Nitrification and In-Situ Uranium Solution Mining

1980 ◽  
Vol 20 (05) ◽  
pp. 415-422
Author(s):  
David Johnson ◽  
Michael J. Humenick
Keyword(s):  
Hydrogen Peroxide ◽  
Ion Exchange ◽  
Clay Minerals ◽  
Core Material ◽  
Column Experiments ◽  
Solution Mining ◽  
Ore Body ◽  
Nitrate And Nitrite ◽  
Uranium Solution

Abstract The objective of this research was to determine thepotential for conversion of ammonia to nitrate as aresult of uranium solution mining operations. Thework included literature evaluation and laboratoryexperimentation in both batch and continuoussystems. Results have indicated that a potential fornitrification could exist for some portions of thesolution mining operating cycle. However, inhibitionof nitrification was observed due to high ammoniaand peroxide concentrations. Nitrification ofammonia also was observed to occur due to chemicaloxidation by peroxide. Introduction The removal of ammonia from underground strataduring restoration of in-situ uranium solution miningsites is a difficult problem because of ammonium-ionaffinity for the clay minerals in the ore body.Ammonium on the ion-exchange sites may be replacedby other cations through an ion-exchange process.Another way to reduce ammonia concentrations inthe ore body would be to convert the ammonia tonitrate and/or nitrate forms of nitrogen not sorbedon clay minerals. Groundwater containing thesenitrogen forms could be removed from the aquiferand treated to remove nitrate and nitrite. Nitrate and nitrite ions have little affinity forclay minerals, move freely in the groundwater, and inhigh concentrations can pose a health hazard tohumans. In infants, high nitrate or nitriteconcentrations may cause a blood disorder known asmethemoglobinemia, which interferes with oxygentransfer in the blood. For the restoration ofgroundwater to meet drinking-water standards, thetotal nitrite/nitrate nitrogen concentration may notexceed 10 mg/L. The objectives of this research were to evaluate thepotential for biological and/or chemical conversionof ammonia to nitrite or nitrate during and afteruranium solution milling and to examine thefeasibility of using biological nitrification as arestoration technique for reducing ammonia concentrations in the ore body. The research programincluded (1) enumeration of autotrophic nitrifyingorganisms and (2) batch and column experiments toexamine nitrification by biological and chemicalmechanisms. Batch experiments were performed attwo concentrations of ammonia, with and without the addition of hydrogen peroxide, to determine theeffects of the alkaline leach solution and hydrogenperoxide on nitrification. Another batch experiment was run with sterile core material and a constantconcentration of hydrogen peroxide to determine theeffect of ammonia concentration on chemical ammonia oxidation. Column experiments wereperformed on core material to examine ammoniaconversion with time and to test the process ofbiological nitrification as a possible restorationtechnique for removing ammonia from the ore body. SPEJ P. 415＾

Preparation of Environment-Friendly Epoxidized Corn Oil as a Plasticizer

2014 ◽  
Vol 852 ◽  
pp. 256-261 ◽  
Author(s):  
Yuan Huai Peng ◽  
Hua Di Lin
Keyword(s):  
Hydrogen Peroxide ◽  
Ion Exchange ◽  
Exchange Resin ◽  
Corn Oil ◽  
Ion Exchange Resin ◽  
Molar Ratio ◽  
Environment Friendly ◽  
Percent Conversion ◽  
Optimized Conditions

An environment-friendly plasticizer, epoxidized corn oil was prepared by the epoxidation of corn oil with peroxyacetic acid which was generated in situ from hydrogen peroxide and glacial acetic using acidic ion exchange resin modified by zinc chloride as catalyst. The product with an epoxy oxygen content of 6.40 w% and a percent conversion to oxirane of 87.67 % was obtained under the following optimized conditions: 15 % modified ion exchange resin feed relative to the weight of corn oil, the molar ratio of 1.7 to 1 with hydrogen peroxide to double bonds, 18% acetic acid feed relative to the weight of corn oil, the reaction time of 5.5 h, the temperature of 75 °C and stirring speed of 600 rpm.

Restoration of Uranium In-Situ Leaching Sites

1980 ◽  
Vol 20 (04) ◽  
pp. 221-227 ◽  
Author(s):  
A.D. Hill ◽  
I.H. Silberberg ◽  
M.P. Walsh ◽  
M.J. Humenick ◽  
R.S. Schechter
Keyword(s):  
Ion Exchange ◽  
New Technology ◽  
Broad Band ◽  
South Texas ◽  
Mining Site ◽  
Solution Mining ◽  
Ore Bodies ◽  
Process Viability ◽  
High Concentrations

Abstract In recent years in-situ leach mining has emerged as a new technology for the recovery of uranium from strata that cannot be mined economically by other means. Because the ore bodies lie within groundwater aquifers, a significant determinant in the process' viability is the requirement that such aquifers be protected from contamination. Since ammonia is one of the constituents of the leach solutions now being field tested, one environmental problem to be resolved is the removal of ammonia at the end of mining. A second related question is the fate of the ammonia that is not removed by the restoration procedure. This paper considers the displacement and migration of ammonium cations in a flowing electrolyte with concomitant ion exchange. The ion exchange is an important feature since, during the solution mining phase, ammonium cations adsorb onto the mineral exchange sites and must be removed from these sites. A mathematical model is used to simulate this process, and the model is tested against the results of laboratory experiments. It is found that the simulations are adequate if an appropriate selection of parameters is made. The model then is used to simulate restoration procedures and to determine the rate of migration of unrecovered ammonium in the groundwater. It is concluded that ammonium removal can be accomplished best using high concentrations of a cation that is exchanged selectively relative to ammonium cation. Introduction In-situ solution mining is a process rapidly being developed for the recovery of uranium from sandstone ore bodies. This mining technique is applicable when the uranium ore is too deep, too small in extent, or of too low a grade to justify using conventional mining techniques. Such ore bodies are numerous in south Texas, occurring along a broad band of the U.S. gulf coastal plain. The solution mining process being used in Texas is primarily an alkaline leach. The sandstone ores that may be solution-mined occur in aquifers, and the uranium is in the insoluble +4 state of oxidation. To be mobilized, the uranium must be oxidized to the +6 state and then complexed with carbonate ions to form the highly soluble uranyl dicarbonate or uranyl tricarbonate ions. Thus, alkaline leach solutions contain an oxidant (usually hydrogen peroxide) and a mixture of carbonates and bicarbonates. To minimize formation damage, most solution mining now employs ammonium carbonate/bicarbonate as the carbonate source. These solutions have been found effective in dissolving the uranium minerals found in south Texas sandstone ores.1 However, the restoration of the mining site is also a primary consideration. Since the ore bodies that can be solution-mined occur in aquifers, government regulations require that water quality at the mining site not be degraded below the quality that existed at the inception of mining. Furthermore, the permitting procedures require that groundwater restoration be completed at one site before the next site on a particular lease may be mined.2 Obviously, environmental aspects will be an important consideration governing the success of in-situ solution mining.

Insight into the enhanced photocatalytic properties of AgBr/Ag4P2O7 composites synthesized via in situ ion exchange reaction

2021 ◽  
Vol 9 (1) ◽  
pp. 104889
Author(s):  
Wyllamanney da S. Pereira ◽  
Fabrício B. Destro ◽  
Cipriano B. Gozzo ◽  
Edson R. Leite ◽  
Júlio C. Sczancoski
Keyword(s):  
Ion Exchange ◽  
Exchange Reaction ◽  
Photocatalytic Properties ◽  
Ion Exchange Reaction ◽  
Insight Into

The Vyredox and Nitredox Methods of in situ Treatment of Groundwater

1988 ◽  
Vol 20 (3) ◽  
pp. 149-163 ◽  
Author(s):  
Carol Braester ◽  
Rudolf Martinell
Keyword(s):  
Water Treatment ◽  
Surface Water ◽  
Traditional Method ◽  
Treatment Method ◽  
Nitrate Treatment ◽  
The Past ◽  
The World ◽  
Nitrate And Nitrite ◽  
Iron And Manganese

Nearly one fifth of all water used in the world is obtained from groundwater. The protection of water has become a high priority goal. During the last decades pollution of water has become more and more severe. Today groundwater is more and more used in comparison with surface water. Recently we have seen accidents, which can pollute nearly all surface water very quickly. Generally the groundwater is easier to protect, as well as cheaper to purify, and above all it is of better quality than the surface water. During the past two decades, alternatives to the traditional method of treating the water in filters have been developed, that is in situ water treatment i.e. the VYREDOX and NITREDOX methods. The most common problem regarding groundwater is too high content of iron and manganese, which can be reduced with the VYREDOX method. In some areas today there are severe problems with pollution by hydrocarbons and nitrate as well, and with modification of the VYREDOX treatment method it is used for hydrocarbon and nitrate treatment as well. The method to reduce the nitrate and nitrite is known as the NITREDOX method.

scholarly journals Experimental and Theoretical Studies of Sonically Prepared Cu–Y, Cu–USY and Cu–ZSM-5 Catalysts for SCR deNOx

Catalysts ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 824
Author(s):  
Przemysław J. Jodłowski ◽  
Izabela Czekaj ◽  
Patrycja Stachurska ◽  
Łukasz Kuterasiński ◽  
Lucjan Chmielarz ◽  
...  
Keyword(s):  
Ion Exchange ◽  
Ultrasonic Irradiation ◽  
Active Phase ◽  
Spectroscopic Studies ◽  
In Situ Drifts ◽  
Ft Ir ◽  
Diffuse Reflectance Infrared ◽  
Experimental And Theoretical Studies

The objective of our study was to prepare Y-, USY- and ZSM-5-based catalysts by hydrothermal synthesis, followed by copper active-phase deposition by either conventional ion-exchange or ultrasonic irradiation. The resulting materials were characterized by XRD, BET, SEM, TEM, Raman, UV-Vis, monitoring ammonia and nitrogen oxide sorption by FT-IR and Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS). XRD data confirmed the purity and structure of the Y/USY or ZSM-5 zeolites. The nitrogen and ammonia sorption results indicated that the materials were highly porous and acidic. The metallic active phase was found in the form of cations in ion-exchanged zeolites and in the form of nanoparticle metal oxides in sonochemically prepared catalysts. The latter showed full activity and high stability in the SCR deNOx reaction. The faujasite-based catalysts were fully active at 200–400 °C, whereas the ZSM-5-based catalysts reached 100% activity at 400–500 °C. Our in situ DRIFTS experiments revealed that Cu–O(NO) and Cu–NH3 were intermediates, also indicating the role of Brønsted sites in the formation of NH4NO3. Furthermore, the results from our experimental in situ spectroscopic studies were compared with DFT models. Overall, our findings suggest two possible mechanisms for the deNOx reaction, depending on the method of catalyst preparation (i.e., conventional ion-exchange vs. ultrasonic irradiation).

scholarly journals Au Modified F-TiO2 for Efficient Photocatalytic Synthesis of Hydrogen Peroxide

Molecules ◽  
2021 ◽  
Vol 26 (13) ◽  
pp. 3844
Author(s):  
Lijuan Li ◽  
Bingdong Li ◽  
Liwei Feng ◽  
Xiaoqiu Zhang ◽  
Yuqian Zhang ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Reaction System ◽  
Reaction Medium ◽  
Pure Tio2 ◽  
H2o2 Production ◽  
Tio2 Photocatalyst ◽  
H2o2 Decomposition ◽  
Spin Resonance ◽  
Photocatalytic Synthesis

In this work, Au-modified F-TiO2 is developed as a simple and efficient photocatalyst for H2O2 production under ultraviolet light. The Au/F-TiO2 photocatalyst avoids the necessity of adding fluoride into the reaction medium for enhancing H2O2 synthesis, as in a pure TiO2 reaction system. The F− modification inhibits the H2O2 decomposition through the formation of the ≡Ti–F complex. Au is an active cocatalyst for photocatalytic H2O2 production. We compared the activity of TiO2 with F− modification and without F− modification in the presence of Au, and found that the H2O2 production rate over Au/F-TiO2 reaches four times that of Au/TiO2. In situ electron spin resonance studies have shown that H2O2 is produced by stepwise single-electron oxygen reduction on the Au/F-TiO2 photocatalyst.

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