GB1567957A - Method for producing needle-shaped fine particles of -goehite - Google Patents
Method for producing needle-shaped fine particles of -goehite Download PDFInfo
- Publication number
- GB1567957A GB1567957A GB180877A GB180877A GB1567957A GB 1567957 A GB1567957 A GB 1567957A GB 180877 A GB180877 A GB 180877A GB 180877 A GB180877 A GB 180877A GB 1567957 A GB1567957 A GB 1567957A
- Authority
- GB
- United Kingdom
- Prior art keywords
- goethite
- bubbles
- ferrous
- fine particles
- solution
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 239000010419 fine particle Substances 0.000 title claims description 21
- 238000004519 manufacturing process Methods 0.000 title claims description 7
- 238000000034 method Methods 0.000 claims description 35
- 229910052598 goethite Inorganic materials 0.000 claims description 29
- 229910021506 iron(II) hydroxide Inorganic materials 0.000 claims description 23
- NCNCGGDMXMBVIA-UHFFFAOYSA-L iron(ii) hydroxide Chemical compound [OH-].[OH-].[Fe+2] NCNCGGDMXMBVIA-UHFFFAOYSA-L 0.000 claims description 23
- 239000012670 alkaline solution Substances 0.000 claims description 18
- 239000007864 aqueous solution Substances 0.000 claims description 12
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N iron oxide Inorganic materials [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 claims description 12
- 239000000843 powder Substances 0.000 claims description 11
- 239000000243 solution Substances 0.000 claims description 11
- 239000003513 alkali Substances 0.000 claims description 10
- 230000001590 oxidative effect Effects 0.000 claims description 10
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 9
- 239000001301 oxygen Substances 0.000 claims description 9
- 229910052760 oxygen Inorganic materials 0.000 claims description 9
- 235000003891 ferrous sulphate Nutrition 0.000 claims description 7
- 239000011790 ferrous sulphate Substances 0.000 claims description 7
- BAUYGSIQEAFULO-UHFFFAOYSA-L iron(2+) sulfate (anhydrous) Chemical group [Fe+2].[O-]S([O-])(=O)=O BAUYGSIQEAFULO-UHFFFAOYSA-L 0.000 claims description 7
- 229910000359 iron(II) sulfate Inorganic materials 0.000 claims description 7
- 150000002505 iron Chemical class 0.000 claims description 6
- 239000007788 liquid Substances 0.000 claims description 6
- 239000012153 distilled water Substances 0.000 claims description 5
- 230000003647 oxidation Effects 0.000 claims description 5
- 238000007254 oxidation reaction Methods 0.000 claims description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 5
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 claims description 4
- 238000006243 chemical reaction Methods 0.000 claims description 4
- 229910052708 sodium Inorganic materials 0.000 claims description 4
- 235000011121 sodium hydroxide Nutrition 0.000 claims description 4
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical class [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims description 3
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 claims description 3
- 229910002651 NO3 Inorganic materials 0.000 claims description 3
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 claims description 3
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 claims description 3
- 229910001854 alkali hydroxide Inorganic materials 0.000 claims description 3
- 150000008044 alkali metal hydroxides Chemical class 0.000 claims description 3
- 235000011114 ammonium hydroxide Nutrition 0.000 claims description 3
- 238000010908 decantation Methods 0.000 claims description 3
- 229960004887 ferric hydroxide Drugs 0.000 claims description 3
- 229960002089 ferrous chloride Drugs 0.000 claims description 3
- NMCUIPGRVMDVDB-UHFFFAOYSA-L iron dichloride Chemical compound Cl[Fe]Cl NMCUIPGRVMDVDB-UHFFFAOYSA-L 0.000 claims description 3
- IEECXTSVVFWGSE-UHFFFAOYSA-M iron(3+);oxygen(2-);hydroxide Chemical compound [OH-].[O-2].[Fe+3] IEECXTSVVFWGSE-UHFFFAOYSA-M 0.000 claims description 3
- 230000005415 magnetization Effects 0.000 claims description 3
- 238000005259 measurement Methods 0.000 claims description 3
- 239000000203 mixture Substances 0.000 claims description 3
- 229910052700 potassium Inorganic materials 0.000 claims description 3
- 239000011734 sodium Substances 0.000 claims description 3
- 239000000725 suspension Substances 0.000 claims description 3
- 230000002093 peripheral effect Effects 0.000 claims description 2
- 239000011591 potassium Substances 0.000 claims description 2
- 235000011118 potassium hydroxide Nutrition 0.000 claims description 2
- 239000002245 particle Substances 0.000 description 10
- HEMHJVSKTPXQMS-UHFFFAOYSA-M sodium hydroxide Substances [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 7
- 229940057995 liquid paraffin Drugs 0.000 description 5
- SZVJSHCCFOBDDC-UHFFFAOYSA-N iron(II,III) oxide Inorganic materials O=[Fe]O[Fe]O[Fe]=O SZVJSHCCFOBDDC-UHFFFAOYSA-N 0.000 description 3
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 239000001257 hydrogen Substances 0.000 description 2
- 229910052739 hydrogen Inorganic materials 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 238000006722 reduction reaction Methods 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 1
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 1
- 229910002588 FeOOH Inorganic materials 0.000 description 1
- 239000000908 ammonium hydroxide Substances 0.000 description 1
- 239000003518 caustics Substances 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- 229910001882 dioxygen Inorganic materials 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- KWYUFKZDYYNOTN-UHFFFAOYSA-M potassium hydroxide Substances [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 1
- 229910000859 α-Fe Inorganic materials 0.000 description 1
Classifications
-
- 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
- G11B5/70647—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 with a skin
-
- 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
- G11B5/70652—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 gamma - Fe2 O3
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/01—Particle morphology depicted by an image
- C01P2004/03—Particle morphology depicted by an image obtained by SEM
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/10—Particle morphology extending in one dimension, e.g. needle-like
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/54—Particles characterised by their aspect ratio, i.e. the ratio of sizes in the longest to the shortest dimension
-
- 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)
- Health & Medical Sciences (AREA)
- Dermatology (AREA)
- General Health & Medical Sciences (AREA)
- Compounds Of Iron (AREA)
- Hard Magnetic Materials (AREA)
Description
(54) METHOD FOR PRODUCING NEEDLE-SHAPED FINE
PARTICLES OF a-GOETHITE (71) We, NIHON SAMGYO GRJOTSU
KABUSHIKIKAISHA, a Corporation of
Japan of 1-19-18 Kandaawajicho, Chiyoda,
Ku, Tokyo, Japan, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:
This invention relates to a method for producing needle-shaped fine particles of a-goethite having a desired uniform particle size. More particularly it relates to a method for producing such needle-shaped fine particles of a-goethite useful for the preparation of y-iron oxide powder (for magnetic recording use and required in electronics industries) or a-iron oxide useful as raw material for the preparation of various kinds of ferrite ceramics.
In the field of magnetic recording employing y-iron oxide powder, it is required to improve magnetic field orientability, transferring characteristic and noise characteristic (noise ratio, ie. ratio of strength of noise to that of recording signal), particularly of the powder as recording body in a magnetic recording tape. As a method for improving these characteristics there is known a method in which particle size of the y-iron oxide power is made as uniform as possible. y-iron oxide is prepared by sub Jecting a-goethite (FeOOH) to a dehydration-reduction reaction at about 350"C in a hydrogen stream to convert it into magnetite (Fe3O4), which is further oxidized at about 250"C in air to give y-iron oxide.
Accordingly, in order to prepare y-iron oxide having a uniform particle size, it is necessary to make uniform the particle size distribution of a-goethite as a starting raw material.
Thus, various methods for preparing fine powders of a-goethite having a uniform particle size have heretofore been studied, but any decisive method for preparing fine powder of a-goethite having a uniform particle size has not yet been developed.
The present invention is based on the discovery that when preparing a-goethite by oxidizing ferrous hydroxide contained in an aqueous alkaline solution with an oxygencontaining gas, if the gas bubbles are small and of substantially uniform diameter, an almost constant number of oxygen molecules are uniformly reacted with each particle of the ferrous hydroxide contained in the reaction system to give needle-shaped fine particles of a-goethite having a uniform particle size.
According to the present invention there is provided a method for producing needleshaped fine particles of a-goethite by oxidizing a ferrous hydroxide suspensoid uniformly dispersed in an aqueous solution of an alkali hydroxide, comprising oxidizing said suspension in a stoichiometric excess of the ferrous hydroxide, with bubbles of air or oxygen of which at least 90% have a diameter of 3 mm or smaller.
For preparing ferrous hydroxide according to the method of the present invention, an alkali may be added to an aqueous solution of an iron salt to form ferrous hydroxide by making the pH of the solution 10 - 13. It is preferable to prevent the ferrous hydroxide formed at that time from oxidizing by the direct contact with the atmosphere. Further it is preferable to adjust the amount of ferrous hydroxide contained in the aqueous alkaline solution to that in the range of 0.1-0.2 mol/f.
The alkali of said aqueous alkaline solution is preferably selected from sodium, potassium and ammonium hydroxide. As for said iron salt, ferrous sulfate, ferrous chloride, ferrous nitrate, and mixtures thereof may be mentioned. It is preferable that the aqueous alkaline solution to be subjected to oxidation has a temperature of 50"C or lower, and contains no ferric hydroxide.
As for the diameter of the bubbles of air or oxygen to be blown into the aqueous alkaline solution for oxidizing the ferrous hydroxide contained in the solution, it is preferable that bubbles having a uniform diameter of 1 mm or smaller form 90% or more of the bubbles.
For generating small bubbles having a substantially uniform diameter, there are various methods. For example according to the method disclosed in British patent no.
1206326 (see Example 1 mentioned below), bubbles suitable for the method of the present invention can be simply generated.
Accordingly, in a preferred embodiment of the invention the bubbles are prepared by supplying air or oxygen to the inside of a cylindrical body closed at its upper end and submerged in the aqueous alkaline solution and rotating the body around its vertical axis.
According to the method of the present invention, needle-shaped fine particles of a-goethite having a ratio of the length of their major axis to that of their minor axis (acicular ratio), of about 10:1 can be prepared in a simple manner, and also agoethite having various desired particle sizes can be prepared by varying the oxidation temperature of ferrous hydroxide contained in the alkaline aqueous solution, and especially the size of bubbles of air or oxygen.
The method of the present invention will be further illustrated below in detail referring to non-limitative Examples.
Example 1
112.2g of ferrous sulfate (Fe2SO4.7H2O) dissolved in 2t of distilled water was introduced in a vessl having an inner volume of abut 5t, and a liquid paraffin was poured on the surface of the solution to form a liquid paraffin layer having a thickness of about 2 cm. While the solution of ferrous sulfate was stirred carefully so as not to disturb the liquid paraffin layer, a solution obtained by dissolving 40 g of caustic soda (NaOH) in 1.5 of distilled water was gradually added to the solution of ferrous sulfate to precipitate ferrous hydroxide.
An apparatus for generating bubbles having a uniform diameter was then submerged in the vessel and an apparatus for oxidizing ferrous hydroxide, as shown in Figure 1 was constructed.
In Figure 1, numeral 1 shows a vessel, numeral 2 shows precipitated particles of ferrous hydroxide contained in an alkali aqueous solution and numeral 4 shows a liquid paraffin layer floating on the surface of the aqueous solution of an alkali 3.
Numeral 5 shows an apparatus for generating bubbles having a uniform diameter, submerged in the aqueous solution of an alkali 3 and disclosed in said British patent
No. 1206326. This apparatus is composed of a rod 7 for supporting a supporting plate 6 above the surface of the liquid, an electric motor 8 mounted onto the supporting plate 6, an inverted cylindrical body having a bottom 10 which is fixed onto the tip of a rotating shaft 9 connected directly to the electric motor 8 and a pipe for feeding air or oxygen gas 11 whose opening is provided inside the inverted cylindrical body having a bottom 10.
While the temperature of the liquid in the vessel was maintained at 50"C and the electric motor was rotated (rotating velocity: 4,000 rpm), air was passed inside the inverted cylindrical body (outer diameter.
40 mm, height: 60 mm) at a rate of 0.9 t/min to carry out oxidation for about one hour.
At that time it was observed that bubbles having a diameter of about 0.5 mm constituted about 95% of the whole of the generated bubbles.
The pHs of the liquid before and after the reaction were 12.4 and 13.0, respectively.
The resulting fine particles of a-goethite were washed six times with distilled water at 50"C by decantation, filtered and dried in vacuo at 500C. The electron microscopic photograph of the fine particle of a-goethite thus prepared is shown in Figure 2. As apparent from Figure 2, almost all of the fine particles of a-goethite are needleshaped. As for their size, the length of the major axis is in the range of 0.2 to 0.4 Il, and the ratio of the length of the major axis to that of the major axis is about 10:1.
Then 10 g of fine particle powder of a-goethite thus obtained was subjected to dehydration-reduction reaction in a nitrogen gas stream containing hydrogen in an amount of 5% by volume, at 330"C for 2 hours, and the resulting material was oxidized in air at 250"C for 1.5 hour to give powder of y-iron oxide, which was then subjected to measurement of magnetic properties. As a result, the coercive force (HC), saturation magnetization (ops) and squareness ratio (R) (rectangular hysteresis loop) were 450 oersted, 67.0 emu/g and 0.55, respectively.
Example 2
An aqueous alkali solution contained in a vessel and having a liquid paraffin layer floating thereupon was prepared by mixing ferrous sulfate with caustic sodium in the same proportion and under the same conditions as in Example 1.
Then the same apparatus for generating bubble having a uniform diameter as in
Example 1 was submerged in the vessel.
While the liquid temperature was maintained at 30"C and an electric motor was rotated at 5,000 rpm, air was passed at a rate of 0.4 e/min to carry out oxidation for 1.5 hour. At that time it was observed that bubbles having a diameter of about 0.3 mm constituted abut 98% of the whole of the bubbles generated.
The pHs of the liquid before and after the reaction were 12.3 and 12.8, respectively.
Formed fine particles of a-goethite were washed six times with distilled water at 300C by decantation, filtered and dried in vacuo at 50"C. The electron microscopic photograph of the fine particles of a-goethite thus prepared is shown in Figure 3. As apparent from Figure 3, the shape of the fine particles of a-goethite was almost the same as those of Example 1, but, as for the size, the length of the major axis was 0.1 - 0.15 Il.
Then 10 g of the dried fine particle powder of a-goethite was treated in the same manner as in Example 1 to give y-iron oxide powder, which was then subjected to measurement of magnetic roperties. As a result, the coercive force HC), saturation magnetization (ops) and squareness ratio were 455 oersted, 70.0 emu/g and 0.55, resectively.
AT WE CLAIM IS:
1. A method for producing needleshaped fine particles of a-goethite by oxidizing a ferrous hydroxide suspensoid uniformly dispered in an aqueous solution of an alkali hydroxide, comprising oxidizing said suspension in a stoichiometric excess of the ferrous hydroxide, with bubbles of air or oxygen of which at least 90% have a diameter of 3 mm or smaller.
2. A method according to claim 1 wherein the ferrous hydroxide contained in the alkaline aqueous solution is prepared by adding an alkali to an aqueous solution of an iron salt without contacting the solution with the atmosphere to form ferrous hydroxide at pH of the resulting solution of 10 13.
3. A method according to claim 2 wherein the iron salt is selected from ferrous sulfate, ferrous chloride, ferrous nitrate and mixtures thereof.
4. A method according to claim 1, 2 or 3 wherein the concentration of the ferrous hydroxide contained in the aqueous alkaline solution is in the range of 0.1 - 0.2 mol per liter of the aqueous alkaline solution.
5. A method according to any one of claims 1 to 4 wherein 90% or more of the bubbles have a diameter of 1 mm or smaller.
6. A method according to any one of claims 1 to 5 wherein the bubbles are prepared by supplying air or oxygen to the inside of a cylindrical body closed at its upper end and submerged in the aqueous alkaline solution, and rotating the body around its vertical axis.
7. A method according to Claim 6 wherein the peripheral linear velocity of the rotating cylindrical body is at least 8 m/sec.
8. A method according to any one of
Claims 1 to 7 wherein the aqueous alkaline solution has a temperature of 50"C or lower.
9. A method acording to any one of claims 1 to 8 wherein the alkali of said aqueous alkaline solution is selected from sodium, potassium and ammonium hydroxides.
10. A method according to any one of claims 1 to 9 wherein the aqueous alkaline solution contains no ferric hydroxide.
11. A method according to claim 1 substantially as described in either of the
Examples.
12. a-goethite obtained by a method according to any one of claims 1 to 11.
13. y or a-iron oxide produced from a-goethite obtained by a method according to any one of Claims 1 to 11.
**WARNING** end of DESC field may overlap start of CLMS **.
Claims (13)
1. A method for producing needleshaped fine particles of a-goethite by oxidizing a ferrous hydroxide suspensoid uniformly dispered in an aqueous solution of an alkali hydroxide, comprising oxidizing said suspension in a stoichiometric excess of the ferrous hydroxide, with bubbles of air or oxygen of which at least 90% have a diameter of 3 mm or smaller.
2. A method according to claim 1 wherein the ferrous hydroxide contained in the alkaline aqueous solution is prepared by adding an alkali to an aqueous solution of an iron salt without contacting the solution with the atmosphere to form ferrous hydroxide at pH of the resulting solution of 10 13.
3. A method according to claim 2 wherein the iron salt is selected from ferrous sulfate, ferrous chloride, ferrous nitrate and mixtures thereof.
4. A method according to claim 1, 2 or 3 wherein the concentration of the ferrous hydroxide contained in the aqueous alkaline solution is in the range of 0.1 - 0.2 mol per liter of the aqueous alkaline solution.
5. A method according to any one of claims 1 to 4 wherein 90% or more of the bubbles have a diameter of 1 mm or smaller.
6. A method according to any one of claims 1 to 5 wherein the bubbles are prepared by supplying air or oxygen to the inside of a cylindrical body closed at its upper end and submerged in the aqueous alkaline solution, and rotating the body around its vertical axis.
7. A method according to Claim 6 wherein the peripheral linear velocity of the rotating cylindrical body is at least 8 m/sec.
8. A method according to any one of
Claims 1 to 7 wherein the aqueous alkaline solution has a temperature of 50"C or lower.
9. A method acording to any one of claims 1 to 8 wherein the alkali of said aqueous alkaline solution is selected from sodium, potassium and ammonium hydroxides.
10. A method according to any one of claims 1 to 9 wherein the aqueous alkaline solution contains no ferric hydroxide.
11. A method according to claim 1 substantially as described in either of the
Examples.
12. a-goethite obtained by a method according to any one of claims 1 to 11.
13. y or a-iron oxide produced from a-goethite obtained by a method according to any one of Claims 1 to 11.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB180877A GB1567957A (en) | 1977-01-17 | 1977-01-17 | Method for producing needle-shaped fine particles of -goehite |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB180877A GB1567957A (en) | 1977-01-17 | 1977-01-17 | Method for producing needle-shaped fine particles of -goehite |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB1567957A true GB1567957A (en) | 1980-05-21 |
Family
ID=9728388
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB180877A Expired GB1567957A (en) | 1977-01-17 | 1977-01-17 | Method for producing needle-shaped fine particles of -goehite |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB1567957A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NL8204902A (en) * | 1981-06-22 | 1984-07-16 | Mitsui Toatsu Chemicals | PROCESS FOR PREPARING GOETHITE. |
| US7910085B2 (en) * | 2007-12-28 | 2011-03-22 | Tdk Corporation | Process for production of iron oxyhydroxide particles |
-
1977
- 1977-01-17 GB GB180877A patent/GB1567957A/en not_active Expired
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NL8204902A (en) * | 1981-06-22 | 1984-07-16 | Mitsui Toatsu Chemicals | PROCESS FOR PREPARING GOETHITE. |
| US7910085B2 (en) * | 2007-12-28 | 2011-03-22 | Tdk Corporation | Process for production of iron oxyhydroxide particles |
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| Date | Code | Title | Description |
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| PS | Patent sealed | ||
| 746 | Register noted 'licences of right' (sect. 46/1977) | ||
| PCNP | Patent ceased through non-payment of renewal fee |