖分运输、改善土壤板结等有关。与采用硫酸铵浸取剂浸矿相比,采用硫酸镁、氯化钙浸取剂浸矿对离子吸附型稀土矿区土壤的生态影响更小,这也为离子吸附型稀土矿绿色开采和浸矿场地污染防治指明了发展方向。     

含铌铁矿粉氢气选择性还原过程中磷行为

 对白云鄂博含铌铁矿粉氢气选择性还原-熔分-铌铁冶炼的提铌方案中磷的行为进行试验研究。在该试验条件下,磷质量分数为0.100%的含铌铁矿粉通氢气还原后熔分,得到磷质量分数小于0.010%、铌质量分数为2.000%的富铌渣,铁中铌质量分数为0.008%、磷质量分数为0.230%,铌磷分离效果明显,同时熔分后铌品位是原来的3.5倍。试验结果表明,氢气在还原阶段能够在还原铁氧化物的同时将Ca3P2O8还原,通过熔分达到铌与磷、铁元素等分离的目的,铌有效地富集在渣中。     

白云鄂博铁球团矿异常还原膨胀的机理

通过对比白云鄂博铁矿、精矿及还原前后球团矿的显微结构,对白云鄂博球团矿异常还原膨胀的机理进行研究。研究结果表明,球团矿气孔中挥发分的爆发扩大了基体裂块间的孔隙,加快了还原气体的扩散,增加了反应面积,使还原速度加快,从而导致了球团矿恶性膨胀。白云鄂博球团矿的“挥发分膨胀理论”是一种全新的理论,对抑制白云鄂博球团矿的恶性膨胀具有重要指导意义。     

Development of a high-performance green Fe–Al2O3 composites using Bayan Obo minerals: Enhancement effects of CeO2

With the deepening understanding for the concept of sustainable development, the utilization of minerals is no longer limited to the traditional way. In this study, an environment friendly method for preparing Fe–Al₂O₃ composites by using natural minerals was investigated. Additionally, the effects of CeO₂ on the properties of composites were studied. The mechanical properties of Fe–Al₂O₃ composites prepared by natural minerals are affected by the brittleness of glass phase. The strength and toughness of the glass phase in the composite are improved successfully by using rare earth oxides, indicating that the natural rare earths in Bayan Obo minerals have an enhanced influence on the properties of composite materials. The results show that the properties of glass phase can be significantly improved by addition of CeO₂. At the optimal addition of 3 wt% CeO₂, the composite achieves the density of 4.21 g/cm³, flexural strength of 401 MPa, Vickers hardness of 13.07 GPa and fracture toughness of 6.58 MPa⋅m^1/2. The composite has excellent mechanical properties, which can be used in engineering as a cheap structural material. This study aims at reducing waste emissions, improving energy efficiencies and avoiding waste of rare earth resources during the preparation of composite materials.     

包头白云鄂博矿钍资源的回收及用于核电燃料的研究现状

包头白云鄂博矿中钍资源非常丰富，近年来随着铁矿石的开采，钍被分配到一些产品或废渣中，这不仅造成钍资源的严重浪费，同时分散了的放射性钍给周边环境造成了严重污染。针对目前世界能源紧张的状况，开发新的能源势在必行，钍作为核能发电燃料的研究近年来已有突破，研究开发钍用于核电燃料研究是一项重大和长远的任务。全面分析了包头白云鄂博钍的资源现状及流向，介绍了在生产稀土的同时提取钍化合物、金属钍的工艺研究状况及钍用于核电燃料的研究进展，探讨了钍在核电燃料中的应用可行性及应用前景。     

包头强磁粗精矿还原焙烧-磁性分离提高铁精矿品位及降低稀土、铌含量的研究

包头选矿厂现流程中强磁粗选铁精矿含稀土及铌矿物较高,用强磁精选分离铁与硅、稀土、铌,效果不很理想,稀土及铌矿物在强磁精选铁精矿中的损失率较高,对后续工艺回收稀土和铌都将产生较大影响。通过对强磁选粗精矿进行了还原焙烧—磁性分离的探索试验,取得了铁精矿含铁63.53%,铁回收率77.97%,其中含REO降至1.35%,Nb2O5降至0.16%,在铁精矿中稀土损失率降至6.04%,铌的损失率降至26.44%,分选指标较好。     

Extraction of tantalum and niobium from tin slags by chlorination and carbochlorination

Chlorination and carbochlorination of tantalum and niobium low-grade concentrate (LGC) and high-grade concentrate (HGC), obtained by leaching of tin slag, were studied using Cl₂ + N₂ and Cl₂ + CO + N₂ gas mixtures. Thermogravimetric analysis and conventional boat experiments were performed between 200 °C and 1000 °C. Chemical analysis, X-ray diffraction (XRD), and scanning electron microscopy (SEM) were used to characterize the samples and reaction products. Chlorination of LGC led to the recovery of about 95 pct of tantalum and niobium compounds at 1000 °C. However, the tantalum and niobium chlorinated compounds were contaminated by chlorides of Fe, Mn, etc. For HGC, chlorination at 1000 °C allowed the extraction of about 84 and 65 pct of the niobium and tantalum compounds, respectively. The recovered condensates were composed of pure tantalum and niobium chlorinated compounds. The apparent activation energies E _a for the chlorination of LGC and HGC, between 850 °C and 1000 °C, were 166 and 293 kJ/mole, respectively. At temperatures lower than 650 °C, the apparent activation energies for the LGC and HGC carbochlorination were 116 and 103 kJ/mole, respectively. Total extraction of the tantalum and niobium compounds was achieved by the carbochlorination of the LGC at 1000 °C. The generated tantalum and niobium chlorinated compounds were contaminated by the chlorides of Fe, Mn, Al, and Ca. The carbochlorination of the HGC at 500 °C allowed complete extraction and recovery of pure tantalum and niobium compounds. These results confirm the importance of obtaining an HGC from tin slag before its subsequent chlorination. The carbochlorination of such a concentrate could be an efficient process for the recovery of relatively pure tantalum and niobium chlorinated compounds at low temperatures.     

微生物技术在稀土资源利用中的研究进展

主要介绍了稀土资源的重要作用及利用现状,对我国的稀土矿分布及特征进行概述,并提出稀土开采存在的问题及微生物采矿的优势。回顾利用微生物进行稀土矿开采的发展进程,总结其研究进展,介绍微生物采矿作用机理的研究,主要包括微生物浸出、吸附和积累稀土元素机理的相关研究,以及稀土矿采矿微生物的分离方法及种属分布等。以中国白云鄂博矿床和澳大利亚Mount Weld矿床中的矿石为例,说明微生物对矿石中稀土元素的提取作用。简述微生物对废弃物中稀土元素的回收作用,及微生物利用稀土元素技术将面临的挑战,并对其未来进行了展望。      

超声波强化浸取离子型稀土矿中稀土

利用超声波的空化作用可有效强化南方离子型稀土矿中稀土的浸出,从而提高稀土浸出率并缩短矿物中稀土总量的分析时间。在20 g/L的硫酸铵浸矿液中超声浸矿30 min,可使离子型稀土的浸出率达99%以上,而传统搅拌法需4 h,甚至浸取过夜。超声法与搅拌法对干扰杂质铁、铝的浸出率相近,加入乙酰丙酮及磺基水杨酸等掩蔽剂后不影响EDTA滴定稀土时的终点判断,且测定结果与电感耦合等离子体发射光谱法测定结果一致性好。     

风化型稀土矿的矿石性质研究

本文研究分析了产于我国两类特有的风化型稀土矿矿石性质。发现风化淋积型稀土矿中稀土赋存是以羟基水合离子吸附在粘土矿物上，矿石具有含水多样性，酸碱缓冲性，吸附稀土离子的化学稳定性和可交换性，稀土配分类型多样性及铈亏效应。黑色风化矿泥中稀土是以胶态沉积相均匀分散在Ｍｎ－Ｆｅ氧化物表面赋存，矿石是非晶相的含稀土泥状集合体，稀土配分是典型的轻稀土配分选择型。