包头白云鄂博矿钍资源的回收及用于核电燃料的研究现状

包头白云鄂博矿中钍资源非常丰富，近年来随着铁矿石的开采，钍被分配到一些产品或废渣中，这不仅造成钍资源的严重浪费，同时分散了的放射性钍给周边环境造成了严重污染。针对目前世界能源紧张的状况，开发新的能源势在必行，钍作为核能发电燃料的研究近年来已有突破，研究开发钍用于核电燃料研究是一项重大和长远的任务。全面分析了包头白云鄂博钍的资源现状及流向，介绍了在生产稀土的同时提取钍化合物、金属钍的工艺研究状况及钍用于核电燃料的研究进展，探讨了钍在核电燃料中的应用可行性及应用前景。     

放射性铌铁精矿中铀钍脱除及分离

通过对国内某企业进口放射性铌铁精矿进行工艺矿物学分析,确定该精矿的主要矿相为烧绿石,同时伴生钛铁矿和白云母,矿石中放射性元素U和Th的含量分别为0.27%和1.03%。针对该铌铁精矿,探索H2SO4-Fe(Ⅲ)、H2SO4-HF-H2O2、H2SO4-HF、H2SO4-HF-H2O2-(NH4)2CO3体系中U和Th的浸出及分离效果,最终确定H2SO4-HF-H2O2-(NH4)2CO3多段浸出工艺能有效实现U和Th的脱除与分离。U、Th的脱除率分别为100%和80%。基于研究提出了铌铁精矿U、Th脱除及分离工艺流程。     

稀土精矿中钍的提取工艺研究进展

核能开发是我国能源战略和经济发展的重要举措,发展核能离不开核燃料。钍是一种重要的核燃料,在核能开发方面具有广阔的应用前景,能有效解决我国能源紧缺等问题。钍极少以独立矿物赋存,大多与稀土矿物共生。主要对近年来稀土精矿中钍的提取工艺研究进展进行了综述,并对稀土精矿中稀土和钍的综合利用发展提出了相关建议。     

白云鄂博矿焙烧浸出-萃取沉淀分离稀土及钍的试验研究

采用焙烧浸出-萃取沉淀法从白云鄂博稀土精矿中分离稀土和钍,得到最佳焙烧浸出条件为:矿酸比1∶1.5、焙烧时间1 h、焙烧温度200℃、水浸液固比8∶1、水浸时间4 h、水浸温度50℃,最佳条件下CeO₂、La₂O₃、Nd₂O₃、Pr₆O₁₁、Sm₂O₃和ThO₂浸出率分别为80.77%、69.24%、95.71%、76.82%、93.31%和98.13%。采用羧酸类萃取-沉淀剂从浸液中萃取分离稀土和钍,在萃取-沉淀剂皂化度70%、料液pH=3.1、萃取-沉淀剂和钍的摩尔比4∶1的最佳条件下,稀土和钍萃取-沉淀率分别为19%和90%,实现了稀土和钍的有效分离。     

Neutron poison distribution in the central reflector to reduce the DLOFC temperature of a Th-LEU fueled OTTO PBMR DPP-400 core

In a previous study using a mixture of thorium and 20 a/o% LEU at 16 gram per fuel sphere heavy metal loading and adjusting the effective fuel enrichment to produce the same amount of cumulative energy per fuel sphere as with the 10 a/o% Low Enriched Uranium (LEU), the maximum Depressurized Loss Of Forced Cooling (DLOFC) temperature was reduced from 2273 to 1925 °C and 1811 °C for a symmetric and asymmetric core, respectively using an once-through-then-out (OTTO) fuelling scheme. This article presents an additional strategy for reducing the maximum DLOFC temperature by placing an optimized distribution of neutron poisons in the central reflector. This strategy produced maximum DLOFC temperatures of 1509 and 1448 °C for the symmetric and the asymmetric cores, respectively. These results are impressive as it means that the less complicated OTTO cycle with its lower capital cost achieved the same cumulative energy produced per fuel sphere than the standard six-pass refuelling scheme and that at substantially lower maximum DLOFC temperatures. Both the addition of the neutron poisons to the central reflector and the creation of a radially asymmetric core resulted in lower burn-ups that had to be reversed by increasing the enrichment of the fuel.     

Bis(Diphenylcarbamoylmethylphosphine Oxide) Ligand Containing 4, 7, 10 – Trioxatridecane Spacer: Novel Effective Extractant for Actinides and Lanthanides

A novel polydentate neutral organophosphorus ligand 1 containing two Ph₂P(O)CH₂C(O)NH- bidentate moieties connected by a 4, 7, 10 - trioxatridecane spacer through amide nitrogen atoms was synthesized and studied as an extractant for U(VI), Th(IV), and lanthanides(III) ions from HNO₃ solutions. The influence of aqueous and organic phases on the extraction efficiency was elucidated and stoichiometry of the complexes extracted was determined. Bis-CMPO ligand 1 was found to possess a higher extraction efficiency towards U(VI), Th(IV), and lanthanides(III) ions than its mono analog diphenylphosphorylacetic acid N-nonylamide 5 and bis-CMPO ligands containing a di- and a triethylene glycol spacers. The values of D_U, D_Th, and D_Ln for compound 1 are more than two orders of magnitude higher than those for its mono-CMPO analog 5.     

Comparative Evaluation of Tri-n-butyl Phosphate (TBP) and Tris(2-ethylhexyl) Phosphate (TEHP) for the Recovery of Uranium from Monazite Leach Solution

Separation of U(VI) from Th(IV) and rare earth elements (REEs) present in monazite leach solution (nitric acid medium) has been studied using tris(2-ethylhexyl) phosphate (TEHP) and tri-n-butyl phosphate (TBP) dissolved in n-paraffin as solvents under varying experimental conditions such as nitric acid, extractant and metal ion concentrations etc. There is an increase in distribution ratio of U(VI) (D _U ) with increase in aqueous phase acidity up to 5 M HNO₃ beyond which a decrease is observed. Typically for 1 × 10^?3 M U(VI), the D_U values increase from 8 (0.5 M HNO₃) to 80 (5 M HNO₃) for 1.1 M TEHP, and from 2 (0.5 M HNO₃) to 43 (5 M HNO₃) for 1.1 M TBP in n-paraffin. The separation factors of U(VI) (β: D_U/D_M) over metal ions (M) such as Th(IV) and Y(III) (chosen as a representative of heavy REEs) are better for TEHP than TBP at all nitric acid concentrations. Batch solvent extraction data have been used to construct the McCabe-Thiele diagrams for the recovery of U(VI) employing TEHP as the extractant. A process flow sheet has been proposed with 0.2 M TEHP in n-paraffin as solvent for the recovery of U(VI) from simulated monazite leach solution in HNO₃ medium.     

Unmodified SBA-15 adsorbents for the removal and separation of Th(IV) and U(VI) ions: the role of pore channels and surface-active sites

ABSTRACT

The removal of Th(IV) and U(VI) by calcinated, non-calcinated, and methyl grafted SBA-15 (abbreviated as SBA-15, SBA-15-NC and SBA-15-MG, correspondingly) were compared to elucidate the role of pores and surface adsorption sites on SBA-15 adsorbents. It was proposed that the contribution of pores and surface-active sites of SBA-15 increases its higher adsorption capacity with respect to the other examined adsorbents. The kinetic studies revealed that the adsorption and also desorption occurred initially on the surface and then to the pores. Adsorption/desorption of the ions into pores was occurred with slow kinetics.     

Precipitation of Thorium or Uranium(VI) Complex Ion with Cobalt(III) or Chromium(III) Complex Cation, (III)

Chloride ion (foreign ion) effect on the precipitation of thorium or uranium (VI) sulfato, carbonato and oxalato complex ions has been studied. The results are in correlation with the chemical species present in the solution.

The precipitation of highly-charged complex ions is affected by chloride ion and the precipitation yield decreases with chloride salt concentration. The precipitation of sulfato complex ion shows only slight dependency on the chloride salt concentration because of the absence of highly-charged sulfato complex ion under the experimental conditions.     

锰结核中放射性含量的测量

锰结核是海洋底部的含多种金属的结核体,主要由锰和铁的氧化物、氢氧化物层所组成。最近我们用反符合屏蔽低本底γ谱仪测量了太平洋底锰结核样品的放射性。样品平均直径约4cm,重量75.2g。对测得的γ能谱进行分析,发现其中含有铀、钍系放射性。 测量装置和安排如图1所示。样品贴近主