Recovery of iron from Baotou rare earth tailings by magnetizing roast

The difference of physicochemical properties among minerals in Baotou rare earth tailings is not significant,which leads to a great difficulty in separation of minerals.In this article,the process of magnetizing roast and low-intensity magnetic separation was used to recover iron.Effect of calcination temperature,holding time and carbon/oxygen ratio on roasting efficiency was investigated.The parameters evaluating magnetizing roast efficiency and theoretical value were determined.X-ray diffraction(XRD)analysis was used to investigate the conversion of Fe phase after roasting.The results show that the best magnetizing roast conditions are calcination temperature of 650℃,holding time of 2.5 h,and carbon/oxygen molar ratio of 3.85.The best magnetization rate is 2.36,which is close to the theoretical value of 2.33.Based on experiments of low-intensity magnetic separation under different intensities,the best current intensity is 2.0 A to obtain the best separation results.Under the best condition,the concentrate grade of iron is 45.45% and the recovery of iron is 68.36%.Most of rare earth,fluorine,and phosphorus are enriched in the magnetic separation tailings.The XRD analysis shows that Fe exists in Fe2O3 before roasting and exists in Fe3O4after roasting.

Enhancing the leaching effect of an ion-absorbed rare earth ore by ameliorating the seepage effect with sodium dodecyl sulfate surfactant

Ameliorating the problem of low leaching efficiency,long leaching period,and high agent consumption should be studied to efficiently exploit ion-absorbed rare earth ore resources.In this study,the surfactant sodium dodecyl sulfate(SDS) is used to enhance the leaching effect of an ion-absorbed rare earth ore by ameliorating the seepage effect for the first time.The effects of surfactant concentration,leaching agent dosage,solution flow velocity,and solution pH on the leaching rate were explored,and the mechanism of SDS was discussed.Under the optimum conditions,the addition of a small amount of SDS(mass fraction0.04%) can increase the leaching rate by about 5%,shorten the leaching period,and reduce the consumption of the leaching agent.SDS significantly ameliorates the seepage effect of the ore body by reducing the surface tension of the leaching agent and ameliorating the wettability of the mineral surface.This effect is the main factor that improves the leaching efficiency.DFT(density functional theory) calculation results show that SDS can react with rare earth ions,which reduces the adsorption strength on clay mineral surfaces.Hence,rare earth ions are easily exchanged by ammonium ions,and mass transfer is enhanced.

Magnetizing roast and magnetic separation of iron in rare-earth tailings

Magnetic separation of iron in rare-earth tailings was achieved by magnetizing roast process with coal as reductant. Effects of the temperature, carbon to oxygen ratio, and cooling type on magnetic susceptibility and composition of rare-earth tailings were investigated. The results show that roast conditions with the temperature of 650 °C, carbon to oxygen ratio of 3.85, and holding time of 2.5 h are in favor of reduction of Fe_2O_3 to Fe_3O_4 when the roasted rare-earth tailings is cooled along with furnace. Under these roast conditions, magnetic susceptibility of rare-earth tailings is 2.36 that is very close to theoretical value(2.33). However, magnetic separation results of iron in rare-earth tailings cooled along with furnace are not satisfactory. Through comparing magnetic separation results of iron in rare-earth tailings cooled by different ways, it is found that water cooling is more favored of magnetic separation of iron in the roasted rare-earth tailings than furnace cooling and air cooling. Grade and recovery of iron in concentrate from rare-earth tailings cooled by water are 45.00%-49.00% and 65.00%-77.50%, respectively.

Extraction of Rare Earth from K-rich Syenite Tailings

The application of K-rich nephline syenite ores would produce some tailings, which will cause many disadvantages such as more land occupation. In this research, an process was obtained to extract rare earth from the K-rich nephline syenite tailings of Gejiu, Yunnan province, China. This tailings mainly composed of K-feldspar, biotite, magnetite, andradite, nepheline and 0.1% rare earth. The chemical compositions are shown in Table 1.

Characterization and Iron Removal Treatment of Ion-Adsorption Rare Earth Tailings in Southern China

The ion-adsorption rare earth tailings have become a serious environmental pollution in Southern China, yet the potential of their economical value has not been fully exploited. In this work, the chemical and mineral compositions of the ion-adsorption rare earth tailings were characterized by Mineral Liberation Analyze (MLA) and XRF. The results show that 91.98 wt% of the tailings are composed of kaolinite and quartz, latter of which was removed by the sieving method. The other minor minerals contain feldspar, biotite, muscovite, titanomagnetite and limonite. Amongst these, the iron-bearing minerals are mostly found in the titanomagnetite and limonite which can be mostly removed by using a periodic high-gradient magnetic separator with a magnetic induction of 0.6 Tesla. The Fe2O3 content of the tailings changed from 2.11 wt% to 1.06 wt% after the sorting process, which met the Chinese national standard of TC-3 grade raw materials for ceramic industry applications. The Fe2O3 content in kaolinite was further decreased after Na2S2O4 treatment.

Separation of Kaolinite from Ion-Adsorption Rare Earth Tailings in Southern China and Iron Removal Treatment

Several hundred million tons of ion-adsorption rare earth tailings exist in Ganzhou, Southern China, which is a severe environmental hazard. To reduce and reutilize the tailing, kaolinite has been separated from the tailings by mechanical separation in laboratory scale and pilot scale. The results show that the tailing is mainly composed of fine kaolinite and coarse quart. Quartz and kaolinite can be separated by sieves, shaker, spiral chute or hydrocyclone, which has the similar results in laboratory scale and pilot scale. 30.2% of the tailings can be re-sourced and applied in ceramic industries. 41.7% of kaolinite can be obtained after sorting and iron removal by magnetic separator in pilot scale, which can be applied in ceramic industries according to the Chinese national standard (TC-3). The results give a progressive solution to re-source the tailings economically.

Phytoremediation of Rare Tailings-Contaminated Soil

In order to achieve the goal of circular economy and sustainable development of ecological environment,it is important to separate and recover associated elements from rare mineral resources.Compared with traditional physical and che-mical remediation methods of contaminated soil,phytoremediation is regarded as the most promising green in-situ restoration technology.The purpose of this review is to efctive alleviate the environmental problems caused by rare tailings contaminated soil through phytoremediation and realize the recovery of uranium-thorium,rare earth elements(REEs)and tantalum niobium.This review took rare tailings with uranium-thorium,REEs tantalum-niobium in China as the research object,then the background,significance,mechanisms and applcation strategies of phytoremediation were elaborated.In additon,the cases of spedies with tolerance to uranium thorium,tantalum niobium as well as REEs and their remediation mechanisms were summarized,respectively.Particularly,the typical plants represented by Bras-sica juncea,Sunflower,Phytolacca americana,Dicramopteris dichotoma,Salix SPP,etc,were very efctive in the reme-diation of rare tailings.The infuence factors of phytoremediation eficiency of tailings contaminated soil were discused.Two main factors were the mobility of heavy metals in soil(external cause)and the ennichment ability of species(inter-nal cause).Since the traditional phytoremediation also had some limitations in view of this,the work discussed some auxiliary methods(such as chelaing agents or microbial assisted restoration)to improve the effiency of phytoreme-diation.Finally,the future development of phytoremediation and potential applcation directions were explored.

Recovery of Rare Earth Elements Present in Mining Tails, by Leaching with Nitric and Hydrochloric Solutions

The rare earth elements (REE) include the group of 15 lanthanides, scandium and yttrium and have diverse applications in technological and nuclear areas. The existence of REE in massive solid mining wastes generated in leaching processes of copper minerals in the Atacama region of Chile generates the possibility of creating added value to the treatment of this type of waste and supporting the development of a circular economy, generating a useful by-product in different industries. In order to know the behavior of these elements present in the solid carrier waste, a leaching process was carried out by using two agents separately, corresponding to hydrochloric and nitric acid. The technical feasibility to recover REE from carrier tail was demonstrated, the best leaching agent for these elements being a hydrochloric solution, obtaining a maximum recovery efficiency of 64.5%, for an acid concentration: 3M, temperature: 40°C and (liquid/solid) ratio: 4. Lanthanum and cerium present the best individual recoveries compared to the other REE, with a maximum efficiency for a hydrochloric solution of 75.7% and 70.0%, respectively. The interaction of operational parameters that most influence the REE recovery corresponds to the temperature and the (liquid/solid) ratio. After 4 hours of leaching, REE recovery efficiencies remain practically constant. Acid consumptions correspond to 11 (kg HCl/ton mining tail) and 29 (kg HNO3/ton mining tail). The highest amount recovery ratios of these elements correspond to 0.355 and 0.224 (kg REE/ton mining tail), for hydrochloric and nitric solutions, respectively. These results influence the types of reagents and parameters to be studied in the following stages of the global process.

Behavior of leaching and precipitation of weathering crust ion-absorbed type by magnetic field

With weathering crust Ion-Absorbed Type Rare Earth （IATRE） ores in southern Jiangxi as an example, rare earth percolation leaching and leaching solution precipitation process research were carried out under conditions of magnetic field. The effect on the rare earth leaching process such as magnetic field strength, magnetization time, magnetization manner, and other factors were discussed. The effect on the mother rare earth liquor sedimentation rate, purity, and crystallization behavior such as magnetic field strength, magnetization time, and magnetization manner were investigated. Leaching and precipitation mechanism of magnetization on IATRE were analyzed. The results showed that the magnetic treatment can improve leaching rate of weathering crust IATRE and the sedimentation rate, and reduce consumption of reagents.

Migration of ammonium nitrogen in ion-absorbed rare earth soils during and post in situ mining: a column study and numerical simulation analysis

Ion-absorbed rare earth mines,leached in situ,retain a large amount of ammonium nitrogen(NH4–N)that continuously releases into the surrounding environments.However,quantitative descriptions and predictions of the transport of NH4–N across mining area with hill slopes are not fully established.Here,laboratory column experiments were designed with an inclined slope(a sand box)to examine the spatial temporal transport of NH4–N in soils collected from the ionic rare earth elements(REE)mining area.An HYDRUS-2D model simulation of the experimental data over time showed that soils had a strong adsorption capacity toward NH4–N.Chemical non-equilibrium model(CNEM)could well simulate the transport of NH4–N through the soil-packed columns.The simulation of the transport-adsorption processes at three flow rates of leaching agents revealed that low flow rate enabled a longer residence time and an increased NH4-N adsorption,but reduced the extraction efficiency for REE.During the subsequent rainwater washing process,the presence of slope resulted in the leaching of NH4–N on the surface of the slope,while the leaching of NH4–N deep inside the column was inhibited.Furthermore,the high-intensity rainfall significantly increased the leaching,highlighting the importance of considering the impact of extreme weather conditions during the leaching process.Overall,our study advances the understanding of the transport of NH4–N in mining area with hills,the impact of flow rates of leaching agents and precipitation intensities,and presents as a feasible modeling method to evaluate the environmental risks of NH4–N pollution during and post REE in situ mining activities.

Anti-adsorption mechanism of ion-adsorption type rare earth tailings

To investigate the process of RE^(3+)anti-adsorption on ion-adsorption type rare earth tailings,the thermodynamics,adsorption kinetics and infrared spectroscopy of these materials were investigated.The results indicate that the initial reaction rate of anti-adsorption of rare earth tailings is fast,but it reaches a balance in 6 min.The formula 1-2a/3-(1-a)2/3=k_2t(k represents rate constant of the reaction,a represents anti-adsorption rate of rare earth ore,t represents anti-adsorption time)of internal diffusion can be used to predict the kinetics of anti-adsorption in IATRE tailings.BecauseΔH<0,ΔG<0,ΔS>0(ΔH,ΔG,ΔS represent change of enthalpy,Gibbs free energy and entropy,respectively),the anti-adsorption of RE^(3+)on ion-adsorption type RE tailings is a spontaneous physical adsorption process.The effects of ligand exchange and strong chemical bond are not found in this process.Because the anti-adsorption process is exothermic,heating will inhibit the reaction and decrease the anti-adsorption performance.According to the infrared spectrum analysis,there are no significant changes in the mineral surface after anti-adsorption.Based on these findings,the anti-adsorption of rare earth tailings is physical adsorption.

玢岩型铁矿床尾矿中磷、稀土战略性矿产资源调查与综合利用研究:以安徽凹山矿田为例

玢岩型铁矿床是铁矿石的重要来源,其除了赋存巨量铁矿资源外,还以产出大量磷灰石为特征,伴生大量的磷、稀土、钒等资源。20世纪,矿业开发大多只回收主要矿种铁,对伴生资源的评价和综合利用较少。文章以凹山玢岩型铁矿田尾矿库为研究对象,开展伴生资源调查评价和综合利用示范研究。通过系统钻探采样、矿物组合分析、元素赋存状态和综合利用实验等研究,文章揭示出尾矿库中经济矿物为磷灰石,可综合利用资源为磷和稀土,并估算尾矿库中磷储量超过115万t、稀土5万t,社会和经济效益巨大,可作为范例进一步研究并推广应用。

NH_(3)SO_(3)改性稀土尾矿催化剂NH_(3)-SCR脱硝活性及SO_(2)/H_(2)O耐受性能研究

采用球磨、微波焙烧方法制备了不同质量分数NH_(3)SO_(3)改性稀土尾矿NH_(3)-SCR脱硝催化剂。通过BET、SEM-EDS、XRD、NH_(3)-TPD、H_(2)-TPR分析了催化剂脱硝活性及SO_(2)/H_(2)O耐受性能。结果表明:NH_(3)SO_(3)改性使催化剂脱硝活性得到了显著提高,10%NH_(3)SO_(3)改性催化剂在300~350℃脱硝活性可达90%左右。SO_(2)/H_(2)O共同作用可将10%NH_(3)SO_(3)改性催化剂脱硝活性提高至97%,其促进作用保持了良好的稳定性,且具有可逆性。NH_(3)SO_(3)改性稀土尾矿后,催化剂比表面积、酸性位点及强度增加,表面活性物质分散度更高,弱化了尾矿矿物晶型,提高了催化剂吸附能力和氧化还原能力,从而提高催化脱硝活性,同时具备优良的SO_(2)/H_(2)O耐受性。

氮添加对稀土尾砂地猴樟幼苗根系生长、生物量分配及非结构性碳水化合物的影响

为探究氮添加对稀土矿尾砂地猴樟(Cinnamomun bodinieri)幼苗生长及非结构性碳水化合物(NSC)含量的影响,以1年生猴樟扦插苗为研究对象,选用硝酸铵钙作为氮肥(含N 15%),设置3种氮肥水平(CK(0)、N1(1.8 g·株^(-1))、N2(3.6 g·株^(-1))),分析不同氮添加水平下猴樟幼苗根系生长、生物量分配和NSC等指标的差异,探讨稀土尾砂地猴樟对氮添加的响应。结果发现:稀土尾砂地氮添加均增加了猴樟幼苗不同组织的生物量积累,其中N1处理下叶生物量、冠层生物量分别较N2处理下显著提升了44.75%、57.43%(P<0.05);N2处理下叶比重分别较CK、N1处理显著提升了123.53%、15.85%(P<0.05)。不论是粗根(直径>2 mm),还是细根(直径≤2 mm),氮添加均显著增加了植物的根长和根表面积(P<0.05),其中N1处理的促进效果最显著(P<0.05);N2处理下的比根长、比表面积均高于CK与N1,且与CK显著差异(P<0.05)。对NSC来说,N1处理提升了叶、茎中的可溶性糖质量分数,而N2处理下细根NSC质量分数分别比CK、N1显著降低了46.49%、28.61%。综上,在稀土矿尾砂地植被恢复过程中,宜选用1.8 g·株^(-1)硝酸铵钙氮肥对猴樟幼苗进行施肥管理。

白云鄂博某难选铁矿石氢基矿相转化——磁选尾矿浮选稀土试验

堆置多年的白云鄂博中贫氧化矿含有铁、稀土等成分,常规工艺难以高效分选,但氢基矿相转化—磁选工艺可高效回收其中的铁。为了解氢基矿相转化过程是否影响富稀土铁尾矿中稀土矿物的可浮性,进行了系统的选矿试验。结果表明,在506E用量4200 g/t、水玻璃用量1800 g/t、矿浆温度65℃条件下,采用2粗3精、中矿顺序返回闭路浮选流程处理矿样,能够获得REO品位59.00%、REO回收率67.91%的稀土精矿。化学成分分析及X射线衍射分析结果表明,浮选精矿中主要成分为稀土氧化物(Ce_(7)O_(12))、独居石及少量萤石,稀土组分有效富集在精矿中;氢基矿相转化过程未对稀土组分的浮选回收造成不利影响。

我国南方稀土尾矿区植物修复的研究进展

稀土开采破坏了生态环境,产生了大量的尾矿废弃地和严重的环境问题.概述了中国南方稀土尾矿区的污染现状和形成原因,综述了矿山土壤修复的物理、化学、微生物和转基因技术的研究进展,指出稀土尾矿生态修复过程中,植物修复优势种的筛选和土壤改良是关键,今后的研究应侧重于植物-REEs-微生物-土壤体系相互作用、REEs超富积植物及稀土矿区经济作物的筛选、新型土壤改良剂的研发.

内蒙古某尾矿回收稀土试验及吸附动力学研究

以内蒙古某尾矿为研究对象,对其进行了工艺矿物学研究。多元素分析结果表明原料中REO含量为6.2%;矿物组成分析结果表明稀土矿物主要为氟碳铈和独居石,还含有少量的氟碳钙铈矿和黄河矿等,脉石矿物主要以铁矿物、萤石、辉石、闪石等为主;粒度筛析结果表明粒度在-25μm占比为62.9%,稀土矿物粒度较细,会对浮选回收造成不利影响。进行吸附动力学研究,选择氟碳铈矿单矿物进行单矿物浮选试验探究P_(8)用量和pH值对矿物可浮性的影响,氟碳铈矿在P_(8)浮选体系中有较好的可浮性,且氟碳铈矿浮选的最佳pH值为9。通过动力学方程对氟碳铈矿吸附P_(8)进行动力学拟合,结果表明P_(8)捕收能力强,适当用量可完全使氟碳铈矿上浮。以浮选为手段回收稀土矿物,在浮选试验中采用捕收性能和选择性都较好的羟肟酸类捕收剂P_(8),对脉石矿物辉石、闪石等矿物具有良好抑制效果的水玻璃作为抑制剂,FM-132作为起泡剂,针对捕收剂用量、抑制剂用量、矿浆浓度、浮选温度以及浮选时间等进行条件试验确定最佳参数。经一粗两精闭路流程,可获得REO品位51.85%、REO回收率79.12%的稀土精矿,最佳参数为工业上对稀土的回收应用提供了技术支持,有利于实现稀土资源的高效利用。

赣南稀土尾矿土壤不同施肥处理对饲料桑农艺性状、产量及品质的影响

为探究赣南稀土尾矿土壤中不同施肥处理对‘粤桑11号’饲料桑(Morus alba‘Yuesang No.11’)的成活率、农艺性状、产量及品质的影响,采用田间随机区组设计,设置对照组(CK:不施肥)、牛沼液(Z)、腐熟牛粪(F)、腐熟牛粪+牛沼液(F+Z)、蚯蚓粪(Q)、蚯蚓粪+牛沼液(Q+Z)6种施肥处理,每个处理5个重复,测定饲料桑连续3年的成活率、农艺性状、产量及品质。结果表明:与CK相比,各施肥处理对饲料桑成活率、株高、主枝茎粗、总枝条数、总叶片数、单株重、产量、粗蛋白含量均有促进作用,其中Q+Z处理的成活率、单株重、产量最高,3年的产量分别为2.53、21.81、42.14 t·hm^(−2)。模糊隶属函数均值法综合评价饲料桑饲用价值,Q+Z处理隶属函数均值最大。综上,在赣南稀土尾矿土壤施用牛沼液、腐熟牛粪、蚯蚓粪对饲料桑的成活率、农艺性状、产量及品质均有提升作用,最佳施肥处理为蚯蚓粪+牛沼液。

稀土尾矿对尾矿陶粒孔结构及性能的影响研究

为提高稀土尾矿的高值化利用,采用稀土尾矿取代生料制备了尾矿陶粒,探究了稀土尾矿掺量对陶粒孔结构和性能的影响。结果表明,稀土尾矿掺量从0增至40%时,陶粒的堆积密度从1042 kg/m^(3)降至495 kg/m^(3),筒压强度从11.7 MPa降至2.1 MPa;平均孔径从0.24 mm增至0.45 mm,孔隙率从43.2%增至65.2%;掺入稀土尾矿对陶粒的1 h吸水率无明显影响,陶粒的1 h吸水率在0.3%~1.3%范围,用稀土尾矿取代生料后的陶粒性能均满足GB/T 17431.1-2010要求。

低浓度轻稀土离子的选择性萃取分离

本文研究了采用1,7-二氮杂15冠5醚(2N15C5)从多离子共存的复杂硫酸盐体系中选择性萃取分离轻稀土离子的过程。结果表明:水相中的高浓度杂质离子主要通过诱导稀土硫酸钠盐沉淀的生成来影响复杂硫酸盐体系的稳定性,从而降低2N15C5对轻稀土离子的选择性萃取分配比。在水相pH<2.0、[SO_(4)^(2-)]/Σ[RE^(3+)]<10、相比R_(O/A)=2∶1、混相时间10 min的情况下,轻稀土离子组与重稀土离子组的单级萃取分离系数可达23.0023,经5级逆流萃取处理后,对应的累积萃取分离系数可达36.7016。该分组萃取分离法可从离子吸附型稀土矿原地浸出尾液中选择性萃取分离低浓度轻稀土离子,负载有机相经稀盐酸洗杂、乙二胺四乙酸溶液反萃处理后可得到轻稀土富集液,轻稀土离子的综合收率为83.98%。