浸矿液pH对离子吸附型稀土浸出行为影响实验研究

为了探究浸矿液pH对离子吸附型稀土浸出行为的影响,从宏观和微观相结合的角度对离子吸附型稀土浸出行为进行了研究。实验采用不同pH硫酸镁溶液作为浸矿液对离子吸附型稀土进行室内模拟柱浸实验,同时采用核磁共振技术测定浸矿过程试样的横、纵两向反演图像及T₂图谱、孔隙结构等参数,分析了不同pH(2～4.5)对离子吸附型稀土浸矿行为的影响规律。结果表明,当pH>2.5时,随浸矿液pH降低,稀土浸出率增加,浸矿过程中试样内部孔隙结构由大孔隙和超大孔隙向小中孔隙演化;当pH<2.5时,随浸矿液pH降低,稀土浸出率减小,浸矿过程中试样内部孔隙先由大孔隙和超大孔隙向小中孔隙演化,随着离子交换反应结束,小中孔隙又向大孔隙和超大孔隙演化。分析认为,这种差异是由于稀土矿体微细颗粒在孔隙表面沉积和释放动态转化过程导致,受离子置换反应引发浸矿液离子强度变化等因素影响。     

我国离子吸附型稀土矿开采提取技术综述

综述了我国离子吸附型稀土矿床的类型与特征和目前采用的各种开采方法与提取工艺。并重点阐述了用原地溶浸法开采离子吸附型稀土矿的浸析机理和开采过程中采用的主要技术措施。     

离子吸附型稀土原地浸析尾矿中稀土和铵的残留量分布及其意义

测定了龙南足洞原地浸析多年后的尾矿中不同空间位置上的稀土和铵残留量,以及尾矿中的粘土矿物对稀土和铵的吸附等温线。结果表明,粘土矿物对稀土的吸附符合朗格缪尔等温线方程,对低浓度稀土有强吸附能力;而对铵的吸附等温线呈直线关系,不符合朗格缪尔等温线方程。尾矿粘土中铵的纯水浸出实验证明,尾矿中的铵可被水浸出而流失。用粘土矿物对稀土和铵的吸附特征差别和矿层内部的渗透特征差别解释了注液区域矿层内部从全风化层到半风化层方向铵和稀土残留量的上升趋势。因此,尾矿中铵和稀土含量的分布可以直接反映原地浸出效果的好坏以及铵的流失情况,用于讨论离子吸附型稀土矿床的内部结构与渗流特征。     

离子吸附型稀土总量快速容量法测定的研究

本文研究了0.2—0.01％范围内离子吸附型稀土矿中稀土总量的直接测定法,其回收率96～102％,变异系数0.96～3.56。方法简便,终点明显,结果稳定可靠。     

离子吸附型稀土原地浸矿及直接分离项目顺利通过江钨集团公司验收

在江钨集团公司的正确领导下，通过寻乌南方稀土有限责任公司全体员工的共同努力，2006年6月初．离子吸附型稀土原地浸矿及直接分离项目稀土分离部分完成了设备安装，并开始投料调试。经过3个多月的艰苦奋斗，整个工艺流程已全部贯通，萃取分离线达到物料平衡。到2006年12月18日止，已处理稀土原矿（以92％REO计）892t，产出产品共计418t，在制品182．14t，除荧光级氧化铕外，其它产品均已产出并达到设计要求。     

攀西稀土矿黑色风化矿泥氯化焙砂柱浸稀土研究

针对攀西稀土矿黑色风化矿泥氯化铵焙烧得到的焙砂 ,为了提高水浸过程中稀土浓度 ,减少非稀土杂质相对含量以便于进一步回收稀土产品 ,本研究对其氯化焙砂进行了柱浸试验研究 ,探索了浸取剂 ,浸取酸度 ,柱径比对浸出液稀土浓度的影响 ,通过与加热搅拌浸取比较 ,得到结果如下 :柱浸稀土浓度能由原来搅拌浸出的4.3g/L提高到 44.8g/L ,稀土浸取率达 93.43% ,非稀土杂质 Al、Fe、Ca相对于稀土的含量分别为 6.5%、3.4%、6.1 %。     

铁锰氧化物对稀土离子的吸附行为研究

采用化学共沉淀法制备铁锰复合氧化物作吸附剂,通过静态和动态吸附实验探究了不同吸附条件对铁锰氧化物吸附稀土离子的影响,对铁锰氧化物吸附稀土离子过程进行了等温吸附模型拟合和吸附动力学、吸附活化能分析,探究了稀土离子在铁锰氧化物上的吸附机理。结果表明,稀土离子在铁锰氧化物上的吸附过程符合Langmuir等温吸附模型;稀土离子在铁锰氧化物上的吸附过程符合准二级动力学模型,属于单层均匀的化学吸附过程,吸附速率控制步骤由化学吸附决定,且温度对吸附动力学影响程度最大;吸附热力学分析表明铁锰氧化物吸附稀土离子是吸热的化学吸附过程,吸附活化能分别为E₍La³⁺)=11.04 kJ/mol、E₍Gd³⁺)=16.85 kJ/mol和E₍Y³⁺)=16.67 kJ/mol;稀土离子与铁锰氧化物上的羟基发生了交换形成了内层络合物,稀土离子取代表面羟基是主要的吸附机制。     

农业废弃物吸附稀土离子的研究进展

稀土元素在工业上大量应用的同时, 给人类身体健康和生态环境带来了危害, 近年来引起了广泛关注.研究发现吸附法相比其他传统水处理方法具有效果较好、操作简单、成本较低等优点, 它是消除稀土离子危害的最具潜力的方法之一; 而农业废弃物吸附剂因是农业副产物具有廉价的特性, 且部分农业废弃物吸附稀土离子时吸附量大、反应速率快, 可作为主要研究对象.文中对农业废弃物吸附材料吸附稀土离子的机理、吸附影响因素、吸附应用与吸附模型研究进展进行总结评述, 并对农业废弃物吸附稀土离子的发展方向进行展望.      

离子吸附型稀土矿淋洗交换稀土动力学问题的研究

从离于吸附型稀土矿提取稀土(离子态稀土)是以洗提交换为基础的。该类稀土矿料主要由石英,高岭石,云母和碎长石所组成,其中高岭石和云母类粘土矿物为铝硅酸盐,是类天然的无机离子交换剂。离子态稀土被吸附于这些粘土矿物上.当用强电解质溶液浸泡或洗提这些矿物时,离子态稀土被其它阳离子交换下来,但     

Insight into leaching of rare earth and aluminum from ion adsorption type rare earth ore: Adsorption and desorption

Clay minerals are inferred to be the primary host materials for ion-exchangeable rare earth in ion adsorption type rare earth ore(IAREO).During the rare earth leaching process,the adsorption and desorption reactions of the cations controlling the leaching process continue to occur at the clay minerals-leaching agent solution interface.In order to understand the leaching mechanism and behavior of rare earth and co-leached aluminum,adsorption,competitive adsorption,and desorption experiments were ...     

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.     

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.     

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.     

Process optimization of rare earth and aluminum leaching from weathered crust elution-deposited rare earth ore with compound ammonium salts

In order to intensify the leaching process of rare earth(RE) and reduce the impurities in the leachate, ammonium chloride(NH4Cl) and ammonium nitrate(NH4NO3) were mixed as a compound leaching agent to treat the weathered crust elution-deposited RE ore. Effects of molar ratio of NH~+_4Cl and NH_4NO_3, ammonium(NH_4) concentration, leaching agent pH and flow rate on the leaching process of RE were studied and evaluated by the chromatographic plate theory. Leaching process of the main impurity aluminium(Al) was also discussed in detail. Results showed that a higher initial ammonium concentration in a certain range could enhance the mass transfer process of RE and Al by providing a driving force to overcome the resistance of diffusion. pH almost had no effects on the mass transfer efficiency of RE and Al in the range of 4 to 8. The relationship between the flow rate and height equivalent to a theoretical plate(HETP) could fit well with the Van Deemter equation, and the flow rate at the lowest HETP was determined. The optimum conditions of column leaching for RE and Al were 1:1(molar ratio) of NH_4Cl and NH_4NO_3, 0.2 mol/L of ammonium concentration, pH 4–8 of leaching agent and 0.5 mL /min of flow rate. Under this condition, the mass transfer efficiency of RE was improved, but no change was observed for Al compared with the most widely used ammonium sulfate. Moreover, the significant difference value(around 20 mL) of retention volume at the peak concentration between RE and Al provided a possibility for their separation. It suggested the potential application of the novel compound leaching agent(NH_4Cl/NH_4NO_3). It was found that the relative concentration of RE in the leachate could be easily obtained by monitoring the pH of leachate.     

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.      

风化壳淋积型稀土矿浸取过程中基础理论研究现状

对风化壳淋积型稀土矿浸取过程中的浸取水动力学、原地浸出渗流规律、浸取稀土动力学、浸取铝动力学、浸取传质浸取过程选择性等基础理论现状进行了概括和分析.指出了目前浸取过程中存在的一些问题和面临的挑战,特别指出应在浸铝浸取动力学过程研究、浸取过程强化研究、堆浸、原地浸出基础理论研究方面有待进一步加强.      

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.     

Molecular dynamics simulation of aluminum inhibited leaching during ion-adsorbed type rare earth ore leaching process

Molecular dynamics simulation was adopted to study the interaction between sulfosalicylic acid and aluminum,lanthanum and yttrium,and adsorption on kaolinite surfaces.A complexation reaction occurs between sulfosalicylic acid and aluminum,with an interaction energy of-10472.05 kJ/mol.O—Al covalent bonds are formed with a peak value of 7.93,while there is only weak adsorption between sulfosalicylic acid and rare earth ions.A hydrogen bonding reaction with 13605.82 kJ/mol energy occurs between sulfosalicylic acid and the surface of kaolinite(100).Thus,sulfosalicylic acid can form a complex with free aluminum ions,and can also be adsorbed on kaolinite by hydrogen bonding with aluminum in kaolinite(100) surfaces.Leaching of ion-adsorbed type rare earth ore was performed with aluminum inhibited,results show that when sulfosalicylic acid dosage increases from 0 to 0.15 wt%,aluminum ion concentration in the leaching solution decreases from 273.23 to 47.19 mg/L.And the effect of leaching pH value on the effect of sulfosalicylic acid on aluminum inhibition was studied,the result shows that,when the leaching pH value is 4.0—5.0,the rare earth leaching rate and the aluminum ion concentration basically remain unchanged.The molecular dynamics simulation results were verified by detection and analysis of XPS and SEM.     

Effects of organic acids on the leaching process of ion-adsorption type rare earth ore

To examine the activation of organic acids on the leaching process of ion-adsorption type rare earth ore(IRE-ore), the leaching behavior of rare earth(RE) and zeta potential of IRE-ore were investigated in the absence and presence of carboxylic acids. The results show that all the tested organic acids(acetic acid,malonic acid, citric acid, tartaric acid, succinic acid, and malic acid) can promote RE extraction. At relatively high concentrations of organic acids, the activation efficiency of organic acids on RE extraction is generally consistent with their complexation ability; whereas at their low concentrations, the change of zeta potential on the IRE-ore surface with organic acid concentration and p H has a close association with RE extraction, which indicates that organic acids can impact the surface electrical property of IREore via their adsorption/desorption, and thereby increase/decrease the affinity of RE ions to IRE-ore.Therefore the influence of organic acids on the IRE-ore surface electrical property also plays an important role in RE extraction in addition to their complexation with RE ions.