酸法浸铀与生物浸铀浸泡试验的对比研究

近年来,生物技术在我国低品位砂岩型铀矿及老采区残留难浸铀矿的开发研究已开始起步。凭借生物浸铀具有的氧化性强、浸出液铀浓度及浸出率高等特点而成为开采该类铀矿的重要手段。文章以新疆某砂岩型难浸铀矿石浸泡浸出试验为例,系统开展了不同酸度条件下酸法浸出及不同Fe3+浓度条件下细菌浸铀试验。试验结果表明,生物浸铀在浸出液平均铀浓度、铀浸出率及浸出量等方面均高于酸法试验结果。     

酸法浸铀与微生物浸铀管浸实验对比研究

我国铀资源的开发利用已经延伸到低品位砂岩型铀矿床以及老采区难开采型铀矿。生物浸铀凭借能够强化浸出过程、改善铀浸出动力学、提高铀浸出率、有利于环境保护等优点成为浸铀采矿的重要手段。文章以新疆某砂岩型铀矿为例,系统开展不同条件下酸法以及Fe3+浓度条件下细菌浸铀管浸实验。实验表明,生物浸铀在动态条件下铀平均浓度、浸出率及浸出量等方面均高于酸浸实验结果。     

强化酸浸提金及除砷和铁的试验研究

对含硫砷难选矿烧渣酸浸氰化提金进行了试验。通过稀酸浸出除砷正交试验,得出酸浸液种类是影响除砷效果最关键的因素,最优工艺参数是酸浸时间为60 min,固液比约1∶2,酸浸温度为20℃,酸浸液种类为5%硫酸。通过强化酸浸提高金浸出率正交试验,得出酸浸温度是影响金浸出率最关键的因素,最优工艺参数是:硫酸浓度65%,矿酸比1∶2,酸浸温度95℃,酸浸时间4 h。通过强化酸浸液除铁探索性试验,有效地提取了酸浸液中的铁,得出单程试验FeSO4·7H2O结晶的收率达到83.01%,其中砷含量为0.03%,经一次洗涤后可降到0.006%。     

借鉴硫酸法钛白生产工艺提高黄金回收率的设想

为了提高难浸金矿中黄金的回收率,提出了借鉴硫酸法钛白生产工艺,利用70％左右浓度硫酸浸出焙烧矿中的铁,使铁进入酸浸液中,剥离铁中的包裹金,从而提高难浸金矿中黄金产率,对黄金行业具有一定的开拓和创新意义,具有良好的经济效益和社会效益。     

难浸含砷炭金精矿预先酸浸-焙烧-氰化工艺实验研究

某地难浸含砷炭金精矿采用预先酸浸,然后进行焙烧,氰化浸出,研究了酸浸条件对金浸出率的影响。结果表明,较优酸浸条件为硫酸浓度100 g/L,添加氯酸钠活化剂5 g/kg,酸浸温度50℃,酸浸时间6 h;630℃焙烧2 h;氰化浸出采用二浸二洗流程,氰化钠浓度控制在0.15%~0.20%,氰化浸出时间为(24+12)h。在此条件下,金的浸出率可高达93%。     

氢氧化钠碱浸SCR废弃催化剂的回收研究

采用氢氧化钠碱浸法从废弃蜂窝式SCR催化剂中回收Ti和W。首先对催化剂进行氢氧化钠碱浸,在超声及油浴加热浸取的条件下使钨生成可溶性的盐与难溶钛酸钠分离,随后经精制流程,精制滤液中的钨酸。本实验研究了碱浸时不同碱液浓度和碱浸温度对钨浸出率的影响。实验结果表明:在温度110℃到140℃之间,提高温度对钨的浸出效率有促进作用,在碱液浓度20%到35%之间,提高碱液浓度对钨的浸出效率有提高作用。在氢氧化钠碱液浓度为35%,碱浸温度为140℃时,钨的浸出率最理想(三氧化钨纯度可达88.68%)。并且在碱浸浓度35%、温度140℃时,最终精钨中WO_3纯度达98.49%。     

煤矸石酸浸除铁的工艺研究

提取煤矸石中的有价元素是煤矸石资源化利用的有效方法之一,本研究针对高铁、低铝、低热值煤矸石,利用稀硫酸浸出其中的铁,达到脱铁富铝的目的。分别考察酸浓度、酸浸温度、液固比、酸浸时间等因素对铁浸出率的影响。结果表明,铁的最佳溶出条件为:硫酸浓度15%,酸浸温度45℃,液固质量比4:1,酸浸时间4h。可以证明在上述条件下,铁的浸出率可以达到82.13%。     

粉煤灰中镓的浸出试验条件

介绍用酸浸法从粉煤灰中回收金属镓的试验结果 ,探讨粉煤灰焚烧温度、焚烧时间、酸浸温度、酸的种类及灰的粒度对浸出结果的影响 ;探索回收镓的最佳工艺参数     

地浸采铀工艺技术及发展研究方向

铀矿的原地浸出(以下简称地浸采铀)工艺是集采、选、冶于一体的新型铀矿开采方法。该方法基础投资少、开采方法简单、环境污染小、能开采低品位铀矿床。地浸采铀方法可分为酸法、碱法和生物浸出法。随着新型砂岩型铀矿床的不断勘探,地浸采铀技术难题不断出现,使其研究方向产生变化。     

低温中和-加压酸浸提取煤矸石中铝铁

以贵州盘县煤矸石为研究对象,为解决其工业生产提取铝铁时酸耗量大、酸利用率低及后续铝铁产品分离困难等问题,根据其矿物组成特点,本文首次采用低温中和-加压酸浸工艺对铝铁提取进行了详细研究。室温下中和最优工艺条件为20%理论酸耗、浸出时间120min、液固比3∶1（硫酸溶液与固体的质量比,以g/g计）;以中和渣为原料,煤矸石理论酸耗为基础,加压酸浸最优工艺条件为浸出时间120min、浸出温度150℃、液固比3.5∶1（硫酸溶液与固体的质量比,以g/g计）。在此条件下,氧化铁浸出率为98.37%,氧化铝浸出率为95.77%,酸浸渣灰分中氧化硅质量分数为90.2%,氧化钛质量分数为9.18%。以最优工艺条件下的酸浸液循环中和新鲜煤矸石,得到的铝铁提取液中氧化铁浓度为57.95g/L,氧化铝浓度为62.20g/L。相比常规酸浸工艺具有酸耗低、酸利用率高等优点。借助X射线衍射仪（XRD）、傅里叶红外光谱仪（FTIR）和扫描电子显微镜（SEM）等分析手段,初步对两步溶出过程进行了机理分析,为煤矸石工业生产提取铝铁提供了新路线和理论支撑。     

Purification of Uranium from a Uranium/Molybdenum Alloy

Abstract

The Savannah River Site will recycle a nuclear fuel comprised of 90% uranium-10% molybdenum by weight. The process flowsheet calls for dissolution of the material in nitric acid to a uranium concentration of 15–20 g/L without the formation of precipitates. The dissolution will be followed by separation of uranium from molybdenum using solvent extraction with 7.5 vol% tributylphosphate in n-paraffin. Testing with the fuel validated dissolution and solubility data reported in the literature. Batch distribution coefficient measurements were performed for the extraction, strip, and wash stages with particular focus on the distribution of molybdenum.     

Properties of Uranium Monophosphide

Properties of uranium monophosphide were determined at room and at high temperatures. Heating UP above 1400°C in vacuum resulted in preferential loss of phosphorus, producing a slight contraction of the cubic lattice. Effect of temperature and time on the densification, lattice structure, and stoichiometry of UP is discussed. Properties determined include hardness, melting temperature, electrical resistivity, vaporization behavior, irradiation behavior, thermal expansion, high-temperature compatibility, and some chemical properties.     

Characterization of Respirable Uranium Aerosols from Various Uranium Alloys in Fire Events

Aerosols dispersed from the oxidation of various uranium alloys exposed to air and direct flame impingement from combustible substrates are characterized. An apparatus was designed to incorporate desired characteristics of previous experiments on uranium to sample aerosol on a kilogram scale in a laboratory environment. Previous studies involving β-phase stabilized uranium (99.25 wt% U:0.75 wt% Ti) were benchmarked using an identical alloy with identical characteristics of the original specimens. Other studies involving a-phase uranium (100 wt% U) were also benchmarked in this experiment. Unique to this study is the use of γ-phase stabilized uranium (94 wt% U:6 wt% Nb). These three alloys represent the crystallographic range of typical uranium metals, providing a complete spectrum of potential uranium aerosolization. Oxidation rates and extents observed in these experiments were directly comparable to existing data and provided correlation between previous studies. These experiments indicate a distinct order-of-magnitude difference between uranium alloy responses to thermal stress.     

Electrical Conductivity of Uranium Dioxide

The electrical conductivity of nearly stoichiometric single-crystal and polycrystalline uranium dioxide was measured from room temperature to 3000°K. Below approximately 550°K, the curve of log σ versus T ⁻¹ is linear with a calculated activation energy of approximately 0.17 ev. Between 550° and 1250°K, however, the shape of the curve changes; this change varies from one specimen to another. The electrical conductivity increases rapidly with increasing temperature above 1250°K with a change from p -type to n -type conduction. The best linear fit of the log σ versus T ⁻¹ curve above 1400°K is σ= 3.57 × 10³ e ^{−(1.15 ev/KT)}. Above 1900°K, the curve deviates slightly from linearity and is best fit by the equation σ= 2.10 × 10⁻² T ^1.4 e ^{−(0.916 ev/KT)}.     

Surface Energy of Uranium Dioxide

Using the method of interfacial angle equilibrium in the system UO₂-Ni, a surface energy of 754±150 ergs/cm² was determined for UO_2.01 at 1500°C in high-purity Ar. The absolute interfacial energies in the system UO₂-Ni at 1500°C were also determined.     

Oxidation Behavior of Uranium Monophosphide

Oxidation of UP at moderate temperatures was studied using DTA, X-ray diffraction, TGA, and chemical analysis. Heating rates, atmosphere, and particle size were varied. Oxidation behavior of UP was significantly different from that of UC, UN, US, and UAs, all of which possess the NaCl-type crystal structure. The greater oxidation resistance of UP was attributed to surface formation of an amorphous phase containing P₂O₅ and UO₂. Existence of this coating was thought to be responsible for the nontarnishing and generally nonpyrophoric nature of UP at room temperature.