CA1069868A - Hydration-disintegration of alloy containing material produced by a reduction-diffusion process - Google Patents
Hydration-disintegration of alloy containing material produced by a reduction-diffusion processInfo
- Publication number
- CA1069868A CA1069868A CA217,522A CA217522A CA1069868A CA 1069868 A CA1069868 A CA 1069868A CA 217522 A CA217522 A CA 217522A CA 1069868 A CA1069868 A CA 1069868A
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- Prior art keywords
- calcium
- cake
- water vapor
- gas
- hydration
- 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.)
- Expired
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Classifications
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
- H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
- H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
- H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
- H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
- H01F1/06—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys in the form of particles, e.g. powder
- H01F1/065—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys in the form of particles, e.g. powder obtained by a reduction
-
- 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
- B22F9/16—Making metallic powder or suspensions thereof using chemical processes
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Manufacture Of Metal Powder And Suspensions Thereof (AREA)
- Hard Magnetic Materials (AREA)
Abstract
HYDRATION-DISINTEGRATION OF ALLOY
CONTAINING MATERIAL PRODUCED BY
A REDUCTION-DIFFUSION PROCESS
Abstract of the Disclosure A self-regulating process for disintegrating reaction product cake to recover rare earth alloy particles contained therein. A support screen is selected having holes through which material of desired size will pass and placed within a hydration zone. The cake is placed on the screen and a water vapor-carrying gas is passed through the zone to react with calcium and/or calcium compounds in the cake to produce calcium hydroxide. The resulting volume expansion disintegrates the cake which, upon disintegrating to the desired size, falls through the holes in the screen away from substantial contact with the incoming water vapor-carrying gas.
CONTAINING MATERIAL PRODUCED BY
A REDUCTION-DIFFUSION PROCESS
Abstract of the Disclosure A self-regulating process for disintegrating reaction product cake to recover rare earth alloy particles contained therein. A support screen is selected having holes through which material of desired size will pass and placed within a hydration zone. The cake is placed on the screen and a water vapor-carrying gas is passed through the zone to react with calcium and/or calcium compounds in the cake to produce calcium hydroxide. The resulting volume expansion disintegrates the cake which, upon disintegrating to the desired size, falls through the holes in the screen away from substantial contact with the incoming water vapor-carrying gas.
Description
, HYDR~TION--DISI~lTEt3RATION OF ALLOY ~ -CONTA~ G M~TERIAL PRODUCED BY
'' `, '.
' ~
The pre~ent invention relates to the treatment of an alloy containing material useful in ths production of magnet3 produced by a reduction-dlffusion proces~ and particularly to the hydration-disintegration of such material without signiicantly deteriorating the potential magnetic properties of the rare earth alloy particle~
contained therein.
U~S~ Patent 3,748,193 - Cech - issued ~uly 24, 1973, which is assigned to th~ a~ignee hereo~, relates to a ~::
reduction-dif~u~ion proces~ or producing rare earth inter-metallic compounds or alloy~. Briefly stated, one embodiment of the di~closed proce~s comprise~ providing a particulate mixture of a rare earth metal oxide~ calc:ium hydride and a metal ~uch a~ cobalt or iron, or alloy~ or mixtures therao~ which can alGo include mangane~e, heating the particulate mixture in a non-reactive atmosphere to ~ ~-decompo~e the calcium hydride and thexeby e~fect redue~tion of the rar~ earth metal con~tituent, th~n heating the resulting mixture in a non-reactive a~mosphere to difu~e the re~ultin~ rare earth metal into the a~orementioned me~al : particlss to ~orm the ~e~ired rare earth intermetallic alloy particle~ which are then recovered ~rom the product~
~' .
98~;~
It is actually calcium resulting from the decomposition of the calcium hydride which acts to reduce the rare earth oxide to form the rare earth metal. If desired, the calcium hydride can be formed in situ by a number of methods. One particular advantage of the use of calcium hydride is that calcium does not alloy in any signi-ficant amount wi-th the cobalt-rare earth alloy or other magnetic rare earth alloys formed herein.
The oxide of the rare earth metals useful in the disclosed patented process are those of the rare earth -metals which are the 15 elements of the lanthanide series having atomic numbers 57 to 71 inclusive. The element ; yttrium (atomic number 39) is commonly found with and included in this group of metals and, in this disclosure, is considered a rare earth metal. Mixtures of rare earth metal oxides can also be used. Representative of the oxides useful in the present invention are samarium oxide (Sm203), yttrium oxide (Y203) and mischmetal oxides (M203), ~ mischmetal being the most common alloy of the rare earth 20 metals which contains the metals in the approximate ratio in which they occur in their most common naturally ;~ occurring ores.
A number of rare earth intermetallic alloys can be formed merely by using the proper amounts of the active constituents. The following equation represents the :: ' ' . .
~C~69~
stoichiometric reaction for forming Co5R, where R is a rare earth metal, by the reduction of the rare earth from the oxide to a constituent of the cobalt intermetallic alloy using samarium as an example:
5 Co + 1/2 Sm203+3/Z CaH2 Co5Sm + 3/2 CaO + 3/2 ~l2.
U.S. Patent 3,748,193 discloses that preferably, an amount of calcium hydride in excess of the stoichio- -metric amount necessary to reduce the rare earth metal ~ .
oxide is used so that the excess calcium hydride is con-; 10 verted to metallic calcium which precipitates at the ; boundaries of -the particles of the resulting cobalt-rare earth intermetallic compound, and that the resulting product mass~can then be placed in air or other oxygen and moisture- :
containing atmosphere to allow the precipitated calcium to oxidize whereupon it undergoes a change in volume sufficient to disintegrate the mass and release the particles of the cobalt-rare ear-th intermetallic compound. :
When an excess amount of calcium hydride is used, a reaction product cake is produced wherein particles of i -; 20 rare earth intermetallic alloy, for example, cobalt-rare earth alloy, are substantially or completely surrounded by calcium and/or calcium oxide. Also, depending on the : particular reaction conditions and atmospheres with which -~ the product cake is contacted, calcium hydride and calciumnitride may also be present, usually in minor amounts, at or between the boundaries of the alloy part:Lcles. Placing :
,~
~ -3-~'"
98~;~
such a cake or lumps thereof in a moisture containing atmosphere to hydra-te calcium and its compounds to produce calcium hydroxide and disintegrate the cake by the accompanying volume expansion in a slow process which tends to be partially blocked off by the disintegrating powder and is not practical on a commercial scale. The problem is tha-t the disintegra-tion does no-t proceed at the same rate uniformly throughout the cake but proceeds in stages since not all of the calcium or calcium compounds can be contacted with the moisture containing atmosphere at the same time. Specifically, with each disintegration additional calcium or calcium compound is exposed and only then becomes available for reaction with the moisture.
The disadvantage inherent in -the use of water or an oxidizing atmosphere is that -they react with the alloy particles and cause them to oxidize and lose their potential magnetic properties.
The present invention provides a significantly faster, substantially self-regulating uniform hydration technique for disintegrating the cake or lumps thereof to a desired size for purposes such as storage or to disintegrate it -to completion to free the particles of rare earth alloy contained therein without significant deterioration. The disintegration proceeds between and along the boundaries of the particles and the final ~g~
disintegrated product i~ usu~lly a fr2e-flowing powder comprlsed of calcium hydroxide and particles o the rare earth alloy.
~riefly ~tated, in the pre~ent proces~ the S reaction product cake i8 c~mpri8ed of alloy p~rticle~ :
substantially or completely surrounded by calcium and/or a calcium compound ~elected from the group consi~ting of calcium oxide, calcium hydride and calcium nitride. The alloy particle~ consi~t e~sentially o r~re earth metal and a metal selected from the group con81s~ing o~ cobalt3 iron, : manganese and alloy~ thereof. The proces~ compri~es pro-viding a ~ydra~ion zone having a gas inlet at one end portion and a reacted ga~ outlet at sub~tantLally the -oppo~ite end portion, A support screen i~ selected having : 15 holes through which material o~ a desired siæe or smal7er passes and placed within the hydration zone ~ub~t~ntially between the ga8 inlet and the reacted gas outlet, The reaction product cake 18 placed on the ~upport screen and a water ~apor-carrying gas i8 flowed through the gas inLet through the hydration zone at a rate which at lea~t envelop~ -the reaction product cake reacting with the calcium and/or ` calcium compounds therein to orm ~ubs~anti~Lly calcium ; hydroxide cau8ing ~ ~ignific~nt volume increa8e which disintegrates the cake. The w~ter vapor~carrying 8a~
initially ha8 a temperature rangln~ from ~bou~ 0C ~o abcut 06~ ~ 6 ~
70C and a relative h~m~di~y ranging ~rom about 5% up t~ 100%, The reaction product c~ke ma~erial 1~ sub~tan~ly iner~ to the gas componen~ of the water v~por-carrying gas.
Th~ re~ulting react~d gas p~88e8 through the reacted gas outlet, The disintegr~ted c~ke f~lls through the holes in the ~upport ~creen upon disintc8rating to the desired ~ize or sm~ller to a collec~ion zone associated with ~he hydr~-tion æone and aw~y from subs~ntial contact with the incoming water vapor-carrying gas.
The ~onm of th~ 8upport 8creen oan vary, For ex~mple, it can b2 plan~r ~nd placed horizont811y acros~ a roB9-~ection of the hydration zone, or it can be ver~ical tube closed a~ its lower end po~tion and placed wLthin a hydra~ion zone ~8 8hown. The 8uppor~ 8crean selected has hole8 through which m~t~ri~l of ~ d~ ed ~ize or ~m811er pa~ses. ~hen the cake di8in~egrates to ~he size of the hole3~ ~t pas8e~ through the 8creen ~ub~tantially upon forming or 8hortly thereafter to a collection ~one providQd ~: ~
in as~ociation with the hydr~tion zone beneath:the ~creen ~ -support. Preferably, th~ screen suppor~ i~ vibrated ~o acceler~te p~s~age of the dis~ntegr~ted ma~eri~l through it, Upon p~ing lnto the collection zone, the disintegrated c~ke i9 removed rom e~ec~ive contact with the incoming w~ar vapor-c~r~ing g~, If de~ired, a number of suppor~
scr2an8 c~n be u~ed in the ~m~ hydratlon zone~ one below ~he o~her, with each ~cr~en having hole~ pro~re~sively : ~6-~O~ 6~3 smaller so that the desired disintegra-tion is carried out progressively in a series.
The water vapor-carrying gas consists essentially of water vapor and a gas to which the alloy particles are substantially inert such as nitrogen or argon. Before it is introduced into the hydration zone, the water vapor-carrying gas has a relative humidity ranging from about 5~ to 100% and a temperature ranglng from about 0 C to 70 C, and preferably, it is close to room temperature, i.e.
20C to 30 C. At a relative humidity below 5~ the water vapor-carrying gas produces a hydration reaction too slow to be commercially useful. With increasing relative humidity, the rate of reaction in the hydration zone increases resulting in a faster disintegration of the cake.
At a temperature below 0C, the water vapor-carrying gas cannot provide the minimum necessary relative humidity, and as a practical matter, temperatures higher than 70C
cannot be used since the hydration reaction to form calcium hydroxide is exothermic, and the product may overheat and begin to oxidize. r~
The water vapor-carrying gas can be passed through the hydration zone upwardly, sideways or downwardly to envelop the reaction product cake material therein. The -particular rate at which the water vapor-carrying gas ~o69s68 passes through the hydration zone depends largely on its initial relative humidity and temperature and the rate at which the reaction product cake disintegrates. As the incoming water vapor-carrying gas passes in contact with the reaction product cake, its water vapor component reacts with the calcium or calcium compound of the cake leaving, in most instances, no significan-t amount of :~
water vapor in the resulting reacted gas passing through the outlet. In the present process, water does not condense on -the reaction product cake during disinte-gration since its hydration is exothermic keeping its temperature higher than that o:~ the water vapor with which it is contac-ted. However, once the reaction -;
product cake is completely disintegrated, i.e. there is no more calcium or calcium compound available for hydration, the temperature of the disintegrated mass cools and such final product should be kept from contact ; with water vapor to prevent condensation of water thereon and its accompanying deterioration of potential magnetic properties.
The reaction of calcium or its compounds in the present process is exothermic, and if desired, a cooling jacket may be used to prevent the hydration zone from over-heating. The hydration zone can be equipped with conventional : . , ~: ;
~0698Çi~ .
equipmen-t such as a humidity sensor, pre-~erably at its upper end portion, to determine -the amount of water vapor left in the reacte~ gas. Preferably, it is provided with thermocouples which are equipp~d to maintain -the disinte-grating mass below a certain desirable maximum temperature, for example 50C, by stopping the introduction of the water vapor-carrying gas into the hydration zone, and once the disintegrating mass cools below the set desired maximum temperature, starting up the reaction again by allowing the water vapor-carrying gas to be passed into the hydration zone. `
Those skilled in the art will gain a further and better understanding of the present invention from the detailed description set forth below, considered in con- -junction with the sole figure accompanying and forming a part of the specification which illustrates the present hydration-disintegration process and shows a vertical cross-section taken through a typical apparatus constructed in accordance with the invention.
A run was made using the apparatus shown in the ~igure. A vertical tubular screen 1 made of conventional aluminum window screen 16 mesh in size supported by 1/2 inch hardware cloth which would allow passage therethrough of disintegrated material less than 1 millimeter in size was placed within hydration zone 2 as shown in the ~698~3 accompanying figure. The hydration zone was purged with dry nitrogen gas. A charge 7 consisting of lumps of reaction product cake having an average diameter size of about 1 inch was placed in the support screen 1 through charge port 3. rrhe reaction product cake was comprised of cobalt-samarium alloy particles substantially of the formula Co5Sm surrounded substantially by calcium and calcium oxide. The alloy particles had an average particle size less than 40 microns. The incoming water vapor-carrying gas, which consisted essentially of water vapor and nitrogen and which had a relative humidity of about 98 and ~ temperature of about 25C, was provided through a conventional home humidifier 4 and passed through a squirrel cage blower 5 through gas inlet 6 and flowed upwardly at a rate which substantially enveloped charge 7 causing it to disintegrate at a rate of up to about 7 lbs. per hour.
Humidity sensor 8 was placed at the upper portion of the hydration chamber 2 to determine the water vapor content of the resulting reacted gas which pass through the reacted gas outlet 9 and which was rec~cled back to the humidifier 4. The humidity sensor 8 showed the resulting reacted gas to have less water vapor than the incoming gas. The disin-tegrated powder fell through the support screen 1 into the collection zone 10 and then into transfer cannister 11. The disin-tegrated powder in transfer cannister 11 was free-flowing.
., s Standard chemical analysis o~ this powder showed it to be comprised substa~tially of calcium hydroxide and particle3 of alloy e~ substantially the formula Co5Sm and a minor amount of cal~ium oxide.
S When the di~integration i~ carried out to completion, the fin~l product i~ genarally compri~ed of the rare earth alloy particles a~d salcium hydroxide. For certain of the~e alloys the particle8 are pref~rably ~epaxated from the c~lcium hydroxide magnetically, and 10 A particularly a~ disclosed in U.S. Pat~nt ~0~ 3, ~,o~d issued ~ d~ ~erman, ~t al, and assignad to the assignee her~o~ where a ~eparation technique of th~
par~icles of rare earth alloy u~ing a rotating multi-pole radially magnetized magnet i~ disclo~ed.
. .
'' `, '.
' ~
The pre~ent invention relates to the treatment of an alloy containing material useful in ths production of magnet3 produced by a reduction-dlffusion proces~ and particularly to the hydration-disintegration of such material without signiicantly deteriorating the potential magnetic properties of the rare earth alloy particle~
contained therein.
U~S~ Patent 3,748,193 - Cech - issued ~uly 24, 1973, which is assigned to th~ a~ignee hereo~, relates to a ~::
reduction-dif~u~ion proces~ or producing rare earth inter-metallic compounds or alloy~. Briefly stated, one embodiment of the di~closed proce~s comprise~ providing a particulate mixture of a rare earth metal oxide~ calc:ium hydride and a metal ~uch a~ cobalt or iron, or alloy~ or mixtures therao~ which can alGo include mangane~e, heating the particulate mixture in a non-reactive atmosphere to ~ ~-decompo~e the calcium hydride and thexeby e~fect redue~tion of the rar~ earth metal con~tituent, th~n heating the resulting mixture in a non-reactive a~mosphere to difu~e the re~ultin~ rare earth metal into the a~orementioned me~al : particlss to ~orm the ~e~ired rare earth intermetallic alloy particle~ which are then recovered ~rom the product~
~' .
98~;~
It is actually calcium resulting from the decomposition of the calcium hydride which acts to reduce the rare earth oxide to form the rare earth metal. If desired, the calcium hydride can be formed in situ by a number of methods. One particular advantage of the use of calcium hydride is that calcium does not alloy in any signi-ficant amount wi-th the cobalt-rare earth alloy or other magnetic rare earth alloys formed herein.
The oxide of the rare earth metals useful in the disclosed patented process are those of the rare earth -metals which are the 15 elements of the lanthanide series having atomic numbers 57 to 71 inclusive. The element ; yttrium (atomic number 39) is commonly found with and included in this group of metals and, in this disclosure, is considered a rare earth metal. Mixtures of rare earth metal oxides can also be used. Representative of the oxides useful in the present invention are samarium oxide (Sm203), yttrium oxide (Y203) and mischmetal oxides (M203), ~ mischmetal being the most common alloy of the rare earth 20 metals which contains the metals in the approximate ratio in which they occur in their most common naturally ;~ occurring ores.
A number of rare earth intermetallic alloys can be formed merely by using the proper amounts of the active constituents. The following equation represents the :: ' ' . .
~C~69~
stoichiometric reaction for forming Co5R, where R is a rare earth metal, by the reduction of the rare earth from the oxide to a constituent of the cobalt intermetallic alloy using samarium as an example:
5 Co + 1/2 Sm203+3/Z CaH2 Co5Sm + 3/2 CaO + 3/2 ~l2.
U.S. Patent 3,748,193 discloses that preferably, an amount of calcium hydride in excess of the stoichio- -metric amount necessary to reduce the rare earth metal ~ .
oxide is used so that the excess calcium hydride is con-; 10 verted to metallic calcium which precipitates at the ; boundaries of -the particles of the resulting cobalt-rare earth intermetallic compound, and that the resulting product mass~can then be placed in air or other oxygen and moisture- :
containing atmosphere to allow the precipitated calcium to oxidize whereupon it undergoes a change in volume sufficient to disintegrate the mass and release the particles of the cobalt-rare ear-th intermetallic compound. :
When an excess amount of calcium hydride is used, a reaction product cake is produced wherein particles of i -; 20 rare earth intermetallic alloy, for example, cobalt-rare earth alloy, are substantially or completely surrounded by calcium and/or calcium oxide. Also, depending on the : particular reaction conditions and atmospheres with which -~ the product cake is contacted, calcium hydride and calciumnitride may also be present, usually in minor amounts, at or between the boundaries of the alloy part:Lcles. Placing :
,~
~ -3-~'"
98~;~
such a cake or lumps thereof in a moisture containing atmosphere to hydra-te calcium and its compounds to produce calcium hydroxide and disintegrate the cake by the accompanying volume expansion in a slow process which tends to be partially blocked off by the disintegrating powder and is not practical on a commercial scale. The problem is tha-t the disintegra-tion does no-t proceed at the same rate uniformly throughout the cake but proceeds in stages since not all of the calcium or calcium compounds can be contacted with the moisture containing atmosphere at the same time. Specifically, with each disintegration additional calcium or calcium compound is exposed and only then becomes available for reaction with the moisture.
The disadvantage inherent in -the use of water or an oxidizing atmosphere is that -they react with the alloy particles and cause them to oxidize and lose their potential magnetic properties.
The present invention provides a significantly faster, substantially self-regulating uniform hydration technique for disintegrating the cake or lumps thereof to a desired size for purposes such as storage or to disintegrate it -to completion to free the particles of rare earth alloy contained therein without significant deterioration. The disintegration proceeds between and along the boundaries of the particles and the final ~g~
disintegrated product i~ usu~lly a fr2e-flowing powder comprlsed of calcium hydroxide and particles o the rare earth alloy.
~riefly ~tated, in the pre~ent proces~ the S reaction product cake i8 c~mpri8ed of alloy p~rticle~ :
substantially or completely surrounded by calcium and/or a calcium compound ~elected from the group consi~ting of calcium oxide, calcium hydride and calcium nitride. The alloy particle~ consi~t e~sentially o r~re earth metal and a metal selected from the group con81s~ing o~ cobalt3 iron, : manganese and alloy~ thereof. The proces~ compri~es pro-viding a ~ydra~ion zone having a gas inlet at one end portion and a reacted ga~ outlet at sub~tantLally the -oppo~ite end portion, A support screen i~ selected having : 15 holes through which material o~ a desired siæe or smal7er passes and placed within the hydration zone ~ub~t~ntially between the ga8 inlet and the reacted gas outlet, The reaction product cake 18 placed on the ~upport screen and a water ~apor-carrying gas i8 flowed through the gas inLet through the hydration zone at a rate which at lea~t envelop~ -the reaction product cake reacting with the calcium and/or ` calcium compounds therein to orm ~ubs~anti~Lly calcium ; hydroxide cau8ing ~ ~ignific~nt volume increa8e which disintegrates the cake. The w~ter vapor~carrying 8a~
initially ha8 a temperature rangln~ from ~bou~ 0C ~o abcut 06~ ~ 6 ~
70C and a relative h~m~di~y ranging ~rom about 5% up t~ 100%, The reaction product c~ke ma~erial 1~ sub~tan~ly iner~ to the gas componen~ of the water v~por-carrying gas.
Th~ re~ulting react~d gas p~88e8 through the reacted gas outlet, The disintegr~ted c~ke f~lls through the holes in the ~upport ~creen upon disintc8rating to the desired ~ize or sm~ller to a collec~ion zone associated with ~he hydr~-tion æone and aw~y from subs~ntial contact with the incoming water vapor-carrying gas.
The ~onm of th~ 8upport 8creen oan vary, For ex~mple, it can b2 plan~r ~nd placed horizont811y acros~ a roB9-~ection of the hydration zone, or it can be ver~ical tube closed a~ its lower end po~tion and placed wLthin a hydra~ion zone ~8 8hown. The 8uppor~ 8crean selected has hole8 through which m~t~ri~l of ~ d~ ed ~ize or ~m811er pa~ses. ~hen the cake di8in~egrates to ~he size of the hole3~ ~t pas8e~ through the 8creen ~ub~tantially upon forming or 8hortly thereafter to a collection ~one providQd ~: ~
in as~ociation with the hydr~tion zone beneath:the ~creen ~ -support. Preferably, th~ screen suppor~ i~ vibrated ~o acceler~te p~s~age of the dis~ntegr~ted ma~eri~l through it, Upon p~ing lnto the collection zone, the disintegrated c~ke i9 removed rom e~ec~ive contact with the incoming w~ar vapor-c~r~ing g~, If de~ired, a number of suppor~
scr2an8 c~n be u~ed in the ~m~ hydratlon zone~ one below ~he o~her, with each ~cr~en having hole~ pro~re~sively : ~6-~O~ 6~3 smaller so that the desired disintegra-tion is carried out progressively in a series.
The water vapor-carrying gas consists essentially of water vapor and a gas to which the alloy particles are substantially inert such as nitrogen or argon. Before it is introduced into the hydration zone, the water vapor-carrying gas has a relative humidity ranging from about 5~ to 100% and a temperature ranglng from about 0 C to 70 C, and preferably, it is close to room temperature, i.e.
20C to 30 C. At a relative humidity below 5~ the water vapor-carrying gas produces a hydration reaction too slow to be commercially useful. With increasing relative humidity, the rate of reaction in the hydration zone increases resulting in a faster disintegration of the cake.
At a temperature below 0C, the water vapor-carrying gas cannot provide the minimum necessary relative humidity, and as a practical matter, temperatures higher than 70C
cannot be used since the hydration reaction to form calcium hydroxide is exothermic, and the product may overheat and begin to oxidize. r~
The water vapor-carrying gas can be passed through the hydration zone upwardly, sideways or downwardly to envelop the reaction product cake material therein. The -particular rate at which the water vapor-carrying gas ~o69s68 passes through the hydration zone depends largely on its initial relative humidity and temperature and the rate at which the reaction product cake disintegrates. As the incoming water vapor-carrying gas passes in contact with the reaction product cake, its water vapor component reacts with the calcium or calcium compound of the cake leaving, in most instances, no significan-t amount of :~
water vapor in the resulting reacted gas passing through the outlet. In the present process, water does not condense on -the reaction product cake during disinte-gration since its hydration is exothermic keeping its temperature higher than that o:~ the water vapor with which it is contac-ted. However, once the reaction -;
product cake is completely disintegrated, i.e. there is no more calcium or calcium compound available for hydration, the temperature of the disintegrated mass cools and such final product should be kept from contact ; with water vapor to prevent condensation of water thereon and its accompanying deterioration of potential magnetic properties.
The reaction of calcium or its compounds in the present process is exothermic, and if desired, a cooling jacket may be used to prevent the hydration zone from over-heating. The hydration zone can be equipped with conventional : . , ~: ;
~0698Çi~ .
equipmen-t such as a humidity sensor, pre-~erably at its upper end portion, to determine -the amount of water vapor left in the reacte~ gas. Preferably, it is provided with thermocouples which are equipp~d to maintain -the disinte-grating mass below a certain desirable maximum temperature, for example 50C, by stopping the introduction of the water vapor-carrying gas into the hydration zone, and once the disintegrating mass cools below the set desired maximum temperature, starting up the reaction again by allowing the water vapor-carrying gas to be passed into the hydration zone. `
Those skilled in the art will gain a further and better understanding of the present invention from the detailed description set forth below, considered in con- -junction with the sole figure accompanying and forming a part of the specification which illustrates the present hydration-disintegration process and shows a vertical cross-section taken through a typical apparatus constructed in accordance with the invention.
A run was made using the apparatus shown in the ~igure. A vertical tubular screen 1 made of conventional aluminum window screen 16 mesh in size supported by 1/2 inch hardware cloth which would allow passage therethrough of disintegrated material less than 1 millimeter in size was placed within hydration zone 2 as shown in the ~698~3 accompanying figure. The hydration zone was purged with dry nitrogen gas. A charge 7 consisting of lumps of reaction product cake having an average diameter size of about 1 inch was placed in the support screen 1 through charge port 3. rrhe reaction product cake was comprised of cobalt-samarium alloy particles substantially of the formula Co5Sm surrounded substantially by calcium and calcium oxide. The alloy particles had an average particle size less than 40 microns. The incoming water vapor-carrying gas, which consisted essentially of water vapor and nitrogen and which had a relative humidity of about 98 and ~ temperature of about 25C, was provided through a conventional home humidifier 4 and passed through a squirrel cage blower 5 through gas inlet 6 and flowed upwardly at a rate which substantially enveloped charge 7 causing it to disintegrate at a rate of up to about 7 lbs. per hour.
Humidity sensor 8 was placed at the upper portion of the hydration chamber 2 to determine the water vapor content of the resulting reacted gas which pass through the reacted gas outlet 9 and which was rec~cled back to the humidifier 4. The humidity sensor 8 showed the resulting reacted gas to have less water vapor than the incoming gas. The disin-tegrated powder fell through the support screen 1 into the collection zone 10 and then into transfer cannister 11. The disin-tegrated powder in transfer cannister 11 was free-flowing.
., s Standard chemical analysis o~ this powder showed it to be comprised substa~tially of calcium hydroxide and particle3 of alloy e~ substantially the formula Co5Sm and a minor amount of cal~ium oxide.
S When the di~integration i~ carried out to completion, the fin~l product i~ genarally compri~ed of the rare earth alloy particles a~d salcium hydroxide. For certain of the~e alloys the particle8 are pref~rably ~epaxated from the c~lcium hydroxide magnetically, and 10 A particularly a~ disclosed in U.S. Pat~nt ~0~ 3, ~,o~d issued ~ d~ ~erman, ~t al, and assignad to the assignee her~o~ where a ~eparation technique of th~
par~icles of rare earth alloy u~ing a rotating multi-pole radially magnetized magnet i~ disclo~ed.
. .
Claims (4)
1. A substantially self-regulating process for hydrating and disintegrating a reaction product cake comprised of alloy particles substantially or completely surrounded by calcium and/or a calcium compound elected from the group consisting of calcium oxide, calcium hydride, and calcium nitride, said alloy particles consisting essentially of rare earth metal and a metal selected from the group consisting of cobalt, iron, manganese and alloys thereof, which comprises providing a hydration zone having a gas inlet at one end portion and a reacted gas outlet at substantially the opposite end portion, providing a collection zone in association with salt hydration zone, selecting a support screen having holes through which material of a desired size or smaller passes, placing said support screen within said hydration zone substantially between said gas inlet and said reacted gas outlet, placing said reaction product cake on said support screen, passing an incoming water vapor-carrying gas through said gas inlet at a rate which at least envelops said reaction product cake reacting with said calcium or said calcium compound therein to form substantially calcium hydroxide causing a significant volume increase which disintegrates said reaction product cake, said incoming water vapor-carrying gas initially having a temperature ranging from about 0°C to about 70°C and a relative humidity ranging from about 5% to 100%, said reaction produce cake being substantially inert to the gas component of said water vapor-carrying gas, passing the resulting reacted gas through said reacted gas outlet, said disintegrated cake falling through said holes in said support screen substantially upon disintegrating to said desired size or smaller to said collection zone away from substantial contact with said incoming water vapor-carrying gas.
2. A process according to claim 1 wherein said incoming water vapor-carrying gas is at room temperature.
3. A process according to claim 1 wherein said support screen is vibrated.
4. A process according to claim 1 wherein said reaction product cake is disintegrated to produce a free-flowing powder comprised substantially of calcium hydroxide and said alloy particles.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US475900A US3877999A (en) | 1974-06-03 | 1974-06-03 | Hydration-disintegration of cobalt-rare earth alloy containing material |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1069868A true CA1069868A (en) | 1980-01-15 |
Family
ID=23889635
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA217,522A Expired CA1069868A (en) | 1974-06-03 | 1975-01-07 | Hydration-disintegration of alloy containing material produced by a reduction-diffusion process |
Country Status (2)
| Country | Link |
|---|---|
| US (1) | US3877999A (en) |
| CA (1) | CA1069868A (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0434669B1 (en) * | 1984-09-29 | 1994-08-10 | Kabushiki Kaisha Toshiba | Method of making a coated magnetic powder and a compressed magnetic powder core |
| US4767450A (en) * | 1984-11-27 | 1988-08-30 | Sumitomo Special Metals Co., Ltd. | Process for producing the rare earth alloy powders |
| US4769063A (en) * | 1986-03-06 | 1988-09-06 | Sumitomo Special Metals Co., Ltd. | Method for producing rare earth alloy |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2633987A (en) * | 1948-12-27 | 1953-04-07 | American Cyanamid Co | Viscosity control in heavy media separation |
| US2683685A (en) * | 1951-07-28 | 1954-07-13 | Standard Oil Dev Co | Elutriation of finely divided solids |
| US3625779A (en) * | 1969-08-21 | 1971-12-07 | Gen Electric | Reduction-fusion process for the production of rare earth intermetallic compounds |
| GB1225887A (en) * | 1969-11-19 | 1971-03-24 | ||
| US3748193A (en) * | 1971-08-16 | 1973-07-24 | Gen Electric | Rare earth intermetallic compounds by a calcium hydride reduction diffusion process |
-
1974
- 1974-06-03 US US475900A patent/US3877999A/en not_active Expired - Lifetime
-
1975
- 1975-01-07 CA CA217,522A patent/CA1069868A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| US3877999A (en) | 1975-04-15 |
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