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WO2006057812A2 - Procede et appareil de decontamination de compositions metalliques fondues - Google Patents

Procede et appareil de decontamination de compositions metalliques fondues Download PDF

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Publication number
WO2006057812A2
WO2006057812A2 PCT/US2005/040548 US2005040548W WO2006057812A2 WO 2006057812 A2 WO2006057812 A2 WO 2006057812A2 US 2005040548 W US2005040548 W US 2005040548W WO 2006057812 A2 WO2006057812 A2 WO 2006057812A2
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WO
WIPO (PCT)
Prior art keywords
molten metal
metal composition
lead
decontamination
iron
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/US2005/040548
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English (en)
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WO2006057812A3 (fr
Inventor
Eric P. Loewen
Larry D. Phelps
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Battelle Energy Alliance LLC
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Battelle Energy Alliance LLC
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Filing date
Publication date
Application filed by Battelle Energy Alliance LLC filed Critical Battelle Energy Alliance LLC
Publication of WO2006057812A2 publication Critical patent/WO2006057812A2/fr
Anticipated expiration legal-status Critical
Publication of WO2006057812A3 publication Critical patent/WO2006057812A3/fr
Ceased legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B9/00—General processes of refining or remelting of metals; Apparatus for electroslag or arc remelting of metals
    • C22B9/02—Refining by liquating, filtering, centrifuging, distilling, or supersonic wave action including acoustic waves
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B13/00—Obtaining lead
    • C22B13/06—Refining
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B13/00—Obtaining lead
    • C22B13/06—Refining
    • C22B13/08—Separating metals from lead by precipitating, e.g. Parkes process
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

Definitions

  • the present invention generally relates to the decontamination and purification of molten metal compositions and, more particularly, to the processing and treatment of lead- containing molten metal compositions in order to remove contaminants therefrom.
  • the molten metal compositions being treated are particularly useful in cooling systems for nuclear power generating units and related applications, with the claimed decontamination apparatus and method facilitating the safe, continuous, and efficient operation of these systems in a rapid and effective manner.
  • lead-containing molten metal compositions as efficient coolants in nuclear reactor systems, various difficulties have likewise been encountered when these materials are employed which will now be discussed.
  • lead-containing molten metal compositions especially lead-bismuth alloys
  • This corrosion can significantly degrade the operating components of the cooling systems, thereby leading to costly damage, leaks, and general system failures (including interruptions in reactor operation).
  • the corrosion problems discussed above are primarily caused by various inorganic contaminants in the lead-containing molten metal compositions including but not limited to the following materials in elemental form and/or various combinations thereof (alloys, compounds, complexes, and the like without limitation): antimony [Sb], arsenic [As], tin [Sn], and tellurium [Te].
  • Sb antimony
  • As arsenic
  • Sn tin
  • Te tellurium
  • U.S. Patent No. 4,496,394 involves a method for removing tin from a molten lead-containing composition by introducing chlorine and oxygen into the composition (which contains tin therein as an impurity) in order to form a tin-containing "dross" (e.g. an oxide composition typically located on the surface of the molten metal composition). Thereafter, the lead is physically separated from the dross.
  • U.S. Patent No. 5,100,466 discloses a method wherein lead is purified using a reactive mixture comprised of sodium and calcium. In accordance with this process, the resulting mixture is allowed to cool which yields three equilibrium phases, one of which (located on the bottom of the product) involves refined lead.
  • the present invention offers a considerable advance in the art of metal purification with particular reference to the decontamination of lead-containing molten metal compositions.
  • the claimed invention provides numerous benefits which, particularly from a collective standpoint, have not been achieved prior to the present invention.
  • the claimed invention is characterized by a multitude of specific benefits in combination, with the foregoing list not necessarily being exhaustive. These benefits include but are not limited to items (1) - (12) recited above both on an individual and simultaneous basis which are attainable in a substantially automatic manner (with the simultaneous achievement of such goals being of particular importance and novelty).
  • the decontamination method and apparatus described herein perform all of the functions mentioned above in a uniquely effective and simultaneous fashion while using a minimal quantity of reactants, reagents, equipment, labor, and operational requirements. As a result, a decontamination system of minimal complexity and high effectiveness is created that nonetheless exhibits a substantial number of beneficial attributes in an unexpectedly efficient manner.
  • a highly efficient method and apparatus are disclosed for removing inorganic contaminants from molten metal compositions, particularly those which contain in whole or in part lead. While the claimed invention shall not be restricted to the treatment of any particular lead-containing molten metal compositions, representative compositions of particular interest include those which are made from elemental lead [Pb], lead-bismuth [Pb-Bi] alloys, or combinations thereof in a variety of proportions without limitation. Furthermore, the present invention shall not be restricted regarding the particular inorganic contaminants which can be removed from the lead- containing molten metal compositions discussed above. However, in a preferred embodiment, the following contaminants shall be considered of primary interest in the claimed invention: antimony, arsenic, tin, tellurium, or combinations thereof.
  • the reducing agent will comprise a material selected from the group consisting of solid particulate carbon [C ⁇ ], hydrogen [H 2(g )], methane [CH ⁇ g )], acetylene [C 2 H 2 C g )], propane [C 3 Hg( g )], or combinations thereof without limitation.
  • At least one reducing agent shall be considered a "default" process step employed in order to obtain optimum results and, in this regard, shall be used unless countervailing circumstances exist which would make it unnecessary as determined by routine preliminary pilot tests. These tests would take into account the particular chemical nature of the lead-containing molten metal composition being treated, the contaminant content thereof, and the environmental conditions which exist within the decontamination system (along with other related factors). It should likewise be noted that the introduction of the reducing agent into the molten metal composition can occur at a variety of intervals or locations in the claimed process and system including before and during decontamination using the decontamination member discussed below.
  • the molten metal composition having the inorganic contaminants therein is placed in contact with at least one decontamination member which is comprised of a composition that will allow the inorganic contaminants in the molten metal composition to diffuse into the decontamination member.
  • the decontamination member will comprise iron [Fe] therein, with optimum results being achieved when an iron- containing alloy is employed (preferably steel).
  • the term "diffuse" shall be construed in the broadest possible sense to involve: (1) entry of the inorganic contaminants into and beneath the surface of the decontamination member to various depths without limitation; (2) interaction of the inorganic contaminants with the decontamination member at the surface thereof without necessarily passing beneath the surface; and/or (3) a combination of [1] and [2] above.
  • the decontamination member is of a type that will have a selective affinity for the inorganic contaminants of interest while avoiding affinity (and diffusion therein as defined above) of the various lead-containing materials (e.g. elemental lead, alloys, compounds, or complexes thereof) that are associated with the lead-containing molten metal composition.
  • the inorganic contaminants can be efficiently removed from the lead-containing molten metal composition in order to effectively decontaminate it.
  • specific operating parameters associated therewith including preferred residence times and the like
  • the lead-containing molten metal composition be maintained at a temperature of about 400 -
  • the inorganic contaminants in the molten metal composition are allowed to diffuse into the decontamination member and consequently be removed from the molten metal composition. In this manner, rapid and effective decontamination of the molten metal composition takes place as stated above. Further information will again be provided in the Detailed Description section regarding other operational parameters associated with the decontamination procedure including residence times, material quantities, and the like. As stated above and in accordance with the claimed process, the inorganic contaminants of concern will diffuse into the decontamination member for removal thereof from the lead-containing molten metal composition.
  • the molten metal composition in contact with the decontamination member will cause at least one iron- containing contaminant (e.g. elemental iron [Fe], alloys, mixtures, compounds, and/or complexes containing iron) to be introduced into the molten metal composition.
  • at least one iron- containing contaminant e.g. elemental iron [Fe], alloys, mixtures, compounds, and/or complexes containing iron
  • Removal of at least some (and preferably all) of the iron-containing contaminant is desired in order to preserve and maintain the overall purity, cooling efficiency, and non-corrosivity of the lead- containing molten metal composition and to likewise avoid undesired precipitation of the iron within the cooling system (which can cause flow restrictions and related problems).
  • Removal of the iron-containing contaminant may be accomplished in various ways without limitation. However, in a preferred and representative embodiment, elimination of the iron-containing contaminant is achieved using at least one iron trap. In particular, effective results are attained through the use of an iron trap system which supplies a magnetic field. The molten metal composition is placed within this magnetic field in order to draw the iron- containing contaminant out of the lead-containing molten metal composition. It should be noted that a decision to employ an iron trap in a given operational environment shall be determined in accordance with routine preliminary pilot tests taking into account the chemical and physical nature of the molten metal compositions being treated, the structural configuration of the decontamination member (and the materials from which it is made), and other operational parameters associated with the decontamination system.
  • this step will be employed as a "default" procedure unless countervailing circumstances indicate otherwise. Additional information concerning this particular aspect of the invention will likewise be outlined in greater detail below. It should likewise be recognized that in some (but not necessarily all) circumstances where a reducing agent is employed, the lead-containing molten metal composition will contain (after decontamination) at least some of the reducing agent therein which remains in an unreacted state. In particular, this reducing agent will be present (at least temporarily) within the molten metal composition after placement of the molten metal composition in contact with the decontamination member.
  • an additional feature of the claimed process can involve the step of removing at least some of the unreacted reducing agent from the molten metal composition (and the system as a whole). This step enables maximum operating efficiency to be maintained within the decontamination and cooling systems (namely, the minimization of corrosion and improved economic performance by the recycling of recovered quantities of reducing agent).
  • a supply of the lead-containing molten metal composition described above is initially provided which includes the previously-listed contaminants therein.
  • a supply of the reducing agent is also provided which is in fluid communication with the supply of the molten metal composition.
  • the reducing agent can be introduced into the molten metal composition on demand.
  • a containment vessel is also provided which is in fluid communication with the supply of the molten metal composition so that the composition can enter the vessel when decontamination is desired.
  • the containment vessel comprises therein the decontamination member outlined above.
  • the decontamination member comprises iron therein (preferably an iron-containing alloy with optimum results being achieved when steel is used for this purpose).
  • the decontamination member is of a type that will allow the inorganic contaminants of concern within the lead-containing molten metal composition to diffuse into the decontamination member when the molten metal composition comes in contact with the decontamination member. In this manner, the contaminants can be removed rapidly and effectively from the molten metal composition.
  • the containment vessel will further comprise at least one outlet port therein for passage of the molten metal composition out of the vessel after the composition comes in contact with the decontamination member.
  • at least one additional outlet port is provided in the containment vessel for the passage of unreacted quantities of the reducing agent out of the vessel (with such quantities being previously combined with the molten metal composition as outlined above).
  • the containment vessel (along with the various conduits and other components of the decontamination system) are produced from a composition which comprises zirconium [Zr] therein (e.g. elemental zirconium or alloys, compounds, mixtures, and complexes which contain at least some zirconium).
  • zirconium [Zr] therein e.g. elemental zirconium or alloys, compounds, mixtures, and complexes which contain at least some zirconium.
  • At least one iron trap is provided which is able to receive the molten metal composition after contact with the decontamination member.
  • the iron trap will again remove iron-containing contaminants from the molten metal composition which were introduced into the composition during contact thereof with the decontamination member.
  • the iron trap will comprise at least one magnet which is able to generate a magnetic field in order to draw the iron-containing contaminants out of the molten metal composition.
  • the decontamination apparatus may likewise include at least one heater which is used to provide heat to the molten metal composition so that optimum temperature levels can be maintained therein during decontamination.
  • the heater can be located in a variety of positions inside and outside the apparatus without limitation although it is preferred that it be positioned on or adjacent the exterior surface of the containment vessel so that direct heating thereof can be accomplished.
  • the apparatus which may be used to implement the claimed methods and processes shall not be restricted by the description provided herein.
  • Various additional components, systems, and sub-systems may be employed in connection with the containment vessel and the other sections of the claimed decontamination apparatus without limitation provided that the main functional capabilities of the system can be implemented in an effective and cost-efficient manner.
  • the apparatus associated with the claimed invention shall not be restricted to any particular equipment types, arrangements, capacities, materials, operational parameters, and the like unless otherwise expressly stated herein.
  • Fig. 1 is a schematically-illustrated view of a representative decontamination system for lead-containing molten metal compositions which may be used to implement the process of the claimed invention. No scale or size relationships shall be construed from the drawing or other limitations implied therefrom.
  • the present invention involves a highly efficient method and apparatus for removing inorganic contaminants from lead-containing molten metal compositions.
  • the technology discussed herein represents a significant advance in the field of molten metal decontamination technology.
  • the claimed method and apparatus are further characterized by an unexpectedly high degree of operational efficiency as previously noted.
  • a system for decontaminating the lead-containing molten metal composition of interest in the present invention is generally shown at reference number 10 which will now be discussed in substantial detail.
  • a nuclear reactor 12 which is being cooled using the lead-containing molten metal composition.
  • the lead-containing molten metal composition to be decontaminated may be associated with any heat-generating apparatus or facility without limitation that is capable of being cooled using materials of this nature.
  • an accelerator-driven radioactive waste transmutator may likewise be cooled using the lead-containing molten metal composition being described herein. Accordingly, the present invention shall not be limited regarding the particular apparatus, device, or system being cooled, or the cooling system in general which would employ the lead-containing molten metal composition of interest.
  • the nuclear reactor 12 includes a cooling system 14 of conventional design which is associated therewith.
  • the cooling system 14 includes a variety of conduits, components, and structures (not shown) which enable the lead-containing molten metal composition to be effectively circulated throughout the heat-generating regions of the nuclear reactor 12 in order to remove fission energy in the form of heat for use in electrical generation, H 2 production, etc.
  • Lead-containing molten metal cooling systems for nuclear applications are again known in the art to which this invention pertains and have been used for decades, with general information involving these systems being disclosed in a variety of articles and references including but not limited to Gromov, B., et al., "Inherently Safe Lead- Bismuth-Cooled Reactors", Atomic Energy, 76(4):332 - 330 (1994) which is incorporated herein by reference. Accordingly, the lead-containing molten metal composition being discussed herein (as well as the processes and devices which are used for decontamination purposes as disclosed below) shall not be considered “reactor-specific” or “cooling system- specific” and may be employed in connection with a number of conventional and non- conventional heat-generating devices and cooling systems without restriction.
  • a supply 16 of a lead-containing molten metal composition (also characterized in an equivalent fashion as a molten metal composition comprising lead therein).
  • the terms "lead-containing molten metal composition” and "molten metal composition comprising lead therein” shall be broadly construed and defined to encompass alloys, compounds, mixtures, complexes, and other combinations of materials (including the use of pure elemental lead [Pb]) which contain in part or in whole at least some lead therein.
  • Pb pure elemental lead
  • the lead-based molten metal composition associated with supply 16 will be discussed in greater detail.
  • the lead-based molten metal composition will be produced from: (1) elemental lead, (2) a lead-containing alloy; or (3) mixtures of [1] and [2].
  • this composition will contain at least some lead therein which is alloyed with one or more other metals or non-metals.
  • some representative examples of metals and non-metals which may be alloyed with lead in the lead- containing molten metal composition include but are not limited to bismuth [Bi], tin [Sn], zinc [Zn], or combinations of two or more of the above elements. It should likewise be noted that, within the lead-containing alloys associated with the supply 16 of the molten metal composition, the various individual materials therein can be used in a wide variety of proportions without limitation provided that at least some lead (optimally at least about 45% by weight or more) is present in the alloys so that the beneficial cooling effects associated with lead can be achieved.
  • lead-bismuth [Pb-Bi] alloy which is characterized by a high degree of cooling capacity and is therefore of considerable interest in nuclear applications.
  • a number of different lead-bismuth alloys can be employed wherein differing amounts of lead and bismuth are present therein.
  • two representative lead-bismuth alloys which are suitable for use in the cooling system 14 are as follows:
  • the supply 16 of the lead-containing molten metal composition will likewise contain at least some inorganic contaminants therein which are naturally present in the raw ore materials associated with the lead. The presence of these contaminants contributes to increased corrosion problems in the cooling system 14 which can adversely impair the operating efficiency and safety of the nuclear reactor 12 or other heat-generating devices as previously discussed.
  • the particular inorganic contaminants which reside within the lead-containing molten metal composition a variety of metals, non-metals, or combinations thereof may be involved.
  • a typical supply 16 of the lead-containing molten metal composition can include therein the following metals and/or non-metals alone or combined (typically in elemental form but possibly in other forms in accordance with the definition of "combinations” recited above): arsenic [As], antimony [Sb], tin [Sn], tellurium [Te], or combinations of two or more of the above-mentioned elements (or with other materials).
  • typical amounts of the above-listed inorganic contaminants are as follows: (A) arsenic (about 0.1 - 0.2% by weight); (B) antimony (about 0.5 - 2% by weight); (C) tin (about 0.1 - 1 % by weight); and (D) tellurium (about 0.1 - 0.5% by weight).
  • Composition Type Components (% by weight)
  • compositions which do not include appreciable amounts of tin and tellurium, with such materials and possibly others being present in other lead- containing molten metal compositions
  • the invention as claimed shall not be limited to the treatment of any particular lead-containing molten metal compositions, with a wide variety of such materials being subject to rapid and effective decontamination as discussed below.
  • the supply 16 of lead- containing molten metal composition is typically maintained at a temperature of about 125 - 1000 0 C during use within the cooling system 14 (for example, about 125 - 1000 0 C for lead-
  • the supply 16 of the molten metal composition is then routed into and through conduit 20 (using one or more conventional pumps 22) and into a containment vessel 24.
  • the conduit 20 includes a first end 26 operatively connected to the cooling system 14 and a second end 30 which is operatively connected to an inlet port or opening 32 in the containment vessel 24.
  • the pump 22 will involve, for example, a standard centrifugal type that is known in the art for molten metal transfer or other comparable pump devices which are suitable for this purpose.
  • zirconium-containing alloys that are suitable for this purpose include but are not limited to the following materials: (A) "Zircaloy-2" (with the approximate content of this alloy being [in % by weight]: tin [1.5%], iron [0.12%], chromium [0.01 %], and nickel [0.05%]) with the balance being zirconium; and (B) "Zircaloy-4" (with the approximate content of this alloy being [in % by weight]: tin [1.5%], iron [0.18%], and chromium [0.01%] with the balance being zirconium) wherein the foregoing values for both alloys are subject to a certain degree of variance.
  • Zirconium- containing compositions of the types listed above (and others) are particularly useful in that they form a self-protective zirconium oxide [ZrO 2 ] layer on the internal surfaces of the components discussed above. This oxide layer can assist in avoiding corrosion and other related problems (especially at operating temperatures within the decontamination system 10
  • zirconium-containing compositions are preferred as previously discussed, various other materials can likewise be employed in connection with the conduits, vessels, etc. of the claimed decontamination system 10 including but not limited to molybdenum [Mo], tantalum [Ta], tungsten [W], and alloys or other combinations of two or more of the above-listed materials (or with other compositions). These alternative materials are particularly effective at temperatures greater than 550 0 C.
  • compositions which can be used effectively as construction materials in connection with the operating components of the decontamination system 10 include iron-chromium-silicon alloys (with these materials being present in varying proportions without limitation) and a Russian alloy known as "EP-823". It should be recognized that a number of different construction materials may be used in connection with the decontamination system 10, with all of the above-mentioned compositions being effective and suitable at the temperature ranges and operational conditions associated with the claimed apparatus and method.
  • a supply 40 of a reducing agent (optimally in gaseous form as indicated below) be provided which is in fluid communication with the supply 16 of the lead-containing molten metal composition so that the reducing agent can be introduced into the molten metal composition on demand.
  • the supply 40 of the reducing agent is retained within a storage vessel 42 having an outlet 44 therein to which the first end 46 of a conduit 50 is operatively attached.
  • the second end 52 of the conduit 50 will include multiple distributor portions 54 (e.g. in the form of, for example, "tuyeres" or lances) which are in operative connection with openings 56 in the conduit 20. In this manner, the reducing agent can be effectively distributed or otherwise delivered into the lead-containing molten metal composition within the conduit 20.
  • the supply 40 of the reducing agent be in a gaseous form which facilitates the delivery thereof into the supply 16 of the lead-containing molten metal composition in a rapid, cost-effective, and efficient manner. Delivery of the reducing agent to the molten metal composition may be achieved in a number of different ways without limitation.
  • the reducing agent 40 within the storage vessel 42 can be maintained in a pressurized state which will allow the reducing agent to be spontaneously and automatically transferred into the conduits 20, 50 (and the molten metal composition) in an effective fashion.
  • the reducing agent in a pressurized state is, in fact, preferred in that this delivery approach is highly efficient and rapid, especially since the cooling system 14 and the claimed decontamination system 10 operate at relatively low pressure levels (e.g. about 1 - 1400 torr).
  • an in-line gas flow pump 60 of a conventional type for example, of a vacuum/diaphragm variety
  • the claimed invention shall not be restricted to any materials, devices, or components which may be used to deliver or transfer the various compositions associated with the invention into, through, and out of the decontamination system 10. A wide variety of different transfer devices and equipment may therefore be employed for these and other purposes without limitation.
  • a reducing agent within the decontamination system 10 should be considered preferred in that it can provide a number of important benefits. Specifically, by creating a reducing environment within the system 10, the formation of oxide layers (for example, one or more layers comprised of lead oxide [PbO] or other oxide materials) on the internal operating surfaces of the decontamination system 10 (especially the decontamination member discussed below) is effectively prevented. If not prevented, oxide layers of this type can coat the decontamination member and thereby prevent access to the surface of this important structure by the lead-containing molten metal composition. As a result, the decontamination process will be blocked and otherwise substantially impeded, with the overall decontamination procedure being discussed in extensive detail below.
  • oxide layers for example, one or more layers comprised of lead oxide [PbO] or other oxide materials
  • the reducing agent be employed. While the use of a reducing agent should nonetheless be considered “optional” (since, under certain circumstances as determined by routine preliminary pilot testing, the decontamination system 10 may operate without it), it should nonetheless be employed as a "default” procedure unless compelling reasons exist to the contrary. It should also be recognized that the claimed invention shall not be restricted to any location, interval, or point at which the supply 40 of reducing agent is added or otherwise introduced into the supply 16 of lead- containing molten metal composition. While the point-of-introduction shown in Fig.
  • the reducing agent can be added into the decontamination system 10 at any point upstream or downstream thereof provided that the reducing agent is introduced into the lead- containing molten metal composition in a manner which prevents oxide layer formation as previously discussed.
  • the materials which can be employed in connection with the supply 40 of the reducing agent a number of different compositions can be used for this purpose without limitation.
  • the reducing agent will be in gaseous form (in order to facilitate rapid and efficient introduction into the molten metal composition) and will involve the following exemplary materials: hydrogen methane [CH 4(g )], acetylene [C 2 HaCg)], propane [C 3 H 8C g)], or combinations of two or more of the above without limitation.
  • hydrogen is preferred in accordance with its ability to significantly reduce the oxygen potential of the molten metal composition.
  • the following chemical reactions occur when hydrogen is combined with the lead-containing molten metal composition: O 2 + H 2 _ H 2 O(I)
  • the present invention shall not be restricted to any particular amount for this purpose.
  • the exact quantity of the reducing agent to be used in a given application or situation is again determined in accordance with routine preliminary pilot tests taking into account numerous parameters including the overall size and capacity of the decontamination system 10, the amount of lead-containing molten metal composition being treated, and other related parameters.
  • the reducing agent namely, one or more of the gaseous compositions listed above
  • the reducing agent will be used in an amount equal to about 0.1 - 10% by weight of the mass flow rate of the decontamination system 10.
  • an excess amount of reducing agent should be used over and above the level which would theoretically be needed to prevent oxide layer formation.
  • This approach should specifically be implemented as a "default" measure in order to be certain that the above-listed goal is effectively achieved.
  • the flow rate associated with the reducing agent this may likewise be determined using routine preliminary pilot studies, with the claimed invention not being restricted in this regard.
  • the particular flow rate to be selected should be sufficient to introduce the chosen amount of reducing agent into the decontamination system 10 over a desired time period, and is therefore readily determined once the desired reducing agent quantity is selected (again taking into account system size and other related parameters).
  • pre-heating of the supply 40 of reducing agent is typically not necessary (unless otherwise indicated by routine preliminary tests).
  • solid particulate carbon [C( S) ] can be employed in connection with the supply 40 of reducing agent (although gaseous materials are again preferred for the reasons given above). Solid carbon compositions will function effectively in the claimed decontamination system 10, especially if temperatures
  • This material would be physically combined (e.g. mixed) with the lead-containing molten metal composition preferably within conduit 20 (or at any point upstream or downstream therefrom in the same fashion as the gaseous reducing agents discussed above).
  • the amount thereof would again be determined by routine preliminary pilot tests taking a number of factors into account including the overall size of the decontamination system 10, the metallurgical nature and content of the molten metal composition, and the like.
  • the supply 16 of the lead- containing molten metal composition is thereafter routed through the second end 30 of conduit 20 and into the containment vessel 24 via the opening 32 therein. Transfer of the molten metal composition will occur using the pump 22 or possibly other auxiliary or supplemental pumping devices (not shown), the need for which will be determined by the overall size and configuration of the decontamination system 10 under consideration. Likewise, transfer of the molten metal composition can take place using the differential pressure across the core of the reactor 12.
  • the containment vessel 24 includes a side wall 62 which is produced from the materials discussed above (optimally a material which comprises at least some zirconium therein including but not limited to elemental zirconium, a zirconium-containing alloy, or combinations thereof).
  • the lead-containing molten metal composition is present within the interior region 64 of the containment vessel 24, it comes in direct physical contact with at least one decontamination member 70 which will now be discussed in detail.
  • the central location of the decontamination member 70 within the interior region 64 of the containment vessel 24 as illustrated in Fig. 1 ensures direct physical contact between the molten metal composition and the decontamination member 70.
  • This process (which generally involves the intentional placement of the lead-containing molten metal composition in contact with the decontamination member 70) constitutes an important development which facilitates the effective removal of the inorganic contaminants (as defined above) from the molten metal composition.
  • the decontamination member 70 involves a structure of varying overall configuration which is separate and distinct from any other structures within the cooling system 14 and decontamination system 10. In particular, it is separate from the conduits, walls, vessels, and other components associated with the foregoing systems 10, 14 and is an independently- functioning structure.
  • the decontamination member 70 again resides in a central location within the interior region 64 of the containment vessel 24 and is surrounded by the side wall 62 thereof. It is particularly positioned within the flow path of the molten lead-containing composition which enters the interior region 64 of the containment vessel 24 so that the molten metal composition may directly contact the decontamination member 70.
  • the decontamination member 70 can involve many different structural configurations, shapes, sizes, surface areas, and the like without limitation.
  • the present invention shall therefore not be limited to any particular dimensions, sizes, and designs in connection with the decontamination member 70.
  • the decontamination member 70 is present in some form (irrespective of size, shape, etc.), it will remove at least some of the inorganic contaminants from the lead-containing molten metal composition and will therefore accomplish the goals of the present invention.
  • the exact size, shape, and structural configuration of the decontamination member 70 will depend on the overall size and capacity of decontamination system 10 in general (and the amount of molten metal composition to be treated) which can be determined in accordance with routine preliminary pilot tests.
  • the particular decontamination member 70 shown therein is comprised of an upper cap-like retaining structure 72 having secured thereto a plurality of individual rod or plate-like elements 74.
  • the elements 74 are produced from the particular materials that accomplish the actual decontamination of the molten metal composition as discussed extensively below.
  • the elements 74 are elongate in character, arranged in an annular (e.g. circular) configuration, and are further retained in position using a bottom-mounted retaining structure 76.
  • the molten metal composition can flow around and between the elements 74 in order to achieve a maximum degree of contact therebetween.
  • the elements 74 which are produced from the chosen decontamination material are readily removable from the system 10 once they become sufficiently "loaded” with contaminants that they are no longer operationally effective as discussed further below.
  • Fig. 1 in connection with the decontamination member 70 constitutes a single representative example thereof, with a number of other structures and overall configurations being possible without limitation.
  • the number of decontamination members 70 in the system 10 may vary from a single unit to multiple units in combination. These units may be elongate, spherical, round, square, or in any other configuration as determined in accordance with the overall configuration of the entire decontamination system 10 and its capacity (with a maximum degree of surface area being desired as a "default" condition).
  • removal of the inorganic contaminants from the lead-containing molten metal composition using the decontamination member 70 is dependent on the following variables: (1) temperature; (2) oxygen potential; (3) surface area; and (4) the types of materials associated with the decontamination member 70 and the lead-containing molten metal composition.
  • the following mathematical correlation is provided in order to explain and otherwise quantify the degree of impurity removal relative to the physical characteristics of the decontamination member 70 (e.g. size, shape, surface area, etc.) and may therefore be used to produce a decontamination member 70 having desired characteristics:
  • the above-listed formula can generally be employed to determine the overall structural characteristics of the decontamination member 70 with particular reference to surface area and the like. However, it should again be recognized that routine preliminary pilot testing can likewise be employed to determine these characteristics (and other features thereof) without limitation.
  • the materials which are used to produce the decontamination member 70 will be discussed in detail.
  • the decontamination member 70 is produced from a composition that will allow the above- mentioned inorganic contaminants to diffuse into the decontamination member 70 (while allowing lead in the molten metal composition to remain unaffected so that it does not diffuse into the decontamination member 70 or otherwise react therewith).
  • the term "diffuse" shall be construed in the broadest possible sense to involve: (1) entry of the inorganic contaminants into and beneath the surface of decontamination member 70 to various depths without limitation; (2) interaction of the inorganic contaminants with the decontamination member 70 at the surface thereof without passing beneath the surface; and/or (3) a combination of [1] and [2] above.
  • the decontamination member 70 is again of a type that will have an affinity for the inorganic contaminants of interest while avoiding an affinity for the various lead-containing materials (e.g. elemental lead, alloys, compounds, or complexes thereof) which are associated with the lead-containing molten metal composition.
  • the decontamination member 70 will be made from a material which comprises or otherwise contains at least some iron therein (e.g. elemental iron or iron-containing alloys, compounds, complexes, or combinations thereof).
  • the decontamination member will be comprised entirely or partially of steel (namely, an iron-based alloy).
  • steel namely, an iron-based alloy.
  • a number of different steel materials can be employed for this purpose without limitation including stainless steels (for example, both austenitic and ferritic stainless steels) and carbon-based steels.
  • steel materials recited above constitute representative examples which shall not restrict the invention in any respect since various other steel and iron-containing compositions can likewise be employed.
  • other steel materials including but not limited to the group of austenitic stainless steels in the "300-series”, the group of ferritic stainless steels in the "400-series”, and "mild” carbon steels in general.
  • the inorganic contaminants recited above will diffuse into or onto (as previously defined) the decontamination member 70.
  • the inorganic contaminants are effectively removed from the lead-containing molten metal composition while allowing lead materials within the molten metal composition to remain therein and not be removed (by diffusion into the decontamination member 70 or otherwise). While the exact physical and chemical mechanisms associated with the decontamination process are not fully understood, it is theorized that a number of specialized reaction processes take place which will now be generally discussed with primary reference to arsenic- based impurities for example purposes.
  • the dissolution of oxygen into the iron- containing decontamination member 70 forms a protective layer of metal oxide that prevents the dissolution of metals (e.g. iron, nickel, and/or chromium) from the decontamination member 70 into the lead-containing molten metal composition.
  • metals e.g. iron, nickel, and/or chromium
  • This situation likewise prevents the above-listed inorganic contaminants from being "exchanged” with the metals set forth above so that they can diffuse into the decontamination member 70.
  • the oxide material discussed above primarily consists of spinelles of iron-chrome oxides with a magnetite layer on the surface of the decontamination member 70.
  • a reducing environment (which may be induced by the addition of a reducing agent as discussed herein) removes these oxides, thereby allowing elements from the decontamination member 70 (e.g. iron, nickel, and/or chromium) to diffuse and dissolve into the molten metal composition.
  • elements from the decontamination member 70 e.g. iron, nickel, and/or chromium
  • inorganic contaminants for example, arsenic
  • iron therein which becomes more "available” in accordance with the diffusion of other materials such as chromium and nickel out of the member 70.
  • Diffusion of the inorganic contaminants into the decontamination member 70 in the manner described above forms metallic combinations (e.g. alloys) within the surface of the decontamination member 70.
  • iron-As iron-arsenic
  • iron arsenide iron arsenide
  • iron from the decontamination member 70 likewise diffuses into the lead-containing molten metal composition, but at a much lower level than, for example, nickel and chromium which are typical elements that reside within steel-based decontamination members 70 of the type discussed above.
  • This situation occurs in accordance with the much lower solubility of iron in the molten metal composition compared with, for instance, chromium and nickel.
  • the solubility limit for iron in molten lead is approximately 1 ppm at 500 0 C.
  • solubility limits for arsenic, nickel, and chromium in molten lead are approximately 31,000 ppm, 32,000 ppm, and 16 ppm, respectively.
  • the high temperature of the lead-containing molten metal composition serves to anneal the decontamination member 70. It is theorized that iron migrates during these elevated temperatures, especially within gaps in the crystalline structure of the decontamination member 70 caused by the dissolution of other components from the member 70 (including chromium, nickel, and/or possibly other elements).
  • Arsenic when present as an inorganic contaminant in the lead-containing molten metal composition, has a lower mobility compared with iron, thereby allowing a layer of iron-arsenide to be formed at the surface of the steel-based decontamination member 70 as the iron migrates to the surface and becomes exposed to the slowly, inwardly-diffusing contaminants (e.g. arsenic in this example).
  • the relative purity of the resulting iron-arsenide layer decreases as the distance from the surface of the decontamination member 70 increases. This situation is caused by the diminished migration of, for example, chromium and/or nickel from the decontamination member 70 as the distance from the surface increases. At these levels (e.g.
  • a decontamination member 70 that is made from 316L, 410, or F-22 steel materials; and (2) a lead-containing molten metal composition of the type discussed above which includes arsenic and antimony as inorganic contaminants
  • the following layer (e.g. film) structures are typically produced in connection with the member 70: [A] a first (e.g. outermost) layer which approaches the stoichiometric composition of iron-arsenide [Fe-As]; and [B] a second (e.g. inner) layer which involves a mixture (e.g. alloy) of iron, arsenic, antimony, and lead [Fe-As- Sb-Pb].
  • these layers result in accordance with the migration of chromium and/or nickel from the decontamination member 70 into the lead-containing molten metal composition, thereby allowing the contaminants (e.g. arsenic) to come in contact with exposed iron as previously discussed.
  • the contaminants e.g. arsenic
  • an "exchange" occurs in connection with the arsenic, thereby permitting it to diffuse (along with antimony and possibly other contaminants) into the member 70.
  • the resulting iron-arsenide layer or layers in the decontamination member 70 are characterized by reduced levels of chromium and/or nickel compared with the quantities of these materials that were initially present in the member 70.
  • the diffusion/ decontamination process produces a relatively pure layer (e.g. film) of iron-arsenide at the surface of the decontamination member 70, with the purity of this material again decreasing as the distance from the surface of the member 70 increases (characterized by inner layers of iron-arsenic-antimony-lead as previously indicated).
  • a relatively pure layer e.g. film
  • iron-arsenide e.g. iron-only
  • a highly reducing environment (produced, for example, through the combination of at least one reducing agent with the lead-containing molten metal composition) is beneficial in the production of an iron-contaminant layer (for example, iron-arsenide) on the steel-based decontamination member 70.
  • an iron-contaminant layer for example, iron-arsenide
  • Such a reducing environment will typically involve an oxygen partial pressure of about 10 - 40 atm in a representative embodiment.
  • there is a higher chemical affinity of various components in the steel e.g. iron, chromium, and/or nickel
  • This situation typically results in surface passivation that prevents the "exchange" of inorganic contaminants (e.g.
  • the decontamination system 10 (preferably the containment vessel 24) will include at least one heater 80 associated therewith as schematically illustrated in Fig. 1.
  • the heater 80 may involve a number of different types, structures, and configurations without limitation including but not limited to those that employ at least one or more electric resistive heating elements, as well as heating systems powered by other fuel sources including natural gas, and the like.
  • the claimed invention shall not be restricted to any particular locations in connection with the heater 80 which may be placed at any position on or within the decontamination system 10 provided that the desired degree of heat is imparted to the lead-containing molten metal composition as discussed further below.
  • the heater 80 (optimally comprising at least one or more electrically resistive elements) will at least partially surround the exterior surface 82 of the side wall 62 associated with the containment vessel 24 as schematically illustrated in Fig. 1.
  • an internal heating system can be provided within the containment vessel 24.
  • one or more laminate layers of graphite (not shown) can be provided on at least a portion of the decontamination member 70. Heat is then applied using a chosen heating source (e.g. an induction coil) positioned outside of the containment vessel 24. The graphite then becomes inductively heated (in accordance with its favorable thermal susception characteristics) which, in turn, heats the decontamination member 70.
  • a chosen heating source e.g. an induction coil
  • the heater 80 can be positioned in a variety of locations.
  • use of the heater 80 should be considered “optional” in that the additional heat generated by the heater 80 may not be necessary depending on a variety of factors as determined by routine preliminary pilot testing (including the overall size associated with the decontamination system 10, the temperature of the incoming molten metal composition, and other related factors). Nonetheless, the use of at 5 least one heater 80 should be considered preferred and employed as a "default" component in the claimed decontamination system 10 unless operating conditions specifically indicate otherwise.
  • the claimed 0 invention shall not be restricted to any particular values.
  • the molten metal composition will be maintained at a temperature of about 400 - 600 0 C during contact thereof with the decontamination member 70. This temperature level is designed to promote favorable reaction kinetics and maximum operating efficiency.
  • the temperature conditions set forth 5 above may be maintained and otherwise achieved using the heater 80 as previously described or, alternatively, the molten metal composition will have a temperature within the foregoing range as a natural consequence of the heat transfer process which occurs in the cooling system 14.
  • the claimed invention shall not be restricted to any particular residence time parameters.
  • the overall residence time as defined herein is a function of temperature and the oxygen potential of the molten metal composition.
  • TABLE II below provides some representative and non-limiting estimated residence times for a decontamination member 70 made from any of the specific steel compositions recited above.
  • the decontamination member 70 associated with the data in TABLE ⁇ will have a single elongate bar-like configuration that is approximately 1 meter long with a surface area of about 1000 cm 2 (wherein a primary goal is to remove arsenic as a contaminant):
  • the decontamination member 70 should be of a type that is readily removable from the system when it becomes saturated (e.g. "loaded") with the inorganic contaminants to a point where it is of diminished operational effectiveness. As to when this point is reached will vary depending on many factors including but not limited to the overall size, surface area, and shape of the decontamination member 70, the level of contamination within the lead-containing molten metal composition, and other related factors.
  • One method for deciding when to remove the decontamination member 70 from the system 10 would be to conduct analytical tests on the member 70 which would generally involve a periodic analysis of the member 70 during system operation using SEM analysis and other related techniques.
  • the claimed invention shall not be restricted to any particular methods or time intervals in connection with the saturation and removal of the decontamination member 70 from the system 10, with a number of different options being available.
  • the side wall 62 of the containment vessel 24 includes at least one main or primary outlet port 90 therein for passage of the decontaminated lead-containing molten metal composition as discussed further below.
  • the side wall 62 of the containment vessel 24 will likewise include at least one additional or secondary outlet port 92 therein, the function of which will now be discussed.
  • the excess/residual reducing agent will involve about 1 - 5% more than is consumed or otherwise needed in the process. Removal of the excess reducing agent is particularly desired since, if allowed to remain in the lead- containing molten metal composition, it can contribute to additional corrosion of the cooling system 14 once the decontaminated molten metal composition is recycled back into the cooling system 14 for reuse. Furthermore, removal, recovery, and reuse of the excess reducing agent can significantly improve the overall cost-efficiency and economic performance of the entire decontamination process. To accomplish the removal (and recovery if desired) of the excess gaseous reducing agent, it is preferred that the decontamination system 10 (with particular reference to the containment vessel 24) be configured and operated so that an open region 94 exists above the supply 16 of molten metal composition.
  • an exposed (e.g. top) surface 96 associated with the molten metal composition exists within the interior region 64 of the containment vessel 24.
  • This exposed surface 96 represents an "interface" between the molten metal composition and the open region 94.
  • the unreacted (e.g. excess/residual) quantities of reducing agent will spontaneously diffuse out of the molten metal composition and reside (in gaseous form) in the open region 94.
  • the vessel 24 will include the outlet port 92 through the upper wall 100 which optimally resides at the top of the vessel 24.
  • Operatively connected to the outlet port 92 is the first end 102 of a conduit 104 which, in a representative embodiment, will contain an in-line vacuum pump 106 of conventional design (or other comparable device) which will draw the excess reducing agent out of the containment vessel 24 and through the conduit 104.
  • the conduit 104 will have a second end 110 that is operatively connected to an opening 1 12 in a storage vessel 114 which can be used to retain the excess (e.g. withdrawn) reducing agent therein (shown at reference number 1 15 in Fig. 1). This reducing agent may then be used for any purpose, discarded, or (optimally) recycled back into the decontamination system 10 for reuse.
  • the storage vessel 114 preferably has an additional opening 116 therein which is operatively connected to the first end 120 of a conduit 122 which, in a representative embodiment, will have another in-line vacuum pump 124 of conventional design (or other comparable device) therein.
  • the conduit 122 further includes a second end 126 that is operatively connected to an opening 130 within the storage vessel 42 which contained the initial supply 40 of the reducing agent.
  • effective recycling of the reducing agent can occur in order to achieve the significant benefits listed above. It should be recognized that the reducing agent removal sub-system discussed herein and shown schematically in Fig. 1 is being presented for example purposes only and shall not limit the invention in any respect.
  • At least some residual water may be generated and spontaneously released from the molten metal composition in accordance with the decontamination procedures discussed herein.
  • This water may be eliminated from the containment vessel 24 in a number of different ways without limitation.
  • the water e.g. steam
  • the storage vessel 1 14 would then include a water trap/separatory system of conventional design (not shown) that could be used to collect water from the materials in the vessel 114.
  • placement of the molten metal composition in contact with the decontamination member 70 will typically cause at least one iron-containing contaminant to be introduced into the molten metal composition.
  • the iron-containing contaminant can involve, for instance, elemental iron and iron-containing alloys, compounds, complexes, or combinations thereof without limitation.
  • a process step will be initiated in which at least some of the iron-containing contaminants will be removed from the lead-containing molten metal composition after decontamination. While this step (and the components associated therewith) should nonetheless be considered “optional” (with the need thereof ultimately being determined by routine preliminary pilot studies), it should be implemented as a "default” procedure unless compelling reasons exist to do otherwise.
  • FIG. 1 an exemplary and non-limiting iron trap 140 is schematically illustrated (with a number of other configurations and types also being possible).
  • the iron trap 140 involves a tubular member 142 having a first end 144 and a second end 146, with the tubular member 142 optimally being designed so that it is readily removable from the decontamination system 10.
  • the first end 144 in the embodiment of Fig.
  • the tubular member 142 may include a pump 150 associated therewith of conventional design (e.g. the same type as pump 22 or otherwise).
  • the decontaminated lead-containing molten metal composition can readily pass from the interior region 64 of the containment vessel 24 into the tubular member 142 associated with the iron trap 140.
  • the tubular member 142 will preferably be produced from an iron-containing composition (e.g. an iron alloy including but not limited to stainless steel) and will have at least one magnet 152 preferably located on the exterior surface 154 of the tubular member 142.
  • a single magnet 152 can be used as shown in Fig. 1 or multiple magnetic elements can instead be employed (not shown) without limitation.
  • the size, shape, capacity, and other characteristics of the tubular member 142, the magnet 152, and the iron trap 140 in general can be varied as needed and desired in accordance with routine preliminary pilot testing and shall not restrict the invention in any respect.
  • preferred and non-limiting magnetic strength values associated therewith will be about 0.1 - 10 gauss.
  • the magnetic field generated by the magnet 152 will cause the solid iron-containing contaminants in the molten metal composition to be drawn out of the composition and become magnetically adhered to the interior surface 160 of the tubular member 142. In this manner, the iron-containing contaminants are effectively removed from the molten metal composition in a rapid and efficient manner. It should be understood that removal of the iron-containing contaminant materials from the molten metal composition is desirable as a "default" procedure for various reasons.
  • the iron-containing contaminants are not removed from the molten metal composition, they can precipitate within lower-temperature regions of the cooling system 14 when the molten metal composition is recirculated for use therein. This precipitation process can, in fact, cause significant flow restrictions in the cooling system 14 and substantially degrade its performance.
  • the tubular member 142 associated with the iron trap 140 can be removed for cleaning or replacement at any desired interval.
  • One method for determining when to remove the tubular member 142 from the decontamination system 10 would be to conduct pilot tests on the member 142 which would involve a periodic analysis of the member 142 during system operation using manual inspection techniques, flow pressure measurements, and other related procedures. These techniques could then be used to determine when the interior surface 160 of the tubular member 142 has become sufficiently "loaded” with iron-containing contaminants to no longer be optimally effective. Once this time period is determined for a given type and quantity of the molten metal composition, it may then be applied as a "standard" for subsequent use in the overall operation of the iron trap 140.
  • these measurements will generally involve a determination of the pressure levels of the molten metal composition moving through the tubular member 142, with diminished pressure levels indicating that the tubular member 142 has become sufficiently "loaded” to warrant its replacement or cleaning. It should also be noted that, aside from the approach outlined above, an on-line "real-time" flow pressure measurement system of a type which is conventional and known in the art may be used in connection with the tubular member 142. Once the flow pressure in the tubular member 142 decreases to a predetermined level, the member 142 can be removed from the decontamination system 10 for replacement or cleaning. It shall therefore be understood that a number of different methods and components may be used to monitor the activity of the iron trap 140 without limitation.
  • the second end 146 of the tubular member 142 associated with the iron trap 140 is operatively connected to the first end 162 of a conduit 164 which includes, for example, an in-line pump 166 of conventional design therein (e.g. of the same type as pump 22 or otherwise).
  • the second end 170 of the conduit 164 is operatively connected to the cooling system 14 so that the decontaminated lead-containing molten metal composition may be transferred through the conduit 164 (using, for example, pump 166) for delivery into cooling system 14 to be reused therein as desired.
  • the claimed invention provides many key benefits in a simultaneous fashion.
  • the present invention is capable of a significant level of decontamination and, in this regard, can provide the benefits listed above.

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  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
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Abstract

L'invention concerne un procédé et un appareil permettant de contaminer des compositions métalliques fondues. L'invention concerne initialement une composition métallique fondue (contenant d'ordinaire du plomb élémentaire ou un alliage de plomb) qui comporte également divers contaminants inorganiques. Ladite composition est mise en contact avec un élément de décontamination spécialisé qui favorise activement la diffusion des contaminants dans cette composition, le résultat étant que les contaminants sont évacués de la composition métallique fondue. Les contaminants particulièrement intéressants dans des compositions métalliques fondues à base de plomb sont notamment l'arsenic, l'étain, l'antimoine, le tellure, et des combinaisons de ceux-ci. Un agent réducteur est combiné de façon optimale avec la composition métallique fondue afin d'empêcher la formation d'oxydes sur l'élément de décontamination, ce dernier contenant, de préférence, du fer sous la forme d'un alliage de fer (par exemple l'acier). Des composants additionnels préférés ajoutés dans le système de décontamination comportent notamment un piège à fer pour évacuer de la composition métallique fondue les contaminants renfermant du fer, ce qui permet de décontaminer rapidement et efficacement ladite composition.
PCT/US2005/040548 2004-11-22 2005-11-08 Procede et appareil de decontamination de compositions metalliques fondues Ceased WO2006057812A2 (fr)

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US9234258B2 (en) 2013-02-25 2016-01-12 U.S. Department Of Energy Apparatus and methods for purifying lead
US11049624B2 (en) * 2015-12-07 2021-06-29 Ge-Hitachi Nuclear Energy Americas Llc Nuclear reactor liquid metal coolant backflow control

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