JPH06122519A - Hydrated amorphous ferric oxide particle powder and its production - Google Patents

Abstract

PURPOSE:To produce hydrated amorphous ferric oxide particle powder on an industrial scale by hydrolyzing jarosite produced from ferrous sulfate suitable as an adsorbent for sulfur oxides, hydrogen sulfide, nitrogen oxides, etc., in air or in a gas or as a deodorant, catalyst, etc. CONSTITUTION:A mixture of an aqueous solution of ferrous sulfate, an aqueous solution of an alkali metal sulfate or ammonium sulfate and an aqueous solution of sulfuric acid is oxidized and the obtained jarosite particles are washed and suspended in water. The aqueous suspension is incorporated with an aqueous solution of an alkali hydroxide or aqueous solution of ammonia and stirred under heating to form hydrated amorphous ferric oxide particles. The particles are separated by filtration, washed and dried to obtain the objective hydrated amorphous ferric oxide particle powder having an average particle diameter of 3-30mum, a BET specific surface area of 150-300m<2>/g and a bulk density of 0.7-1.1g/mL.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to amorphous ferric oxide hydroxide particles and a method for producing the same.

The main uses of the amorphous ferric oxide hydroxide powder according to the present invention are adsorbents such as sulfur oxides, hydrogen sulfide and nitrogen oxides in the air and gases, deodorants and catalysts. is there.

Further, paints, printing inks, cosmetics, rubbers,
It can also be used as a raw material for color pigments for plastics, ferrite, magnetic particle powder for magnetic recording, and the like.

[0004]

2. Description of the Related Art Sulfur oxides, hydrogen sulfide, etc. in the atmosphere and gases, nitrogen oxides, etc. are the main causes of air pollution. Exhaust gas has been discharged, and although various measures have been taken, it is still inadequate, and it has excellent adsorption capacity for sulfur oxides, hydrogen sulfide, nitrogen oxides, etc. in gas. There is a strong demand for the development of agents and deodorants.

[0005] This fact is, for example, that the concentration of nitrogen oxides in the atmosphere in cities does not decrease even if various measures are taken, "Chemical Society of Japan" (1985), page 2315, published by The Chemical Society of Japan. Not only that, but also an increasing trend is seen, and efforts to remove nitrogen oxides are becoming more and more important. ”

Conventionally, activated carbon, silica gel, zeolite and the like are generally well known as adsorbents.

[0007]

Although an adsorbent having excellent adsorption ability for sulfur oxide, hydrogen sulfide, etc., nitrogen oxide, etc. is currently most demanded, the known adsorbents as mentioned above are It has been pointed out that it is still insufficient as an adsorbent for sulfur oxides, hydrogen sulfide and nitrogen oxides.

This fact is explained, for example, by "Inorganic compounds such as activated carbon and various metal oxides in order to adsorb and remove sulfur dioxide," pp. 665, "Chemical Society of Japan", published by The Chemical Society of Japan (1978). However, there are still problems with the adsorption capacity, selectivity, regeneration method, etc., and the development of new adsorbents is desired. ”And the above-mentioned“ Chemical Society of Japan ”(1985). ) On page 2315, “general adsorbents such as activated carbon, silica gel and zeolite are effective for NO ₂ , but their ability to adsorb NO is not sufficient. It is desired. ”

It is also known that iron oxide hydroxide particles are excellent in adsorption ability for sulfur compounds such as sulfur oxides.

This fact is due to, for example, the fact that since the finding that the iron oxide hydroxide has a high ability to chemisorb SO ₂ on page 681 of the Journal of the Chemical Society of Japan (1980) published by the Chemical Society of Japan, SO ₂ For the purpose of studying its potential as a chemical adsorption material, SO ₂ from a mixed gas close to the combustion furnace exhaust gas composition
As a result of conducting an adsorption experiment, it was found that the SO ₂ adsorption capacity was hardly influenced by the coexisting H ₂ O, and the like.

By the way, the deodorant adsorbs malodorous substances such as sulfur compounds and nitrogen compounds on the surface of the deodorant. Therefore, the larger the specific surface area of the deodorant is, the higher the adsorption capacity is. Only a large specific surface area is required.

[0012] This fact is because, for example, in the study of gas molecule adsorption on a solid surface, "Powder with a large surface area" is used in "Journal of the Chemical Society of Japan" (1980), p. There are many ... ".

In order to increase the specific surface area, it is generally sufficient to reduce the size of particles. Also, when used as a catalyst, the larger the specific surface area, the higher the catalytic activity.

However, the specific surface area of the iron oxide hydroxide particles as described above is not more than about 100 m ² / g in practice because the particles agglomerate as the particles become finer, so the adsorption capacity is still insufficient. In addition, the bulk density is as high as about 0.5 g / ml or less, and dust is easily generated, so that workability such as handling is poor.

Therefore, as the adsorbent, the deodorant and the catalyst, an amorphous substance having a high activity and a large specific surface area and a large bulk density and excellent workability are strongly demanded. Is a technical subject to meet this demand.

As a method for obtaining amorphous iron oxide particles, Japanese Patent Publication No. 59-27608 and Japanese Unexamined Patent Publication No. 64-83.
522 and "Metaradical Transactions B (METALLURGICAL TRANSACT
IONS B) "Vol. 10B (1979) No. 439
Each of the technical means described on page 446 is known.

In the technical means disclosed in Japanese Patent Publication No. 59-27608, in which amorphous iron oxide is obtained by heating the goethite to remove the water of crystallization, the goethite is obtained by heating and dehydrating the goethite. It is the hematite that was made. Further, the technical means disclosed in Japanese Patent Laid-Open No. 64-83522 is a hydrated iron oxide wall microcapsule obtained by an interfacial reaction method from a W / O type emulsion composed of an aqueous iron nitrate solution and an organic solvent and an aqueous sodium hydrogen carbonate solution. is there. Further, in the technical means for hydrolyzing jarosite described in the above-mentioned “Metaradical Transactions B”, it is described that hematite crystals are formed as a result of X-ray diffraction.

[0018]

The above technical problems can be achieved by the present invention as follows.

That is, in the present invention, the spherical particles have an average diameter of 3
-30 μm, BET specific surface area 150-300 m ² / g
And amorphous ferric oxide hydroxide powder having a bulk density of 0.7 to 1.1 g / ml,

An oxygen-containing gas is passed through a mixed solution of an aqueous solution of ferrous sulfate, an aqueous solution of a sulfate of an alkali metal or ammonium ion, and an aqueous solution of sulfuric acid to carry out an oxidation reaction in the temperature range above 45 ° C. and below the boiling point. , By generating jarosite particles, washing the generated jarosite particles, and then dispersing in water to form an aqueous suspension, and by adding an aqueous alkali hydroxide solution or an aqueous ammonia solution to the suspension and stirring with heating, Generate crystalline ferric hydroxide particles,
The produced amorphous ferric hydroxide particles were filtered, washed and dried to form a spherical shape having an average diameter of 3 to 30 μm, a BET specific surface area of 150 to 300 m ² / g and a bulk density of 0.7 to 1. ．
A method for producing amorphous ferric hydroxide oxide particles, characterized in that amorphous ferric hydroxide oxide powder particles of 1 g / ml are obtained;

An oxygen-containing gas is passed through a mixed solution of an aqueous solution of ferrous sulfate, an aqueous solution of a sulfate of an alkali metal or ammonium ion, and an aqueous solution of sulfuric acid to carry out an oxidation reaction in the temperature range above 45 ° C. and below the boiling point. A first step of producing jarosite particles, filtering the produced jarosite particles to recover a filtrate, and then adding a new ferrous sulfate and an alkali hydroxide or ammonia to the filtrate recovered in the first step. A jarosite particle is generated by aerating an oxygen-containing gas into a new mixed solution containing the above-mentioned compound to carry out an oxidation reaction in the temperature range above 45 ° C. and below the boiling point.
Of the jarosite particles produced in the second step by repeating the reaction of the second step by using the filtrate collected by filtering the jarosite particles produced in the second step to produce jarosite particles, The jarosite particles obtained in the third step of filtering and the first to third steps are washed and then dispersed in water to obtain an aqueous suspension, and the suspension is treated with an aqueous alkali hydroxide solution or an aqueous ammonia solution. In addition, by heating and stirring, amorphous ferric hydroxide-containing ferric oxide particles are produced, and the produced amorphous ferric hydroxide-containing ferric oxide particles are separated by filtration, washed, and dried to have a spherical average diameter of 3 to 10. 30 μm, BE
The T specific surface area is 150 to 300 m ² / g and the bulk density is 0.
A fourth step of obtaining an amorphous ferric hydroxide oxide hydroxide particle powder of 7 to 1.1 g / ml, and a method for producing an amorphous ferric hydroxide oxide powder powder,

An oxygen-containing gas is passed through a mixed solution of an aqueous solution of ferrous sulfate, an aqueous solution of a sulfate of an alkali metal or ammonium ion, and an aqueous solution of sulfuric acid to carry out an oxidation reaction in the temperature range above 45 ° C. and below the boiling point. , A jarosite particle is produced, and a slurry obtained by washing the produced jarosite particle, or a mixed solution of an aqueous solution of ferrous sulfate and a sulfate aqueous solution of an alkali metal or ammonium ion, and an aqueous solution of sulfuric acid, an oxygen-containing gas is added. A jarosite particles by performing an oxidation reaction in the temperature range of more than 45 ° C. and not more than the boiling point by aeration, and the generated jarosite particles are filtered off to recover the filtrate, and then the first step is performed.
An oxygen-containing gas is passed through a new mixed solution prepared by newly adding ferrous sulfate and alkali hydroxide or ammonia to the filtrate recovered in the step of, and the oxidation reaction is performed in the temperature range above 45 ° C. and below the boiling point. Thus, by repeating the reaction of the second step with the second step of producing the jarosite particles, and subsequently using the filtrate recovered by filtering the jarosite particles produced in the second step, Particles are formed and the formed jarosite particles are filtered off.
And the slurry obtained by washing the jarosite particles obtained in each of the first to third steps consisting of the above step is dispersed in water to prepare an aqueous suspension in the range of 100 to 1000 g / l as jarosite. After that, an alkali hydroxide aqueous solution or an ammonia aqueous solution is added to make the alkali addition ratio equal to or more than SO _{4 in} jarosite, and the mixture is heated and stirred at a temperature range of 30 to 90 ° C. for 5 to 60 minutes. Amorphous ferric hydroxide oxide particles are produced, and the produced amorphous ferric hydroxide particles are filtered, washed, and dried to have a spherical shape, an average diameter of 3 to 30 μm, and a BET specific surface area of 150. ~ 30
A method for producing amorphous ferric oxide hydroxide particles, characterized by obtaining amorphous ferric hydroxide oxide powder particles having a bulk density of 0.7 to 1.1 g / ml at 0 m ² / g. is there.

Next, various conditions for carrying out the present invention will be described.

The concentration of the reaction solution in the present invention is 0.1 to 2.0 mol / l as Fe. More preferably, it is 0.2 to 1.0 mol / l. When it is less than 0.1 mol / l, productivity is deteriorated and it is not economical.
If it exceeds 0 mol / l, crystals such as sodium sulfate and the like other than jarosite particles may be precipitated in the reaction tank or the like, which makes handling difficult.

As the alkali metal or ammonium ion sulfate aqueous solution used in the present invention, an aqueous solution of sodium sulfate, potassium sulfate, ammonium sulfate or the like can be used.

The above-mentioned sulfate aqueous solution in the present invention is 5 to 200 mol% with respect to Fe in the ferrous sulfate aqueous solution. If it is less than 5 mol%, it is difficult to form jarosite particles, and if it exceeds 200 mol%, the reaction rate becomes slow, which is not economical.

The sulfuric acid aqueous solution used in the present invention is
It is 0.02-0.1 mol / l. 0.02 mol /
When it is less than 1, it is not preferable because α-FeOOH is mixed, and when it exceeds 0.1 mol / l, the reaction rate becomes slow, which is not preferable.

As the alkali hydroxide used in the second step of the present invention, crystals of sodium hydroxide, potassium hydroxide or the like, or ammonia gas can be used. Alkali hydroxide or ammonia is the second
It is equimolar to the ferrous sulfate used in the step.

The alkali hydroxide or ammonia used in the second step of the present invention is the same as the alkali metal or ammonium ion sulfate aqueous solution used in the first step. Even if the same particles are not used, jarocite particles are produced, but since the composition differs depending on the alkali, jarosite particles having different compositions are mixed.

The reaction temperature in the present invention is in the temperature range above 45 ° C. and below the boiling point. More preferably 60-80 ° C
Is. If it is lower than 45 ° C., the reaction rate becomes very slow, and if it exceeds the boiling point, special equipment is required, which is not preferable.

The oxidizing means in the present invention is carried out by aerating an oxygen-containing gas (for example, air) in the solution, and also by agitating the aerated gas or mechanical operation.

The present invention is not limited to the method of repeating the batch method shown in the examples, but the reaction solution is continuously withdrawn, the jarosite particles and the filtrate are separated by filtration, and the filtrate is returned to the reaction tank and ferrous sulfate is added. It can also be carried out by a method of continuously supplying and alkali to the reaction tank.

In the present invention, when the jarosite particles are produced, A
l, Si, P, Mn, Co, Ni, Cu, Zn, Mg,
Different elements such as Ca, Ti, Cr, Sn and Pb can also be added.

The jarosite particles used in the production of the amorphous ferric oxide hydroxide particles according to the present invention are washed and then added with an aqueous alkali hydroxide solution or an aqueous ammonia solution and heated and stirred. The washed jarosite particles mean that when iron etc. remain on the jarosite particles, colloidal precipitation occurs when the alkali is added, resulting in agglomeration of particles or clogging of filter cloth. This is because it causes problems.

The concentration of the aqueous suspension for producing amorphous ferric oxide hydroxide particles in the present invention is 100 to 1000 g / l as jarosite. When it is less than 100 g / l, it is not economical, and when it exceeds 1000 g / l, the stirring is insufficient but the reaction is difficult to be uniformly carried out depending on the stirring ability.

The aqueous alkali hydroxide solution or aqueous ammonia solution used to form the amorphous ferric hydroxide-containing particles may be the same as the alkaline hydroxide or ammonia. The amount of alkali added is equivalent to or more than SO _{4 in} jarosite. If the amount is less than the equivalent, unreacted jarosite may remain, which is not preferable. The alkali concentration may be high, but economically 1.1 equivalent or less is preferable.

In this case, the same alkaline aqueous solution as when the jarosite particles were produced may be used, or a different alkaline aqueous solution may be used.

The temperature for heating and stirring is 30 to 90 ° C., and the stirring time is 5 to 60 minutes. If the temperature is lower than 30 ° C, it is necessary to perform cooling or the like, which is not preferable. If the stirring time is less than 5 minutes, unreacted substances remain unreacted, and if it exceeds 60 minutes, crystallization occurs, which is not preferable.

In the present invention, the jarosite particles in the form of spheres having an average diameter of 3 to 30 μm, which are obtained by aggregating the plate-like, hexahedral, octahedral, etc. particles obtained under the above-mentioned production conditions, are hydrolyzed under the above-mentioned conditions. As a result, a spherical shape having an average diameter of 3 to 30 μm and a BET specific surface area of 150 to 300 m
Amorphous ferric oxide hydroxide particles having a bulk density of 0.7 to 1.1 g / ml at ² / g can be obtained.

[0040]

[Operation] Oxygen-containing gas is passed through a mixed solution of an aqueous solution of ferrous sulfate, an aqueous solution of a sulfate of an alkali metal or ammonium ion, and an aqueous solution of sulfuric acid to carry out an oxidation reaction in a temperature range above 45 ° C and below the boiling point. This makes it possible to generate only jarosite particles in the form of spheres having an average diameter of 3 to 30 μm in which tabular, hexahedral, octahedral, etc. particles are aggregated.

Alternatively, in the first step, an oxygen-containing gas is passed through a mixed solution of an aqueous solution of ferrous sulfate, an aqueous solution of a sulfate of an alkali metal or ammonium ion, and an aqueous solution of sulfuric acid, and the temperature is higher than 45 ° C. and not higher than the boiling point. By carrying out the oxidation reaction in the temperature range, it is possible to generate only jarosite particles having a spherical shape with an average diameter of 3 to 30 μm, in which tabular, hexahedral, octahedral, etc. particles are aggregated.

Next, in the second step, based on the following reaction formula 1, to prevent the total volume of the reaction solution from increasing in the filtrate recovered by filtering the jarosite particles obtained in the first step, A new mixed solution is prepared by supplementing ferrous sulfate crystals and alkali hydroxide crystals or ammonia gas in an amount corresponding to the yield of jarosite particles produced in the first step. By using the obtained new mixed solution and performing an oxidation reaction under the same conditions as in the first step, only jarosite particles equivalent to those in the first step can be produced.

The inventor has found that the reaction formula 1 of the second step is as follows: 3FeSO ₄ + 3ROH → RFe ₃ (SO ₄ ) ₂ (OH) ₆ + R ₂ SO ₄ (where R = K ⁺ , Na ⁺ , NH ⁺ And so on.)

The compositions of the filtrate recovered in the first step and the filtrate recovered in the second step of the present invention are almost the same and are as follows. Fe ²⁺ = 5 to 40 g / l Fe ³⁺ = 5 to 15 g / l R = 0.5 to 30 g / l SO ₄ ^2- = 70 to 150 g / l (however, R = K ⁺ , Na ⁺ , NH ⁺ Etc.)

Therefore, by using the filtrate recovered in the second step and repeating the same reaction as in the second step, only jarosite particles can be produced.

In the present invention, the powdery jarosite particles are used for hydrolysis with alkali hydroxide or ammonia to produce amorphous ferric oxide hydroxide particles.

The fact that the substance is amorphous can be explained by the fact that no clear peak was observed as shown in FIG. 4 as a result of X-ray diffraction, and the substance was hydrated as shown in FIG. By thermal analysis (SSC5000 thermal analysis system, Seiko Denshi Kogyo Co., Ltd.), strongly adsorbed water having a peak of about 200 ° C. is removed after removing adhered water at a temperature of less than 150 ° C. Is clear from.

In the technical means for hydrolyzing jarosite particles described in the above-mentioned "Metaradical Transactions B", hematite crystals are formed, but the concentration of the aqueous suspension, the alkali concentration, the heating temperature and Since the stirring time was not controlled, it is considered that hematite crystals were generated as shown in Comparative Examples below.

Further, as described above, since the starting material of the jarosite particles obtained thus far is ferric sulfate, the production history of the jarosite particles obtained from the ferrous sulfate of the present invention is different. I think that the hydrolysis conditions may differ due to the difference.

[0050]

The present invention will be described below with reference to Examples and Comparative Examples.

The average particle size of the particles in the following examples and comparative examples is shown by the average value of the numerical values measured from electron micrographs. The bulk density was obtained by adding powder to a 100 ml measuring cylinder until the volume reached 100 ml and weighing the weight at that time.

<Production of Jarosite Particle Powder> Examples 1 to 7 Comparative Examples 1 and 2;

Example 1 2500 ml of a 1.8 mol / l FeSO ₄ aqueous solution,
1000 ml of 0.45 mol / l Na ₂ SO ₄ aqueous solution
(Corresponds to 10 mol% with respect to Fe in the FeSO ₄ aqueous solution) and 0.23 mol / l H ₂ SO ₄ 1000
ml (corresponding to 0.05 mol / l in all reaction solutions) was charged into a reaction vessel to prepare a mixed solution, and air was added to
The mixture was blown at a rate of 00 ml / min with stirring to carry out an oxidation reaction at a temperature of 70 ° C. for 24 hours to form a precipitate.

The formed precipitate was filtered, washed and dried by a conventional method to obtain 209 g of particle powder.

As a result of X-ray diffraction, the obtained particle powder was jarosite, and was a particle having a 22 μm hexahedral agglomerated spherical shape.

Example 2 In the first step, 2500 ml of a 1.8 mol / l FeSO ₄ aqueous solution and 0.45 mol / l Na ₂ SO _{4 were used.}
1000 ml of the aqueous solution (corresponding to 10 mol% with respect to Fe in the FeSO ₄ aqueous solution) and 1000 ml of 0.23 mol / l H ₂ SO ₄ (0.05 mo in all reaction solutions)
It corresponds to 1 / l. ) Is charged into a reaction vessel to prepare a mixed solution, air is blown at a rate of 15000 ml / min, and the mixture is stirred to carry out an oxidation reaction at a temperature of 70 ° C. for 24 hours to form a precipitate of the first step. The filtrate was collected by filtration.

Next, in the reaction of the second step, F was added to 4300 ml of the filtrate recovered by filtering off the precipitate of the first step.
eSO ₄ · 7H ₂ O crystals 359g of NaOH crystals 52g
(Corresponding to a equimolar to FeSO ₄ · 7H ₂ O.)
Was dissolved into a mixed solution and charged into a reaction vessel. Air was blown into the mixed solution at a rate of 15000 ml / min and the mixture was stirred, and an oxidation reaction was carried out at a temperature of 70 ° C. for 24 hours to form a precipitate in the second step.

Subsequently, the precipitate of the second step was filtered and recovered, and 4300 ml of the recovered filtrate was used to carry out an oxidation reaction under the same conditions as the reaction of the second step to produce the precipitate of the third step. And filtered off.

The precipitates obtained in the first to third steps were washed and dried by a conventional method to give 209 g, 205
g, 212 g of particle powder was obtained.

As a result of X-ray diffraction, each of the obtained particle powders was jarosite. As shown in the scanning electron micrographs (× 2000) shown in FIGS.
The particles were in the form of agglomerated spheres having a size of μm, 22 μm, and 21 μm.

Examples 3 to 7 and Comparative Examples 1 to 2 Concentration and amount of ferrous sulfate aqueous solution in the first step of Example 2, type, concentration, amount of alkaline metal sulfate aqueous solution and amount of Fe Ratio, concentration of sulfuric acid aqueous solution,
In the second and third steps, the amount used, the concentration with respect to the total reaction solution, and the reaction temperature, ferrous sulfate 7 corresponding to the yield of the jarosite particle powder in the immediately preceding step, respectively.
Example 2 except that the amount of hydrate used, the same amount of alkali hydroxide used, and the same reaction temperature were variously changed.
A jarosite particle powder was obtained in the same manner as in.

In Comparative Example 1, goethite particles were mixed, and in Comparative Example 2, jarosite particles were not produced.

The main manufacturing conditions and various characteristics at this time are shown in Tables 1 and 2.

[0064]

[Table 1]

[0065]

[Table 2]

<Production of Amorphous Ferric Hydroxide Hydroxide Particle Powder> Examples 8 to 24 Comparative Examples 3 to 6;

Example 8 Precipitate of jarosite particles obtained in Example 2 8600
After washing ml (corresponding to 400 g as jarosite), it was dispersed in 1000 ml of water to obtain a suspension.

193 ml of an 18 mol / l NaOH aqueous solution (1.0 ml based on SO _{4 in} jarosite) was added to the suspension.
It corresponds to 5 equivalents. ) Is added and the temperature is 60 ° C.
The mixture was heated and stirred for 0 minutes to form a brown precipitate.

The formed precipitate was filtered, washed and dried by a conventional method to obtain 190 g of brown particle powder.

As a result of X-ray diffraction, the obtained particle powder did not show a clear peak as shown in FIG. 4, and as shown in FIG. 5, thermal analysis showed that strongly chemisorbed water was present. 6
As shown in the electron micrograph (× 100), the particles are spherical and have an average diameter of 18 μm and a BET specific surface area of 250 m ² /
The powder was amorphous ferric oxide hydroxide particles having a bulk density of 0.78 g / ml.

Examples 9 to 24, Comparative Examples 3 to 6 Examples except that the type of jarosite particle powder, the concentration of the aqueous dispersion, the type and amount of the alkaline aqueous solution, and the temperature and time of heating and stirring were changed variously. Amorphous ferric oxide hydroxide particles were obtained in the same manner as in 8.

The particle powders obtained in Comparative Examples 3 to 6 were X.
As a result of observation by line diffraction, clear peaks were observed in Comparative Examples 3 and 4, and in Comparative Examples 5 and 6, the reaction was insufficient and jarosite was mixed.

Table 3 shows the main manufacturing conditions and various characteristics at this time.

[0074]

[Table 3]

[0075]

INDUSTRIAL APPLICABILITY According to the present invention, there is an amorphous ferric oxide hydroxide particle powder obtained by hydrolyzing jarosite particles produced by using inexpensive ferrous sulfate, which has a spherical shape. Large particles with an average diameter of 3 to 30 μm and a BET specific surface area of 1
Very large with 50-300 m ² / g, and high bulk density of 0.7-1.1 g / ml, which has low dust generation and excellent workability. It is suitable as an agent and a catalyst.

It can be also used as a raw material for paints, printing inks, cosmetics, color pigments for rubber and plastics, ferrite and magnetic particle powder for magnetic recording.

[0077]

[Brief description of drawings]

FIG. 1 is a scanning electron micrograph (× 2) showing a particle structure of a jarosite particle powder obtained in the first step of Example 2.
000).

FIG. 2 is a scanning electron micrograph (× 2) showing the particle structure of the jarosite particle powder obtained in the second step of Example 2.
000).

FIG. 3 is a scanning electron micrograph (× 2) showing the particle structure of the jarosite particle powder obtained in the third step of Example 2.
000).

FIG. 4 is an X-ray diffraction diagram of the amorphous ferric oxide hydroxide particles powder obtained in Example 8.

FIG. 5 is a thermal analysis chart of the amorphous ferric oxide hydroxide particles obtained in Example 8.

FIG. 6 is a scanning electron micrograph (× 10) showing the particle structure of the amorphous ferric hydroxide oxide powder obtained in Example 8.
0).

Claims (4)

[Claims] 1. A spherical average particle diameter of 3 to 30 μm, B
Amorphous ferric oxide hydroxide powder having an ET specific surface area of 150 to 300 m ² / g and a bulk density of 0.7 to 1.1 g / ml. 2. An oxygen-containing gas is passed through a mixed solution of an aqueous solution of ferrous sulfate, an aqueous solution of a sulfate of an alkali metal or ammonium ion, and an aqueous solution of sulfuric acid to carry out an oxidation reaction in the temperature range above 45 ° C. and below the boiling point. Thereby, the jarosite particles are produced, and after the produced jarosite particles are washed, they are dispersed in water to form an aqueous suspension, and an aqueous solution of an alkali hydroxide or an aqueous ammonia solution is added to the suspension and the mixture is heated and stirred. , Producing amorphous ferric oxide hydroxide particles, filtering and washing the produced amorphous ferric hydroxide particles,
When dried, it has a spherical shape with an average diameter of 3 to 30 μm, a BET specific surface area of 150 to 300 m ² / g, and a bulk density of 0.7 to
A process for producing amorphous ferric oxide hydroxide particles, characterized in that the amorphous ferric hydroxide oxide powder particles of 1.1 g / ml are obtained. 3. An oxygen-containing gas is passed through a mixed solution of an aqueous ferrous sulfate solution, an aqueous solution of a sulfate of an alkali metal or ammonium ion, and an aqueous solution of sulfuric acid to carry out an oxidation reaction in the temperature range above 45 ° C. and below the boiling point. Thereby, the first step of producing jarosite particles, filtering the produced jarosite particles to recover the filtrate, and then adding a new ferrous sulfate and an alkali hydroxide to the filtrate recovered in the first step or A second step of producing jarosite particles by aerating an oxygen-containing gas into a new mixed solution containing ammonia and performing an oxidation reaction in the temperature range of higher than 45 ° C. and lower than the boiling point, and subsequently, The jarosite particles produced in the second step are separated by filtration, and the reaction of the second step is repeated using the filtrate recovered to produce jarosite particles. The jarosite particles obtained in the third step of filtering off the site particles and each of the first to third steps are washed and then dispersed in water to obtain an aqueous suspension. Amorphous ferric oxide hydroxide particles are produced by adding an aqueous ammonia solution and stirring with heating, and the produced amorphous ferric hydroxide particles are filtered, washed and dried to give a spherical average diameter. Is 3 to 30 μm, BE
The T specific surface area is 150 to 300 m ² / g and the bulk density is 0.
A fourth step of obtaining an amorphous ferric hydroxide-containing hydroxide particle powder of 7 to 1.1 g / ml. 4. An oxygen-containing gas is passed through a mixed solution of an aqueous solution of ferrous sulfate, an aqueous solution of a sulfate of an alkali metal or ammonium ion, and an aqueous solution of sulfuric acid to carry out an oxidation reaction in the temperature range above 45 ° C. and below the boiling point. Thus, to produce jarosite particles, a slurry obtained by washing the produced jarosite particles, or a mixed solution of a ferrous sulfate aqueous solution and a sulfate aqueous solution of an alkali metal or ammonium ion, and a sulfuric acid aqueous solution, oxygen. By aerating the contained gas and carrying out the oxidation reaction in the temperature range above 45 ° C. and below the boiling point,
The first step of producing jarosite particles, filtering the produced jarosite particles to recover the filtrate, and then adding the ferrous sulfate and alkali hydroxide or ammonia to the filtrate recovered in the first step. A second step of generating jarosite particles by passing an oxygen-containing gas through the newly added mixed solution and performing an oxidation reaction in the temperature range higher than 45 ° C. and lower than the boiling point, and subsequently, a second step Using the filtrate recovered by filtering the jarosite particles produced in the process
By repeating the reaction of the step of, the jarosite particles are produced, and the jarosite particles obtained in each of the first to third steps consisting of the third step of filtering the produced jarosite particles are washed. The obtained slurry is dispersed in water to form jarosite as an aqueous suspension in the range of 100 to 1000 g / l, and then an aqueous alkali hydroxide solution or an aqueous ammonia solution is added to the jarosite to alkalinize SO _{4 in} jarosite. By making the addition ratio equivalent or more and heating and stirring in the temperature range of 30 to 90 ° C. for 5 to 60 minutes,
Amorphous ferric hydroxide oxide particles are produced, and the produced amorphous ferric hydroxide particles are filtered, washed, and dried to form a spherical average diameter of 3 to 30 μm, and BET specific surface area of 150 to Three
A process for producing amorphous ferric oxide hydroxide particles, which comprises obtaining amorphous ferric hydroxide oxide powder particles having a bulk density of 0.7 to 1.1 g / ml at 00 m ² / g.