Local concentration of middle and heavy rare earth elements in the col on the weathered crust elution-deposited rare earth ores

This present study focused on investigating the content and relative enrichment multiple of rare earth elements(REEs) in different terrain of weathered ore body, and the value of light rare earth elements/middle and heavy rare earth elements(LREEs/HREEs), in order to understand the mobilization and redistribution of HREEs, Furthermore, the abrasion pH was investigated as well, The results show that the average contents of HREEs in the knap, ridge and col are 37.26, 61.71, and 271.3 μg/g, respectively. The value of LREEs/HREEs is decreased from 16.78 to 7.914 between knap and col and the relative enrichment multiple of HREEs is as follows: C_(Col-HREEs) C_(Ridge-HREEs) 0. It is indicated the HREEs is concentrated in the col and the enrichment degree of HREEs is stronger than the ridge and the knap. Rare earth elements fractionation is exhibited in the different terrain of weathered ore body. Based on this study, the finding that HREEs concentrate in the lower terrain of weathered crust elution-deposited rare earth ores, such as in the col, would become a marker or indicator to search for middle and heavy rare earth enriched zone.     

生物表面活性剂对原矿中稀土淋洗效果的影响

为实现我国南方离子型稀土矿的无铵浸析,以生物表面活性剂-皂角苷为浸矿剂,通过淋洗实验探讨了皂角苷浓度、溶液pH、原矿粒径、固液比对稀土淋洗效果的影响,结果表明:在原矿粒径为0.25 mm,皂角苷浓度50 g/L、pH=5.5和固液比(g/mL, 下同)1:15条件下,振荡24 h后,皂角苷对稀土的淋洗效率可达76.78 %.而在柱淋洗实验中,累积淋洗效率为43.16 %,仅不到硫酸铵的1/2;原因在于皂角苷对稀土的淋洗效率会受溶液和原矿的性质、流速等因素的影响,导致淋洗反应迟缓,拖尾期长.      

Kinetics model for leaching of ion-adsorption type rare earth ores

This paper aims to establish a mathematical model that can analyze the whole leaching kinetics process of ion-adsorption type rare earth ores. This leaching process is composed of three steps: (1) ammonium ions arrive at the ore particle surface through the diffusion layer; (2) ammonium ions exchange with rare earth ions; and (3) rare earth ions enter into the external solution through the diffusion layer. In the leaching process, it is hypothesized that the ore particle size remains constant. The process of ammonium ions and rare earth ions passing through the diffusion layer was described by the Fick law, and the reversible ion exchange process between ammonium ions and rare earth ions was described by the Kerr model. A leaching kinetics model of rare earth ions by ammonium ions was constructed. Accuracy of this kinetics model was verified with laboratory tests. It is found that the correlation coefficients of all data are greater than 0.9000. The proposed kinetics model is therefore feasible for kinetics analysis throughout the leaching process.     

Progress in green and efficient enrichment of rare earth from leaching liquor of ion adsorption type rare earth ores

Ion adsorption type rare earth ores (IATREOs) are a valuable strategic mineral resource in China, which feature a complete composition of fifteen rare earth elements and are rich in medium and heavy rare earth (RE) elements. In the leaching process for recovering rare earth elements from IATREOs, many impurities will be leached together with rare earth elements and enter the leaching liquor. An impurity removal-precipitation enrichment technique is currently applied to selectively recovery rare earth elements from the leaching liquor with the high content of impurities and low concentration of rare earth elements by using ammonium bicarbonate in the industry. However, a high loss of rare earth elements and severe ammonia nitrogen pollution are caused by this process. Therefore, more beneficial impurities removal technologies, mainly for aluminum, and green enrichment technologies with lower pollution are now urgently needed. For this purpose, this paper analyzed two aspects of research progress in recent decades: the green separation of rare earth elements and aluminum from leaching liquor and the green and efficient enrichment of rare earth elements. Finally, an approach for the high-efficiency and green enrichment of rare earth elements from leaching liquor of the IATREOs is proposed in several aspects, including impurity inhibition leaching, neutralization and impurity removal, alkaline calcium and magnesium salt precipitation enrichment, and centrifugal extraction enrichment.     

风化壳淋积型稀土矿的基础研究

文章评述了40年来风化壳淋积型稀土矿的基础研究,包括矿床的成因及特征、稀土矿物的组成及性质,稀土与黏土矿物的关系、稀土在黏土矿物中的吸附及迁移理论,论述了风化壳淋积型稀土矿的稀土元素配分的特征及四大效应,并探讨了稀土浸出机理和风化壳淋积型稀土矿稀土浸取的三代工艺,提出了风化壳淋积型稀土矿基础研究和浸出工艺的发展方向及亟待解决的问题.      

Dissolved rare earth elements estimation of ion-absorption rare earth ores using reflectance spectroscopy in south Jiangxi province,China

Ion-absorption rare earth ores are an important mineral resource in China. Nowadays, the unauthorized mining has become a serious problem, resulting in severe water pollution and the wastage of rare earth elements (REEs). Being able to estimate the concentration of dissolved REEs in water bodies near mines is essential for tackling this environmental problem. Conventionally, quantitative analyses of the contents of dissolved REEs are performed using laboratory-based techniques, which can be time consuming and costly. Spectral reflectance is a rapid and cost-effective means of characterizing the chemical compositions of light-absorbing materials. In this study, reflectance spectroscopy was performed on dissolved REEs, and the correlation between their reflectance characteristics and REE content was determined. A total of 50 aqueous media samples collected in south Jiangxi Province and 25 laboratory-produced aqueous media samples were tested, and their reflectance spectra and REE contents were measured using reflectance spectroscopy and inductively coupled plasma mass spectrometry, respectively. Next, the reflectance, differential reflectance, and absorption depth were analysed based on the REE content. Six diagnostic absorption features related to REEs are recognised in the visible and near-infrared wavelength regions, along with several smaller peaks. It indicates that the results of the absorption depth analysis are in accordance with the absorption spectra characteristics of the REEs, with the R² value being higher than 0.97. The intensity of each of the six absorption bands exhibits a linear correlation to the total REE content. Therefore, linear regression models can be derived for estimating the total concentration of REEs in aqueous media samples. What's more, the detection limit for REEs is determined to be about 30 μg/L. Thus, it can be concluded that reflectance spectroscopy is a suitable technique for estimating the concentration of dissolved REEs.     

Clean separation technologies of rare earth resources in China

After a review on the conventional separation process of rare earths (RE), hyperlink extraction technology was introduced and a potential process was proposed for clean separation of RE. A great amount of acid, base and water was consumed in the conventional RE separation process which included the procedures of raw material dissolving, extraction separation and precipitation. Therefore hyperlink extraction technology had been developed, by which the repeated consumption of acid and base could be avoided during the extraction process. And based on the theory and successful applications of the hyperlink extraction technology, we proposed the integral hyperlink process in which the intermediate acid resulted in individual procedures would be recycled and reused after being treated. The proposed process would make it feasible to consume no chemicals except for oxalic acid, and so could be a promising clean separation technology with a significant reduction on consumption and emission.     

风化壳淋积稀土矿浸取动力学基础理论研究

风化壳淋积型稀土开采先后经历了池浸、堆浸和原地浸矿,目前采用原地浸矿法.研究风化壳淋积型稀土浸取动力学有助于从本质上提高浸矿效率和资源回收率,为高效、科学开采风化壳淋积型稀土矿提供理论依据,进一步完善风化壳淋积型稀土的原地浸出理论和技术.为此对风化壳淋积型稀土矿浸取动力学基础理论进行研究,并针对现有浸矿工艺,指出了影响浸取效率的因素,提出了提高风化壳淋积型稀土浸取速度的方法与措施.      

Research progress of rare earth separation methods and technologies

Strategical elements,such as rare earth elements,play a crucial role in the industry,especially in producing high-tech materials.Major global industries have developed a strong dependence on rare earth materials.Every year,there are innovations in industries such as modern technology,green energy,or communications technology,which need more strategic metals to improve investment profitability.This article reviews advances in rare earth separation methods and techniques to guide and recommend the...     

电感耦合等离子体质谱法测定金属矿中稀土和稀散元素

金属矿中稀土和稀散元素的测定对其综合利用具有重要意义。难溶元素Nb、Ta、Zr、Hf采用酸溶法处理时较难溶解完全,Nb、Ta采用碱熔法处理后再用王水浸取存在不稳定的问题。实验采用偏硼酸锂熔融样品,酒石酸体系浸取,解决了上述Nb、Ta等元素测定中遇到的难题。通过选择待测同位素和干扰校正方法在线校正,以10 μg/L¹⁸⁵Re和10 μg/L¹⁰³Rh为混合内标,采用电感耦合等离子体质谱法(ICP-MS)对浸取液进行测定,实现了对金属矿中La、Ce、Pr、Nd、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb、Lu、Y共15种稀土元素,及Nb、Ta、Zr、Hf、Ga、Rb、Cd、Cs、In、Tl共10种稀散元素的测定。方法校准曲线的线性相关系数均大于0.999 7,方法检出限为0.03～0.85 μg/g,定量限为0.09～2.55 μg/g。将实验方法应用于铅矿石、钨矿石、钽矿石和锆矿石标准物质中稀土和稀散元素的测定,结果的相对误差(RE)为-5.33%～6.67%,相对标准偏差(RSD,n=12)不大于9.8%。采用实验方法对洛宁铅锌多金属矿区的样品进行测定,结果的相对标准偏差(n=5)不大于9.3%。     

阻抑甲基红褪色光度法测定稀土矿石中痕量铌

在稀硫酸介质中,铌显著阻抑溴酸钾氧化甲基红的褪色反应,据此建立了催化动力学光度法测定痕量铌的新方法,同时研究了该方法的动力学条件。方法的检出限1.6×10-11g/mL,线性范围为0.12～1.2ng/mL,回收率在102%～104%之间,RSD在2.4%～3.2%之间,用于稀土矿石中痕量铌的测定,结果满意。     

A two-parameter model for ion exchange process of ion-adsorption type rare earth ores

The establishment of a mathematical model for the ion exchange process is key to creating a theoretical basis for the mining of ion-adsorption type rare earth ores. Ore samples from Xinfeng, Xunwu and Anyuan were used as the test ore samples in the present study and equilibrium batch tests of ore sample leaching using various ammonium sulfate concentrations were performed. The results show that, after leaching, there is a negative exponential relationship between the ratio of the solid-phase rare earth ion concentration to the aqueous-phase rare earth ion concentration and the initial ammonium ion concentration. However, there is a linear relationship between the natural logarithm of the ratio of the solid-phase ammonium ion concentration to the aqueous-phase ammonium ion concentration and the initial ammonium ion concentration. Based on the above two functional relationships, a two-parameter model for the equilibrium ion exchange process of ion-adsorption type rare earth ores was established. Using the established model to analyze the test data the model error for the Xunwu ore sample is found to be less than 5%. The proposed model is more accurate compared with the Kerr model. The two-parameter model proposed in this study provides theoretical support for the numerical simulation of column leaching (in-situ leaching) of ion-adsorption type rare earth ores.     

电感耦合等离子质谱法测定离子型稀土原矿中离子相稀土总量

采用电感耦合等离子质谱法(ICP-MS)直接测定离子型稀土原矿中离子相稀土总量,实验对浸取溶液、浸取溶液的浓度及用量、被测元素的同位素、样品酸度、内标元素、仪器的最佳工作参数进行了选择,建立了优化分析条件.单一元素标准加入的回收率为95%~105%,离子相稀土总量回收率为98.4%,相对标准偏差小于5%,测定范围为:0.010%~0.50%.方法准确可靠,操作简单,精密度和准确度都能满足分析要求.     

Investigating the use of an ionic liquid for rare earth mineral flotation

Common collectors for rare earth mineral(REM) flotation,which include carboxylates and hydroxamates,face problems such as being non-selective and sensitive to impurity ions.A type of ionic liquid(IL),tetraethylammonium mono-(2-ethylhexyl)2-ethylhexyl phosphonate([N_(222)][EHEHP]),has been investigated previously for rare earth elements(REE) solvent extraction,and was proven to be selective and effective.In this work,[N_(222)][EHEHP] was evaluated as a collector in bastnasite(a primary REM source for REE production) flotation for the first time.The results were compared with quartz and hematite,two common gangue minerals in REM deposits.Zeta potential measurements and Fouriertransform infrared spectroscopy(FT-IR) were completed to investigate the surface chemical properties involved in the flotation of these minerals using this collector.The findings were compared with microflotation results.FT-IR and zeta potential measurements suggest adsorption of the collector's phosphonate group onto bastn(a|")site and hematite,likely through chemisorption;whereas for quartz,the minimum micro flotation recovery is likely due to no adsorption of IL on its surface.Micro flotation re sults show higher collectability of [N2222] [EHEHP] for hematite than bastnasite,the latter only shows appreciable recovery at pH 5 with elevated dosage of IL(500 g/t).To achieve better separation,a two-stage flotation scheme was designed and evaluated by bench scale flotation on a synthetic mineral mixture.The concentrates and tails were analyzed by magnetic separation,and it is found that bastnasite recovery over 90% with maximum upgrade ratio 1.7 can be achieved with elevated collector dosage.     

Application of surfactant for improving leaching process of weathered crust elution-deposited rare earth ores

Weathered crust elution-deposited rare earth ores(WREOs) in China are the main source of medium and heavy rare earths in the world.In order to improve the seepage and the mass transfer of traditional ammonium salt leaching process of WREOs,surfactants were added in the ammonium sulfate leaching solution and the ammonium chloride leaching solution.The leaching kinetics,the mass transfer process,and the adhesion work reduction factor calculated from the interfacial properties were studied to revea...     

ICP-AES法测定稀土(镁)硅铁中La和Ce

采用ICP AES法测定稀土(镁)硅铁中La和Ce含量,并对样品的溶解方法、基体及共存元素的影响、分析谱线进行了研究。方法简便、快速,精密度和准确度较好。     

风化壳淋积型稀土矿原地浸矿负压收液研究

为了探求风化壳淋积型稀土矿原地浸取工艺中负压收液的可能性及其效果,通过浸矿剂渗透规律及负压收液机理的研究,对负压收液影响因素及边界范围、负压收液试验方法、负压值与收液率的关系、负压收液工艺及其抽取方式进行了探究.优化了收液方式和条件,得出了收液率与负压值基本上呈线性关系,最佳的抽液方式为停机时间10 min,开机时间50 min,三孔联抽,负压值维持在2.66×104Pa以上.随后进行了万吨级矿块工业试验,以进一步验证优化条件,获得了理想的试验结果及技术经济指标,其中REO浸取率达77.5%.     

Enhancing mineral liberation of a Canadian rare earth are with microwave pretreatment

Liberation. as an attribute of mineralogy characteristic. whose impacts on finely disseminated Canadian rare earth ore was studied with microwave pretreatment. Samples of a light rare earth ore along with mostly ankerite and biotite as dominant gangue minerals as well as bastnaesite, strontianite and goethite as dominated minerals were exposed to further comminution by ball mill and microwave pretreatment fragmentation. Mineralogical characteristics were analyzed by using a mineral liberation analyzer(MLA).The results indicated that tight association mutually penetrates among dominated minerals in the range size of -300 + 212 μm and 212 + 150 μm and gangue minerals in the form of adjacent type. fine vein type. shell type and packing type. Temperature in the ore samples pre-treated by microwave can rapidly rise to 250 ℃ with microwave power of 0-1.5 kW and microwave time of 0-2 min. Applying the microwave pretreatment merely reduces the hardness of the ore causing the fracture of rare earth ore, but this does not transform or change the original mineralogy characteristics of the ore samples. On the basis of above study. the liberation value of bastnaesite, strontianite and goethite with microwave pretreatment is greater than with conventional comminution when the liberation class is above 75%. The distribution of particle size of rare earth ore samples is better with microwave pretreatment than with conventional comminution for particle size of 7.4 × 10~(-5) m. With microwave pretreatment, the theoretical grade-recovery of bastnaesite. strontianite and goethite in the rare earth ore attains better results than with conventional comminution at a given grade.     

Enhancing mineral liberation of a Canadian rare earth ore with microwave pretreatment

Liberation, as an attribute of mineralogy characteristic, whose impacts on finely disseminated Canadian rare earth ore was studied with microwave pretreatment. Samples of a light rare earth ore along with mostly ankerite and biotite as dominant gangue minerals as well as bastnaesite, strontianite and goethite as dominated minerals were exposed to further comminution by ball mill and microwave pretreatment fragmentation. Mineralogical characteristics were analyzed by using a mineral liberation analyzer (MLA). The results indicated that tight association mutually penetrates among dominated minerals in the range size of ?300 + 212 μm and ?212 + 150 μm and gangue minerals in the form of adjacent type, fine vein type, shell type and packing type. Temperature in the ore samples pre-treated by microwave can rapidly rise to 250 °C with microwave power of 0–1.5 kW and microwave time of 0–2 min. Applying the microwave pretreatment merely reduces the hardness of the ore causing the fracture of rare earth ore, but this does not transform or change the original mineralogy characteristics of the ore samples. On the basis of above study, the liberation value of bastnaesite, strontianite and goethite with microwave pretreatment is greater than with conventional comminution when the liberation class is above 75%. The distribution of particle size of rare earth ore samples is better with microwave pretreatment than with conventional comminution for particle size of 7.4 × 10^?5 m. With microwave pretreatment, the theoretical grade–recovery of bastnaesite, strontianite and goethite in the rare earth ore attains better results than with conventional comminution at a given grade.     

Leaching ion adsorption rare earth by aluminum sulfate for increasing efficiency and lowering the environmental impact

The leaching efficiency(LE) of ion adsorption rare earth(IARE) by the sulfate and chloride of ammonium,magnesium and aluminum were comparatively determined using column leaching method. It is found that at equal equivalent concentration of cation, the LE of IARE by aluminum sulfate is the highest, and the zeta potential of clay mineral particles in the tailing is near to zero, which means a lower risk of landslide and pollutant emission. Furthermore, the optimum concentration of aluminum sulfate is determined to be0.02 mol/L, which is much lower than that of ammonium sulfate and magnesium sulfate. To reduce the production cost and environmental impact, we proposed a multi-stage leaching process, which was firstly leaching with ammonium sulfate and then with aluminum sulfate, following by water washing and lime neutralizing. With the ratio of ammonium sulfate to aluminum sulfate varying from 1:0 to 0.5:0.5, the residual ammonium in tailing decreases from 11.2% to 0.6%, however, the LE of RE shows an optimum value at 0.8:0.2. By neutralizing the pH of tailing with lime water to over 6, the ion concentration in water rinsing solution can meet the requirement for water discharge. At the same time, the zeta potential of clay particles is found to be around-5 mV, means a relatively lower risk of landslide. These facts indicate that the LE of IARE can be increased and the danger caused by tailings landslides and pollutant emissions can be reduced by replacing ammonium sulfate with aluminum sulfate as leaching reagent.