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.     

羧酸盐复合浸取剂对中重稀土浸出强化研究

以缅甸稀土矿与福建稀土矿为研究对象,采用柱浸工艺方法,研究风化壳淋积型稀土矿的矿石性质,分析乙酸铵添加浓度对风化壳淋积型稀土矿轻、中重稀土浸出的影响。结果表明,缅甸和福建稀土矿分别属于中钇型中重稀土选择型稀土矿和富铕轻稀土选择型稀土矿,并且均存在铈负异常和铕负异常现象。乙酸铵最佳添加浓度为0.04mol/L,稀土浸出可达到浸出平衡,浸出率提升到95%,同时乙酸铵主要通过增强钇元素的浸出,使缅甸稀土矿轻/中重稀土比值从1.04下降到0.98,福建稀土矿轻/中重稀土比值从1.65下降到1.47,表明乙酸铵能够明显提高中重稀土的浸出。     

Reduction leaching of rare earth from ion-adsorption type rare earths ore with ferrous sulfate

The practice of in-situ leaching of the ion-adsorption type rare earths ore with ammonium sulfate could only leach most of rare earth in ion-exchangeable phase,but not the colloidal sediment phase.Therefore,the reduction leaching of rare earth from the ion-adsorption type rare earths ore with ferrous sulfate was innovatively put forward.The soak leaching process and the column leaching process were investigated in the present study.It was determined that ion-exchangeable phase could be released,and part of colloidal sediment phase rare earth could be reduction leached by the cations with reduction properties.The mechanism of reduction leaching was discussed with the Eh-pH diagram of cerium.Moreover,the stronger reduction of reductive ions,the greater acidity of leaching agent solution,and the higher reductive ion concentration,could result in the higher rare earth efficiency and the bigger cerium partition in the leaching liquor.In the ferrous sulfate column leaching process,the rare earth leaching rate and the rare earth efficiency were a little higher than with(NH_4)_2SO_4 agent,and the rare earth efficiency and the partitioning of cerium in leaching liquor could be about 102% and 5.31%,respectively.However,the ferrous sulfate leaching process revealed some problems,so compound leaching with magnesium sulfate and a small amount of ferrous sulfate was proposed to an excellent alternative leaching agent for further studies,which may realize efficiency extraction and be environment-friendly.     

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。     

某离子型稀土矿浸出试验

以中国南方地区某离子型稀土矿为研究对象,采用搅拌浸出和柱浸的方式,研究不同条件下矿样中稀土及杂质元素的浸出情况,为离子型稀土矿产资源的绿色高效开采提供参考。结果表明,浸出液固比对离子相稀土浸出率影响较大,浸出时间影响较小,离子相稀土浸出过程时间短,反应迅速;柱浸过程中离子相稀土流出速率最快,达到平衡时间短,杂质元素前期浸出浓度高,后续拖尾严重;离子相稀土浸出率随着样品深度的增加不断降低,符合南方离子型稀土成矿规律;硫酸铵浸出过程中铵根离子损失量较大,最低损失率超过11.31%,硫酸根不参与金属离子的交换反应过程,回收率最高可达99.22%。     

Lattice Boltzmann model for simulation on leaching process of weathered elution-deposited rare earth ore

The lattice Boltzmann model with coupled chemical reaction was proposed to simulate the ion exchange process of rare earth leaching and verified by comparison with both empirical correlation of mass transfer coefficient and unreacted-core shrinking model. By simulation, the zonation phenomenon of leaching reagent in the leaching column was presented, and the breakthrough curve of leaching reagent was obtained. When t=50 s, there existed the saturated and exchange zones, and the leaching reagent concentration decreased gradually from 20 to 9.3 g/L. In accordance with the breakthrough curve, the breakthrough capacity of ion-type rare earth ore and the adsorbed ion concentration of leaching reagent were derived, the time of t=25 s was the breakthrough point of ammonium ion in leaching reagent and the breakthrough capacity of the rare earth ore was 125 g/L. Besides, the chemical kinetics parameters used for the solute transfer process of rare earth leaching were obtained by the simulation and then were used to determine the rate-limiting steps of rare earth leaching process.     

Mineral properties and leaching characteristics of volcanic weathered crust elution-deposited rare earth ore

Weathered crust elution-deposited rare earth ore is an important resource of rare earths, including grantic weathered crust elution-deposited rare earth ore and volcanic weathered crust elution-deposited rare earth ore. The development condition of the weathered crust, weathering degree and mineral composition of these ores will be different because of the differences between their parent rocks and weathered crust causes of mineralogy path. Therefore, mineral properties and leaching characteristics of volcanic weathered crust elution-deposited rare earth ore from Chongzuo(CZ), Guangxi province were investigated. It was found that the CZ rare earth ore was a typical mid-yttrium and rich-europium ore, with the overall rare earth(REE) grade in ion-exchangeable phase of 0.15%. Partide size classification showed that finer particle had a higher REE grade. Column leaching tests showed that the leaching efficiency of REE was above 94% with leaching agent concentration of 0.20 mol/L, liquid-solid ratio of 4:3, flow rate of 0.60 mL/min, and initial pH value around 5.67. Compared to ammonium sulfate leaching, magnesium sulfate leaching was advantaged by nearly zero ammonia nitrogen emission while their REE leaching was almost equivalent.     

电感耦合等离子体质谱法测定离子型稀土矿中离子相稀土总量及分量

采用硫酸铵溶液提取离子型稀土原矿试样中离子相稀土,以硫酸铵溶液为基体配制校准系列溶液,建立了电感耦合等离子体质谱法(ICP-MS)测定样品溶液中离子相稀土总量及分量的方法。实验表明:对于10.00 g离子型稀土矿试样,加入100 mL 50 g/L硫酸铵溶液振荡15 min后放置30 min可有效提取出离子相稀土;采用5.0 g/L硫酸铵溶液进行校准系列溶液的基体匹配,选择¹⁰³Rh-¹⁸⁵Re双内标可有效校正硫酸铵的基体效应及仪器信号的漂移影响;选择合适的同位素消除了可能存在的质谱干扰。在最佳条件下进行测定,15个稀土元素的校准曲线在10.0~100.0 μg/L范围内线性相关系数均大于0.999 91,方法检出限在0.10~0.66 μg/g之间。方法应用于不同离子型稀土矿区中离子相稀土总量及分量的测定,结果与电感耦合等离子体原子发射光谱法(ICP-AES)一致,相对标准偏差(RSD,n=11)在1.0%~5.2%之间,回收率在98%~104%之间。     

基于组合赋权-云模型的离子型稀土矿开采工艺评价

为保护资源和生态环境,促进稀土产业绿色可持续发展,基于现代控制理论的能观测性和能控性新视角,采用CRITIC-G1组合赋权与云模型相结合的方法,构建了离子型稀土矿开采工艺评价模型,并对不确定开采条件下的原地浸矿工艺与堆浸工艺进行了评价.研究得出:①基于保护资源和生态环境的目的,离子型稀土矿开采工艺评价指标体系不仅要考虑...     

离子型稀土矿浸出过程微细颗粒迁移规律及调控

离子型稀土矿在浸出过程中浸出剂与矿石表面水合机制较为复杂,颗粒间的桥式胶结因离子吸附交换过程中存在多种作用力与分散作用而容易发生断裂,从而使微细颗粒发生迁移和重新排列,并在孔喉处沉淀,产生堵塞现象,影响离子型稀土的浸出效率。为揭示离子型稀土矿在原地浸出过程中微细颗粒的迁移规律,并找到适宜的调控方法,以龙南足洞离子型稀土矿为研究对象,采用实验室柱式溶浸法,考察了浸出剂质量浓度、黏度、流速、水力梯度、矿体高度及矿体含水率对微细颗粒迁移的影响。结果表明,离子型稀土矿浸出过程微细颗粒的迁移是影响浸出效率的重要因素之一。在外力的作用下,微细颗粒在浸出过程中易随浸出剂发生迁移运动。当调控浸出剂质量浓度低于4%,浸出剂黏度不超过1.5 mPa?s,水力梯度小于0.75,浸出剂流速低于3 mL/min,原矿含水量大于11%时,矿体中微细颗粒迁移率较低,矿体渗透性保持良好,有利于浸出液的渗流和稀土离子的浸取。     

南方离子型稀土一维水平入渗规律试验研究

离子型稀土原地浸矿工艺中浸矿液入渗直接影响稀土资源的高效开采与利用.基于自制试验装置进行离子型稀土一维水平入渗试验,溶浸液选取3 %硫酸铵溶液,研究了4种不同粒径稀土的累积入渗长度、湿润锋运移速率、入渗率等变化规律.结果表明:随着入渗时间的递增,累计入渗长度呈先快速增加、后缓慢发展的趋势;湿润锋运移速率和入渗率先达到最大值、后快速减小再趋于稳定,湿润锋运移速率与时间之间的关系符合幂函数关系v=λ·t-0.5;土样饱和渗透系数为0.001 3~0.002 5 cm/min,其数值随着最大粒径增大而递增,研究结果有利于实现原地浸矿的科学化.      

离子型稀土不同浸出剂柱浸对比试验

针对离子型稀土原地浸出工艺现有氨氮污染问题,考察镁盐、铝盐等非铵浸出剂对稀土浸出过程的影响。以赣州稀土矿样为研究对象,选择硫酸镁与硫酸铵通过柱浸的方式进行对比试验,同时考察铝盐与铵盐、镁盐联合浸出效果的影响,测定浸出液成分,分析不同浸出剂浸出效果的差异。结果表明：相同质量分数的硫酸铵和硫酸镁浸出效率相当,硫酸铵可达91.37%,硫酸镁可达89.22%;添加铝盐后的稀土浸出率仅76%左右,铝盐的添加不能促进稀土浸出效率的提升;铵盐柱浸顶水洗涤后铵根离子可降低至76 mg/L,镁盐柱浸顶水洗涤后镁离子可降低至27 mg/L,镁离子比铵根离子更容易洗涤去除。硫酸镁作为浸出剂能够从根本上解决离子型稀土矿山氨氮污染问题。     

采用固氟氯化法从氟碳铈矿中提取稀土氯化动力学的研究进展

针对我国主要的稀土矿物氟碳铈稀土矿目前在分解回收中主要采用浓硫酸焙烧法产生氟化氢污染环境的问题,清华大学核能与新能源研究院从1998年以来开展了氧化镁固氟、氯化铵选择性氯化提取氟碳铈中稀土及其动力学的研究。选择我国典型的稀土矿物包头混合型稀土矿及山东氟碳铈稀土矿展开研究,确定了适宜的工艺条件、氯化选择性和氟的转化形态。稀土以氯化稀土形式被浸取,对于两种稀土矿物稀土浸出回收率均在85%以上。氯化铵氯化稀土的氯化动力学符合Bagdasarym提出的多相区域反应动力学模型,氯化反应的速率αRE遵从Erofeev方程。氯化铵氯化不同形态氧化稀土氯化反应表观活化能的大小顺序为:EaLa2O3+CeO2相似文献   

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.      

离子型稀土资源开采负外部性的能控性与能观测性分析

离子型稀土资源开采在现行技术条件下无论采用原地浸矿还是堆浸工艺均会产生负外部性,通过对原地浸矿、堆浸工艺条件下离子型稀土资源开采负外部性表现形式以及基于现代控制理论对离子型稀土资源开采负外部性的能控性和能观测性的简要分析,得出以下初步结论:①离子型稀土资源采用原地浸矿工艺开采的负外部性的能控性会难于采用堆浸工艺; ②离子型稀土资源采用堆浸工艺开采的负外部性的能观测性会比采用原地浸矿工艺容易。此外,建议进一步优化原地浸矿、堆浸工艺,再从离子型稀土资源开发全过程及其负外部性的能控性和能观测性角度系统比较这两种工艺,明确各种浸取工艺的适用条件。      

Coordination-reduction leaching process of ion-adsorption type rare earth ore with ascorbic acid

The magnesium sulfate(MgSO₄)-ascorbic acid(Vc) compound leaching technique can extract rare earth elements(REEs) existing in ion-exchangeable phase and colloidal phase from ion-adso rption type rare earth ore through the synergy effect of coordination and reduction,but its reaction process and mechanism remain unclear.In this paper,the coordination-reduction leaching mechanism was analyzed from the perspectives of leaching thermodynamics and kinetics,which provide theoretical guidance...     

Non-ammonia enrichment of rare earth by magnesium oxide from rare earth leaching liquor in magnesium salt system

In order to solve the problem of ammonia-nitrogen pollution in the enrichment process of the ionadsorption type rare earth ore,the technology of non-ammonia precipitation with magnesium oxide precipitant was carried out.It is determined that the rare earth precipitation efficiency is 99.6% and the purity of rare earth concentrates is only 85.89 wt%under the optimum precipitation conditions.And the contents of MgO,SO_3 and Al_2O_3 in the rare earth concentrates are 5.12 wt%,6.77 wt%and 1.78 wt%,respectively.Furthermore,the thermo-decomposition process of precipitates was investigated by TGDSC,XRD and FI-IR.The thermal decomposition process consists of two stages:the dehydration of rare earth hydroxide and alkaline rare earth sulfate within 900 ℃ and the thermal decomposition of RE_2O_2SO_4 at 900-1300 ℃.Therefore,a high-temperature calcinations method for removing SO_3 from precipitates is proposed.When the precipitates are calcined at 1300 ℃ for 2 h,the rare earth concentrates with a purity of 92.03 wt%can be acquired.Moreover,the content of SO_3 in the concentrate is only 0.46 wt%.In the MgO precipitation and high-temperature calcinations process,the raw material cost is low and the quality of rare earth concentrates is acceptable.It could have great significance for nonammonia enrichment of rare earth from the rare earth leaching liquor,and finally solve the problem of ammonia nitrogen in the extraction process of the ion-adsorption type rare earth ore within magnesium salt system.     

离子吸附型稀土矿除铝技术研究进展

赣南离子吸附型稀土矿富含中、重稀土元素,具有极高的经济价值及重要的战略意义.在对大量文献资料进行查阅及分析的基础上,介绍铝在离子吸附型稀土矿中的赋存形态、浸出行为以及对稀土工业生产的影响,系统地阐述离子吸附型稀土矿浸取过程中除铝技术的研究和实践进展,并对现有技术进行分析总结,提出未来离子吸附型稀土矿除铝技术应向环境友好型发展,并实现除铝产物资源化、商品化.      

Recovery of rare earths from ion-absorbed rare earths ore with MgSO4-ascorbic acid compound leaching agent

The magnesium sulfate leaching technology for the ion-absorbed rare earths ore can solve the ammonia pollution problem existing in ammonium sulfate leaching process. However, the leaching capacity of magnesium sulfate is slightly weaker than that of ammonium sulfate, resulting in a bigger consumption of magnesium sulfate. In this paper, the MgSO_4-ascorbic acid compound leaching agent had been demonstrated to deal with the ion-absorbed rare earths ore. The ascorbic acid could form a stable coordination with rare earth ions, so that it can strengthen the leaching of ion-exchangeable phase.Moreover, ascorbic acid has a strong reductive property, it can leach the colloidal sediment phase rare earth as well. The present study investigates the effect of the initial pH and the composition of leaching agent on the rare earth leaching. It is determined that the rare earth leaching efficiency is 107.5% under the condition of pH 2.00,0.15 mol/L magnesium sulfate and 1.0 g/L ascorbic acid in leaching agent. In this case, the content of the ion-exchangeable phase and colloidal sediment phase rare earth in the leaching residues are both only 0.02‰. The leaching efficiency of colloid sediment phase rare earth can be 85.7%,so that the Ce partition in the leaching liquor increases to be 5.77%. The magnesium-ascorbic acid compound leaching agent is proposed to be a promising choice to deal with the ion-absorbed rare earths ore, which can realize the efficient leaching, low consumption of MgSO_4 and environmentally friendly leaching.     

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.