DE2132950B2 - Process for producing nickel or iron - Google Patents

Description

^{stfck! tolf} "ss

»On

TvSSS according to claim 1, thereby core- ».ration at & r« t = r. draws that r & kekarboiiyl inside a «b * imvfpS bEOgtnanf

BCD of the drawing. increase in carbony gas ^^^ - ™

4. Procedure, aach claim 2, characterized by, for example, 2000, 3000 or even SOOOppm that the decomposition at a one. Stick- sii.J accordingly only to be recommended if the material content of at least 0.01 · /. overall in the powder "ο nickel higher Suckstoff ^ haltc asc" sm may Be.m währleistenden concentration of nitric oxide ER decomposition of iron carbonyl ^s £? however, 5 or _fo l _gt and 10 volume percent of a Stickstoffox> ds good overall

5. Process according to one or more of the appropriate. j "" _e """,,""a""claims 2 to 4, characterized in that the other hand, the decomposition temperature depends on the means of decomposing in a steel container with niirierier" respective carbonyl and the f ~ * ^s E "^; inner surface This is how the decomposition of nickel carbonyl takes place

6 method na ^ claim 1, characterized on the surface of Nickclpellets after, de m denotes that iron carbonyl inside a known moon process at temperatures ur. He heated the decomposition tank in A, essence of 230 = C, because at temperatures above .230 C m nitrogen oxide at a temperature of 230 to 290 ⁰ C 30 interior of a decomposition tank nickel powder is decomposed. forms. Temperatures of at least 230 C are also possible. η

7. The method according to claim 1, characterized required for the production of iron powder draws that iron carbonyl in one on a temperature The process according to the invention is ^ following

temperature above the decomposition temperature using the example of the decomposition of Nickelcarbonvldamof Iron carbonyls heated fluidized bed decomposes in the interior of a decomposition age to ΝκΚ, -Ι-sets powder is explained in more detail. ",, ..,"

^{Set l} In British Patents 1061579 and

1 062 580 are processes for thermal decomposition

of nickel carbonyl in the presence of ammonia

40 and oxygen to different powders depending on the process conditions are described in detail. In particular after that in the first-mentioned patent specification

The invention relates to a method for the method described above that can produce ammonia of nickel and iron due to thermal concentration and the ratio of ammonia to it Decomposition of nickel and iron carbonyl. 45 oxygen spherulitic particles are generated.

There are a number of processes / around thermal decomposition in the process according to the second-mentioned patent known from metal carbonyls. So when writing can with low ammonia concentration the well-known moon process nickel carbonyl over and in the presence of oxygen a powder with Nickel pellets passed, their temperature above the Zer- sel.r low carbon and in the absence The settling temperature of carbonyl is a powder with a fairly low nickel 50 of oxygen knock down and in this way the pellets are made to carbon content, enlarge. The thermal decomposition of carbonyls The decomposition tanks usually exist

in the interior of a decomposition tank there is also steel, which due to the presence of ammonia Nickel or iron powder is nitrided with depending on the process, which leads to that in such containers conditions different forms of powder particles. 55 the powder is free of black carbon particles. Another known method is, the thermal decomposition takes place in the presence of Carbonyl on the surface of hot powder particles nitrogen oxide, nitrogen peroxide or nitrogen oxide to deposit the nickel, iron or other place of ammonia or ammonia and oxygen, Materials are made and coated with nickel or iron so that a given orolyte can be placed in a container should be pulled; this takes place in a fluidized powder of discrete particles with a raised decomposition layer or prepare a powder suspension at the carbonyl rate. The optimal behavior Gas. driving conditions depend on the desired. The invention is based on the surprising solid-powder properties, but can in manufacturing position that the rate of decomposition of a powder given properties the temperature Nickel and iron carbonyls with otherwise the same 65 and consequently also the rate of decomposition Conditions, in particular the same temperature and higher than in the presence of ammonia and acidic carbonyl concentration in the presence of substance, and is also the required concentration of nitrogen oxide or nitrogen monoxide, nitrogen oxide tration of nitrogen oxide less than in the case of the

Ammonia. In any case, preference is given to nitrogen oxide, which is far more potent than the other two oxides.

The thermal decomposition of nickel carbonyls can be carried out at temperatures of 230-350 ⁰ C. Below 230 ^° C., so little carbonyl is decomposed that the process cannot be carried out economically. A high proportion of fibrous particles about 35O ⁰ C is formed. Thus, there is a very suitable temperature at 290 ⁰ C. _t0

The method according to the invention is suitable for producing nickel powder with a low carbon content and / or discrete spherulitic particles.

The amount of nitrogen oxide in question depends on the decomposition temperature and increases as it increases. In the case of nitric oxide and the manufacture of a nickel powder with a low carbon content, a certain reduction in the carbon content can be achieved with very low concentrations of the oxide, ie 1 ppm. Achieve this in particular if the decomposition tank is nitrided inside beforehand and the process is carried out continuously. Experiments have shown that as the concentration of nitrogen oxide increases, the carbon content of the powder initially falls and d: nn increases again. Normally, the carbonyl concentration in the mixed gas introduced into the decomposition tank is 8 percent by volume: at this concentration and a decomposition temperature of 29CC, the nitrogen oxide concentration should be 50 to 220 ppm. At a concentration in excess of 250 ppm, the carbon content of the powder may be higher than when decomposed in the absence of slick oxide. Regardless of the carbonyl concentration, the concentration of the nitrogen oxide at a decomposition temperature of 290C should be about 0.06 to 0.25 ° _O , based on the volume fraction of the carbonyl in the mixed gas.

At lower decomposition temperatures of 230 ³ C, the nitrogen oxide concentration is accordingly 25 to 110 ppm, ie 0.03 to 0.12 percent by volume of the carbonyl content; at higher temperatures it rises correspondingly to 100 bL · 300 ppm, ie 0.12 to 0.4 Voiu.nprozent of Carbonyianteils at 32O ⁰ C. The conditions in which a powder of low carbon content is obtained, are through the field ABCD in F i g. 7 of the drawing.

To produce a powder sphäroüthiiches, the nitrogen oxide concentration at 29o C ⁰ should be at least 0.09 volume percent of the Carbonylanteils. At low decomposition temperature of the above-mentioned minimum concentration decreased accordingly, but the nitrogen oxide concentration should be at least 0.012 percent by volume at a decomposition temperature of 230 ⁰ C. Similarly, the minimum is the nitric oxide concentration at higher decomposition temperatures gTöße ·· and is at 320 ⁰ C for at least 0.2 volume percent.

Unless a low carbon content is important, the nitrogen oxide concentration can be considerable are higher, although when producing a spherulitic powder from one concentration over 1.25 percent by volume or also 0.625 percent by volume, based on the carbonyl content, d. H. at 1000 or 500 ppm, based on the mixed gas containing 8 percent by volume of nickel carbonyl, none Benefits result in more.

It is obvious that the shape of the Piilverteilchen depends on the nitrogen uptake of the Pulvejs and generally give sphäroiithiscbe particles when the powder contains at least 0.01 ° / ₀ nitrogen, even though the chemistry of the underlying is still unclear. However, it can be assumed that under the given decomposition conditions a reaction

NO + CO - N + CO ₂

as well as similar reactions in which atomic nitrogen is produced, albeit to a lesser extent, if the decomposition takes place in the presence of nitrogen peroxide and nitrogen trioxide. In in any case the nitrogen peroxide is less effective than the nitrogen oxide and the nitrogen trioxide still less effective. It is therefore necessary with the less effective oxides in view of a the same process result can be used with higher concentrations than in the case of sticko \ yds.

In numerous experiments, the conditions could be determined that must be complied with To reveal nickel powder with different properties. These attempts were all in one and the same decomposition tank as e; is described in the aforementioned British patents. carried out. The container was made of low carbon steel and was as a result of a previous operation nitrided inside with ammonia. The container was \ on in diameter 25 cm and external heating. In all experiments, carbon monoxide was 7 to 9 percent by volume Nickel carbonyl via a gas inlet at the top of the decomposition vessel at a rate of 2000 l / h introduced, unless other figures are given. The nitric oxide was at room temperature fed into the gas stream in a certain amount. The inlet temperature of the mixed gas became kept at about 50C by means of water cooling.

The powders produced in the individual processes had different shapes and can be used accordingly the F i g. Classify 1 to 1 as follows:

F i g. 1: stalky

F i g. 2: angular, shaped-columnar.

F i g. 3: quasi-spherolithic,

F i g. 4: spherulitic.

The F i g. 1 to 4 represent transmitted light recordings at a thousandfold magnification. That according to the invention The spherulitic powders produced by the method were also magnified five thousand times using a /.b^ast electron microscope Examined magnification, it was surprisingly found that the surface of the powder particles (Fig. 6) is smoother than with thermal decomposition in the presence of ammonia and oxygen (F 1 g. 5 \ its powder particles below the optical Microscope have a similar appearance.

In a first series of experiments, the decomposition temperature was 290 ° C. and the concentration became of nitrogen oxide changed. In Table T below are the various volume concentrations of nickel carbonyls, the concentration of nitrogen oxide in ppm obtained with a Fisher sizing sieve certain particle size, the bulk density of the powder, the content of carbon and nitrogen and the particle shape are listed. In the trials A to C are comparative tests. Included

int corresponds to experiment A to experiment 1 after > Ritic patent specification 1 062 580, while test B was carried out in a decomposition vessel that was not internally nitrided. Trial C was on the other hand, carried out in an internally nitrided container.

Table I.

attempt Ni (CO) ₁ -
Conc. NO Grain size Schütt
weight C. N Particle loc (VJ (ppm) (μ) (g / cm ") (V.) (7.) A. 9.0 _ 4.47 2.47 , 057 <.001 stalky C. 8.0 - 4.37 2.41 .029 <.001 stalky B. 7.0 - 3.66 1.99 .039 <.001 sterngetig 1 8.5 1000 4.96 3.21 .069 .17 spherulitic 2 8.5 500 5.25 3.23 .056 .08 spherulitic 3 8.5 250 5.95 3.71 .023 .024 spherulitic 4th 8.0 125 5.76 3.60 .022 .014 spherulitic 5 8.0 62 6.73 3.29 .017 .008 quasi-spherulitic 6th 8.0 31 6.74 3.03 .020 .005 angular and irregular moderate

According to the data in Table I above, a second series of tests

the optimum of the nitrogen oxide concentration at 62 ppm, looking at a low carbon content optimum

if a powder with a low carbon content it is maintained as nitrogen oxide concentration of 62 ppm and

should be procreated. It is also found that this varies the decomposition temperature. It resulted

Powder in the presence of ammonia and acid - the data in Table II below.
substance must contain at least 0.01% nitrogen,
so that the particles become spherulitic.

Table II

attempt temperature
( ⁰ Q Ni (CO) ₁ -
Conc.
( ⁰ W Grain size
(μ) Schütt
weight
(g / cm ¹ ) C.
(V.) N
(7.) Particle shape 7th
5
8th
9 320
290
260
230 8.0
8.0
8.5
9.0 4.43
6.73
7.80
9.02 2.66
3.29
3.11
3.75 .032
.017
.018
.014 .006
.008
.011
.038 angular
quasi-spherulitic
spherulitic
spherulitic

In a further series of tests, the nitrogen oxide concentration was increased to 125 ppm and the decomposition temperature was also varied. This resulted in the data compiled in the following table HI:

Table III

attempt temperature
( ⁰ Q Ni (CO), -
Conc.
(V.) Grain size
(μ> Schütt
weight
(g / cm ^J ) C.
(VJ N
(· / ·> Particle shape 10
4th
11
12th 320
290
260
230 9.0
8.0
9.0
9.0 4.56
5.76
7.49
8.06 2.86
3.60
3.75
3.85 .021
.022
.014
.018 .008
.014
.025
.051 angular
spherulitic
spherulitic
spherulitic

The data in Tables II and III clearly show that the largest spherulitic particles and results in an effectiveness ensuring a low carbon content at a low decomposition temperature. In addition, it can be seen how the shape of the particles changes with the temperature when the addition of nitrogen oxide is constant changes.

Experiment 7 shows that even at a high decomposition temperature Powders with low carbon content and normal particle size and bulk density of powder type A can be produced. In contrast, one fell for a spherulitic

Powder optimal ammonia and oxygen concentration of 2000 ppm NH ₃ and 1500 ppm O _s at the same temperature, flow rate of the

Gas and carbonyl concentration only a B powder with a carbon content of 0.12%.

With the exception of Experiments A and B, the free carbon content was in all of the experiments Powders negligibly small. Even with a high nitrogen oxide concentration, the Abgts could be used for chromatography no nitric oxide can be detected.

That the powder output increases by increasing the flow velocity of the gas mixture.

: rn lets show two further experiments whose data

compiled in Table IV below

nd, and among which experiment 7 is repeated for comparison purposes and another experiment D was carried out in an internally nitrided decomposition vessel, but in the absence of nitrogen oxide.

Table IV

/ request temperature
CQ Flow
swiftly
speed
(mVh) Ni (CO), -
Conc.
(7o) NO
(ppm) Grain size
(μ) Rubble-
weight
(g / cm *) C.
(7o) N exhaust
(Ni / m) D.
7th
13th
14th 320
320
320
320 2
2
3
4th 8.5
8.0
8.5
8.5 62
62
62 2.75
4.43
3.8
4.69 1.67
2.66
2.26
2.67 .048
.032
.035
.027 <.001
.006
.006
.008 traces
traces

Table IV shows that the addition of nitrogen oxide in this case increases the particle size and the bulk density, but reduces the carbon content and results in a low absorption of nitrogen in the powder. In addition, despite the doubling of the speed, the characteristic features of the powder, in particular the low carbon content, were retained.
Experiment D shows how low the bulk weight is in the absence of nitrogen oxide; the opening powder had some properties of the B powder

Table V, below are some Vergleichsiihlen again, which were the 'arbonylanteils obtained in experiments with the three Stickloffoxyden under the same process conditions ■ ei a decomposition temperature of 260 ⁰ C and flexi Oxydkonzentration of 1.25 percent by volume.
Table V

attempt additive grain
size
(μ) Schütt
weight
(g / cm ») C.
(7o) N
(7o / 15th
16
17th NO
N ₂ O,
NO ₂ 7.92
4.45
3.38 4.22
3.07
2.43 .026
.036
.036 .12
.11
.08

When carbonyl iron powder is produced by animal-based decomposition of iron carbonyl vapor inside a decomposition container, the effect of nitrogen oxide shows itself in a reduction in particle size at a given temperature and carbonyl concentrate! At relatively? E-Bettingen temperatures of for example 230 to 280 ⁰ C _t ei "I .jt a powder of discrete particles, while l * i löheren temperatures corresponding to a B-Nickellulver the PuWerteilchen are fibrous and have a geingeres bulk density.

Such powders can also be produced in the absence of nitrogen oxides by increasing the temperature will. However, this is with an essential

ao increase in the carbon content of the powder. The method according to the invention therefore allows in the presence of nitrogen oxides an iron powder with relatively small discrete particles or fibrous particle aggregations with lower carbon

a5 fuel content and in this way a avoid or shorten subsequent decarburization and thus save costs.

The aforementioned advantages are shown in tests with nitrogen oxide, which were carried out in a laboratory container made of low-carbon steel with a diameter of 25 cm and external heating. In all experiments, a mixed gas of carbon monoxide with 60 percent by volume of iron carbonyl was introduced into the decomposition container via a gas inlet at the top of the container at a rate of 250 l / h, ie at 150 l / h, carbonyl vapor. The nitrogen oxide was introduced in the specified amount into a stream of gas at room temperature. The temperature at the gas inlet of the decomposition container was set to about 110 ^° C. with air cooling. The temperature in the decomposition container was measured on half the radius and kept the same in the zone 30 to 90 cm below the container head.

In the tests, the container temperatures were 260, 290 and 31O ⁰ C with different contents of nitrogen oxide.

The following table \ I gives the decomposition temperature, the volume concentration of the nitrogen oxide, the particle size measured with a Fisher sizing sieve, the bulk density and the carbon and the nitrogen content of the powder. Tests R, S and T are comparative tests.

Table VI

\ 7ilfMWh temperature NO conc. Grain size Bulk weight C. N VCrSUCB ( ⁰ Q (7,) (μ) (Sicm *) (· / ·) (7.) R. 260 8.1 4.3 0.62 <0.005 S. 290 - 4.92 3.92 0.91 <0.005 T 310 - 3.9 3.3 1.03 <0.005 18th 260 0.1 4.69 4.07 0.93 0.08 19th 260 1.0 4.04 3.73 0.72 0.43 20th 260 5.0 4.10 3.60 0.58 0.59 21 260 10.0 3.65 2.97 0.50 0.93 22nd 290 0.1 2.76 1.3 0.90 0.01

209581/331

ίο

A comparison of experiments 18 to 21 with experiment R shows that even a nitrogen oxide concentration. tration of 0.1 percent by volume leads to a noticeable reduction in particle size, which extends up to a concentration of 10 percent by volume continues. At the same time, the nitrogen content of the powder also increases progressive.

As the nitrogen oxide concentration rises, the carbon content of the powder also rises, and then falls again. However, in order to produce a powder with a particle size of about 5 μ without adding nitrogen oxide, the decomposition temperature must be set to about 290 ° C. The data from experiment S show that at this temperature in the absence of nitrogen oxide from the powder it has a carbon content of 0.91 ° / ₀ , while in experiment T, with a decomposition temperature of 310 ° C., the carbon content increases to 1.03 ° / ₀ increased. Mkhin leads to an addition of nitrogen oxide of at least 0.2%, preferably of at least 0.5 or even 1%, /.u a powder with a significantly lower carbon content for a given particle size.

In the experiment 22, the Zersetzimgstemperatur was raised to 290 "C and the mixed gas zuger.stzt 0.1% nitric oxide. This led to the formation of fibrous Pulveraggregat'onen low density, that is, the ^c iaüttgewicht was only 0.75 g / cm ³ . A further increase in the decomposition temperature in the presence of 0,1 ° / ₀ nitric oxide resulted in extremely light and voluminous powder, looked like cotton.

The presence of nitrogen oxide during the decomposition of the iron carbonyls surprisingly also leads to

ίο an improvement in the electromagnetic properties of the powder, both in the unground and in the ground state.

Ip Table YII are the Q values at three frequencies and the magnetic permeability of the powders from Experiments R, S, and 18 to 24 as well as H also just a 2 hour grinding in a laboratory mill compiled. The data show that in the presence of 0.1% nitric oxide the properties after grinding are much better than those of the Α powder and better in the un-ground state than that of the comparative powder and that the higher the nitrogen oxide concentration, the greater the improvement is.

Table VII

attempt temperature NO conc. 20MH? Q unground Perm. 20 MHz Q ground Fcfm. ( ⁰ C) (7.) 133 50MHz 10.9 138 50 mKi 9.7 R. 260 <130 150 11.0 - 141 - S. 290 137 <130 11.8 167 - 11.3 18th 260 0.1 164 144 12.2 166 152 12.1 19th 260 1.0 132 158 12.0 J64 163 10.9 20th 260 5.0 169 157 11.6 171 175 10.6 21 260 10.0 169 176

For comparison purposes, the properties of a commercially available ME standard iron powder were compared to the powders of experiments 19 and 20 compared. The standard commercial powder is usually ground Used condition.

Table VIII

powder Grain size
(μ) SchüUgewichi
(g / cm ') C.
(7o) N
(7o) 20MHz Q
50MHz Perm. ME
19th
20th 4.33
3.98
4.05 4.41
4.16
4.33 0.76
0.72
0.58 0.56
0.43
0.59 169
166
164 1§2
163
175 12.2
12.1
10.9

The comparison of Table VIII shows that the properties of the comparison powders are essentially the same at 20 MHz, while the properties of the powder produced in the presence of nitrogen oxide are better at 50 MHz. An important advantage of the powder produced by the process according to the invention is that it has a significantly lower temperature coefficient, the permeability, than the ME powder, ie the temperature coefficient of the powder from the experiment was 20 according to the. Grinding only + 43 · 10- · / ⁰ C, while the temperature coefficient of the ME powder was + W3 · 10- ^e / ° C. The low temperature coefficient of the powder produced by the process according to the invention should be due to the low decomposition temperature

^ o be thing.

To the effectiveness of the nitrogen oxydb among others To examine decomposition conditions, special tests were carried out in which a mixture of Eisencarbonyldampf and Kohiemnonoxyd nut and blown without nitrogen from the bottom into a fluidized bed of iron powder in a decomposition chamber became. The decomposition container was made of steel and had a diameter of 75 cm; he was outside

provided with a heating coil and was charged with the mixed gas at a rate of 3.5 m ³ / h at a temperature of 160 ⁰ C. The initial weight of the fluidized bed was 2.5 kg. The vortex temperature was set to 290, 250 and 230 ° C within three series of tests. In these experiments, the iron carbonyl was partly deposited on the iron particles and partly formed new particles, so that the weight of the fluidized bed increased over time. In each series of experiments, the concentration of the iron carbonyl in the mixed gas was adjusted so that a maximum rate of decomposition and complete decomposition of the carbonyl was ensured. The results of the tests are summarized in Table IX below, which shows the fluidized bed temperature, the concentration of nitrogen oxide, the maximum rate of decomposition in kilograms per hour and the carbon content of the deposited iron. During the experiments, the carbonyl concentration varied from 5 to 30 percent by volume.

Table IX

NO conc. Maximum C. temperature Decomposition (7o) speed (V _n ) ( ⁰ C) _ (kg / h) 1.12 290 0.3 1.63 1.07 290 2.02 *) 1.74 250 0.3 0.594 0.74 250 - 0.926 2.5 230 0.3 0.33 1.15 230 0.327

*) Limited by the maximum heat supply.

The data in the above table show that the addition of nitrous oxide at temperatures above 24O ⁰ C considerably increases the rate of decomposition of iron carbonyls and at the same time at all temperatures, the carbon content of the deposited iron is significantly reduced.

For this purpose 2 sheets of drawings

Claims (1)

l 2 («, ©«) «tor StteJStsffipfcioxyä räie wfeA On the other hand, the 'afiniitog consists in a method of patent claims: SSwS« «^« dem * * επηί ** 6 2 ^ 1. Process for producing nickel or settling in the presence of one of the aforementioned gases Iron by thermal decomposition of nickel- 5 ^ cIgI- ^