US3702761A - Carbonyl nickel powder and production thereof - Google Patents
Carbonyl nickel powder and production thereof Download PDFInfo
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- US3702761A US3702761A US159258A US3702761DA US3702761A US 3702761 A US3702761 A US 3702761A US 159258 A US159258 A US 159258A US 3702761D A US3702761D A US 3702761DA US 3702761 A US3702761 A US 3702761A
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- carbonyl
- nickel
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- nitric oxide
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- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 title abstract description 91
- 238000004519 manufacturing process Methods 0.000 title description 11
- MWUXSHHQAYIFBG-UHFFFAOYSA-N Nitric oxide Chemical compound O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 abstract description 92
- 229910052759 nickel Inorganic materials 0.000 abstract description 50
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 abstract description 25
- 229910052799 carbon Inorganic materials 0.000 abstract description 25
- LZDSILRDTDCIQT-UHFFFAOYSA-N dinitrogen trioxide Chemical compound [O-][N+](=O)N=O LZDSILRDTDCIQT-UHFFFAOYSA-N 0.000 abstract description 8
- OMBRFUXPXNIUCZ-UHFFFAOYSA-N dioxidonitrogen(1+) Chemical compound O=[N+]=O OMBRFUXPXNIUCZ-UHFFFAOYSA-N 0.000 abstract description 8
- 239000008188 pellet Substances 0.000 abstract description 4
- 239000012798 spherical particle Substances 0.000 abstract description 4
- -1 NICKEL CARBONYL Chemical class 0.000 abstract 1
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 38
- 239000000843 powder Substances 0.000 description 37
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 30
- 239000007789 gas Substances 0.000 description 21
- 229910052757 nitrogen Inorganic materials 0.000 description 19
- 238000000034 method Methods 0.000 description 18
- 230000008569 process Effects 0.000 description 18
- 125000002915 carbonyl group Chemical group [*:2]C([*:1])=O 0.000 description 16
- 229910021529 ammonia Inorganic materials 0.000 description 15
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 11
- 239000001301 oxygen Substances 0.000 description 11
- 229910052760 oxygen Inorganic materials 0.000 description 11
- 239000002245 particle Substances 0.000 description 11
- 238000000354 decomposition reaction Methods 0.000 description 7
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 5
- 229910002091 carbon monoxide Inorganic materials 0.000 description 5
- 238000005979 thermal decomposition reaction Methods 0.000 description 4
- 230000008901 benefit Effects 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 229910001209 Low-carbon steel Inorganic materials 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 2
- 238000007792 addition Methods 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 230000007246 mechanism Effects 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000005121 nitriding Methods 0.000 description 2
- 238000001878 scanning electron micrograph Methods 0.000 description 2
- 239000010959 steel Substances 0.000 description 2
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000007323 disproportionation reaction Methods 0.000 description 1
- 239000008246 gaseous mixture Substances 0.000 description 1
- 238000010348 incorporation Methods 0.000 description 1
- 230000001788 irregular Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 239000008247 solid mixture Substances 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Images
Classifications
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- 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
- C22B23/00—Obtaining nickel or cobalt
- C22B23/06—Refining
- C22B23/065—Refining carbonyl methods
-
- 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
- B22F9/30—Making metallic powder or suspensions thereof using chemical processes with decomposition of metal compounds, e.g. by pyrolysis
- B22F9/305—Making metallic powder or suspensions thereof using chemical processes with decomposition of metal compounds, e.g. by pyrolysis of metal carbonyls
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B15/00—Other processes for the manufacture of iron from iron compounds
- C21B15/04—Other processes for the manufacture of iron from iron compounds from iron carbonyl
-
- 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
- C22B5/00—General methods of reducing to metals
- C22B5/02—Dry methods smelting of sulfides or formation of mattes
- C22B5/20—Dry methods smelting of sulfides or formation of mattes from metal carbonyls
-
- 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
- Y10S75/00—Specialized metallurgical processes, compositions for use therein, consolidated metal powder compositions, and loose metal particulate mixtures
- Y10S75/953—Producing spheres
Definitions
- Nickel carbonyl is thermally decomposed to nickel powder or pellets in the presence of nitric oxide, nitrogen trioxide or nitrogen peroxide in concentrations of 1-5000 ppm. or more.
- gas concentrations and temperatures in the range 230-35 0 C. the powder can be produced with substantially spherical particles or with low carbon content or both.
- the present invention relates to the production of metallic nickel and more particularly to the production of metallic nickel by the thermal decomposition of nickel carbonyl.
- Nickel carbonyl has been decomposed in various ways. For example, nickel carbonyl is passed over nickel pellets heated above the decomposition temperature of the carbonyl to deposit nickel on the surface of the pellets so that they increase in size. Nickel carbonyl has also been decomposed in the hot free space of a decomposer to produce nickel powder having variously shaped particles according to the temperatures employed. Nickel carbonyl has also been decomposed on the surface of hot powder particles, which can be nickel or other materials, that are to be coated with nickel, in the form of a fiudized bed or a suspension of powder in the stream of carbonylcontaining gas.
- 3,367,768 discloses a process for decomposing nickel carbonyl to spherical nickel powders by decomposing nickel carbonyl in the presence of controlled amounts of ammonia and oxygen to incorporate at least about 0.01% nitrogen in the powder to insure that the powder assumes a spherical shape.
- nickel carbonyl can be decomposed to metallic nickel having low carbon contents at increased rates by adding special oxides of nitrogen to the decomposer. If added in sufficient quantities the special oxides of nitrogen are also effective in producing spherical nickel powder.
- Another object of the present invention is to thermally decompose nickel carbonyl to produce a metallic nickel product that contains minimum amounts of carbon.
- the invention also contemplates providing a process for thermally decomposing nickel carbonyl to produce spherical nickel powder.
- An even further object of the present invention is to provide spherical carbonyl nickel powder having smooth surfaces.
- FIGS. 1 to 4 are representations of photomicrographs of carbonyl nickel powder having increasing nitrogen contents from FIG. 1 to FIG. 4 taken by transmitted light at a magnification of 1,000 times.
- FIG. 5 is a scanning electron micrograph of prior art spherical carbonyl nickel powder at a magnification of 10,000 times
- FIG. 6 is a scanning electron micrograph of spherical carbonyl nickel powder in accordance with the present invention at a magnification of 10,000 times.
- the present invention contemplates a process for thermally decomposing nickel carbonyl.
- a nickel carbonyl decomposing zone is established and is heated to a temperature high enough to decompose nickel carbonyl but below the temperature at which carbon formation will occur during the decomposition of nickel carbonyl.
- At least one nitrogen oxide selected from the group consisting of nitric oxide, nitrogen trioxide and nitrogen peroxide in small but effective amounts to increase the rate of nickel carbonyl decomposition and nickel carbonyl-containing gas are fed to the decomposing zone to decompose the nickel carbonyl to metallic nickel.
- the present invention is based on the discovery that the rate of thermal decomposition of nickel carbonyl under otherwise similar conditions of temperature and carbonyl concentration is increased by the presence of at least one nitrogen oxide selected from the group consisting of nitric oxide (NO), nitrogen trioxide (N 0 or nitrogen peroxide (N02), and according to the present invention nickel is produced by the thermal decomposition of nickel carbonyl in the presence of one of these gases.
- nitrogen oxide selected from the group consisting of nitric oxide (NO), nitrogen trioxide (N 0 or nitrogen peroxide (N02)
- the amount of the oxides of nitrogen employed can vary widely, and these gases have been found to be effective in concentrations ranging from 1 to 1,000 parts per million of the carbonyl-containing gases. Even higher concentrations can be used, but the presence of the oxide of nitrogen during the decomposition introduces nitrogen into the nickel produced, and as the concentration increases so does the nitrogen content of the product. Very high concentrations, e.g. up to 2,000 or 3,000 or even 5,000 p.p.m., can therefore only be employed when relatively high nitrogen contents in spherical powders can be tolerated.
- nitrogen oxides will now be described in more detail in relation to the production of carbonyl nickel powder, that is to say powder made by the thermal decomposition of nickel carbonyl vapour in the hot free space of a decomposer.
- nitric oxide nitrogen peroxide or nitrogen trioxide is used in place of ammonia or ammonia and oxygen as described in US. Pat. No. 3,367,767, it is found that powder consisting of discrete particles can be produced at an increased rate in a vessel of given size.
- the optimum conditions vary with the properties required in the powder, but broadly for the production of powder of given properties the temperature (and therefore the rate) of decomposition can be higher than when ammonia and oxygen are added, and, moreover, the concentration of oxide of nitrogen required is less than that of ammonia.
- nitric oxide which is more effective than the other two oxides.
- greater amounts of nitrogen trioxide or nitrogen peroxide are required than when nitric oxide is employed.
- the production of powder can be carried on in the temperature range of 230 to 350 C. Below 230 C. so small a proportion of the carbonyl is decomposed to powder that the process is not practicable on an industrial scale. Above 350 C. a high proportion of filamentary aggregates are formed. A very suitable temperature is 290 C.
- the amount of oxide of nitrogen required varies with the temperature, decreasing as the temperature decreases.
- some reduction in the carbon content is obtained with very small amounts of nitric oxide, that is to say, as little as 1 part per million, particularly if the vessel walls have previously been nitrided and the process is operated continuously.
- the walls of the reactor can be initially nitrided by introducing ammonia into the reactor and heating the reactor to nitriding temperatures, e.g., 500 C., for at least one hour, e.g., 3 hours.
- -It is found that as the concentration of nitric oxide increases, the carbon content falls and then rises again.
- the nickel carbonyl is introduced into the decomposer, as a gas mixture of carbon monoxides containing 8% nickel carbonyl, and at this concentration and at 290 C.
- the concentration of nitric oxide should be from 50 p.p.m. to 2.00 p.p.m. Above 250 p.p.m. the carbon content of the powder can actually be higher than if no nitric oxide is added.
- the nitric oxide should be from about 0.06% to about 0.25% of the carbonyl, whatever the concentration of the carbonyl.
- the nitrogen oxide concentration in the gaseous mixture is correspondingly lowered, being from 25 to 1 p.p.m., i.e. 0.03% to 0.12%, at 230 C., and at higher temperatures it is correspondingly increased, being from 100 to 300 p.p.m., i.e. 0.12% to 0.4% at 320 C.
- the concentration of nitric oxide at 290 C. should be at least 0.09% of that of the carbonyl. If the temperature is lower, this minimum can be correspondingly reduced, but at 230 C. should be at least 0.012%. Likewise at higher temperatures the minimum concentration of nitric oxide must be higher, being at least 0.2% at 320 C.
- the concentration of nitric oxide can be considerably higher, but so far as the production of spherical powder is concerned there is no advantage in exceeding 1.25% or even 0.625% of the carbonyl concentration.
- FIG. 1-spiky FIG. 2-angular, the spikes becoming rounded FIG. 3nearly spherical FIG. 4--spherical Spherical powder made by the process of the invention has also been examined using the scanning electron microscope at a magnification of X5000 and X10000 and it is surprisingly found that the surface of these powders is smoother than powders made by the use of ammonia and oxygen which have a similar appearance under the optical microscope.
- the difference in surface characteristics of spherical carbonyl nickel powder produced by decomposing nickel carbonyl in the presence of ammonia and oxygen, as taught in U.S. Pat. No. 3,367,768, and in the presence of nitric oxide is shown in FIGS. 5 and 6.
- the decomposer temperature was maintained at 290 C., nitric oxide was used and the concentration of the nitric oxide was varied. Table I below shows the concentration of the carbonyl by volume, the amount of nitric oxide introduced (in parts per million), the particle size of the powder as measured in the Fisher apparatus, the bulk density of the powder, the carbon and nitrogen contents of the powder and the particle shape.
- the first three tests, A, B and C are given by way of comparison. Test A, which is in fact the test numbered 1 in -U.S. Pat. No. 3,367,767, and Test B were carried out in the decomposer before its walls were nitrided. Test C was carried out at a time when the walls of the decomposer were nitrided.
- This table shows an optimum concentration of nitric oxide to be 62 ppm. at 290 C. and nickel carbonyl concentrations between 8% and 8.5% when powder of low carbon content is required. It also shows that, as when ammonia and oxygen are added, a minimum of 0.01% nitrogen is required in the powder to produce a spherical particle shape.
- Table IV shows that the addition of nitric oxide always increases the particle size and bulk density, lowers the carbon content and introduces a small amount of nitrogen into the powder, and that, despite doubling the gas flow rate for tests 13 and 14, the powder characteristics were maintained, particularly the low carbon content.
- Test D demonstrates how in the absence of nitric oxide bulk densities were low, and in fact the powder had some 10 E Type characteristics.
- Tables II and III clearly indicate that the highest a concentration of the oxide of nitrogen that equalled nitriding efficiency, leading to spherical particles and low 1.25% by volume of the carbonyl. carbon contents, is obtained at low decomposer tem- TABLE v peratures. Further, the particle shape can be modified by varying the decomposer temperature while maintaining G Fisher Bulk Percent as value, density, a constant add1t1on of n1tr1c oxide. Test additive microns gmSJCG.
- Oxygen unde con uncnon with the production of nickel powder, it may the same conditions of temperature, rate of gas flow and also be used f f Pmdllctlon oftmckel Pellets, for which carbonyl concentration Type B powder '(agglomerates of the iiecomposltwn terrolperawre W111 generally be less than interlocking spiky filaments) containing 0.12% carbon 230 was produced.
- Aprocess for decomposing nickel carbonyl to metalreproduced by way of comparison and a further experilic nickel which comprises establishing a nickel carbonyl ment (D) carried out in the nitrided decomposer but in decomposing zone, heating the decomposing zone to a the absence of nitric oxide is also reported temperature high enough to decompose nickel carbonyl TABLE IV Carbonyl Decomposi- Gas eoncen- Nitric Fisher Bulk Percent Ni in tion temp, flow, tration oxide, value, density, outlet Test C. Mfi/hr. (percent) p.p.m. microns gins/cc. C N gas 320 2 8.5 2.75 1.67 .048 .001 Nil. 320 2 8.0 62 4.43 2.66 .032 .006 Nil. 320 3 8.6 62 as 2.26 .035 .006 Trace. 320 4 8.5 62 4.69 2.67 .027 .008 Do.
- a nitrogen oxide selected from the group consisting of nitric oxide, nitrogen trioxide, and nitrogen peroxide in small but effective amounts to increase the rate of nickel carbonyl decomposition and nickel carbonyl-containing gas, to decompose the nickel carbonyl to metallic nickel at an increased rate.
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Abstract
NICKEL CARBONYL IS THERMALLY DECOMPOSED TO NICKEL POWDER OR PELLETS IN THE PRESENCE OF NITRIC OXIDE, NITROGEN TRIOXIDE OR NITROGEN PEROXIDE IN CONCENTRATIONS OF 1-5000 P.P.M. OR MORE. BY SUITABLE CHOICE OF GAS CONCENTRATIONS AND TEMPERATURES IN THE RANGE 230-350*C. THE POWDER CAN BE PRODUCED WITH SUBSTANTIALLY SPHERICAL PARTICLES OR WITH LOW CARBON CONTENT OR BOTH.
Description
Q 1972 D. M. LLEWELYN 3,702,761
CARBONYL NICKEL POWDER AND PRODUCTION THEREOF Filed July 2, 1971 3 Sheets-Sheet 1 FIG.2
Nov. 14, 1972 D. M. LLEWELYN 3,702,761
CARBONYL NICKEL POWDER AND PRODUCTION THEREOF 3 Sheets-Sheet 2 Filed July 2, 1971 FIG FIG.4
Nov. 14, 1972 D. M. LLEWELYN 3,702,761
CARBONYL NICKEL POWDER AND PRODUCTION THEREOF Filed July 2, 1971 I5 Sheets-Sheet 5 PRIOR ART United States Patent M US. Cl. 75-.5 AA 8 Claims ABSTRACT OF THE DISCLOSURE Nickel carbonyl is thermally decomposed to nickel powder or pellets in the presence of nitric oxide, nitrogen trioxide or nitrogen peroxide in concentrations of 1-5000 ppm. or more. By suitable choice of gas concentrations and temperatures in the range 230-35 0 C. the powder can be produced with substantially spherical particles or with low carbon content or both.
The present invention relates to the production of metallic nickel and more particularly to the production of metallic nickel by the thermal decomposition of nickel carbonyl.
Nickel carbonyl has been decomposed in various ways. For example, nickel carbonyl is passed over nickel pellets heated above the decomposition temperature of the carbonyl to deposit nickel on the surface of the pellets so that they increase in size. Nickel carbonyl has also been decomposed in the hot free space of a decomposer to produce nickel powder having variously shaped particles according to the temperatures employed. Nickel carbonyl has also been decomposed on the surface of hot powder particles, which can be nickel or other materials, that are to be coated with nickel, in the form of a fiudized bed or a suspension of powder in the stream of carbonylcontaining gas.
One of the problems encountered in decomposing nickel carbonyl is contamination of the metal product, particularly nickel powder, with carbon. The carbon is produced by the disproportionation of carbon monoxide, and the amount produced increases with increasing temperatures. In U.S. Patent No. 3,367,767, a process for decomposing nickel carbonyl in a steel reactor having nitrided walls and in the presence of controlled amounts of ammonia and oxygen to produce nickel powder with low carbon contents is disclosed. US. Patent No. 3,367,768 discloses a process for decomposing nickel carbonyl to spherical nickel powders by decomposing nickel carbonyl in the presence of controlled amounts of ammonia and oxygen to incorporate at least about 0.01% nitrogen in the powder to insure that the powder assumes a spherical shape. These processes Work reasonably well, but in practice the oil-gases, primarily carbon monoxide, must be treated to separate the ammonia and oxygen from the carbon monoxide. Although attempts have been made to avoid the foregoing problems, none, as far as I am aware was entirely successful when carried into practice commercially on an industrial scale.
It has now been discovered that nickel carbonyl can be decomposed to metallic nickel having low carbon contents at increased rates by adding special oxides of nitrogen to the decomposer. If added in sufficient quantities the special oxides of nitrogen are also effective in producing spherical nickel powder.
It is an object of the present invention to provide a process for thermally decomposing nickel carbonyl at increased rates.
3,702,761 Patented Nov. 14, 1972 Another object of the present invention is to thermally decompose nickel carbonyl to produce a metallic nickel product that contains minimum amounts of carbon.
The invention also contemplates providing a process for thermally decomposing nickel carbonyl to produce spherical nickel powder.
An even further object of the present invention is to provide spherical carbonyl nickel powder having smooth surfaces.
Other objects and advantages will become apparent from the following description taken in conjunction with the accompanying figures in which:
FIGS. 1 to 4 are representations of photomicrographs of carbonyl nickel powder having increasing nitrogen contents from FIG. 1 to FIG. 4 taken by transmitted light at a magnification of 1,000 times.
FIG. 5 is a scanning electron micrograph of prior art spherical carbonyl nickel powder at a magnification of 10,000 times, and
FIG. 6 is a scanning electron micrograph of spherical carbonyl nickel powder in accordance with the present invention at a magnification of 10,000 times.
Generally speaking, the present invention contemplates a process for thermally decomposing nickel carbonyl. A nickel carbonyl decomposing zone is established and is heated to a temperature high enough to decompose nickel carbonyl but below the temperature at which carbon formation will occur during the decomposition of nickel carbonyl. At least one nitrogen oxide selected from the group consisting of nitric oxide, nitrogen trioxide and nitrogen peroxide in small but effective amounts to increase the rate of nickel carbonyl decomposition and nickel carbonyl-containing gas are fed to the decomposing zone to decompose the nickel carbonyl to metallic nickel.
The present invention is based on the discovery that the rate of thermal decomposition of nickel carbonyl under otherwise similar conditions of temperature and carbonyl concentration is increased by the presence of at least one nitrogen oxide selected from the group consisting of nitric oxide (NO), nitrogen trioxide (N 0 or nitrogen peroxide (N02), and according to the present invention nickel is produced by the thermal decomposition of nickel carbonyl in the presence of one of these gases.
The amount of the oxides of nitrogen employed can vary widely, and these gases have been found to be effective in concentrations ranging from 1 to 1,000 parts per million of the carbonyl-containing gases. Even higher concentrations can be used, but the presence of the oxide of nitrogen during the decomposition introduces nitrogen into the nickel produced, and as the concentration increases so does the nitrogen content of the product. Very high concentrations, e.g. up to 2,000 or 3,000 or even 5,000 p.p.m., can therefore only be employed when relatively high nitrogen contents in spherical powders can be tolerated.
It should be noted that'all gaseous compositions or additions are given on a volumetric basis unless otherwise stated while solid compositions are given on a weight basis.
The use of nitrogen oxides will now be described in more detail in relation to the production of carbonyl nickel powder, that is to say powder made by the thermal decomposition of nickel carbonyl vapour in the hot free space of a decomposer.
When nitric oxide, nitrogen peroxide or nitrogen trioxide is used in place of ammonia or ammonia and oxygen as described in US. Pat. No. 3,367,767, it is found that powder consisting of discrete particles can be produced at an increased rate in a vessel of given size. The optimum conditions vary with the properties required in the powder, but broadly for the production of powder of given properties the temperature (and therefore the rate) of decomposition can be higher than when ammonia and oxygen are added, and, moreover, the concentration of oxide of nitrogen required is less than that of ammonia.
It is advantageous to use nitric oxide, which is more effective than the other two oxides. To achieve equivalent results greater amounts of nitrogen trioxide or nitrogen peroxide are required than when nitric oxide is employed.
The production of powder can be carried on in the temperature range of 230 to 350 C. Below 230 C. so small a proportion of the carbonyl is decomposed to powder that the process is not practicable on an industrial scale. Above 350 C. a high proportion of filamentary aggregates are formed. A very suitable temperature is 290 C.
The amount of oxide of nitrogen required varies with the temperature, decreasing as the temperature decreases. Considering nitric oxide, and assuming that low carbon content is required, some reduction in the carbon content is obtained with very small amounts of nitric oxide, that is to say, as little as 1 part per million, particularly if the vessel walls have previously been nitrided and the process is operated continuously. When a steel reactor is employed, the walls of the reactor can be initially nitrided by introducing ammonia into the reactor and heating the reactor to nitriding temperatures, e.g., 500 C., for at least one hour, e.g., 3 hours. -It is found that as the concentration of nitric oxide increases, the carbon content falls and then rises again. Typically the nickel carbonyl is introduced into the decomposer, as a gas mixture of carbon monoxides containing 8% nickel carbonyl, and at this concentration and at 290 C. the concentration of nitric oxide should be from 50 p.p.m. to 2.00 p.p.m. Above 250 p.p.m. the carbon content of the powder can actually be higher than if no nitric oxide is added.
Converted into percentage of the carbonyl by volume, at 290 C. the nitric oxide should be from about 0.06% to about 0.25% of the carbonyl, whatever the concentration of the carbonyl.
In controlling the carbon content of the carbonyl nickel powder, at lower temperatures the nitrogen oxide concentration in the gaseous mixture is correspondingly lowered, being from 25 to 1 p.p.m., i.e. 0.03% to 0.12%, at 230 C., and at higher temperatures it is correspondingly increased, being from 100 to 300 p.p.m., i.e. 0.12% to 0.4% at 320 C.
When the object is to produce spherical powder, the concentration of nitric oxide at 290 C. should be at least 0.09% of that of the carbonyl. If the temperature is lower, this minimum can be correspondingly reduced, but at 230 C. should be at least 0.012%. Likewise at higher temperatures the minimum concentration of nitric oxide must be higher, being at least 0.2% at 320 C.
If low carbon content is not important, the concentration of nitric oxide can be considerably higher, but so far as the production of spherical powder is concerned there is no advantage in exceeding 1.25% or even 0.625% of the carbonyl concentration.
It is clear that the shape of the powder depends on the incorporation of nitrogen into the powder, but the mechanism by which this occurs is unclear. Whatever the mechanism is, nitrogen peroxide is less efiective than nitric oxide, and nitrogen trioxide is still less effective. It is therefore necessary to use increased quantities of these gases in order to obtain results equivalent to those obtained with nitric oxide.
The way in which the process can be controlled to produce powders of difierent properties is shown by the results of a large number of tests. All these were carried out in an externally heated decomposer having a diameter of 10 inches and mild steel walls, which are nitrided as a result of use in numerous processes in which ammonia has been added. In all the tests carbon monoxide gas containing from 7% to 9% of nickel carbonyl was fed into the decomposer through an inlet at the top at a rate (unless otherwise stated) of 2,000 litres per hour. The oxide of nitrogen, when used, was injected into the gas stream at a measured rate at room temperature. The temperature at the inlet to the decomposer was maintained at about 50 C. by water cooling.
The particles obtained varied in shape as shown in the accompanying figures, and were classified as follows:
FIG. 1-spiky FIG. 2-angular, the spikes becoming rounded FIG. 3nearly spherical FIG. 4--spherical Spherical powder made by the process of the invention has also been examined using the scanning electron microscope at a magnification of X5000 and X10000 and it is surprisingly found that the surface of these powders is smoother than powders made by the use of ammonia and oxygen which have a similar appearance under the optical microscope. The difference in surface characteristics of spherical carbonyl nickel powder produced by decomposing nickel carbonyl in the presence of ammonia and oxygen, as taught in U.S. Pat. No. 3,367,768, and in the presence of nitric oxide is shown in FIGS. 5 and 6. FIG. 6 dramatically confirms that spherical carbonyl nickel powder produced by decomposing nickel carbonyl in the presence of nitric oxide and containing at least about 0.01% nitrogen has smooth surfaces as compared with the rough surface of spherical carbonyl nickel powder produced by decomposing nickel carbonyl in the presence of ammonia and oxygen.
In the first set of tests the decomposer temperature was maintained at 290 C., nitric oxide was used and the concentration of the nitric oxide was varied. Table I below shows the concentration of the carbonyl by volume, the amount of nitric oxide introduced (in parts per million), the particle size of the powder as measured in the Fisher apparatus, the bulk density of the powder, the carbon and nitrogen contents of the powder and the particle shape. The first three tests, A, B and C, are given by way of comparison. Test A, which is in fact the test numbered 1 in -U.S. Pat. No. 3,367,767, and Test B were carried out in the decomposer before its walls were nitrided. Test C was carried out at a time when the walls of the decomposer were nitrided.
TABLE I Chemical character- Fisher B istics, percent value, density, microns gms./cc. C N Particle shape 4. 47 2. 47 057 001 Spiky. 4. 37 2. 41 029 001 Do. 3. 66 1. 99 039 001 Do. 4 96 3. 21 069 17 Spherical. 5 25 3. 23 056 08 Do. 5 3. 71 023 024 Do. 6. 76 3. 60 022 014 D0. 6. 73 3. 29 017 008 Nearly spherical. 6. 74 3. 03 020 005 Angular and irregular.
This table shows an optimum concentration of nitric oxide to be 62 ppm. at 290 C. and nickel carbonyl concentrations between 8% and 8.5% when powder of low carbon content is required. It also shows that, as when ammonia and oxygen are added, a minimum of 0.01% nitrogen is required in the powder to produce a spherical particle shape.
In the next series of tests a nitric oxide concentration of 62.5 p.p.m. was maintained and the decomposer temperature was varied, with the following results:
Table IV shows that the addition of nitric oxide always increases the particle size and bulk density, lowers the carbon content and introduces a small amount of nitrogen into the powder, and that, despite doubling the gas flow rate for tests 13 and 14, the powder characteristics were maintained, particularly the low carbon content.
Test D demonstrates how in the absence of nitric oxide bulk densities were low, and in fact the powder had some 10 E Type characteristics.
TABLE II Chemical character- Decomposi- Carbonyl Fisher Bulk istics, percent tion temp., concn., value, density, Test percent microns gms./ec C N Powder shape 320 8.0 4. 43 2. 66 032 006 Angular. 290 8. 6. 73 3. 29 017 008 Nearly spherical. 260 8. 5 7. 80 3.11 018 011 Spherical. 230 9. 0 9. 02 3. 75 014 038 Do.
In the next series of tests the concentration of nitric Finally Table V shows comparative results obtained oxide was increased to 125 p.p.m., and the decomposer with the same oxides of nitrogen under identical conditemperature was again varied, with the following results:
tions, namely a decomposer temperature of 260 C. and
TABLE III Decompo- Chemical characsition Carbonyl Fisher Bulk teristics, percent temp, concn., value, density, Powder 0. percent microns gins/cc. C N shape 320 9.0 4.56 2.86 .021 .00., Angular. 290 3.0 5.76 3.60 .022 .014 Spherical. 260 0. 0 7. 49 3.75 014 026 Do. 230 9. 0 s. 06 3.85 .018 .051 D0.
Tables II and III clearly indicate that the highest a concentration of the oxide of nitrogen that equalled nitriding efficiency, leading to spherical particles and low 1.25% by volume of the carbonyl. carbon contents, is obtained at low decomposer tem- TABLE v peratures. Further, the particle shape can be modified by varying the decomposer temperature while maintaining G Fisher Bulk Percent as value, density, a constant add1t1on of n1tr1c oxide. Test additive microns gmSJCG. O N Test 7 shows that even at high decomposluon tem- 15 N0 M2 M2 ms peratures, powders of low carbon content can be pro- 16 N302 4.46 3.07 .036 .11 duced with the normal particle size and bulk density 17 N02 of Type A powder (discrete, angular particles). In contrast, with optimum ammonia and oxygen concentration pflthollgh l Present lnvefltlon 0 been described In (2,000 p.p.m. ammonia and 1,500 ppm. Oxygen) unde con uncnon with the production of nickel powder, it may the same conditions of temperature, rate of gas flow and also be used f f Pmdllctlon oftmckel Pellets, for which carbonyl concentration Type B powder '(agglomerates of the iiecomposltwn terrolperawre W111 generally be less than interlocking spiky filaments) containing 0.12% carbon 230 was produced. It 1s to be understood that other modifications and var- I ll h tests (except A d B) h f carbon 18110118 may also be resorted to without departing from tent of the powders was negligible, Even at high inlet the Spirit and SCOPE Of thfi invention, as those skilled in concentrations nitric oxide was not detected in the outlet the art W111 readily understand. Such modifications and gas by chromatograph, 0 variations are considered to be within the purview and The advantage that the output can be increased by inscope of the invention and appended claims. creasing the rate of gas flow is shown by two further I claim: tests, reported in Table IV below, in which Test 7 is 1. Aprocess for decomposing nickel carbonyl to metalreproduced by way of comparison and a further experilic nickel which comprises establishing a nickel carbonyl ment (D) carried out in the nitrided decomposer but in decomposing zone, heating the decomposing zone to a the absence of nitric oxide is also reported temperature high enough to decompose nickel carbonyl TABLE IV Carbonyl Decomposi- Gas eoncen- Nitric Fisher Bulk Percent Ni in tion temp, flow, tration oxide, value, density, outlet Test C. Mfi/hr. (percent) p.p.m. microns gins/cc. C N gas 320 2 8.5 2.75 1.67 .048 .001 Nil. 320 2 8.0 62 4.43 2.66 .032 .006 Nil. 320 3 8.6 62 as 2.26 .035 .006 Trace. 320 4 8.5 62 4.69 2.67 .027 .008 Do.
but below the temperature at which carbon formation will occur during the decomposition of nickel carbonyl, feeding to the decomposing zone a nitrogen oxide selected from the group consisting of nitric oxide, nitrogen trioxide, and nitrogen peroxide in small but effective amounts to increase the rate of nickel carbonyl decomposition and nickel carbonyl-containing gas, to decompose the nickel carbonyl to metallic nickel at an increased rate.
2. The process as described in claim 1 wherein the decomposing zone is the free space of a reactor and the free space is maintained at a temperature between about 230 C. and 350 C. to produce carbonyl nickel powder.
3. The process as described in claim 2 wherein the free space of the reactor is bounded by nitrided mild steel walls.
4. The process as described in claim 1 wherein the nitrogen oxide is nitric oxide.
5. The process as described in claim 1 wherein the concentration of nitrogen oxide in the carbonyl-containing gas is between about 1 part per million and 5,000 parts per million.
6. The process as described in claim 4 wherein the carbonyl-containing gas contains between about 50 parts per million and 200 parts per million nitrogen oxide to produce carbonyl nickel powder with low carbon contents.
7. The process as described in claim 4 wherein the nickel carbonyl is decomposed at a temperature between about 230 C. and 330 C. and the nitric oxide is present in amounts between about 25 parts per million and 100 parts per million at 230 C. and is correspondingly increased with temperature to 100 parts per million and 300 parts per million at 320 C. to produce carbonyl nickel powders with low carbon contents.
8. The process as described in claim 4 wherein the nitric oxide is added to the nickel carbonyl-containing gas in amounts equivalent to at least about 0.012% of the nickel carbonyl at 230 C. and increasing to at least about 0.2% of the nickel carbonyl at 320 C. to produce spherical carbonyl nickel powders with smooth surfaces.
References Cited UNITED STATES PATENTS 2,844,456 7/1958 Llewelyn et a1. 75.5 AA
WAYLAND W. STALLARD, Primary Examiner
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB3295970 | 1970-07-07 |
Publications (1)
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US3702761A true US3702761A (en) | 1972-11-14 |
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Application Number | Title | Priority Date | Filing Date |
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US159258A Expired - Lifetime US3702761A (en) | 1970-07-07 | 1971-07-02 | Carbonyl nickel powder and production thereof |
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Country | Link |
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US (1) | US3702761A (en) |
BR (1) | BR7104243D0 (en) |
CA (1) | CA950208A (en) |
GB (1) | GB1332901A (en) |
ZA (1) | ZA714229B (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4018596A (en) * | 1973-05-15 | 1977-04-19 | The International Nickel Company, Inc. | High shrinkage powder body |
US20060048606A1 (en) * | 2004-09-03 | 2006-03-09 | Coley Kenneth S | Process for producing metal powders |
-
1970
- 1970-07-07 GB GB3295970A patent/GB1332901A/en not_active Expired
-
1971
- 1971-06-28 ZA ZA714229A patent/ZA714229B/en unknown
- 1971-07-02 US US159258A patent/US3702761A/en not_active Expired - Lifetime
- 1971-07-06 BR BR4243/71A patent/BR7104243D0/en unknown
- 1971-07-06 CA CA117,527,A patent/CA950208A/en not_active Expired
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4018596A (en) * | 1973-05-15 | 1977-04-19 | The International Nickel Company, Inc. | High shrinkage powder body |
US20060048606A1 (en) * | 2004-09-03 | 2006-03-09 | Coley Kenneth S | Process for producing metal powders |
US7344584B2 (en) | 2004-09-03 | 2008-03-18 | Inco Limited | Process for producing metal powders |
Also Published As
Publication number | Publication date |
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BR7104243D0 (en) | 1973-04-10 |
GB1332901A (en) | 1973-10-10 |
CA950208A (en) | 1974-07-02 |
ZA714229B (en) | 1972-03-29 |
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