Studies on uranium recovery from a U-bearing Radoniów Dump

Abstract This work reports the possibility of uranium recovery from a post-mining uranium ore dump in Poland by a bioleaching method. The studies were conducted on the dump leaching model with the mass of 570 kg of uranium bearing mineral material from Radoniów pile and in the periodic bioreactor with a work volume of 80 dm3 and with mechanical mixing and aeration of the charge. The uranium concentration in the examined material was about 800 ppm. In this process, the consortium of microorganisms isolated from former mines was used. It was composed of the following microorganisms: Bacillius, Pseudomonas, Sphingomonas, Thiobacillus, Halothiobacillus, Thiomonas, and Geothrix. The efficiency of the uranium bioleaching process was 98% in the reactor, and a yield of 70% was obtained in the dump leaching model. The post-leaching solution contained significant amounts of uranium ions that were separated in two stages: (1) by ion chromatography and then (2) by a two-step precipitation method. The resulting solution was a source of ammonium diuranate, the precursor of yellowcake (uranium oxides).

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The transformation and enrichment of rare earth sulfate in Bayan Obo ore water leaching solution by dibenzyl phosphate based extraction-precipitation method

Separation and Purification Technology ◽

10.1016/j.seppur.2021.119464 ◽

2021 ◽

pp. 119464

Author(s):

Hailan Zhi ◽

Luo Feng ◽

Shuainan Ni ◽

Jianguo Cui ◽

Xiaoqi Sun

Keyword(s):

Rare Earth ◽

Precipitation Method ◽

Water Leaching ◽

Leaching Solution ◽

Bayan Obo

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Synthesis and Electrochemical Properties of 0.5Li2MnO3•0.5LiMn0.5Ni0.5O2

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.105-106.664 ◽

2010 ◽

Vol 105-106 ◽

pp. 664-667

Author(s):

Sheng Wen Zhong ◽

Wei Hu ◽

Qian Zhang

Keyword(s):

Cathode Material ◽

Electrochemical Properties ◽

Specific Capacity ◽

Precipitation Method ◽

Electrochemical Performances ◽

Discharge Specific Capacity ◽

Xrd Patterns ◽

Co Precipitation ◽

Two Stages ◽

Calcined Temperature

The precursor of Mn0.75Ni0.25CO3 is prepared by carbonate co-precipitation method. And the cathode material 0.5Li2MnO3•0.5LiMn0.5Ni0.5O2 is synthesized with two stages calcining temperatures T1 and T2. T1 represents 400°C, 500°C, 600°C and T2 is selected at 750°C, 850°C, 950°C respectively. XRD Patterns shows that the cathode material has the integrated structures of Li2MnO3 and LiMO2, and it has better crystallization during the rise of calcined temperature at 950°C. The electrochemical performances tests indicates that the initial discharge specific capacity are greater than 220mAh/g at the current density 0.2 mA/cm2 in 2.5-4.6V at room temperature. When cathode material is calcined at 750°C, its discharge specific capacity even reach to 248mAh/g, but the cathode material has more perfect general electrochemical properties during calcined temperature at 950°C.

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Influence of ZrO2 Nanoparticles on the Microstructural Development of Cement Mortars with Limestone Aggregates

Applied Sciences ◽

10.3390/app9030598 ◽

2019 ◽

Vol 9 (3) ◽

pp. 598

Author(s):

Danna Trejo-Arroyo ◽

Karen Acosta ◽

Julio Cruz ◽

Ana Valenzuela-Muñiz ◽

Ricardo Vega-Azamar ◽

...

Keyword(s):

Xrd Analysis ◽

Sem Analysis ◽

Precipitation Method ◽

Zro2 Nanoparticles ◽

Microstructural Development ◽

Cement Ratio ◽

Cement Mortars ◽

Crystallite Sizes ◽

Co Precipitation ◽

Two Stages

In this research, the effect of the addition of zirconium oxide-synthesized nanoparticles on the microstructural development and the physical–mechanical properties of cement mortars with limestone aggregates was studied. Zirconia nanoparticles were synthesized using the co-precipitation method. According to XRD analysis, a mixture of tetragonal (t) and monoclinic (m) zirconia phases was obtained, with average crystallite sizes around 15.18 and 17.79 nm, respectively. Based on the ASTM standards, a mixture design was obtained for a coating mortar with a final sand/cement ratio of 1:2.78 and a water/cement ratio of 0.58. Control mortars and mortars with ZrO2 additions were analyzed for two stages of curing of the mortar—7 and 28 days. According to SEM analysis, mortars with ZrO2 revealed a microstructure with a high compaction degree and an increase in compressive strength of 9% on the control mortars. Due to the aggregates’ characteristics, adherence with the cement paste in the interface zone was increased. It is suggested that the reinforcing effect of ZrO2 on the mortars was caused by the effect of nucleation sites in the main phase C–S–H and the inhibition of the growth of large CH crystals, and the filler effect generated by the nanometric size of the particles. This produced a greater compaction volume, suggesting that faults are probably originated in the aggregates.

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Immobilization of Cr(VI) in Soil Using a Montmorillonite-Supported Carboxymethyl Cellulose-Stabilized Iron Sulfide Composite: Effectiveness and Biotoxicity Assessment

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph17176087 ◽

2020 ◽

Vol 17 (17) ◽

pp. 6087

Author(s):

Dading Zhang ◽

Yanqiu Xu ◽

Xiaofei Li ◽

Zhenhai Liu ◽

Lina Wang ◽

...

Keyword(s):

Soil Remediation ◽

Contaminated Soil ◽

Photoelectron Spectroscopy ◽

Carboxymethyl Cellulose ◽

Iron Sulfide ◽

Soil Mass ◽

Precipitation Method ◽

Removal Capacity ◽

Leaching Solution ◽

Co Precipitation

A novel composite of montmorillonite-supported carboxymethyl cellulose-stabilized nanoscale iron sulfide (CMC@MMT-FeS), prepared using the co-precipitation method, was applied to remediate hexavalent chromium (Cr(VI))-contaminated soil. Cr(VI)-removal capacity increased with increasing FeS-particle loading. We tested the efficacy of CMC@MMT-FeS at three concentrations of FeS: 0.2, 0.5, and 1 mmol/g, hereafter referred to as 0.2 CMC@MMT-FeS, 0.5 CMC@MMT-FeS, and 1.0 CMC@MMT-FeS, respectively. The soil Cr(VI) concentration decreased by 90.7% (from an initial concentration of 424.6 to 39.4 mg/kg) after 30 days, following addition of 5% (composite–soil mass proportion) 1.0 CMC@MMT-FeS. When 2% 0.5 CMC@MMT-FeS was added to Cr(VI)-contaminated soil, the Cr(VI) removal efficiency, as measured in the leaching solution using the toxicity characteristic leaching procedure, was 90.3%, meeting the environmental protection standard for hazardous waste (5 mg/kg). The European Community Bureau of Reference (BCR) test confirmed that the main Cr fractions in the soil samples changed from acid-exchangeable fractions to oxidable fractions and residual fractions after 30 days of soil remediation by the composite. Moreover, the main complex formed during remediation was Fe(III)–Cr(III), based on BCR and X-ray photoelectron spectroscopy analyses. Biotoxicity of the remediated soils, using Vicia faba and Eisenia foetida, was analyzed and evaluated. Our results indicate that CMC@MMT-FeS effectively immobilizes Cr(VI), with widespread potential application in Cr(VI)-contaminated soil remediation.

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Synthesis of Magnesium Aluminate Spinel Powder from the Purified Sodium Hydroxide Leaching Solution of Black Dross

Processes ◽

10.3390/pr7100741 ◽

2019 ◽

Vol 7 (10) ◽

pp. 741 ◽

Cited By ~ 1

Author(s):

Nguyen ◽

Lee

Keyword(s):

Sodium Hydroxide ◽

Ball Milling ◽

Calcination Temperature ◽

Precipitation Method ◽

Magnesium Aluminate ◽

Magnesium Aluminate Spinel ◽

Complete Conversion ◽

Milling Method ◽

Leaching Solution ◽

Co Precipitation

Synthesis of magnesium aluminate spinel (MgAl2O4) was investigated by employing ball milling and co-precipitation methods. The starting materials (aluminum hydroxides) were obtained from the purified sodium hydroxide leaching solution of black dross. The characteristics of the synthesized spinel was analyzed through X-ray diffraction (XRD), scanning electron microscopy (SEM) images. In this work, the effect of calcination temperature and time on the formation of spinel by the two methods was compared. Calcination temperature showed a great effect on the formation of spinel in both methods. The results showed that the co-precipitation method has many advantages over the ball milling method. In ball milling method, complete conversion of the starting materials to spinel was impossible even at 1500 °C, while complete conversion to spinel was accomplished at 1000 °C for 5 h by the co-precipitation method. The average size of the spinel synthesized at these optimum conditions of the co-precipitation method was about 17 nm. A process can be developed to synthesize spinel from the black dross which is regarded as hazardous materials.

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Treatment of Waste Cutting Oil Emulsions by Leaching Solutions of White Mud

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.356-360.1570 ◽

2011 ◽

Vol 356-360 ◽

pp. 1570-1574

Author(s):

Tao Wu ◽

De Jun Sun ◽

Yu Jiang Li ◽

Guo Chen Zhang

Keyword(s):

Low Cost ◽

High Specific Surface Area ◽

Precipitation Method ◽

Oil Emulsion ◽

Excess Surface ◽

Alkaline Conditions ◽

Leaching Solution ◽

Oil Emulsions ◽

White Mud ◽

Maximum Removal

A leaching solution of white mud was prepared from this waste material of soda production, and used for treatment of waste cutting oil emulsion. In alkaline conditions, the leaching solution of white mud generates hydroxide precipitates, which have relatively high specific surface area and excess surface energy, and readily adsorb the pollutants in waste cutting oil emulsion. The chemical composition of the white mud was determined and the hydroxide precipitates were characterized. The maximum removal efficiency (of turbidity, oil contents and TOC) was obtained at an adsorbent dosage of 4.0 g/L, pH 12.0 and 25°C. Leaching solutions of white mud could be used as an effective and low-cost material for treatment of waste cutting oil emulsion by the precipitation method.

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Refining Process and Identifying Content of Local Iron Sand

Materials Science Forum ◽

10.4028/www.scientific.net/msf.1028.26 ◽

2021 ◽

Vol 1028 ◽

pp. 26-31

Author(s):

Togar Saragi ◽

Gustiani A. Pramesti ◽

Muhammad Abdan Syakuur ◽

Norman Syakir ◽

Sahrul Hidayat ◽

...

Keyword(s):

Crystal Structure ◽

Refining Process ◽

Precipitation Method ◽

Elemental Content ◽

Purification Process ◽

X Ray ◽

Fe Content ◽

Simple Processing ◽

Co Precipitation ◽

Two Stages

We reported simple processing of local iron sand in order to increase the purity of magnetic phase. The refining process of iron sand is carried out in two stages, namely the iron sand extract using a permanent magnet and the purification process. The purification process was carried out by co-precipitation method in varying of the dissolving temperatures and volume of HCl. The iron salt solution formed is then precipitated using NH4OH solution and then sintered at 100 °C and 1000 °C, respectively. All samples are characterized by X-ray fluorescence (XRF) and X-ray diffraction (XRD) to identify the elemental content and the crystal structure. From the XRF measurements, it was found that the Fe content before purification process was 32.68 %, increasing to 33.12 % after purification process with HCL volume of 75 ml and sintered at 100 °C. From XRD measurement, it was found that the crystal structure of iron sand before purification process was dominated by magnesioferrite (33.2 %), and magnetite (20.2 %). After purification process at 1000 °C, the magnesioferrite phase increased to 80.2 % and 50.2 % for HCl volume of 50 ml and 75 ml, respectively, while the magnetite phase increase to become 34.5 % for 100 ml of HCl.

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System for measuring the uranium concentration of liquid effluents from the enriched uranium recovery facility at the Oak Ridge Y-12 Plant

10.2172/4120730 ◽

1976 ◽

Author(s):

R.A. Gallman

Keyword(s):

Uranium Concentration ◽

Uranium Recovery ◽

Oak Ridge ◽

Enriched Uranium

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Leaching improvement of ceramic cores for hollow turbine blades based on additive manufacturing

Advances in Manufacturing ◽

10.1007/s40436-019-00273-2 ◽

2019 ◽

Vol 7 (4) ◽

pp. 353-363 ◽

Cited By ~ 1

Author(s):

Wei-Jun Zhu ◽

Guo-Qiang Tian ◽

Yang Lu ◽

Kai Miao ◽

Di-Chen Li

Keyword(s):

Additive Manufacturing ◽

Carbon Fibers ◽

Turbine Blades ◽

Casting Method ◽

Precision Casting ◽

Leaching Process ◽

Comprehensive Properties ◽

Leaching Solution ◽

Two Stages ◽

Alternate Solution

Abstract The precision casting method based on alumina-based ceramic cores is one of the main techniques used to manufacture hollow turbine blades. Additive manufacturing (AM) technology provides an alternate solution to fabricating ceramic cores quickly and precisely. As the complexity of the structure increases and the strength of the material improves, the leaching process of the cores becomes more complicated. This study proposes a compound pore-forming method to increase the porosity of ceramic cores by adding a preformed-pore agent and materials that convert to easy-to-corrode phases. The preformed-pore agents (e.g., carbon fibers) can be burned off during sintering to form pores before the leaching, and the easy-to-corrode phases (e.g., CaCO3, SiO2, β-Al2O3) can be leached firstly to form pores during the leaching process. The pores formed in the aforementioned two stages increase the contact area of the cores and leaching solution, thus improving the leaching rate. In the current study, the additive amount of the preformed-pore agent was optimized, and the effect of the easy-to-corrode phases on the comprehensive properties of the cores was then compared. Based on this, the corresponding model was established.

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