引入铀矿细菌浸出工艺实现水冶单一型向混合型转变的可行性研究

相山铀矿田矿石元素组合有多种类型,铀-多元素矿化的空间分布具有明显的规律,根据矿性的不同,水冶由单一型向混合型转变,是多矿山单水冶厂型铀矿企业将来的发展趋势。通过研究不同浸出工艺自身的优缺点,经过合理搭配可以彼此之间互补,从而提高矿石浸出率、降低化工原材料的损耗,有效的控制水冶成本。在多金属的硫化矿床中,通常含有黄铁矿（Fe S2）,在有细菌的条件下,细菌将亚铁氧化为三价铁,硫氧化为硫酸,其中三价铁是一种很有效的矿物氧化剂和浸出剂,所以引入铀矿细菌浸出工艺,可完善水冶混合型工艺,降低酸耗。通过试验表明细菌浸出在实际生产中的可行性,根据试验结果,再对实际生产中细菌浸出存在的问题提出建议,通过工艺互补,从而达到最佳生产方案。混合型水冶的建立目前仍然受很多因素的制约,如何解决制约因素、合理分配、调节工艺参数等问题需进一步探讨解决。     

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。     

某铀矿矿石品位变化同堆浸氧化剂(二氧化锰)加入量关系研究简

铀矿山采用堆浸方法处理铀矿石时,氧化剂加入量对铀浸出效果有重要影响.因此当铀矿矿石岩性发生变化,其堆浸氧化剂加入量也需要作相应的调整.解决好氧化剂加入量和矿石品位变化关系对提高铀矿山湿法冶金回收率和矿山经济效益具有重要意义.通过对某铀矿水冶工艺车间的工艺流程分析发现,该铀矿目前生产工艺中氧化剂（Mn02）加入量没有结合铀矿石岩性变化,尤其是矿石品位变化.理论计算的氧化剂加入量和长期采用固定加入量存在很大差异,造成了氧化剂的浪费.该铀矿山酸法堆浸氧化剂加入量应作相关研究给予调整,氧化剂加入量调整对矿区节能减排提高经济效益具有重要实际意义.     

氧化剂对超临界CO_2流体浸取矿石中铀的影响

铀是重要的核能燃料,而铀的高效采冶特别是低品位铀矿资源的开发是核电发展的基础。文中采用实验室自主研制的多功能超临界CO_2浸取装置来浸取铀矿石。利用正交设计,研究氧化剂种类、压强、反应时间、温度对铀浸出率的影响,得出超临界CO_2流体浸取铀矿石的最佳工艺参数。研究表明:以Fe_2(SO_4)_3为氧化剂时,浸出效果最佳。使用Fe_2(SO_4)_3为氧化剂时,在压强为12 MPa、反应时间120 min、温度为45℃的条件下,超临界CO_2流体对铀的浸出率达到90.24%。超临界CO_2流体可望应用于实际低品位铀矿山中铀的提取。     

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。     

粉煤灰提取氧化铝试验研究

原灰用硫酸浸出时,各工艺参数对浸取率的影响进行了试验、讨论.从而得出各参数的最佳值.     

钛铁矿制备高纯钛白粉浸出工艺优化

本文采用"硫酸浸出-水解结晶除杂-钛盐水解-煅烧"工艺从钛铁矿中回收钛白粉.综合考察了浸出过程中温度、搅拌强度、时间、固液比、硫酸浓度等因素对浸出率的影响.实验结果表明,浸出过程中最佳浸出参数为浸出剂浓度为18.4mol/L的硫酸、浸出温度为160℃、浸出时间为90min、浸出搅拌强度为400r/min、固液比为1∶1...     

铁浓度对某铀矿浸铀菌群的影响

微生物堆浸具有技术提高铀的浸出率,缩短生产周期,节省硫酸及氧化剂,降低生产成本,减少对环境所造成的不利影响的优点。某铀矿是我国重要的铀矿山,在2009年之后,该铀矿陆续开展一系列的微生物堆浸实验和生产项目,在文章中,笔者讨论以及分析了不同浓度的亚铁和三价铁对该铀矿中浸铀菌群的影响。结果表明,低浓度的二价铁和高浓度的三价铁都有利于菌群的氧化,并且该铀矿菌群的最适总铁浓度为8 g/L。     

含锗烟尘的硫酸浸出工艺研究

为简化含锗烟尘浸出过程,提出一段硫酸浸出工艺。浸出工艺条件为：浸出温度90℃,初始硫酸质量浓度120g／L,液固比8mL／g,浸出时间2．5h,搅拌转速120r／min。在该条件下,锌、锗浸出率分别为99．1％和87．61％左右,最终硫酸质量浓度约34．80g／L。去除不溶性锗后,锗浸出率可达到97．21％。     

IN SITU LEACHING OF URANIUM USING DILUTE SULFURIC ACID AND MOLECULAR OXYGEN

The technical feasibility of in situ uranium leaching using dilute sulfuric acid and molecular oxygen has been assessed and the important process parameters examined by use of laboratory high pressure leaching columns.

The dilute H₂SO₄/O₂ lixiviant was effective in leaching uranium from the ore samples tested. The leaching process was chemical reaction rate limited and can be represented using pseudo first-order kinetics. The leaching rate constant is proportional to the proton concentration of the lixiviant.

Much of the uranium was leached from the ore before decomposition of carbonate minerals by the acid was complete. Acid consumption per pound of U₃O₈ increased sharply as the uranium recovery level exceeded 70%. There appears to be a minimum oxygen pressure for effective uranium leaching. A pressure of 2758 KPa was adequate for the ore samples tested     

IN SITU LEACHING OF URANIUM USING DILUTE SULFURIC ACID AND MOLECULAR OXYGEN

The technical feasibility of in situ uranium leaching using dilute sulfuric acid and molecular oxygen has been assessed and the important process parameters examined by use of laboratory high pressure leaching columns.

The dilute H₂SO₄/O₂ lixiviant was effective in leaching uranium from the ore samples tested. The leaching process was chemical reaction rate limited and can be represented using pseudo first-order kinetics. The leaching rate constant is proportional to the proton concentration of the lixiviant.

Much of the uranium was leached from the ore before decomposition of carbonate minerals by the acid was complete. Acid consumption per pound of U₃O₈ increased sharply as the uranium recovery level exceeded 70%. There appears to be a minimum oxygen pressure for effective uranium leaching. A pressure of 2758 KPa was adequate for the ore samples tested     

黑曲霉产有机酸浸出铀矿石的影响因素

为了解培养基种类、培养温度和pH值等因素对黑曲霉产生的混合有机酸浸出铀矿石的影响,从铀矿山水样中分离、纯化得到了一株真菌--黑曲霉,应用马铃薯-蔗糖培养基（potato sucrose agar,PSA）和葡萄糖-玉米浆培养基(dextrose corn syrup,PCS)进行黑曲霉培养,获得了不同培养温度下产生的pH值不同的黑曲霉产混合有机酸,并将之作为浸出剂用于浸铀实验研究。研究表明,黑曲霉产生的有机酸的主要组分为草酸和柠檬酸等有机酸,培养基种类的不同会影响黑曲霉所产有机酸的浸铀效果,采用PSA培养基培养的黑曲霉产生的有机酸浸铀效果更好（p<0.05）。培养温度和混合有机酸的pH值也会对黑曲霉代谢产物的铀浸出率有显著性影响（p<0.05）,且二者具有交互效应,pH值对铀浸出率的影响相对较大。应用PSA培养基时,最佳培养温度为25℃,最佳代谢产物pH值为2.3;应用PCS培养基时,最佳培养温度为30℃,最佳混合有机酸pH值为2.0。培养基种类、温度和pH值主要通过改变黑曲霉产生的有机酸的成分和含量对铀浸出率产生影响。     

Recovery of Uranium from Seawater by Immobilized Tannin

Abstract

Tannin compounds having multiple adjacent hydroxy groups have an extremely high affinity for uranium. To prevent the leaching of tannins into water and to improve the adsorbing characteristics of these compounds, we tried to immobilize tannins. The immobilized tannin has the most favorable features for uranium recovery; high selective adsorption ability to uranium, rapid adsorption rate, and applicability in both column and batch systems. The immobilized tannin can recover uranium from natural seawater with high efficiency. About 2530 μg uranium is adsorbed per gram of this adsorbent within 22 h. Depending on the concentration in seawater, an enrichment of up to 766,000-fold within the adsorbent is possible. Almost all uranium adsorbed is easily desorbed with a very dilute acid. Thus, the immobilized tannin can be used repeatedly in the adsorption-desorption process.     

Sono-chemical leaching of uranium

A fundamental study on the mechanism of uranium leaching in nitric acid and sulphuric acid media has been carried out to understand the effect of the ultrasound on leaching. The use of ultrasound clearly improves the leaching rate within the studied leach acid media. The enhancement in the leaching rate in the presence of ultrasound is higher with low leach acid concentration of nitric acid (HNO₃), and it is high at high leach acid concentration in the case of sulphuric acid (H₂SO₄) being used as a leachant, when compared to conventional mechanical agitation. The basic reason behind this observed variation is explained on the basis of the reaction mechanism involving the oxidative conversion of acid insoluble tetravalent uranium form to the soluble hexavalent form of uranium in the presence of ultrasound at a faster rate.     

PCR-测序法分析铀生物堆浸过程中微生物群落结构变化特征

文章采用PCR-直接测序法研究了铀生物堆浸不同浸铀阶段(前期酸化、酸化、前期菌液淋洗、菌液浸铀)微生物群落结构的变化。采用试剂盒法提取了矿石样品中宏基因组DNA,以细菌的16S rDNA通用引物27F/1492R扩增16S rDNA片段,建立16S rDNA克隆文库。从每个处理结果中筛选100个阳性克隆,阳性克隆子直接送测序,用NCBI Blastn程序进行基因数据比对分析,结果表明:从前期酸化阶段到菌液浸出阶段,菌落多样性呈减弱趋势,对浸铀有直接或间接作用的嗜酸性微生物:嗜酸性氧化硫硫杆菌(Acidithiobacillus thiooxidans)、嗜酸性氧化亚铁硫杆菌(Acidithiobacillus ferrooxidans)等的含量呈增加趋势。在菌液浸出阶段,pH值低于最小值1.8时,细菌多样性较高,对浸铀有直接或间接作用的嗜酸性微生物丰度较低。说明嗜酸性微生物对铀的浸出可能有重要作用,生物堆浸过程中需要严格调控pH值。     

浅谈地表堆浸的矿堆酸化

对于酸耗较高的矿石堆,酸化时间较长,如果酸化过程控制不当,将会带来一定的问题和麻烦,轻者可能降低矿堆的渗透性,使堆浸周期延长、浸出率降低;重者可能造成局部板结,甚至造成整堆报废。通过矿堆酸化过程的分析,找出了影响矿堆酸化的主要因素,提出了改善矿堆酸化效果的措施。对铀矿堆浸生产有一定的指导意义,对金、银、铜等矿石堆浸有一定参考价值。     

Oxidative leaching kinetics of molybdenum-uranium ore in H2SO4 using H2O2 as an oxidizing agent

The processing of molybdenum-uranium ore in a sulfuric acid solution using hydrogen peroxide as an oxidant has been investigated. The leaching temperature, hydrogen peroxide concentration, sulfuric acid concentration, leaching time, particle size, liquid-to-solid ratio and agitation speed all have significant effects on the process. The optimum process operating parameters were: temperature: 95°C; H₂O₂ concentration: 0.5 M; sulfuric acid concentration: 2.5 M; time: 2 h; particle size: 74 μm, liquid-to-solid ratio: 14 ∶ 1 and agitation speed: 600 rpm. Under these experimental conditions, the extraction efficiency of molybdenum was about 98.4%, and the uranium extraction efficiency was about 98.7%. The leaching kinetics of molybdenum showed that the reaction rate of the leaching process is controlled by the chemical reaction at the particle surface. The leaching process follows the kinetic model 1 ? (1?X)^1/3 = kt with an apparent activation energy of 40.40 kJ/mole. The temperature, concentrations of H₂O₂ and H₂SO₄ and the mesh size are the main factors that influence the leaching rate. The reaction order in H₂SO₄ was 1.0012 and in H₂O₂ it was 1.2544.