JPS6020329B2 - Method for producing ferromagnetic oxide - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a spinel-type ferromagnetic oxide.

As a method for producing spinel-type ferromagnetic oxides, an alkali is added to an aqueous solution of ferrous salt to form a white precipitate of ferrous iron, and then the aqueous solution in which this precipitate is suspended is gradually oxidized to form magnetite or A so-called "wet oxidation method" for producing iron oxyhydroxide or a mixture thereof has been developed, and this method is already in practical use as an effective method for producing ferrite and treating waste liquids containing heavy metals.

In this method, it is important to set conditions such as reaction temperature, pH setting, oxidation conditions, etc., and it must be carried out under specific conditions in order to produce magnetite and ferrite.

Figure 1 shows how the crystal structure of the iron compound produced changes depending on the alkali addition ratio and reaction temperature when air oxidation is actively carried out after adding alkali to a ferrous salt solution. This is what is shown. As is clear from the figure,
At a high reaction temperature, Fe304 is produced, and at a low reaction temperature, Fe00 is produced, so the reaction must be carried out at a high temperature to obtain magnetite, which is a magnetic oxide particle. However, it is not impossible to perform the oxidation reaction at room temperature without relying on the above reaction conditions, but the oxidation reaction requires special equipment and takes a long time. Various problems remained in addition to processing operations and processing time. The present invention solves the above problems all at once, and does not require an oxidation reaction, and is almost unaffected by the reaction temperature, pH setting, or other processing conditions, and can be carried out instantaneously using simple equipment. The present invention provides a method that can produce ferromagnetic oxides.

That is, the present invention is a method in which pydocrosite and ferrous ions are reacted in a solution with a pH of 6 or higher to produce a ferromagnetic oxide. The present inventor has discovered that the pydocrocyte (yFe
When ferrous ions are added to a solution of 00H), magnetite (Fe
304) was found to be generated.

It is known that 2yFe00H+FeOH-→Fe304 Jubutsu○10day10yFe00day easily dissolves in a strongly acidic region because it adsorbs ferrous ions in the form of Fe20.

When the pH of the liquid is 6 or higher, especially in an alkaline region, ferrous ions are adsorbed in the form of FeOH+, so the above reaction occurs, and magnetite is formed as sediment. In the above reaction, during the reaction, 10 is produced and the liquid returns to the acidic side, so it is necessary to maintain the liquid mottling at 6 or higher at all times during the reaction by adding an alkali.

However, if the liquid is strongly alkaline, there is no need to add alkali. In addition, if the pH of the solution when adding ferrous ions is below 6, add an alkali to pH 6.
Adjust H to 6 or higher. As described above, it is sufficient to maintain the pH of the liquid at 6 or more during the reaction, and the axial region of the liquid when ferrous ions are added does not matter. Furthermore, ferrous ions may be supplied in either solid or liquid form. As is clear from the above formula, the amount of ferrous ion added is 1/2 of the total amount of Fe00 in terms of molar ratio.

If the amount of ferrous ion added is small, yFe00 days will remain in the solution, making it impossible to obtain highly pure magnetite. Further, in the above reaction, the reaction temperature does not matter at all.

This is because adsorption of ferrous ions to yFe00H' occurs over the entire temperature range in a solution with a pH of 6 or higher. In addition to these adsorption functions, the reason why the above reaction occurs instantaneously even at low temperatures is that yFe00 has a crystal structure very similar to Fe304, and the activation energy required for the structural change to Fe304 is extremely small. It is thought that this is because Note that yFe00 day can be obtained by oxidizing ferrous ions in a normal temperature solution in an acidic region. Therefore, by generating yFe00 days in a liquid containing heavy metal ions, such as heavy metal-containing waste liquid, and subsequently performing the above-mentioned treatment on this solution, the yFe00 days generated in the liquid are used to transfer heavy metal ions into the crystal lattice. It is possible to obtain ferrites that have been worked on. Of course pH 6
yFe00 days may be added to the above heavy metal-containing waste liquid, and in either case, magnetite and ferrite can be produced with simple operations without requiring special equipment. As described above, according to the present invention, the reaction temperature characteristics shown in FIG. 1 are not affected at all.

It also has the excellent effect of being able to produce magnetite and ferrite almost instantaneously without requiring the strict production conditions or special equipment required by conventional methods, and in particular, making it possible to produce ferromagnetic oxides extremely easily through room-temperature reactions. be. Examples of the present invention are shown below. (Example 1) 750 of a pH 5.5 solution containing FeC12
At a liquid temperature of 25° C., air was blown at a rate of 1.5 per minute to oxidize Fe20 ions and generate Fe00.

Furthermore, in this solution (pH 5.5), 2.5 days of FeCl
2 was added, and the pH of the solution was adjusted to several levels in the range of 5 to 10 by changing the amount of alkali added to the solution, and the precipitates generated in the solution in each case were investigated. At PH04 or higher, black precipitates were formed instantaneously (5 to 6 minutes), and all of these were Fe3Q. However, when the spots were 5.8 or less, there was no change in the color of the liquid, and the precipitate obtained was a mixture of yFe00 day and Fe(OH)2. The components of the precipitate were analyzed by powder x-ray diffraction, Mössbacher earth vector, electron microscopy, and chemical analysis. This also applies to the following examples.
Figure 2 shows the yFeoOH particles generated in the liquid, and Figure 3 shows the Fe particles generated in the liquid when the pH is set to 6.4 or higher.
304 is an electron micrograph showing particles of No. 304. (Example
2) Using the same method as in Example 1, yFe00 was generated in the solution using 5 days of FeC12, and then the solution was heated to an alkaline region (p
H8, 9, 10.11), and 2.5 evening Fe
A pH 2 solution containing C12 and an alkaline solution were added at the same time, and the pH of each solution was maintained at 8, 9, 10, and 11.

After adding all the FeC12 solutions, complete Fe304 was produced in both spot solutions. Also, 2.5 evening F
eC12 was added as an alkaline suspension of 8, 9, 10, 11 to these at pH 8, 9, 10, 1 containing yFe00 days.
The results were the same even when a suspension of No. 1 was added. (Example 3) In the same solution (pH 8, 9, 10, 11) as in Example 2,
After adding 3 to 5% of FeC, Cd20, Cd20, Cd20, and Zn20 to FeC12, a solution containing 2.5 TFeC12 was added to each solution in alkali IJ in the same manner as in Example 2. At the same time, the pH of the solution was adjusted to 8, 9, 10, and 11, respectively.
I kept it.

All precipitates formed in each solution were ferrite containing these metal ions. It has been found that these metal ions are completely incorporated into the lattice points of the ferrite, and remelt only when the ferrite slightly dissolves in an acidic region of pH 3 or less. Further, the concentration of metal ions in the solution when ferrite was formed was 0.01 or less at a liquid temperature of 25°C. To other Ti V40, Ni
The same results were obtained when the same test was conducted on liquids containing metal ions such as 20, M2, and C10.

[Brief explanation of drawings]

Figure 1 is a diagram showing the changes in the product depending on the alkali addition ratio and reaction temperature in the secondary method, Figure 2 is an electron micrograph of yFe added to the liquid on day 00, and Figure 3 is the product produced by the method of the present invention. This is an electron micrograph of magnetite. Figure 1 Figure 2 Figure 3

Claims (1)

[Scope of Claims] 1. A method for producing a ferromagnetic oxide, which comprises reacting lepidocrocite and ferrous ions in a solution with a pH of 6 or more to produce ferromagnetic precipitated particles. 2 Approximately 1/2 molar ratio of the total amount of lepidocrocite
2. A method for producing a ferromagnetic oxide according to claim 1, characterized in that ferrous ions of: