GB2059409A - Process for producing hydrated iron oxide - Google Patents
Process for producing hydrated iron oxide Download PDFInfo
- Publication number
- GB2059409A GB2059409A GB8031808A GB8031808A GB2059409A GB 2059409 A GB2059409 A GB 2059409A GB 8031808 A GB8031808 A GB 8031808A GB 8031808 A GB8031808 A GB 8031808A GB 2059409 A GB2059409 A GB 2059409A
- Authority
- GB
- United Kingdom
- Prior art keywords
- treatment
- suspension
- goethite
- process according
- heat
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 title claims abstract description 22
- 238000000034 method Methods 0.000 title claims description 38
- 239000000725 suspension Substances 0.000 claims abstract description 39
- 229910052598 goethite Inorganic materials 0.000 claims abstract description 38
- AEIXRCIKZIZYPM-UHFFFAOYSA-M hydroxy(oxo)iron Chemical compound [O][Fe]O AEIXRCIKZIZYPM-UHFFFAOYSA-M 0.000 claims abstract description 38
- 239000007864 aqueous solution Substances 0.000 claims abstract description 19
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 claims abstract description 18
- 230000032683 aging Effects 0.000 claims abstract description 18
- 238000010438 heat treatment Methods 0.000 claims abstract description 18
- 229910001448 ferrous ion Inorganic materials 0.000 claims abstract description 15
- VTLYFUHAOXGGBS-UHFFFAOYSA-N Fe3+ Chemical compound [Fe+3] VTLYFUHAOXGGBS-UHFFFAOYSA-N 0.000 claims abstract description 11
- 229910001447 ferric ion Inorganic materials 0.000 claims abstract description 11
- 239000007800 oxidant agent Substances 0.000 claims abstract description 9
- 230000001590 oxidative effect Effects 0.000 claims abstract description 6
- 238000002156 mixing Methods 0.000 claims abstract description 4
- BAUYGSIQEAFULO-UHFFFAOYSA-L iron(2+) sulfate (anhydrous) Chemical compound [Fe+2].[O-]S([O-])(=O)=O BAUYGSIQEAFULO-UHFFFAOYSA-L 0.000 claims description 12
- 229910000359 iron(II) sulfate Inorganic materials 0.000 claims description 9
- 239000011790 ferrous sulphate Substances 0.000 claims description 7
- 235000003891 ferrous sulphate Nutrition 0.000 claims description 7
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical group OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims description 5
- 238000006386 neutralization reaction Methods 0.000 claims description 5
- XTEGARKTQYYJKE-UHFFFAOYSA-M Chlorate Chemical compound [O-]Cl(=O)=O XTEGARKTQYYJKE-UHFFFAOYSA-M 0.000 claims description 4
- 238000009835 boiling Methods 0.000 claims description 2
- 239000002585 base Substances 0.000 description 15
- 239000000843 powder Substances 0.000 description 13
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 12
- 238000004519 manufacturing process Methods 0.000 description 10
- SZVJSHCCFOBDDC-UHFFFAOYSA-N iron(II,III) oxide Inorganic materials O=[Fe]O[Fe]O[Fe]=O SZVJSHCCFOBDDC-UHFFFAOYSA-N 0.000 description 9
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 9
- 239000000243 solution Substances 0.000 description 7
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 6
- 150000003839 salts Chemical class 0.000 description 6
- 229910021578 Iron(III) chloride Inorganic materials 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 4
- 150000001875 compounds Chemical class 0.000 description 4
- RBTARNINKXHZNM-UHFFFAOYSA-K iron trichloride Chemical compound Cl[Fe](Cl)Cl RBTARNINKXHZNM-UHFFFAOYSA-K 0.000 description 4
- 239000006247 magnetic powder Substances 0.000 description 4
- 239000002244 precipitate Substances 0.000 description 4
- 239000000047 product Substances 0.000 description 4
- 238000003756 stirring Methods 0.000 description 4
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 3
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 3
- 238000002441 X-ray diffraction Methods 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 239000008367 deionised water Substances 0.000 description 3
- 229910021641 deionized water Inorganic materials 0.000 description 3
- 229910001873 dinitrogen Inorganic materials 0.000 description 3
- -1 ferrous compound Chemical class 0.000 description 3
- 239000002245 particle Substances 0.000 description 3
- 239000007858 starting material Substances 0.000 description 3
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 238000001914 filtration Methods 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- VKJKEPKFPUWCAS-UHFFFAOYSA-M potassium chlorate Chemical compound [K+].[O-]Cl(=O)=O VKJKEPKFPUWCAS-UHFFFAOYSA-M 0.000 description 2
- BZSXEZOLBIJVQK-UHFFFAOYSA-N 2-methylsulfonylbenzoic acid Chemical compound CS(=O)(=O)C1=CC=CC=C1C(O)=O BZSXEZOLBIJVQK-UHFFFAOYSA-N 0.000 description 1
- 238000004438 BET method Methods 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 230000003679 aging effect Effects 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 229910001854 alkali hydroxide Inorganic materials 0.000 description 1
- 229910001860 alkaline earth metal hydroxide Inorganic materials 0.000 description 1
- 230000005587 bubbling Effects 0.000 description 1
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 description 1
- 239000000920 calcium hydroxide Substances 0.000 description 1
- 229910001861 calcium hydroxide Inorganic materials 0.000 description 1
- 150000004649 carbonic acid derivatives Chemical class 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000011065 in-situ storage Methods 0.000 description 1
- 238000010348 incorporation Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 description 1
- 229910052753 mercury Inorganic materials 0.000 description 1
- 231100000989 no adverse effect Toxicity 0.000 description 1
- 239000000049 pigment Substances 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
- 229910000859 α-Fe Inorganic materials 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G49/00—Compounds of iron
- C01G49/02—Oxides; Hydroxides
- C01G49/06—Ferric oxide [Fe2O3]
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
- G11B5/62—Record carriers characterised by the selection of the material
- G11B5/68—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent
- G11B5/70—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer
- G11B5/706—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer characterised by the composition of the magnetic material
- G11B5/70626—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer characterised by the composition of the magnetic material containing non-metallic substances
- G11B5/70642—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer characterised by the composition of the magnetic material containing non-metallic substances iron oxides
- G11B5/70678—Ferrites
- G11B5/70684—Ferro-ferrioxydes
- G11B5/70689—Magnetite
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/12—Surface area
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/42—Magnetic properties
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Compounds Of Iron (AREA)
- Hard Magnetic Materials (AREA)
Abstract
A hydrated iron oxide comprising goethite as a main component is produced by mixing a base with an aqueous solution comprising ferrous ions as a main component and with an oxidizing agent for oxidizing the ferrous ions into ferric ions, and subjecting the alkaline suspension to a heat-treatment and optionally an ageing treatment.
Description
SPECIFICATION
Process for producing hydrated iron oxide
The present invention relates to a hydrated iron oxide comprising goethite as a main component.
Recently, goethite has been used in various fields such as in pigment as a source of ferrite and as a source of magnetic powders for magnetic recording media. The demand for goethite has therefore increased.
Various processes for producing a hydrated iron oxide comprising goethite as a main component by mass production methods and at economical cost have been proposed, in view of the increase in demand for goethite.
Goethite has been produced by adding an aqueous solution of a base at a concentration of 10 to 50% of the base sufficient for neutralization, to an aqueous solution of a ferrous compound such as ferrous sulfate to give a pH of about 4 and then bubbling air into the solution. The resulting goethite has not been of satisfactory quality because of the incorporation of relatively large amounts of impurities and the uneven configuration of particles which make the product unsatisfactory as a source of magnetic recording media.
A process for producing goethite by oxidation under alkaline conditions, instead of under acidic conditions has been proposed to overcome the above-mentioned disadvantages, and goethite of high purity with an even configuration of particles has been obtained in this way. The process, however, has disadvantages. Since the oxidation is carried out under alkaline conditions, it requires about twice the amount of base required for neutralization of the ferrous compound. The use of a larger amount of a base is disadvantageous from the point of increased production costs and the difficulty of water washing to remove the base after the reaction. There is also the problem that sodium hydroxide the base most commonly used, is still produced in large quantities by the mercury process which is a source of pollution.
It has been proposed to produce goethite from a ferric compound instead of the ferrous compound as the starting material. In the latter process, a base is added to an aqueous solution of the ferric compound in an amount slightly in excess (by a few %) of the amount required for neutralization and the mixture is treated by ageing for a long period or treated in an autoclave at a high temperature such as 150 to 2000C for about 1 hour to obtain goethite. The resulting goethite is of high purity with an even configuration of particles and thus of high quality. It takes about 100 to 200 hours to obtain goethite of good industrial quality by the ageing treatment. The productivity is remarkably low. On the other hand, treatment in an autoclave is not suitable for economical industrial mass production.
The latter process for producing goethite using the ferric compound as the starting material has not therefore been satisfactory.
As discussed, the conventional processes for producing a hydrated iron oxide comprising goethite as a main component have not been satisfactory as industrial processes, and accordingly, some improvement has been required.
The inventor has studied processes for producing a high quality hydrated iron oxide comprising goethite as a main component by mass production and at economical cost, from the viewpoints of product source saving, pollution, energy saving, productivity and product quality. As a result, the inventor has concluded that certain processes using the ferric compound as the starting material would be optimum for producing a hydrated iron oxide. In order to overcome the above-mentioned disadvantages, the inventor has concentrated on processes for producing goethite relatively quickly, without an autoclave and with only a modest consumption of base.
There are certain other important problems as regards the industrial process. The ferric salt is usually expensive in comparison with the cost of ferrous salts. In an industrial process, an aqueous solution of ferric chloride is the most commonly used ferric ion solution. An aqueous solution of ferric chloride is corrosive so that the apparatus has to be made of expensive anticorrosive materials. It seems desirable to generate the ferric salt in situ by oxidizing a ferrous salt so as to convert the ferrous ions into ferric ions, instead of using ferric chloride or the like as the source of the ferric salt.
In this process, it is still necessary to overcome other disadvantages of the conventional processes which use a ferric salt, for example the need for a long ageing treatment or a heat-treatment using an autoclave.
It is an object of the present invention to produce a high-quality hydrated iron oxide comprising goethite as a main component by a mass production process, relatively quickly and without the need for an autoclave or anti-corrosive equipment.
The present invention provides a process for producing a hydrated iron oxide comprising goethite as a main component, which process comprises mixing a base with an aqueous solution comprising ferrous ions as a main component and with an oxidizing agent for oxidizing the ferrous ions into the ferric ions, and subjecting the resulting alkaline suspension to a heat-treatment and optionally an ageing treatment.
The inventor has found that goethite of high quality can be rapidly obtained by heating an alkaline suspension comprising three main components, namely an aqueous solution of a ferrous ion (Fe2+), an oxidizing agent for oxidizing the ferrous ions into ferric ions (Fe3+) and a base.
Using the process of the invention, the advantages of the processes using ferric ions can be attained without using ferric chloride as a ferric ion source and goethite of high quality can be obtained relatively quickly without the need for a long ageing treatment or the use of an autoclave.
It is not clearly understood why the need for the
heat-treatment is minimized by converting the
ferrous salt into the ferric salt, in comparison with
the known process using the aqueous solution of
ferric ions obtained by dissolving a ferric salt.
However the process of the present invention has
been found to have several advantages as an
industrial process.
In the process of the present invention, the
aqueous solution of the ferrous ions as a main
component, the oxidizing agent for oxidizing the
ferrous ion into the ferric ion and the base are
mixed to prepare the alkaline suspension.
A typical aqueous solution of ferrous ions for
use in the process is a solution of ferrous sulfate.
Other ferrous salts can be also used. A suitable
oxidizing agent is hydrogen peroxide or a chlorate such as potassium chlorate or sodium chlorate. In the preparation, it is preferably to add the oxidizing agent gradually to the aqueous solution of the ferrous salt and then to add the solution of the base with stirring. The amount of the base is preferably slightly in excess, for example, by 1 to
10%, of the amount required for neutralization. A typical base is sodium hydroxide, but other alkali or alkaline earth metal hydroxides and carbonates such as potassium hydroxide and calcium hydroxide may be used.
The resulting alkaline suspension has a reddish brown color. The suspension is heat-treated to form goethite. The heat-treatment can be carried out at any desired temperature up to 10000, preferably higher than 450C, to change the color of the suspension from reddish brown into brownish yellow. Usually the heat-treatment is carried out for less than a few tens of hours. For example, the suspension is changed from reddish brown into brownish yellow at 550C in about 20 hours, completing the formation of goethite.
The resulting precipitate can be separated by filtration, washed with water and dried to give a fine acicular goethite powder.
The inventor has also found that the reaction for forming goethite can be accelerated by removing impurities which prevent the formation of goethite by separating at least a part of the solution from the alkaline suspension or by incorporating a small amount of ferrous ions in the suspension.
The former process can be carried out by separating the solution from the alkaline suspension obtained by mixing the three components by filtration or centrifugal separation and adding further aqueous base solution and heat-treating the resulting suspension.
The latter process can be easily carried out by controlling the amount of oxidizing agent used so as to leave a small amount of ferrous ions in the suspension to be heat-treated.
It is possible before or after the heat-treatment to subject the suspension to an ageing treatment.
When the alkaline suspension is heated at a high temperature such as 9000 from the beginning, goethite is not formed as satisfactorily as it could be. It is preferable to subject the alkaline suspension to an ageing treatment before the heat-treatment. The ageing treatment can be carried out at a temperature of 20 to 400 C, preferably at ambient temperature, for 3 to 20 hours with mild stirring whereby the alkaline suspension is changed from reddish brown into brown. When the suspension is heated after some ageing treatment, the quality of goethite is still high and the total treatment time can be remarkably shortened. The heat-treatment is usually carried out when the color has changed from reddish brown to brown, and generally requires less than 20 hours.The ageing effect useful for the conversion into goethite reaches its optimum level at a relatively early stage. When the temperature is raised after such stage, there is no adverse effect. After the ageing treatment, the suspension can be heated at a temperature from 7000 to the boiling point. The formation of goethite is accelerated by the heat-treatment. The suspension is changed to yellow as the formation of goethite is completed.
In the process of the present invention, the corrosion of equipment is not a problem and goethite of high quality can be produced by mass production methods, rapidly and at low cost. The industrial advantages of the process of the present invention are considerable.
The present invention will be illustrated by the following examples and references which are provided for purposes of illustration only and are not to be construed as limiting the invention.
EXAMPLE 1
In 1 liter of deionized water, 112 g. of ferrous sulfate (FeSO4 7H20) was dissolved and 90 ml. of 10% hydrogen peroxide solution gradually added and then 500 ml. of 2N-aqueous solution of sodium hydroxide was added with stirring. The resulting reddish brown suspension was heated at 5500 + 30C for 20 hours whereby the color of the suspension was changed to brownish yellow.
The precipitate was washed with water, filtered and dried to obtain a brownish yellow powder.
By X-ray diffraction, it was confirmed that the product was goethite. According to a measurement by the BET method, the powder had a specific surface area of 77.6 m2/g.
The powder was dehydrated at 60000 and reduced at 40000 in an atmosphere of nitrogen gas containing ethanol to obtain magnetite. The magnetic characteristics of the magnetite were a coercive force of 437 Oe and a saturation magnetic moment per unit weight of 80.7 emu/g.
The magnetite can be used as a magnetic powder for a magnetic recording medium.
EXAMPLE 2
Into 1 liter of a deionized water, 278 g. of ferrous sulfate (FeSO4#7H20) was dissolved and 300 ml. of 10% hydrogen peroxide solution was added at a rate of 10 mljmin. by a constant volumetric pump with stirring to prepare a reddish brown alkaline suspension having pH of about 12.5.
The suspension was treated by an ageing treatment at 2500 + 30C for 20 hours and then, treated by a heat-treatment at 9200 + 200 for 2 hours. After cooling the suspension, the precipitate was washed with water and filtered and dried to obtain a yellow powder.
According to the X-ray diffraction, it was confirmed that the yellow powder is goethite. The powder had a specific surface area of 53.3 m2/g.
The yellow powder was dehydrated at 60000 and reduced at 40000 in an atmosphere of nitrogen gas containing ethanol to obtain magnetite. The magnetite had magnetic characteristics of a coercive force of 454 Oe and a saturation magnetic moment per unit weight of 83.2 emu/g. The magnetite can be used as a magnetic powder for a magnetic recording medium.
REFERENCE 1
The reddish brown suspension was prepared by the process of Example 2 and the suspension was treated by an ageing treatment at 2500 + 30C for
60 hours. The suspension was not changed to
yellow.
REFERENCE 2
The reddish brown suspension was prepared by the process of Example 2 and the suspension was treated, without any ageing treatment, by a heattreatment at 9200 + 20C for 2 hours. The suspension was not changed to yellow. The suspension was further heated for 10 hours and cooled and washed with water and filtered and dried. The powder was brown and was not
goethite.
EXAMPLE 3
Into a deionized water, 139 g. of ferrous sulfate was dissolved to prepare 500 ml. of an aqueous solution of ferrous sulfate and a small amount of sulfuric acid was added to be pH of 1.3 and then, 200 ml. of 0.5 M aqueous solution of potassium chlorate (KOlO3) was added and the mixture was heated at 600 C. After 1 hour, 200 ml. of 6 N aqueous solution of sodium hydroxide was added to obtain a reddish brown suspension having pH of
12.5. The suspension was treated by an ageing treatment at 2500 + 30C for 20 hours and then, was treated by a heat-treatment at 9200 + 20C for 3 hours. After cooling the suspension, the precipitate was washed with water and filtered and dried to obtain a yellow powder.
According to the X-ray diffraction, it was
confirmed that the yellow powder was goethite.
The powder had a specific surface area of
45.5 m2/g.
The yellow powder was dehydrated at 60000 and reduced at 40000 in an atmosphere of
nitrogen gas containing ethanol to obtain
magnetite. The magnetite had magnetic
characteristics of a coercive force of 448 Oe and a
saturation magnetic moment per unit weight of
82.3 emu/g. The magnetite can be used as a
magnetic powder for a magnetic recording
medium.
Claims (9)
1. A process for producing a hydrated iron oxide comprising goethite as a main component, which process comprises mixing a base with an aqueous solution comprising ferrous ions as a main component and with an oxidizing agent for oxidizing the ferrous ions into the ferric ions, and subjecting the resulting alkaline suspension to a heat-treatment and optionally an ageing treatment.
2. A process according to claim 1 , wherein said aqueous solution of ferrous ions is an aqueous solution of ferrous sulfate.
3. A process according to claim 1 or claim 2, wherein said oxidizing agent is a hydrogen peroxide solution or a chlorate.
4. A process according to any preceding claim, wherein said ageing treatment is carried out before the heat-treatment, at least until the color of said alkaline suspension changes from reddish brown to brown.
5. A process according to any preceding claim, wherein said ageing treatment is carried out at 20 to 4000.
6. A process according to any preceding claim, wherein said heat-treatment is carried out at a temperature from 4500 to the boiling point of the suspension.
7. A process according to any preceding claim, wherein said base is added in an amount slightly in excess of that required for neutralization.
8. A process according to any preceding claim, wherein the suspension is aged after the heat treatment.
9. A process according to claim 1, substantially as herein described with reference to any one of the Examples.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP12635679A JPS5650123A (en) | 1979-10-02 | 1979-10-02 | Manufacture of iron oxide hydrate |
| JP12635779A JPS5650124A (en) | 1979-10-02 | 1979-10-02 | Manufacture of iron oxide hydrate |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB2059409A true GB2059409A (en) | 1981-04-23 |
Family
ID=26462563
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8031808A Withdrawn GB2059409A (en) | 1979-10-02 | 1980-10-02 | Process for producing hydrated iron oxide |
Country Status (3)
| Country | Link |
|---|---|
| DE (1) | DE3037348A1 (en) |
| GB (1) | GB2059409A (en) |
| NL (1) | NL8005432A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6224385B1 (en) | 1997-07-15 | 2001-05-01 | Honda Giken Kogyo Kabushiki Kaisha | Job aiding apparatus |
-
1980
- 1980-10-01 NL NL8005432A patent/NL8005432A/en not_active Application Discontinuation
- 1980-10-02 DE DE19803037348 patent/DE3037348A1/en not_active Withdrawn
- 1980-10-02 GB GB8031808A patent/GB2059409A/en not_active Withdrawn
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6224385B1 (en) | 1997-07-15 | 2001-05-01 | Honda Giken Kogyo Kabushiki Kaisha | Job aiding apparatus |
Also Published As
| Publication number | Publication date |
|---|---|
| DE3037348A1 (en) | 1981-04-23 |
| NL8005432A (en) | 1981-04-06 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |