Electrical properties of phases in the ZrO2 - Y2O3 - La2O3 system

An investigation was made of the electrical properties of phases with the cubic fluorite, pyrochlor, and C-Y₂O₃ structures, and the tetragonal ZrO₂ structure (T-ZrO₂) in the ternary system ZrO₂ - Y₂O₃ - La₂O₃. For comparison, the electrical conductivity of a number of specimens with the fluorite structure in the binary system ZrO₂ - Y₂O₃ and with the pyrochlor structure in the ternary system HfO₂ - Y₂O₃ - La₂O₃ was also studied. The specimens were prepared from nanocrystalline powders synthesized by the hydrolysis of zirconium salts in an acid medium at high temperatures. Conductivity was measured over the range 300–950°C in air. It was shown that phases with the fluorite and T-ZrO₂ structures in the investigated systems possess the highest electrical conductivities. Translated from Poroshkovaya Metallurgiya, Nos. 3/4(412), pp. 40–46, March–April, 2000.     

钾长石-萤石-硫酸体系中分解钾长石的探讨

介绍一种利用天然矿物低成本分解钾长石的方法和工艺,在研究了反应机理的基础上,对反应物及比例、加热条件、反应容器、酸用量和反应时间等进行试验,钾的提取率可稳定在96%以上,未分解的钾长石不高于1％。副产物回收利用,生产成本大大降低。     

萤石尾矿基多孔陶瓷负载零价铁的制备及其降解亚甲基蓝废水

以工业固体废弃物萤石尾矿和高炉粉尘为主要原料,通过碳热还原法制备了萤石尾矿基多孔陶瓷负载零价铁(FT/BFD@Fe⁰)复合材料,并用于降解亚甲基蓝(MB)废水。系统探究了废水pH、废水初始浓度、高炉粉尘添加量、FT/BFD@Fe⁰投加量、温度对FT/BFD@Fe⁰吸附性能的影响,并探究了相关反应机理。结果表明,当pH=7、初始MB质量浓度20 mg/L、高炉粉尘添加量15%、FT/BFD@Fe⁰投加量10 g/L、温度15℃时,FT/BFD@Fe⁰对亚甲基蓝的去除效率在3 h内达到了92.0%。热力学分析与动力学模型表明,FT/BFD@Fe⁰对亚甲基蓝吸附反应过程符合准二级动力学模型和Langmuir模型。     

陕南蟒岭矿集区天明一带萤石矿床稀土元素地球化学特征及其成矿意义

天明一带萤石矿床位于陕南蟒岭矿集区东部,该矿集区是陕南重要的萤石矿产地之一。本文通过对该萤石矿床矿石样品的分析测试,研究其稀土元素地球化学特征,初步探讨成矿流体性质、成矿环境及矿化作用过程。研究表明,该矿床矿石稀土元素含量偏低,ΣREE介于25.69×10^-6～43.23×10^-6,平均36.64×10^-6,LREE/HREE介于3.30～10.65,平均6.72。δEu=0.76～1.45,多数为正Eu异常,δCe=0.75～0.97,表现出弱负Ce异常,Eu、Ce异常暗示萤石矿床形成于中低温、氧化的环境。矿石La/Ho-Y/Ho图解、(La+Y)-Y/La图解指示成矿物质和流体可能来自富氟的蟒岭花岗质岩浆,有外缘物质的加入或混染作用,围岩地层中的碳酸盐岩可能参与其中。Tb/Ca-Tb/La图解显示矿床属热液成因,Tb/Ca-Tb/La、Tb/La-Sm/Nd图解暗示可能经历了多个期次的成矿活动。推测天明一带萤石矿床为浅成中低温热液成因,其成矿可能与蟒岭花岗质岩浆热液相关。     

江西香炉山钨尾矿中萤石综合回收技术的研究

江西香炉山钨尾矿含氟化钙7.10%、碳酸钙8.00%,属萤石含量低而方解石含量高的尾矿,尾矿中萤石的经济价值不高,当前售价约在2 000元/t以内,但为了提高矿产资源综合回收利用率和尽量延长尾矿库使用寿命,开展了钨尾萤石的综合回收技术研究。采用预处理—萤石浮选—酸浸工艺,获得产率为3.88%,Ca F291.88%,回收率为50.26%的萤石精矿,说明香炉山钨尾中的萤石可得到有效回收。本文对萤石综合回收工艺及条件试验进行了论述,并根据尾矿的矿物学特征,对影响萤石回收指标的因素进行了分析,对三氧化钨在萤石分离工艺中的走向进行了查定。     

新型抑制剂对高钙萤石矿抑制机理及工艺研究

针对CaF₂品位30.32%、CaCO₃品位35.42%的某高钙萤石矿,以油酸钠为萤石捕收剂、新型药剂SS-1为抑制剂,通过单矿物试验研究了抑制剂SS-1对萤石和方解石浮选性能的影响,采用接触角和吸附测试对抑制剂SS-1的抑制机理进行了分析。结果表明,在中性条件下,SS-1大量吸附在方解石表面,抑制了方解石的上浮,方解石回收率从66.93%降低到9.88%;同时,抑制剂SS-1少量吸附在萤石表面,对萤石浮选起到了促进作用,萤石回收率从96.03%提高到96.56%。根据单矿物试验分析结果,对高钙萤石实际矿进行了多段浮选试验研究,确定了粗精矿再磨、一粗八精一扫、中矿顺序返回闭路工艺流程,最终获得了CaF₂品位97.86%、回收率89.59%的萤石精矿。     

GF组合药剂浮选柿竹园多金属矿萤石的研究

针对柿竹园矿矿石性质复杂,萤石品位低,嵌布粒度细,共生关系复杂,研制出能有效分散泥化絮团和强烈抑制易浮微细粒脉石的组合药剂GF,采用粗精矿再磨、中矿集中再选及强磁脱硅工艺,从浮钨尾矿回收萤石,获萤石精矿品位98.47%,回收率71.19%。     

地物化综合方法在新县陡山萤石矿勘查中的探索应用

萤石矿属于我国战略性矿产,随着地表和浅部萤石资源逐渐枯竭,未来不断加大萤石矿资源勘查力度、进度及增加萤石储量势在必行,根据工作区成矿特征及规律,选择合理地物化综合方法能够高效提高浅覆盖区、深部萤石矿体的找矿效率。本文根据河南省新县陡山萤石矿的成矿特征及规律,依托土壤地球化学测量所圈定的氟元素异常区快速定位预测隐伏萤石矿体的成矿远景区。开展地表追索及异常查证,结合可控源音频大地电磁测深重点区段剖面解译成果,推测控矿构造在深部延伸的规模及方向,预测萤石矿化带在深部的成矿空间、成矿规律,利用钻探工程对重点预测区进行深部验证,初步发现8条萤石矿体,获取萤石(333)+(334)矿石量64.08万吨,为该区进一步开展萤石矿勘查提供了重要的依据。     

Effect of Pr on the electrical and chemical properties of cerium oxide prepared by combustion method

Nanoparticles of Ce_1−xPr_xO₂ (X: 0.6 and 0.8), were synthesized by the combustion method using citric acid as chelating and fuel agent. The X-ray diffraction patterns and Rietveld refinements confirm that samples shown as a single phase in a cubic fluorite structure, with an increase in the lattice parameter as a function of Pr concentration. The crystallite size domains obtained by the Scherrer formula, confirm values around 10 and 37 nm. The scanning electron microscopy images, show that the solids are composed of dense heterogeneous aggregates. The X-ray photoelectron spectroscopy, reveals that oxides are composed of cerium and praseodymium cations in oxidation states 4+ and 3+ respectively. The TPR-H₂ profiles indicate that cerium and praseodymium cations present in the obtained systems are completely reduced to Ce³⁺ and Pr³⁺ at temperatures above 790°C. The impedance spectroscopy data at room temperature showed that the conduction processes for the two systems take place at the grain boundaries. The Ce_0.2Pr_0.8O₂ system offer lower resistance, due to the high amount of Pr³⁺ ions inserted in the structure and the high amount of oxygen vacancies formed in the synthesis process.     

A new class of high-entropy fluorite oxides with tunable expansion coefficients,low thermal conductivity and exceptional sintering resistance

High-temperature thermal barrier coating (TBC) materials are desired for the development of high-efficient gas turbines and diesel engines. Herein, to meet up with this requirement, a new class of high-entropy fluorite-type oxides (HEFOs) has been synthesized via a solid-state reaction method. Comparing to La₂Ce₂O₇, a promising TBC material, the HEFOs exhibit similar high thermal expansion coefficients (TECs) of 11.92×10⁻⁶∼12.11×10⁻⁶ K^-1 at temperatures above 673 K but a better TEC matching performance at the temperature range of 473–673 K. It is also found that through tuning the average A-site cation radius, the TEC of the HEFOs could be tailored efficiently. The HEFOs also possess low thermal conductivities of 1.52-1.55 W∙m^-1∙K^-1 at room temperature, which is much lower than that of La₂Ce₂O₇ and comparable to pyrochlores as Gd₂Zr₂O₇. Moreover, the HEFOs display good sintering resistance and phase stability even at temperatures as high as 1873 K. The combination of these fascinating properties makes the HEFOs good candidates for thermal barrier coating and thermal insulating materials.