US3069256A - Preparation of thorium intermetallic compound dispersion - Google Patents
Preparation of thorium intermetallic compound dispersion Download PDFInfo
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- US3069256A US3069256A US50095A US5009560A US3069256A US 3069256 A US3069256 A US 3069256A US 50095 A US50095 A US 50095A US 5009560 A US5009560 A US 5009560A US 3069256 A US3069256 A US 3069256A
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- thorium
- alloy
- bismuth
- lead
- magnesium
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- ZSLUVFAKFWKJRC-IGMARMGPSA-N 232Th Chemical compound [232Th] ZSLUVFAKFWKJRC-IGMARMGPSA-N 0.000 title claims description 67
- 229910052776 Thorium Inorganic materials 0.000 title claims description 66
- 229910000765 intermetallic Inorganic materials 0.000 title claims description 23
- 239000006185 dispersion Substances 0.000 title claims description 20
- 238000002360 preparation method Methods 0.000 title description 4
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 claims description 41
- 238000002844 melting Methods 0.000 claims description 25
- 229910052751 metal Inorganic materials 0.000 claims description 22
- 239000002184 metal Substances 0.000 claims description 22
- 229910045601 alloy Inorganic materials 0.000 claims description 21
- 239000000956 alloy Substances 0.000 claims description 21
- 239000011777 magnesium Substances 0.000 claims description 17
- 229910052749 magnesium Inorganic materials 0.000 claims description 16
- 238000000034 method Methods 0.000 claims description 16
- UDRRLPGVCZOTQW-UHFFFAOYSA-N bismuth lead Chemical compound [Pb].[Bi] UDRRLPGVCZOTQW-UHFFFAOYSA-N 0.000 claims description 15
- 229910000978 Pb alloy Inorganic materials 0.000 claims description 14
- 238000010438 heat treatment Methods 0.000 claims description 12
- 229910001264 Th alloy Inorganic materials 0.000 claims description 10
- 239000000203 mixture Substances 0.000 claims description 8
- PFQYKLITIGMIPH-UHFFFAOYSA-N lead thorium Chemical compound [Pb].[Th] PFQYKLITIGMIPH-UHFFFAOYSA-N 0.000 claims description 6
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims description 5
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 claims description 5
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 claims description 5
- HQLKQUPSRRVXPN-UHFFFAOYSA-N bismuth thorium Chemical compound [Bi].[Th] HQLKQUPSRRVXPN-UHFFFAOYSA-N 0.000 claims description 5
- 239000011575 calcium Substances 0.000 claims description 5
- 229910052791 calcium Inorganic materials 0.000 claims description 5
- 239000011734 sodium Substances 0.000 claims description 5
- 229910052708 sodium Inorganic materials 0.000 claims description 5
- 229910052725 zinc Inorganic materials 0.000 claims description 5
- 239000011701 zinc Substances 0.000 claims description 5
- 238000005275 alloying Methods 0.000 claims description 4
- JCXGWMGPZLAOME-UHFFFAOYSA-N bismuth atom Chemical compound [Bi] JCXGWMGPZLAOME-UHFFFAOYSA-N 0.000 description 24
- 229910052797 bismuth Inorganic materials 0.000 description 18
- 230000008018 melting Effects 0.000 description 12
- 150000003586 thorium compounds Chemical class 0.000 description 5
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 4
- 238000005266 casting Methods 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 239000002245 particle Substances 0.000 description 4
- CTNKBLMNHFSRFU-UHFFFAOYSA-N [Th].[Mg] Chemical compound [Th].[Mg] CTNKBLMNHFSRFU-UHFFFAOYSA-N 0.000 description 3
- 230000001413 cellular effect Effects 0.000 description 3
- 150000001875 compounds Chemical class 0.000 description 3
- 150000002739 metals Chemical class 0.000 description 3
- 239000011780 sodium chloride Substances 0.000 description 3
- 229910001152 Bi alloy Inorganic materials 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 230000001427 coherent effect Effects 0.000 description 2
- 239000012530 fluid Substances 0.000 description 2
- 229910002804 graphite Inorganic materials 0.000 description 2
- 239000010439 graphite Substances 0.000 description 2
- 229910052750 molybdenum Inorganic materials 0.000 description 2
- 239000011733 molybdenum Substances 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 238000000859 sublimation Methods 0.000 description 2
- 230000008022 sublimation Effects 0.000 description 2
- 238000005092 sublimation method Methods 0.000 description 2
- MZQZQKZKTGRQCG-UHFFFAOYSA-J thorium tetrafluoride Chemical compound F[Th](F)(F)F MZQZQKZKTGRQCG-UHFFFAOYSA-J 0.000 description 2
- 229910000861 Mg alloy Inorganic materials 0.000 description 1
- 238000009395 breeding Methods 0.000 description 1
- 230000001488 breeding effect Effects 0.000 description 1
- 210000002421 cell wall Anatomy 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000002939 deleterious effect Effects 0.000 description 1
- 239000002270 dispersing agent Substances 0.000 description 1
- 238000004821 distillation Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 229910001092 metal group alloy Inorganic materials 0.000 description 1
- 230000009257 reactivity Effects 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- -1 thorium bismuthide compound Chemical class 0.000 description 1
- 238000005303 weighing Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C43/00—Alloys containing radioactive materials
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F9/00—Making metallic powder or suspensions thereof
-
- 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
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S376/00—Induced nuclear reactions: processes, systems, and elements
- Y10S376/90—Particular material or material shapes for fission reactors
Definitions
- the invention relates to a method of preparing a dispersion of thorium bismuthide or thorium-lead compound in bismuth lead or bismuth-lead alloy and more particularly relates to a method of preparing a dispersion of such a thorium intermetallic compound in fine particulate form.
- thorium bismuthide in bismuth or bismuth-lead alloy or thorium-lead compound in lead or lead-bismuth alloy are an advantageous form of thorium which is useful as a fluid blanket material.
- a desirable property of a thorium intermetallic compound dispersion to be used as a fluid blanket is that it be pumpable.
- difficulties have been encountered in avoiding dense compact crystalline forms, or grossly enlarged platelets which are up to centimeters in diameter. Neither of these forms are readily pumped.
- the invention is predicated on the discovery that upon heating an alloy consisting of about 10 to 50 percent by Weight of thorium the balance a magnesium metal, thereby to sublime or distill away the magnesium metal and leave a thorium sponge, and thereafter on heating the so-prepared thorium sponge in contact with a low melting metal selected from the group consisting of bismuth, lead or bismuth-lead alloy, a fine particulate, pumpable dispersion of thorium intermetallic compound is obtained.
- thorium intermetallic compound refers to the intel-metallic compounds of thorium with bismuth and with lead.
- an alloy of thorium and magnesium is provided by heating together under an inert atmosphere the requisite amounts of the metals to form an alloy consisting of about 10 to 50 percent by Weight of thorium; the balance being magnesium metal.
- a magnesium metal is defined as a metal selected from magnesium and magnesium alloyed with up to 5 Weight percent of a volatile metal selected from the group consisting of calcium, sodium, zinc and mixtures thereof.
- an alloy of thorium and magnesium metal may also be prepared from a compound of thorium, preferably thorium fluoride.
- the thorium compound is heated together with an excess of molten magnesium metal under an inert atmosphere to effect the reduction of the thorium compound, the soformed thorium alloying directly with the excess of molten magnesium metal.
- Intimate contact and reactivity of the relatively high melting thorium compounds with the relatively low melting magnesium metal are generally facilitated by taking up the thorium compound in a saline composition which is then admixed with molten magnesium metal.
- Patent No. 2,678,267 thorium fluoride is admixed with NaCl and KCl to form a saline mixture which is melted and reacted with molten magnesium in the preparation of magnesium-thorium alloy.
- the thorium alloy selected or provided by preparation thereof should contain from about 50 to percent by weight of magnesium metal, more preferably 70 to 85 percent in order to form the desired porous sponge-like thorium mass during the sublimation'step.
- a thorium dispersion may be formed therefrom in reasonably short times, such as 1 or 2 hours, it is essential that the residual thorium obtained in the present process have a particulate, skeletal, or cellular form in which the average shortest dimension of particle or cell wall is relatively small, e.g., less than 0.1 inch.
- the thorium has an average shortest dimension in the range of about 0.02 to 0.05 inch.
- Sublimation or distillation of the volatile light metal is carried out, broadly speaking, in a manner generally well understood in the art of purifying volatile metals.
- the thorium alloy is placed in a suitable container, such as a molybdenum boat, which is placed in a sublimer, i.e., a horizontal furnace adapted to be evacuated and having an arrangement to collect the metal subliming or distilling from the thorium alloy.
- the furnace is generally evacuated to a reduced pressure lower than about 0.1 mm. of Hg and heating is begun to selectively volatilize the said magnesium metal from the thorium.
- thorium residue is not heated to a high enough temperature, it is crumbly and unsintered and tends to be pyrophoric on exposure to air.
- thorium intermetallic compound dispersion is to be prepared in the same furnace in the absence of air, the stability in air is not important and a final temperature of about 750 to 800 C. is satisfactory.
- the sublimation process is usually completed in 5 to 10 hours, depending upon the amount of alloy. Larger amounts of alloy require longer heating periods.
- the resulting sponge is allowed to cool and is then dispersed in bismuth, lead or any alloy of bismuth and lead, any of which may be employed as a blanket material solvent or dispersant medium in a nuclear reactor system.
- a dispersion of a thorium-lead intermetallic compound such as ThPbg
- a dispersion of a thorium bismuthide compound is formed, the thoriumlead compounds forming only in bismuth-leadalloy containing more than about percent by weight of lead, the balance bismuth.
- the dispersion process is carried out by heating one part by weight of the thorium sponge together with from 5 to parts by Weight of pieces of bismuth, lead or bismuth-lead alloy.
- the metals are placed in a suitable container such as a graphite crucible and heated in a furnace provided with means of maintaining an inert atmosphere.
- a suitable container such as a graphite crucible and heated in a furnace provided with means of maintaining an inert atmosphere.
- the thorium forms thorium bismuthide or thorium-lead compound which spalls off the surface of the sponge until the conversion to intermetallic compound is completed.
- thorium tend to dissolve in the hismuth, lead, or bismuth-lead alloy, and on cooling the resulting thorium low-melting metal alloy very large platelets of thorium compound are precipitated.
- Dispersion of 10 to 20 gram quantities of thorium sponge in 100 to 200 grams of bismuth, lead, or bismuth-lead alloy is generally completed in about 45 minutes to one hour at 600 C. Larger quantities of sponge and low-melting metal require longer times.
- the so-prepared dispersion of thorium intermetallic compound may be used directly as a blanket in a breedertype nuclear reactor. Or if desired, it may first be further diluted with additional bismuth, lead, or bismuth-lead to accommodate a given reactor design.
- Example as an example of the process of the invention a magnesium-thorium alloy was prepared by melting together thorium and magnesium under an inert atmosphere and decanting the alloy from the dross. Forty and five-tenths (40.5) grams of the resulting alloy consisting of about 30 percent by weight of thorium, the balance magnesium, was placed in a molybdenum boat-type sublimer and the sublimer furnace was evacuated to about 0.020 mm. Hg pressure. The furnace was first brought to a temperature of 550 C. and then the temperature was brought, over the space of five hours, to 700 C. The 700 C. temperature was maintained for about seven hours to assure the complete removal of the magnesium as well as the formation of a coherent sponge weighing about 13.5 grams.
- the thorium sponge was placed in a graphite crucible along with .125 gram of oxide-free, 0.5 inch diameter bismuth rods.
- the crucible and contents were placed in an evacuable electric furnace.
- the furnace was purged of air and filled with an inert gas. Then the furnace was brought to and maintained at a temperature of 600 C. for one hour. During the one hour period the bismuththorium mixture was agitated several times.
- the furnace was then allowed to cool and the contents of the crucible solidified as a casting.
- the casting was removed from the crucible, sectioned, and examined by the metallographic method.
- the casting was found to consist of a finely divided dispersion in bismuth of thorium bismuthide particles which exhibited a maximum dimension of about 10 microns. Chemical examination of the casting indicated the concentration of residual magnesium was less than 200 parts per million.
- the improved method of preparing said thorium sponge which comprises: alloying a magnesium metal selected from the group consisting of magnesium, and magnesium containing up to weight percent of calcium, sodium, zinc and mixtures thereof, with thorium under an inert atmosphere, the amount of magnesium metal in the soprepared thorium alloy being about 50 to 90 percent by weight of the alloy; and under a pressure of less than about 0.1 mm. of Hg, heating said alloy initially to a temperature of about 550 C. and thereafter gradually to a temperature in the range of 650 to 900 (3., thereby to volatilize
- the improved method of preparing said thorium sponge which comprises: providing an alloy consisting of thorium and a magnesium metal selected from the group consisting of magnesium, and magnesium alloyed with up to 5 weight percent of calcium, sodium, zinc, and mixtures thereof, the proportion of said magnesium metal in the alloy being about 50 to 90 percent by weight of the alloy, the balance thorium; and under a pressure of less than about 0.1 mm. of Hg, heating said alloy initially to a temperature of about 550 C. and gradually to a temperature in the range of 650 to 900 C., thereby to volatil
- the method of preparing a fine particulate dispersion of a thorium intermetallic compound selected from the group consisting of thorium-bismuth and thoriumlead intermetallic compounds, in a low-melting metal selected from the group consisting of bismuth, lead and bismuth-lead alloys which comprises: alloying a magnesium metal selected from the group consisting of magnesium, and magnesium alloyed withup to 5 weight percent of calcium, sodium, zinc, and mixtures thereof, with thorium under an inert atmosphere, the amount of said magnesium metal in the so-prepared alloy being about 50 to percent by weight of the alloy, the balance thorium; heating said alloy under a pressure of less than about 0.1 mm.
- the method of preparing a fine particulate dispersion of thorium bismuthide in a low-melting metal selected from the group consisting of bismuth, and bismuthlead alloy containing up to 90 weight percent lead, the balance bismuth which comprises: contacting a thorium sponge-like mass having an average cellular wall thickness of less than about 0.05 inch withfrom 5 to 100 parts by weight of said low-melting metal per part of thorium sponge-like mass under an inert atmosphere, at a temperature above the melting point of the low-meling metal and below about 700 C.
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Manufacture Of Metal Powder And Suspensions Thereof (AREA)
- Manufacture And Refinement Of Metals (AREA)
- Powder Metallurgy (AREA)
Description
No Drawing. Filed Aug. 17, 1960, Ser. No. 50,095 4 Claims. c1. 75-12217 The invention relates to a method of preparing a dispersion of thorium bismuthide or thorium-lead compound in bismuth lead or bismuth-lead alloy and more particularly relates to a method of preparing a dispersion of such a thorium intermetallic compound in fine particulate form.
In nuclear reactors neutrons escaping from the core are often utilized to breed, or form, additional fuel material. Breeding consists mainly of exposing a blanket material such as thorium to the escaping neutrons. Very fine dispersions of thorium bismuthide in bismuth or bismuth-lead alloy or thorium-lead compound in lead or lead-bismuth alloy are an advantageous form of thorium which is useful as a fluid blanket material.
A desirable property of a thorium intermetallic compound dispersion to be used as a fluid blanket is that it be pumpable. Heretofore difficulties have been encountered in avoiding dense compact crystalline forms, or grossly enlarged platelets which are up to centimeters in diameter. Neither of these forms are readily pumped.
It is therefore a principal object of the invention to provide a method of preparing a readily pumpable dispersion of thorium intermetallic compound in fine particulate form in bismuth, lead or bismuth-lead alloy.
The invention is predicated on the discovery that upon heating an alloy consisting of about 10 to 50 percent by Weight of thorium the balance a magnesium metal, thereby to sublime or distill away the magnesium metal and leave a thorium sponge, and thereafter on heating the so-prepared thorium sponge in contact with a low melting metal selected from the group consisting of bismuth, lead or bismuth-lead alloy, a fine particulate, pumpable dispersion of thorium intermetallic compound is obtained.
For the purposes of the specification and claims the term thorium intermetallic compound refers to the intel-metallic compounds of thorium with bismuth and with lead.
In carrying out the method of the invention an alloy of thorium and magnesium is provided by heating together under an inert atmosphere the requisite amounts of the metals to form an alloy consisting of about 10 to 50 percent by Weight of thorium; the balance being magnesium metal.
For the purpose of the specification and claims a magnesium metal is defined as a metal selected from magnesium and magnesium alloyed with up to 5 Weight percent of a volatile metal selected from the group consisting of calcium, sodium, zinc and mixtures thereof.
In accordance with the invention, an alloy of thorium and magnesium metal may also be prepared from a compound of thorium, preferably thorium fluoride. The thorium compound is heated together with an excess of molten magnesium metal under an inert atmosphere to effect the reduction of the thorium compound, the soformed thorium alloying directly with the excess of molten magnesium metal. Intimate contact and reactivity of the relatively high melting thorium compounds with the relatively low melting magnesium metal are generally facilitated by taking up the thorium compound in a saline composition which is then admixed with molten magnesium metal. As an example, according to U.S.
Patent No. 2,678,267, thorium fluoride is admixed with NaCl and KCl to form a saline mixture which is melted and reacted with molten magnesium in the preparation of magnesium-thorium alloy.
In any event, the thorium alloy selected or provided by preparation thereof should contain from about 50 to percent by weight of magnesium metal, more preferably 70 to 85 percent in order to form the desired porous sponge-like thorium mass during the sublimation'step. In order that a thorium dispersion may be formed therefrom in reasonably short times, such as 1 or 2 hours, it is essential that the residual thorium obtained in the present process have a particulate, skeletal, or cellular form in which the average shortest dimension of particle or cell wall is relatively small, e.g., less than 0.1 inch. Preferably the thorium has an average shortest dimension in the range of about 0.02 to 0.05 inch.
Sublimation or distillation of the volatile light metal is carried out, broadly speaking, in a manner generally well understood in the art of purifying volatile metals. The thorium alloy is placed in a suitable container, such as a molybdenum boat, which is placed in a sublimer, i.e., a horizontal furnace adapted to be evacuated and having an arrangement to collect the metal subliming or distilling from the thorium alloy. The furnace is generally evacuated to a reduced pressure lower than about 0.1 mm. of Hg and heating is begun to selectively volatilize the said magnesium metal from the thorium.
Melting of the thorium once it is substantially magnesium-free is to be avoided because the formation of a porous residue is thereby prevented, resulting in either a dense sponge or massive thorium, neither of which is readily dispersed in bismuth or lead. However, at the beginning of the heating period the melting of low-melting magnesium-thorium intermetallic compounds is not deleterious and magnesium distills from the molten alloy. If it is desired tocarry out the preparation entirely by the sublimation process, heating is commenced at a temperature at least slightly below the melting temperature of the thorium alloy. In any event, the temperature is gradually increased over a period of hours to a temperature in the range fo 650 to 900 C. Temperatures above 800 C. are employed to assure more complete removal of the magnesium metal as well as to cause sintering of the residual thorium into a fairly coherent mass. If the thorium residue is not heated to a high enough temperature, it is crumbly and unsintered and tends to be pyrophoric on exposure to air. If the thorium intermetallic compound dispersion is to be prepared in the same furnace in the absence of air, the stability in air is not important and a final temperature of about 750 to 800 C. is satisfactory. At 700' to 800 C. the sublimation process is usually completed in 5 to 10 hours, depending upon the amount of alloy. Larger amounts of alloy require longer heating periods.
The resulting sponge is allowed to cool and is then dispersed in bismuth, lead or any alloy of bismuth and lead, any of which may be employed as a blanket material solvent or dispersant medium in a nuclear reactor system.
If lead is employed, a dispersion of a thorium-lead intermetallic compound, such as ThPbg, is obtained. In bismuth and most bismuth-lead alloys, a dispersion of a thorium bismuthide compound is formed, the thoriumlead compounds forming only in bismuth-leadalloy containing more than about percent by weight of lead, the balance bismuth.
The dispersion process is carried out by heating one part by weight of the thorium sponge together with from 5 to parts by Weight of pieces of bismuth, lead or bismuth-lead alloy. The metals are placed in a suitable container such as a graphite crucible and heated in a furnace provided with means of maintaining an inert atmosphere. At a temperature in the range of 550 to 650 C. the thorium forms thorium bismuthide or thorium-lead compound which spalls off the surface of the sponge until the conversion to intermetallic compound is completed. At temperatures above about 700 C. appreciable quantities of thorium tend to dissolve in the hismuth, lead, or bismuth-lead alloy, and on cooling the resulting thorium low-melting metal alloy very large platelets of thorium compound are precipitated. Dispersion of 10 to 20 gram quantities of thorium sponge in 100 to 200 grams of bismuth, lead, or bismuth-lead alloy is generally completed in about 45 minutes to one hour at 600 C. Larger quantities of sponge and low-melting metal require longer times.
The so-prepared dispersion of thorium intermetallic compound may be used directly as a blanket in a breedertype nuclear reactor. Or if desired, it may first be further diluted with additional bismuth, lead, or bismuth-lead to accommodate a given reactor design.
Example As an example of the process of the invention a magnesium-thorium alloy was prepared by melting together thorium and magnesium under an inert atmosphere and decanting the alloy from the dross. Forty and five-tenths (40.5) grams of the resulting alloy consisting of about 30 percent by weight of thorium, the balance magnesium, was placed in a molybdenum boat-type sublimer and the sublimer furnace was evacuated to about 0.020 mm. Hg pressure. The furnace was first brought to a temperature of 550 C. and then the temperature was brought, over the space of five hours, to 700 C. The 700 C. temperature was maintained for about seven hours to assure the complete removal of the magnesium as well as the formation of a coherent sponge weighing about 13.5 grams. The thorium sponge was placed in a graphite crucible along with .125 gram of oxide-free, 0.5 inch diameter bismuth rods. The crucible and contents were placed in an evacuable electric furnace. The furnace was purged of air and filled with an inert gas. Then the furnace was brought to and maintained at a temperature of 600 C. for one hour. During the one hour period the bismuththorium mixture was agitated several times. The furnace was then allowed to cool and the contents of the crucible solidified as a casting. The casting was removed from the crucible, sectioned, and examined by the metallographic method. The casting was found to consist of a finely divided dispersion in bismuth of thorium bismuthide particles which exhibited a maximum dimension of about 10 microns. Chemical examination of the casting indicated the concentration of residual magnesium was less than 200 parts per million.
We claim:
1. In the method of preparing a fine particulate dispersion of a thorium intermetallic compound selected from the group consisting of thorium-bismuth and thorium-lead intermetallic compounds, in a low-melting metal selected from the group consisting of bismuth, lead and bismuth-lead alloys, wherein a thorium sponge is prepared and heated in contact with said low-melting metal, the improved method of preparing said thorium sponge which comprises: alloying a magnesium metal selected from the group consisting of magnesium, and magnesium containing up to weight percent of calcium, sodium, zinc and mixtures thereof, with thorium under an inert atmosphere, the amount of magnesium metal in the soprepared thorium alloy being about 50 to 90 percent by weight of the alloy; and under a pressure of less than about 0.1 mm. of Hg, heating said alloy initially to a temperature of about 550 C. and thereafter gradually to a temperature in the range of 650 to 900 (3., thereby to volatilize said magnesium metal from the alloy and leave a thorium sponge.
2. In the method of preparing a fine particulate dispersion of a thorium intermetallic compound selected from the group consisting of thorium-bismuth and tho rium-lead intermetallic compounds, in a low-melting metal selected from the group consisting of bismuth, lead and bismuth-lead alloys, wherein a thorium sponge is prepared and heated in contact with said low melting metal, the improved method of preparing said thorium sponge which comprises: providing an alloy consisting of thorium and a magnesium metal selected from the group consisting of magnesium, and magnesium alloyed with up to 5 weight percent of calcium, sodium, zinc, and mixtures thereof, the proportion of said magnesium metal in the alloy being about 50 to 90 percent by weight of the alloy, the balance thorium; and under a pressure of less than about 0.1 mm. of Hg, heating said alloy initially to a temperature of about 550 C. and gradually to a temperature in the range of 650 to 900 C., thereby to volatilize the magnesium metal from the alloy and leave a thorium sponge. I
3. The method of preparing a fine particulate dispersion of a thorium intermetallic compound selected from the group consisting of thorium-bismuth and thoriumlead intermetallic compounds, in a low-melting metal selected from the group consisting of bismuth, lead and bismuth-lead alloys, which comprises: alloying a magnesium metal selected from the group consisting of magnesium, and magnesium alloyed withup to 5 weight percent of calcium, sodium, zinc, and mixtures thereof, with thorium under an inert atmosphere, the amount of said magnesium metal in the so-prepared alloy being about 50 to percent by weight of the alloy, the balance thorium; heating said alloy under a pressure of less than about 0.1 mm. of Hg, initially to a temperature of about 550 C. and gradually to a temperature in the range of 650 to 900 C., thereby to volatilize said magnesium metal from the alloy and leave -a thorium sponge having an average cellular wall thickness of less than about 0.05 inch; contacting said thorium sponge with from 5 to parts by weight of said low-melting metal per part of thorium at a temperature above the melting point of the low-melting metal and below about 700 C. for a time sufficient for the thorium sponge to form an intermetallic compound of thorium and said low melting metal, thereby to precipitate said intermetallic compound in the form of solid particles having a maximum dimension of about 1 millimeter.
4. The method of preparing a fine particulate dispersion of thorium bismuthide in a low-melting metal selected from the group consisting of bismuth, and bismuthlead alloy containing up to 90 weight percent lead, the balance bismuth, which comprises: contacting a thorium sponge-like mass having an average cellular wall thickness of less than about 0.05 inch withfrom 5 to 100 parts by weight of said low-melting metal per part of thorium sponge-like mass under an inert atmosphere, at a temperature above the melting point of the low-meling metal and below about 700 C. for a time suflicient for said thorium sponge-like mass to form the intermetallic compound thorium bismuthide, thereby to precipitate said intermetallic compound in the low melting metal in the form of solid particles having a maximum dimension of about 1 millimeter.
References Cited in the file of this patent UNITED STATES PATENTS 2,434,775 Sosnick J an. 20, 1948 2,910,417 Teitel Oct. 27, 1959 2,915,445 Bryner Dec. 1, 1959 2,952,508 Bryner et al. Sept. 20, 1960
Claims (1)
1. IN THE METHOD OF PREPARING A FINE PARTICULATE DISPERSION OF A THORIUM INTERMETALLIC COMPOUND SELECTED FROM THE GROUP CONSISTING OF THORIUM-BISMUTH AND THORIUM-LEAD INTERMETALLIC COMPOUNDS, IN A LOW-MELTING METAL SELECTED FROM THE GROUP CONSISTING OF BISMUTH, LEAD AND BISMUTH-LEAD ALLOYS, WHEREIN A THORIUM SPONGE IS PREPARED AND HEATED IN CONTACT WITH SAID LOW-MELTING METAL, THE IMPROVED METHOD OF PREPARING SAID THORIUM SPONGE WHICH COMPRISES: ALLOYING A MAGNESIUM METAL SELECTED FROM THE GROUP CONSISTING OF MAGNESIUM, AND MAGNESIUM CONTAINING UP TO 5 WEIGHT PERCENT OF CALCIUM, SODIUM, ZINC AND MIXTURES THEREOF, WITH THORIUM UNDER AN INERT ATMOSPHERE, THE AMOUNT OF MAGNESIUM METAL IN THE SOPREPARED THORIUM ALLOY BEING ABOUT 50 TO 90 PERCENT BY WEIGHT OF THE ALLOY; AND UNDER A PRESSURE OF LESS THAN ABOUT 0.1 MM. OF HG, HEATING SAID ALLOY INITIALLY TO A TEMPERATURE OF ABOUT 550*C. AND THEREAFTER GRADUALLY TO A TEMPERATURE IN THE RANGE OF 650 TO 900*C., THEREBY TO VOLATILIZE SAID MAGNESIUM METAL FROM THE ALLOY AND LEAVE A THORIUM SPONGE.
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US50095A US3069256A (en) | 1960-08-17 | 1960-08-17 | Preparation of thorium intermetallic compound dispersion |
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US50095A US3069256A (en) | 1960-08-17 | 1960-08-17 | Preparation of thorium intermetallic compound dispersion |
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Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3251745A (en) * | 1961-12-11 | 1966-05-17 | Dow Chemical Co | Nuclear reactor and integrated fuelblanket system therefor |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2434775A (en) * | 1943-05-08 | 1948-01-20 | Sosnick Benjamin | Process for making foamlike mass of metal |
US2910417A (en) * | 1955-05-27 | 1959-10-27 | Robert J Teitel | Uranium bismuthide dispersion in molten metal |
US2915445A (en) * | 1955-06-22 | 1959-12-01 | Bryner Joseph Sanson | Formation of intermetallic compound dispersions |
US2952508A (en) * | 1953-09-16 | 1960-09-13 | Rayonier Inc | Viscose process and products produced thereby |
-
1960
- 1960-08-17 US US50095A patent/US3069256A/en not_active Expired - Lifetime
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2434775A (en) * | 1943-05-08 | 1948-01-20 | Sosnick Benjamin | Process for making foamlike mass of metal |
US2952508A (en) * | 1953-09-16 | 1960-09-13 | Rayonier Inc | Viscose process and products produced thereby |
US2910417A (en) * | 1955-05-27 | 1959-10-27 | Robert J Teitel | Uranium bismuthide dispersion in molten metal |
US2915445A (en) * | 1955-06-22 | 1959-12-01 | Bryner Joseph Sanson | Formation of intermetallic compound dispersions |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3251745A (en) * | 1961-12-11 | 1966-05-17 | Dow Chemical Co | Nuclear reactor and integrated fuelblanket system therefor |
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