离子型稀土矿石颗粒粒度分布及变化规律研究

渗流问题和边坡稳定性问题是离子型稀土矿床原地浸矿工艺面临的两个基本问题,而颗粒粒度分布被认为是土壤最基本的物理性质之一,对土壤水流动、溶质和颗粒迁移以及水土流失等起关键作用。通过浸矿实验、筛分分析和激光粒度分析研究了离子型稀土矿石颗粒粒度分布特征及其影响因素和变化规律。研究结果表明,离子型稀土矿石颗粒粒度分布受成矿母岩、风化程度、水土流失和颗粒垂向迁移、原地浸矿活动等因素的影响,呈如下变化规律:(1)当成矿母岩为中、粗粒结构,且石英含量高时,稀土矿石颗粒易呈双峰式粒度分布,即微粒组分(0.2 mm)和中、粗粒组分(2 mm)含量较高,细粒组分(0.2 mm~2 mm)含量相对较低,原地浸矿活动过程中容易造成水土流失和颗粒垂向迁移,并易诱发滑坡灾害;(2)受风化程度和颗粒垂向迁移的影响,稀土矿石微粒组分的含量随深度增大常呈先升后降的抛物线形态;(3)原地浸矿活动可促进稀土矿石的进一步风化,并加剧较细颗粒的垂向迁移,从而影响稀土矿石颗粒粒度分布。     

风化壳淋积型稀土矿原地浸出微观渗流机制

为了揭示风化壳淋积型稀土矿原地浸出微观渗流机制,通过扫描电镜实验和图像处理技术,定量分析浸矿后四种稀土矿样的上、中、下部的微观孔隙结构特征(孔隙尺度、孔隙分布、孔隙形状)的变化规律,探讨宏观渗透系数与其的关系。研究结果表明,矿石颗粒的孔隙率由大、超大孔隙比例和与总孔隙数共同决定,随矿样深度增加而减小;下部矿样的孔隙尺度均匀程度最高,而中部矿样的最低;随着矿样深度增加,孔隙分布越来越分散,平均孔隙形状系数逐渐增大,孔隙形状特征变得越来越复杂;浸矿中-0.075 mm粒径矿石颗粒迁移导致微观孔隙结构特征和有效颗粒粒径改变,这是影响稀土矿石渗透性能变化的主要因素。研究成果有望为实现高效回收中重稀土资源提供理论依据。     

风化壳淋积型稀土矿浸取分形动力学研究

风化壳淋积型稀土矿粒径分布特征是影响浸取性能的主要因素之一。以五种重组江西风化壳淋积型稀土矿为研究对象,通过柱浸实验和分形理论相结合的研究手段,探究稀土矿的粒径分布特征与分形维数的关系,以及其对浸取动力学性能的影响规律。结果表明,随着分形维数增大,小粒径颗粒质量含量随之增大,而大粒径颗粒质量含量随之减少,尤其是小于0.150 mm和大于1.400 mm粒径颗粒质量占比变化幅度较大,其余粒径颗粒变化幅度较小。随着分形维数增加,浸出的稀土浓度峰值逐渐增大,浸矿中稀土浓度峰值出现的时间变晚,稀土浸取率达到平衡所需要的时间变长。基于分形理论,构建了风化壳淋积型稀土矿浸取分形动力学模型,并证实了新模型具有较高的准确性,能够较好的定量描述浸矿中不同分形维数的稀土矿样的浸取动力学特性。     

离子吸附型稀土矿分形特性及土-水特征曲线预测研究

离子吸附型稀土矿石(土)的土-水特征与矿体渗透性能关联紧密,对于稀土资源浸取率有重要影响,利用分形维数预测土-水特征曲线具有工程价值.为了探究不同粒径范围离子吸附型稀土矿石(土)的分形特性,选取龙南足洞矿区稀土矿样进行筛分,采用粒度分析仪测量(＜0.075 mm,0.075 mm～0.25 mm,0.25 mm～0.5...     

轻稀土矿城市路尘中重金属含量的粒径分布与空间分异

以典型轻稀土矿尾矿坝附近的工业区和居民区为研究区,首先通过分析不同粒径城市路尘中重金属元素的质量载荷,讨论了路尘中重金属元素含量的粒径分布和空间分异;然后通过主成分分析及稀土特征参数计算,识别了路尘中金属元素的来源。研究结果表明,稀土尾矿坝路尘中重金属元素变异系数较大,空间差异显著,工业区路尘中的金属含量和质量载荷通常高于居民区;重金属元素Cr在8种不同粒径路尘中质量载荷均较大;粒径0.075 mm的路尘中金属质量载荷最大,随路尘粒径增大金属质量载荷显著减小;尾矿坝路尘中重金属元素的主要人为来源是工业源、燃烧源和交通源,主要自然来源是成土母质;稀土元素主要来自于土壤扬尘、矿源以及工业源。     

湖北某稀土矿石工艺矿物学研究

运用MLA、偏光显微镜、化学分析、电子探针等测试手段,对湖北某正长岩-正长斑岩型稀土矿石的化学成分、元素分配、嵌布特征、解离度等工艺矿物学参数进行了详细的研究,确定了稀土矿物的种类及赋存状态。稀土元素有两种存在形式,其中以独立矿物形式存在的占90.66%,主要形成独居石、氟碳铈矿、氟碳钙铈矿和褐帘石;分散状态占9.34%,稀土元素作为类质同象形式或显微包裹体导致分散。稀土矿物嵌布粒度普遍较细,独居石粒径一般0.02 mm~0.03 mm;氟碳酸盐矿物粒径一般0.01 mm~0.02 mm;褐帘石粒径一般0.01 mm~0.03 mm。稀土矿物与伴生矿物的嵌布形式复杂多样,主要与方解石、铁白云石、长石等伴生矿物密切连生。     

浸矿对离子型稀土矿强度影响的试验研究

为研究浸矿对离子型稀土矿物理力学性质的影响,分别对浸矿前后的稀土矿样做直接剪切试验,根据库仑定律求出稀土矿的抗剪强度指标,结合颗粒筛分试验,分析浸矿对离子型稀土矿颗粒粒径和强度的影响规律,结果表明：浸矿发生的离子交换反应改变了离子型稀土矿颗粒的成分、粒径和级配,进而改变了稀土矿区的强度等力学性质;浸矿使稀土矿黏聚力降低50%左右,内摩擦角约增加15%,级配变差。本文的研究将为稀土开采中的边坡稳定和浸矿后尾矿的治理和综合利用提供一定的理论指导。     

浸矿液对离子型稀土矿孔隙影响机制研究

为了研究浸矿液对离子型稀土矿孔隙的影响机制,通过柱浸试验,借助CT扫描图像处理技术及扫描电镜手段,分析了颗粒重配比下稀土矿渗透性,浸出前后矿体孔隙率变化以及颗粒表面微观形貌变化情况,试验结果显示:离子型稀土矿浸出液渗流速率随浸出时间不断下降直至稳定,浸出前后矿体孔隙率呈时空差异性变化,浸出后矿体高度下降了8. 66 mm,孔隙率减小了4. 47%,矿物颗粒表面孔裂隙增大增多并呈贯通趋势。提出并探讨了浸矿液对离子型稀土矿孔隙4种影响机制:颗粒迁移、扩散双电层作用、化学反应作用和压力溶解。分析表明,4种机制的作用结果不同,其中颗粒迁移、扩散双电层作用和压力溶解导致矿体孔隙率减小,而化学反应作用导致矿体孔隙率变大; 4种机制的作用效果室内试验和现场实际不一样,室内试验:颗粒迁移化学反应作用扩散双电层作用压力溶解,现场实际:化学反应作用扩散双电层作用颗粒迁移压力溶解。浸出后矿体孔隙率增大或减小最终取决于矿体自身条件和物理化学综合作用结果。     

临汾盆地褐土剖面磁化率与粒度垂直变化特征及相关性研究

[目的]研究临汾盆地褐土剖面磁化率与粒度垂直变化特征及相关性.[方法]在临汾市尧都区农田取120 cm深的土壤剖面,每5 cm连续采样,对所取的24个土样进行磁化率和粒度的分析.[结果]磁化率随土壤深度增加而递减,>50 μm粒级含量随着土壤深度的增加而递减,10～50、1～10、<1 μm粒级含量随着土壤深度的增加而递增.地表以下0～30 cm为砂土,30～120 cm为粉土.磁化率与1～10、<1 μm粒级含量均呈极显著负相关,与>50 μm粒级含量呈极显著正相关,与10～50 μm粒级含量不相关.频率依赖系数XFD1.0与>50 μm粒级含量呈负相关,与10～50、1～10、<1 μm的粒级含量呈正相关;XFD0.1与10～50 μm粒级含量呈极显著负相关,与>50 μm粒级含量呈显著负相关.[结论]磁性颗粒主要赋存于粗颗粒物质中;磁化率及粒度对沉积环境和古气候的变化有一定的响应.     

模拟酸雨对赣南稀土矿淋滤实验研究

采用模拟土柱淋滤实验研究酸雨条件下浸矿土壤和尾矿土壤中氮化物的迁移.选取有机玻璃管为试验柱,模拟酸雨淋滤液pH为5.4~5.6,测量两类土壤中NH₄+-N、NO₃--N、有效氮含量,实验结果表明:稀土土壤对铵态氮有一定截留作用,铵态氮流失是导致矿区土壤及周边水环境污染的主要原因;铵态氮在两类土壤的含量随着淋洗量增加而逐渐减少;硝态氮在两类土壤的含量随着淋洗量增加呈现先减少至最低再有所回升,且受土壤pH和土壤埋深影响;有效氮在两类土壤中的迁移特征与铵态氮相似. 实验研究为有效控制赣南稀土矿土壤污染和水体污染提供理论基础.      

渗流作用下风化壳淋积型稀土矿细观孔隙结构演化特征

为研究风化壳淋积型稀土矿浸出过程中溶液渗流作用对孔隙结构的影响,以去离子水为溶浸液开展浸矿实验。对浸出前后矿样进行显微CT扫描,获取了试样内部结构图像,利用阈值分割算法得到了浸出前后稀土矿样的孔隙结构图像。进而,研究了溶液渗流作用下试样孔隙结构的变化特征,分析了渗流作用对试样孔隙率、孔隙体积、孔隙长度、孔隙宽度和孔隙方位角等参数的影响。结果表明:稀土矿孔隙形状和尺寸在渗流作用下发生显著变化,且在粗细颗粒接触区最为明显;溶液渗流作用使得稀土矿孔隙率增大,孔隙总数量减少,孔隙总体积增大。渗流作用下矿样中小孔隙数量减少,大孔隙数量增多,各尺寸区间的孔隙数量变化率随孔隙尺寸的增大呈现先增大后减小的趋势。溶液渗流作用下孔隙长宽比分布更加集中,孔隙方位角在各角度区间的分布更加均匀,孔隙各向异性增强。      

离子型稀土一维垂直入渗规律及最大粒径的影响试验研究

为了研究不同最大粒径离子型稀土土样对入渗规律的影响,利用自制的试验装置进行离子型稀土垂直入渗试验.水头高度恒定为 6 cm,土样最大粒径分别为 2.36 mm、1.18 mm、0.6 mm 和 0.3 mm. 在试验结果的基础上,利用改进的 Green-Ampt 模型分析离子型稀土入渗的饱和导水率和基质吸力. 结果表明,随着入渗时间的递增,累积入渗深度和湿润锋运移速率分别呈 “快速增加-缓慢发展 ”和 “快速减小-缓慢发展”的趋势.湿润锋运移速率与入渗时间之间满足幂函数关系,土样最大粒径对幂函数参数有较大影响.入渗率与湿润锋倒数之间具有良好的线性相关性.随着土样最大粒径的增加,饱和导水率和基质吸力也逐渐增加,二者与最大粒径之间呈指数函数关系.      

Optimization of rare earth carbonate reactive-crystallization process based on response surface method

Rare earth carbonate precipitation is mainly amorphous,of large volume and difficult to filter.To prepare crystalline rare earth carbonate,mother liquor of heavy rare earth was taken as research object,and the experimental scheme was designed based on the response surface central composite design(CCD)method.The concentration of mother liquor,aging time and seed crystal dosage were taken as independent variables,and the particle size of rare earth carbonate was taken as the response value to establish a quadratic polynomial numerical model to optimize the reactive-crystallization process of rare earth carbonate.The results show that these three factors have significant effect on the particle size of rare earth carbonate,and the influence order is mother liquid concentration aging time seed crystal dosage.Moreover,the interaction between mother liquor concentration and seed crystal dosage has a significant effect on the size of rare earth carbonate particles.The optimal parameters predicted by the model are as follows:the concentration of mother liquid is 1.75 g/L,seed crystal dosage is 13.56 wt%,and aging time is 8 h.Under these conditions,the predicted particle size is 28.74 μm,and the experiment particle size is 28.23 μm,between both,the relative error is 0.73%,which indicates that the established response surface model has a good prediction effect and a certain practical significance to guide the reactive-crystallization process of rare earth carbonate.The obtained rare earth carbonate has a crystallinity of 97.82%,uniform particles size,and low-hydrated crystals with a tengerite structure.     

Effects of rare earth on inclusions and corrosion resistance of 10PCuRE weathering steel

The types,morphologies and distributions of nonmetallic inclusions in Cu-P weathering steels with and without rare earth were analyzed through a quantitative image analyzer,scanning electron microscopy(SEM)and energy dispersive spectroscopy(EDS)attached to SEM.Solid-soluble content of rare earth in the steels was analyzed by non-aqua electroanalysis and ICP.The results showed that rare earth modified the types and the morphologies of inclusions in the weathering steels.The small spherical rare earth oxysulfides and rare earth sulphides replaced the elongated MnS inclusions in the RE weathering steels.The rare earth inclusions dispersedly distributed and most inclusions were smaller than 2 μm in size.The optimum content of RE was 0.0065%-0.016% for 10PCuRE weathering steels containing about0.002% oxygen and 0.004% sulfur.Solid-soluble content of rare earth in steels was(14-20)x 10-6,which can act as a micro-alloying element.The corrosion resistance of 10PCuRE weathering steels and Q235 were studied by dry-wet cyclic immersion test.Their corrosion rates were obtained respectively.The polarization curves and pitting corrosion behaviors of weathering steels with and without rare earth were measured by electrochemical methods.The corrosion resistance of Cu-P weathering steels was improved by adding an appropriate amount of rare earth.Less and fewer rare earth inclusions largely decreased pitting susceptibility and rate of pit propagation.The pitting potential and the resistance against pitting corrosion of the RE weathering steel were significantly improved due to the modification of rare earth to inclusions.     

Anti-swelling mechanism of DMDACC on weathered crust elution-deposited rare earth ore

In order to inhibit the swelling of the clay minerals in the in-situ leaching process of weathered crust elution-deposited rare earth ores (WCE-DREO), diallyl dimethyl ammonium chloride (DMDACC) was introduced as an anti-swelling agent and combined with (NH₄)₂SO₄ as a novel composite leaching agent. It can be found that the novel composite leaching agent exhibits a good anti-swelling performance and leaching capacity of rare earth, and has great potential on the actual exploitation of WCE-DREO. The anti-swelling mechanism of DMDACC was studied by characterization analysis. The results show that DMDACC with positive charges can be adsorbed on the clay particles by the electrostatic attraction and hydrogen bonds, and neutralize the negative charge of the clay particles. The double electrical layers are suppressed and the repulsion force between clay sheets decreases. It causes the clay particles prone to aggregate. Moreover, DMDACC can enter the interlayer and expel out the water molecules in interlayer. The interlayer spacing is decreased and the hydration swelling of the clay particles is weakened. It can provide a theoretical basis for the development of novel anti-swelling agents.     

稀土粉体性能的评价体系(Ⅱ):颗粒特性的评价

稀土粉体(氢氧化稀土、稀土碳酸盐、稀土草酸盐、稀土氧化物和氟化物等)的颗粒性能方面的指标对稀土新材料的开发具有重要意义.晶粒特性、表面特性、颗粒特性、颗粒群特性和应用特性等五方面构成了稀土粉体性能的评价体系.本文对颗粒特性的评价进行了讨论,颗粒大小分布、颗粒形状、颗粒团聚参数、团聚强度、团聚体结构、孔隙率是描述颗粒特性的六个指标.     

稀土Y对气雾化制备PH13-8Mo钢粉末特性的影响

摘要：研究了不同含量的稀土Y对选区激光熔化技术(SLM)用PH13 8Mo钢粉末特性的影响,并通过Thermo-Calc热力学软件、粉体综合特性测试仪、霍尔流速计、激光粒度分析仪、扫描电镜和电子探针等方法对不同Y含量的PH13-8Mo钢粉末特性的变化规律进行研究。结果表明,随着金属粉末中Y含量的增加,金属粉末的松装密度从3.73提高到3.93g/cm3,50g粉末的自由流动时间从25.44减小到25.11s,粉末的流动性变好。同时,PH13 8Mo钢粉末的平均粒径从37.29减小到30.99μm,粉末的粒度分布区间变窄。研究还发现,不含Y的PH13-8Mo钢粉末的组织由树枝晶和等轴晶组成,而Y质量分数为0.080%的PH13 8Mo钢粉末的组织均由等轴晶组成。综上,在PH13.8Mo钢粉末中加入稀土Y,粉末的特性得到优化。     

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.     

烧结Nd-Fe-B磁体的温度稳定性缺陷分析

采用SEM、EDAX及粒度分析手段,研究了烧结Nd-Fe-B磁体开路磁通不可逆损失(hirr)异常偏高的原因。结果表明,磁体显微组织中晶粒尺寸分布不均匀及存在少量粗大晶粒,是导致其温度稳定性缺陷的主要因素,表现为少数产品hirr异常偏高。在磁体工业生产过程中,改进原料的铸锭和制粉技术,避免出现粗大粉末颗粒,减少极细粉末颗粒的数量,保证磁体显微组织精细均匀,是制备温度稳定性高的烧结Nd-Fe-B磁体的基本措施。     

The roles of rare earth dispersoids and process

Low cycle fatigue tests were conducted at 482 °C (900 °F) on forgings and extrusions of a rapidly solidified powder metallurgy titanium base alloy with and without rare earth additions. The variables studied were process temperature and heat treatment. Rare earth dispersions reduced fatigue life, and fracture surfaces indicated internal fatigue crack initiation at rare earth particles.