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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 775 records · Page 43
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Technetium recovery from high alkaline solution

Disclosed are methods for recovering technetium from a highly alkaline solution. The highly alkaline solution can be a liquid waste solution from a nuclear waste processing system. Methods can include combining the solution with a reductant capable of reducing technetium at the high pH of the solution and adding to or forming in the solution an adsorbent capable of adsorbing the precipitated technetium at the high pH of the solution.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2022

Experimental Steps toward a Density Law for Chlorine-Crediting Criticality Models of Aqueous Plutonium solutions

Criticality accident prevention is an essential safety consideration for all operations involving fissionable and fissile materials. Predictive criticality calculations using advanced neutron transport codes, such as Monte Carlo N-Particle Transport (MCNP), are invaluable tools for designing and implementing operational limits. While indispensable, these tools are limited by the quality and accuracy of the inputs that the user provides to define the modeled system. Parameters such as atomic composition, shape, and material density must be accurately defined to obtain a meaningful result. In the case of material property details for a plutonium model, accurate material characterization data is sometimes sparse. Thus limitations in calculation accuracy can be reduced by improving our knowledge of material properties in the targeted fissile systems. One of the biggest remaining challenges to accurately defining fissile systems is the description of aqueous fissile solutions. Even simple properties, such as density, are not well-known for fissile solutions relevant to nuclear energy and security. Described here are initial efforts undertaken to improve criticality calculation inputs for fissile plutonium chloride solutions in water. This effort is focused on experimentally determining accurate solution characteristics for ternary plutonium chloride/hydrochloric acid/water systems, by measurement of water activity and solution density. The effect of inputting experimental densities for these solutions into MCNP criticality calculations is compared to the traditional approach of modeling an idealized (and fictitious) plutonium-water mixture. Expansion of these efforts to a working density law for aqueous plutonium chloride solutions is also discussed.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2012

Development of In-Can Melting Process Applied to Vitrification of High Activity Waste Solutions (HAWS): Glass characterizations and process tests results - 12442

The CEA has selected vitrification for specific High-Activity nuclear Waste Solutions (HAWS) containing large quantities of salts. This choice has led the CEA Marcoule to develop a compact 'in-can' batch melting process in which the melting pot is disposable and serves as the primary canister for the solidified glass. This process is particularly suitable for the treatment of small waste quantities (less than 10 m{sup 3} per year) and low flow rates (5 to 10 L/h) which do not justify the use of a Cold Crucible Induction Melter. The unit capacity is approximately one hundred kilograms of glass a week operating alternately between feeding during the day and surveillance at night. In order to be fully representative of the glove box to be implemented, a new nonradioactive pilot-scale unit in which the core process (furnace and dust scrubber) is completely enclosed with glove box simulation was built at CEA Marcoule in 2008. The equipment includes all the systems and components necessary to perform full-scale tests: feed system, furnace and complete off-gas treatment system. The nominal tests were performed in 2009 and 2010 to verify that no problems arose in vitrifying solutions under the specified conditions. Two different liquid feeds representatives of the current HAWS stored and future solutions were used. The transient runs were carried out in this facility in 2010. Their objectives were to validate the glass product with different operating conditions and to determine optimum parameters for transient phases such as decreased volatility during standby phases. Finally, all the material obtained under nominal conditions or different operating conditions (e.g. initial glass frit quantity, standby temperature or restart procedure of feeding after night surveillance) have been characterized and described. The impact of transient phases on the process is then discussed in terms of volatility, thermal balance, etc., and compared with nominal tests results. Off-gas treatment system (OGTS) assessments determined preliminary decontamination factors for the OGTS components and allowed comparison between the two types of solutions and for different operating parameters. Since 2005 CEA Marcoule has been developing an 'in-can melting' vitrification process for specific High Activity Nuclear Waste Solutions. The tests carried out to date have validated the feasibility of this process and confirmed the direct vitrification option in which the liquid and solid feed streams are supplied directly to a disposable melting pot. CEA Marcoule began process qualification testing in 2009 in a new facility using equipment representative of the devices that will be installed in a glove box. The nominal mode tests performed in 2009 and 2010 were used to determine nominal operating conditions for the process: - a nominal process temperature of 1100 deg. C; - a maximum glass production rate of 5 kg/h; - a liquid feed solution flow rate of 5 L/h or less if the glass production rate exceeds the preceding maximum value; - a liquid recycle rate of 0.5 L/h for a nominal solution feed rate 5 L/h. They also produced glass samples generally meeting our expectations, and allowed us to measure the characteristic properties (viscosity, density, thermal conductivity, chemical durability). The first test of transient operation in 2010 yielded glass consistent with expectations and showed that reducing the temperature had no significant effect on the volatility of the constituent elements. However, a significant impact on the release of elements at the beginning of the test was observed with a larger initial quantity of glass frit on startup. The process qualification program will now continue with tests of degraded operating modes. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2017

Integrated Solutions for Interim Used Fuel Management: From Pool Unloading to Safe Delivery to Recycling or Repository Facilities - 17235

Safe management of used nuclear fuel (UNF) is key to the survival of the nuclear industry. That is why it is more important than ever to have a consent-based, practical, credible, and sustainable roadmap for managing the back-end of the nuclear cycle. Worldwide UNF Light Water Reactors (LWR) inventories are currently around 200,000 tons and are estimated to grow to more than 350,000 tons by 2030, and operating nuclear reactors in the U.S. continue to discharge UNF every 18 to 24 months. International experience has demonstrated that the development of a permanent geological repository can be a multi-decade process, especially in the face of public acceptance challenges. Meanwhile, the solution for permanent disposal of UNF in the U.S. is moving at a glacial pace. As a result, industrial stakeholders have been forced to find practical interim UNF storage solutions in order to continue safely operating their reactors. Among those interim solutions are the cask- or canister-based dry storage systems that have dramatically increased in the last 10 years as they provide flexibility for expansion with a low up-front investment. With interim dry storage in place for more than 30 years, our industry is entering a new phase as we are forced to prepare for a few more decades before geological repositories begin operating. Consequently, interim dry storage has to be extended for 80 years or more. Thus, new considerations have to be taken into account to ensure the safety of this stored used fuel: - Interim storage systems are aging; - High burn-up fuel behavior overtime is uncertain; - Used fuel is losing its self-protection; - The number of shutdown sites without a fuel transfer facility, such as a pool, is increasing; - Some owners of Independent Spent Fuel Storage installation (ISFSI) at shutdown sites are not nuclear operators anymore. With increasing uncertainties, AREVA TN -- based on its long expertise with used fuel transportation and interim storage systems -- is adapting its portfolio to develop integrated and flexible solutions that will remove the burden of interim used fuel management from nuclear operators. AREVA TN is developing comprehensive solutions to reduce risks including the continued supply of proven safe high-performance dry storage systems; on-site services to safely transfer used fuel from pool to pad; the optimization of fuel heat load in the storage pool and pad; innovative aging management services including inspection, monitoring and repair; a realistic solution for consolidated interim storage with a priority to remove Used Nuclear Fuel stored in dry storage systems from shutdown sites; world-class transport and logistics services to safely move the used fuel from nuclear reactor sites to consolidated storage and repository or recycling as applicable, and turnkey management of shutdown ISFSIs. Due to the lack of an available path for transporting used fuel away from reactors, nuclear operators are faced with many challenges and growing uncertainties. Our presentation will describe the practical solutions developed and being developed in order to manage used fuel on behalf of nuclear operators and allows them to continue focusing on the important job of producing carbon-free clean energy. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2016

Transitions From Stochastic to Point Kinetics Models In Fissile Solutions

Fissile solutions form an integral part of the fuel cycle, being used to store and process both fresh fuel and waste. Fissile solutions are also found within Aqueous Homogeneous Reactors (AHRs) including research reactors such as CRAC and SILENE and also potential future systems which could be used for the production of medical isotopes. In the case of fissile solutions in the fuel cycle, avoiding criticality is a priority but accidents have occurred in which a significant number of fissions occurred. In the case of AHRs, a sustained neutron population and fission rate is desired. In both cases the ability to simulate transients where changes in reactivity cause the neutron population to increase are important. A popular method for the simulation of such transients is the point kinetic method which allows the capture of the major features of a transient at a fraction of the computational runtime and code complexity of more comprehensive modelling technologies. A limitation of the point kinetics method and other mainstream methods of predicting neutron behaviour is that they assume the neutron population is large enough that the mean behaviour will be observed. When the neutron population is low, however, the deviation around the mean behaviour is expected to be relatively large as there is an aleatoric uncertainty arising from the uncertain fate of individual neutrons. Such limitations are of particular importance when the reactivity of a system is rapidly increasing while the neutron population is low, which is often true in accident scenarios involving fissile solutions. This provides the motivation for the coupling of point kinetics and a probabilistic models of fissile solutions. This summary aims to explore some of the behaviours resulting from a low neutron population and rising reactivity using a coupled probabilistic and point kinetics model of a fissile solution. As the effects of a low neutron population are the primary concern of this summary, the point kinetics and thermal hydraulic models used will be relatively simple but these models should be sufficient to capture the most important behaviours of the system in the first minute or so of a transient. This work is an extension of the work found in [1]. In that work the methodology was applied to fast pulses produced by systems such as Godiva and its results were found to compare favourably to experimental and analytical results, such as the burst wait time, in [2]. This work focuses on the application of this methodology to a fissile solution but the method could be applied to a number of criticality safety or reactor operation scenarios through suitable modification of the point kinetics model and would produce a more accurate prediction of the peak power obtained when a system first becomes critical compared to the use of a standard point kinetics model. (authors)

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2024

Preparation of acid-deficient uranyl nitrate solutions

A solution of acid deficient uranyl nitrate has a formula of UO2(OH)y(NO3)2-y, where y ranges from 0.1 to 0.5. The solution is prepared by placing UxOz in aqueous nitric acid to produce a uranium solution, wherein x is 1 to 3 and z is 2 to 8; placing the uranium solution under a pressure greater than atmospheric pressure in a sealed reaction chamber; and heating the uranium solution to a desired temperature of between 150° C. and 250° C. by applying microwave energy to the uranium solution. The uranium solution is maintained at the desired temperature under a pressure of from 5 atmospheres to 40 atmospheres for a hold time of 15 minutes to 6 hours to produce the desired acid deficient uranyl nitrate.

Brown, Daniel↗
DOE OSTI2025

Colloidal Behavior of Plutonium Oxide in Concentrated Electrolyte Solutions

The Hanford Site in Washington State manages legacy high-level radioactive waste streams that display major chemistry and engineering challenges, including the high salt levels and pH values that correspond to conditions under which many classical concepts describing chemical reactivity cannot be applied. One particular challenge that needs to be tackled at Hanford is that Pu concentrations, [Pu], in the soluble phases of the tank wastes are higher than expected based on the solubility of crystalline PuO2, which is widely accepted to be caused by the formation of PuO2 colloid, consisting of nano- to submicron-sized particles (PuO2 NPs). Fundamental research underpinning the behavior of PuO2 NPs under conditions not only relevant to the Hanford tank waste but at high ionic strength in general is needed to reliably predict the chemical reactivity of PuO2 NPs and develop engineering solutions to safely and efficiently process high-level radioactive waste into forms suitable for long-term storage. In this work, we study the behavior of PuO2 NPs (particle size ~100 nm) under high ionic strength conditions by reacting it with highly concentrated (up to 5 M) salt solutions. We explore different electrolyte compositions to elucidate the impact of different anions (NO3-, Cl-, ClO4-, SO42-, C2O42-, CO32-) on the stability of PuO2 NP in the acidic and alkaline pH regime. PuO2 NP aggregation and precipitation as function electrolyte concentration is tracked by a combination of liquid scintillation counting, dynamic light scattering for determination of particle size distributions, and zeta potentials as a proxy for particle charge. At acidic pH, electrolytes containing non-coordinating anions, such as NaNO3, NaCl, and NaClO4 mostly stabilize PuO2 NPs over a large electrolyte concentration range, showing only subtle differences in their reactivity. Other electrolyte anions show a more pronounced effect on the PuO2 NP stability: SO42-, binds directly to the particles’ surface, reverses the particle charge, and precipitates the PuO2 NPs efficiently even at intermediate sulfate concentrations (>0.1 M). In contrast, C2O42- is found to lead to high [Pu] in solution, in the milli-molar range, even at mildly acidic pH (~4). Thermodynamic modeling of the dissolved Pu concentrations using PHREEQC is unable to predict the observed [Pu] in the acidic pH regime, supporting the influence of colloids in maintaining elevated [Pu]. It is noteworthy that the current thermodynamic databases do not include constants for colloidal Pu phases and cannot accurately predict many of the high ionic strength solutions relevant to this work. The mechanisms and models responsible for these observations will need further investigation in the future. At high pH values (~12), PuO2 NPs exhibits classical sol-gel chemistry, meaning that upon destabilization of the colloidal sol, for example by addition of concentrated NaOH, highly porous and viscid PuO2 coagulates are formed that consist of a three-dimensional network likely held together by physical interactions. The PuO2 NP coagulate shows no significant reversibility of the aggregation when contacted with concentrated brines; however, PuO2 NPs can be efficiently resuspended in solution by addition of diluted electrolytes, alkaline solutions containing high amounts of carbonate, or simple addition of water. Especially carbonate is shown to stabilize PuO2 NPs in solution at high pH, characterized by stable colloidal suspensions that are resistant against sedimentation during centrifugation. Thermodynamic modeling of the carbonate system was able to predict an increasing dissolved Pu concentration with increasing carbonate concentration. However, the model was profoundly sensitive to the fixed redox potential and does not include any thermodynamic constants for colloidal Pu species.

Neumann, Julia↗
DOE OSTI2018

Mathematical Analysis of the Solidification Behavior of Plain Steel Based on Solute- and Heat-Transfer Equations in the Liquid–Solid Zone

An analytical approximate solution to non-linear solute- and heat-transfer equations in the unsteady-state mushy zone of Fe-C plain steel has been obtained, assuming a linear relationship between the solid fraction and the temperature of the mushy zone. The heat transfer equations for both the solid and liquid zone along with the boundary conditions have been linked with the equations to solve the whole equations. The model predictions (e.g., the solidification constants and the effective partition ratio) agree with the generally accepted values and with a separately performed numerical analysis. The solidus temperature predicted by the model is in the intermediate range of the reported formulas. The model and Neuman’s solution are consistent in the low carbon range. A conventional numerical heat analysis (i.e., an equivalent specific heat method using the solidus temperature predicted by the model) is consistent with the model predictions for Fe-C plain steels. The model presented herein simplifies the computations to solve the solute- and heat-transfer simultaneous equations while searching for a solidus temperature as a part of the solution. Thus, this model can reduce the complexity of analyses considering the heat- and solute-transfer phenomena in the mushy zone.

36 MATERIALS SCIENCE↗
DOE OSTI2021

A Systematic Way to Extend the Debye–Hückel Theory beyond Dilute Electrolyte Solutions

An extended Debye–Hückel theory with fourth order gradient term is developed for electrolyte solutions; namely, the electric potential φ(r) of the bulk electrolyte solution can be described by ∇ 2 φ(r) = κ 2 φ(r) + L Q 2 ∇ 4 φ(r), where the parameters κ and L Q are chosen to reproduce the first two roots of the dielectric response function of the bulk solution. Three boundary conditions for solving the electric potential problem are proposed based upon the continuity conditions of involving functions at the dielectric boundary, with which a boundary element method for the electric potential of a solute with a general geometrical shape and charge distribution is derived. Solutions for the electric potential of a spherical ion and a diatomic molecule are found and used to calculate their electrostatic solvation energies. In this work, the validity of the theory is successfully demonstrated when applied to binary as well as multicomponent primitive models of electrolyte solutions.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

Instantaneous, parameter-free methods to define a solute’s hydration shell

A range of methods are presented to calculate a solute’s hydration shell from computer simulations of dilute solutions of monatomic ions and noble gas atoms. The methods are designed to be parameter-free and instantaneous so as to make them more general, accurate, and consequently applicable to disordered systems. One method is a modified nearest-neighbor method, another considers solute-water Lennard-Jones overlap followed by hydrogen-bond rearrangement, while three methods compare various combinations of water-solute and water-water forces. The methods are tested on a series of monatomic ions and solutes and compared with the values from cutoffs in the radial distribution function, the nearest-neighbor distribution functions, and the strongest-acceptor hydrogen bond definition for anions. The Lennard-Jones overlap method and one of the force-comparison methods are found to give a hydration shell for cations which is in reasonable agreement with that using a cutoff in the radial distribution function. Further modifications would be required, though, to make them capture the neighboring water molecules of noble-gas solutes if these weakly interacting molecules are considered to constitute the hydration shell.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2014

Structure solution of DNA-binding proteins and complexes with ARCIMBOLDO libraries

The structure solution of DNA-binding protein structures and complexes based on the combination of location of DNA-binding protein motif fragments with density modification in a multi-solution frame is described. Protein–DNA interactions play a major role in all aspects of genetic activity within an organism, such as transcription, packaging, rearrangement, replication and repair. The molecular detail of protein–DNA interactions can be best visualized through crystallography, and structures emphasizing insight into the principles of binding and base-sequence recognition are essential to understanding the subtleties of the underlying mechanisms. An increasing number of high-quality DNA-binding protein structure determinations have been witnessed despite the fact that the crystallographic particularities of nucleic acids tend to pose specific challenges to methods primarily developed for proteins. Crystallographic structure solution of protein–DNA complexes therefore remains a challenging area that is in need of optimized experimental and computational methods. The potential of the structure-solution program ARCIMBOLDO for the solution of protein–DNA complexes has therefore been assessed. The method is based on the combination of locating small, very accurate fragments using the program Phaser and density modification with the program SHELXE. Whereas for typical proteins main-chain α-helices provide the ideal, almost ubiquitous, small fragments to start searches, in the case of DNA complexes the binding motifs and DNA double helix constitute suitable search fragments. The aim of this work is to provide an effective library of search fragments as well as to determine the optimal ARCIMBOLDO strategy for the solution of this class of structures.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2016

The “2T” ion-electron semi-analytic shock solution for code-comparison with xRAGE: A report for FY16

This report documents an effort to generate the semi-analytic "2T" ion-electron shock solution developed in the paper by Masser, Wohlbier, and Lowrie, and the initial attempts to understand how to use this solution as a code-verification tool for one of LANL's ASC codes, xRAGE. Most of the work so far has gone into generating the semi-analytic solution. Considerable effort will go into understanding how to write the xRAGE input deck that both matches the boundary conditions imposed by the solution, and also what physics models must be implemented within the semi-analytic solution itself to match the model assumptions inherit within xRAGE. Therefore, most of this report focuses on deriving the equations for the semi-analytic 1D-planar time-independent "2T" ion-electron shock solution, and is written in a style that is intended to provide clear guidance for anyone writing their own solver.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2025

Mechanical Solutions Scan Report

Power lines, poles, and towers are the backbone of the United States (U.S.) electric-power grid. These transmission and distribution networks route electricity from generator to loads. The characteristics of these routes are rapidly changing -- trending towards decentralized renewable generation, electric heating, vehicle charging, and large data-center loads. Coupled with aging infrastructure and the increased frequency of extreme weather events, there is concern about the future reliability and transmission capacity of conductors and adjacent components. This scan report seeks to provide an overview of mechanical solutions to challenges caused by extreme weather events associated with components of transmission and distribution infrastructure, including conductor heat sag, ice accumulation, wind, and wildfire. Many options could increase transmission capacity or reliability, and these are at various stages of technological readiness. Some have only been lab tested, while some have been widely deployed in the U.S. or overseas for decades. The solution categories and providers featured in this report are intended to be comprehensive at the time of publication and to serve as a reference for decision-makers concerned about transmission and distribution reliability. There are two other categories of large, complex solutions, which are not covered in this report: replacing existing conductors with advanced conductors and implementing digital grid enhancing technologies. A separate scan report titled “Advanced Conductor Scan Report,” which discusses advanced carbon-core conductors, was published by the Idaho National Laboratory (INL) in 2023. Information on digital technologies, such as dynamic line ratings, power-flow controllers, and other power electronics and communications-based devices, can be found on the Grid- Enhancing Technologies landing page. Mechanical grid-enhancing technologies, or solutions covered in this report, often do not require full equipment replacement and do not rely on digital components. Mechanical technologies are overlooked because they may be older, simpler, or seemingly “more obvious” than digital or carbon-core technologies. However, it is wise to consider mechanical solutions in a thorough evaluation of grid enhancing technology solutions.

24 - POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2019

Removal of Methylene Blue from Aqueous Solutions Using Poly(vinyl alcohol)/Montmorillonite Nanocomposite Hydrogels: Taguchi Optimization

Nanocomposite hydrogel adsorbents on the basis of poly(vinyl alcohol) containing 0, 4, 8 and 12 wt% (based on dry basis) of montmorillonite were prepared using a cyclic freezing–thawing process. The capabilities of the adsorbents in adsorbing of a cationic dye, methylene blue, were studied in aqueous solutions having different temperatures, pH and concentrations. The Taguchi method was utilized to optimize the controllable factors, including the montmorillonite loading level, the solution temperature and pH and also the methylene blue concentration in adsorption solution. The prepared nanocomposite hydrogel adsorbents were characterized by Fourier transform infrared spectroscopy and their gel content and swelling values were also measured. The results showed that the gel content and swelling of nanocomposite hydrogel adsorbents had a direct and inverse dependency to the loading level of incorporated montmorillonite to adsorbent, respectively. The successful dye adsorption by the prepared nanocomposite hydrogel adsorbents was confirmed by the Fourier transform infrared spectroscopy. Based on the Taguchi method, the optimized conditions for methylene blue adsorption were found as: montmorillonite loading level of 12 wt%, adsorption temperature of 50 °C, pH of the aqueous solution of 9 and methylene blue concentration in adsorption solution of 5 mg/L. The percentage contribution of each parameter on the removal of methylene blue was determined using the Analysis of Variance method and the following order was found: temperature > concentration of methylene blue in solution > montmorillonite loading level in adsorbent > pH.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Investigation of the Branching of Solutions of the Problems of Synthesis of Radiating Systems with Flat Aperture According to a Given Amplitude Directivity Pattern

We continue our investigation of the nonuniqueness of solutions in the problems of synthesis of radiating systems with flat apertures depending on two parameters characterizing the size of the aperture and the solid angle in which the required amplitude directivity pattern is defined. The existence and properties of the real (primary) solutions of four types are clarified. We study the problems of branching of primary solutions of the second type. In the first approximation, we determine the analytic representations of complex-valued solutions branched from a real solution and investigate their main properties. The numerical experiments are carried out to analyze the efficiency of real and branched complexvalued solutions.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2019

A large family of optical solutions to Kundu–Eckhaus model by a new auxiliary equation method

The present study suggests a large family of optical solutions to the Kundu–Eckhaus model. Modified form of an auxiliary equation approach have been used to set the solution families. Compatible variable transform reduces the governing equation to a non linear ordinary differential equation. The parameters of the predicted solution in finite series form are determined by substitution of the solution into this ODE. The results cover a large family of optical solutions that are determined by implementation of various techniques in the literature. In this perspective, the modifed form of the a auxiliary equation approach is evaluated as a generalization of different methods widely used to construct the solutions.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2018

Distribution of P{sub 2}O{sub 5} and Na{sub 2}O Between Solid Solution and Liquid Phase in the CaO-SiO{sub 2}-Fe{sub 2}O{sub 3}-P{sub 2}O{sub 5}-Na{sub 2}O Slag System with High P{sub 2}O{sub 5} Content

The phosphorus content in hot metal will increase in future, because iron ores are steadily deteriorating in quality. Na{sub 2}O addition to slag is considered an effective method for increasing the efficiency of dephosphorization. In addition, Na{sub 2}O modification also facilitates phosphorus recovery from dephosphorization slag with high P{sub 2}O{sub 5} content by selective leaching. Therefore, it is necessary to investigate the distribution ratios of P{sub 2}O{sub 5} and Na{sub 2}O between solid solution and liquid phase in the CaO-SiO{sub 2}-Fe{sub 2}O{sub 3}-P{sub 2}O{sub 5}-Na{sub 2}O slag system. A linear relationship was found between the distribution ratio of P{sub 2}O{sub 5} and the Na{sub 2}O content in slag, and was independent of P{sub 2}O{sub 5} content. When the Na{sub 2}O content was high, the Na{sub 2}O content in the solid solution approached saturation and a new 2CaO·SiO{sub 2}-2CaO·Na{sub 2}O·P{sub 2}O{sub 5} solid solution formed. The addition of Na{sub 2}O decreased the P{sub 2}O{sub 5} content in solid solution, while it increased the mass fraction of solid solution in slag. The distribution ratio of P{sub 2}O{sub 5} increased with increase in the Fe{sub 2}O{sub 3} content and basicity of slag. An increase in P{sub 2}O{sub 5} content in slag results in an increase in the activity coefficient of P{sub 2}O{sub 5} both in the liquid phase and in the solid solution.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Effect of Sulfide Concentration on the Corrosion and Cavitation Erosion Behavior of a Manganese-Aluminum Bronze in 3.5% NaCl Solution

The effect of sulfide concentration on the corrosion and cavitation erosion behavior of a cast manganese-aluminum bronze (MAB) alloy in 3.5% NaCl solution was investigated. The electrochemical results showed that when the sulfide concentration exceeded 50 ppm, hydrogen evolution reaction dominated the cathodic process because of the very negative corrosion potential of MAB, and the formation of a copper sulfide film on MAB was a diffusion-controlled process. The mass loss rate of MAB after longer-term immersion was ordered by the sulfide concentration as: 20/50 ppm > 100 ppm > zero > 200 ppm. In the 200 ppm sulfide solution, the mass loss rate of MAB was the lowest, because of the formation of a thin and homogeneous copper sulfide film. In the other sulfide solutions, the formation of a less-protective film with both oxides and sulfides resulted in higher mass loss rate of MAB. Moreover, selective phase corrosion occurred at the β and κ phases in solutions with sulfide addition less than 100 ppm. For all solutions, it was the mechanical attack that dominated cavitation erosion degradation. The cavitation erosion–corrosion synergy was lower in high sulfide solutions, because the corrosion products on MAB could reduce the mechanical impact under cavitation erosion.

36 MATERIALS SCIENCE↗