JPS58202504A - Manufacture of iron oxide for oxide permanent magnet - Google Patents

Abstract

PURPOSE:To effectively utilize as an iron oxide material for an oxide permanent magnet an iron oxide film (mill scale) produced in the iron hot-rolling process, by previously oxidizing the film (mill scale) so that a specific treating condition is not exceeded. CONSTITUTION:When a mill scale is utilized as an iron oxide material for an oxide permanent magnet, it is necessary to transform the greater part of Fe<2+> into Fe<3+>. For this reason, an iron oxide film (mill scale) produced in the iron hot-rolling process is oxidized in an atmosphere, prepared by adding oxygen into an ordinary atmosphere, at 300 deg.C for a period of time not exceeding two hours. It is thereby made possible to obtain an iron oxide having an oxidized degree not less than 80%.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to securing a new source of iron oxide, which is the main raw material for oxide permanent magnets.

Iron oxide (hereinafter referred to as mill scale) obtained as a by-product of the pickling process during rolling of steel sheets [Solesner method or [by the Lurgy method], iron oxide produced by the sintering method of iron sulfide ore, etc. have been used.

These iron oxides were generally called hematite expressed as MeFe20s. In the future, it is expected that the supply of these iron oxides will become unstable and the price will fluctuate due to changes in the surface treatment method of steel sheets in the steel industry. This has become an issue that needs to be addressed. Mill scale is iron oxide in an incompletely oxidized state (t) and contains a large amount of Fg2+ ions. To use this as an iron oxide raw material for acid-biride permanent magnets.

Fa ions are pre-oxidized to F- ions,
+3 or fJa or Sr carbonate and its mixture.

When calcining the coalesce, it undergoes an oxidation process to become two-light.

It became clear that it was necessary to 1. The object of the present invention is to solve the above problems and to effectively utilize mill scale, which is inexpensive and available in large quantities, as a raw material for iron oxide for oxide permanent magnets.

In the process of manufacturing oxide permanent magnets using the iron oxide coating generated during the hot rolling process of iron as the iron oxide raw material, the present invention is characterized in that the iron oxide coating is previously oxidized at 600 υ or more for a time not exceeding 2 hours. It is characterized by:

Further, the present invention is disclosed in Japanese Patent Publication No. 44-9795.

When producing iron oxide for ferrite from mill scale,
It stipulates that the mill scale be roasted at 550 υ - 1100 υ for 2 hours or more and then subjected to oxidation treatment, but in the present invention, the oxidation treatment time is much shorter than that stated in the above publication. There it is.

It can also be used as an iron oxide raw material for ferrite.

It has become.

Table 1 shows the mill scale A used in the present invention.

Representative of unused iron oxide raw material B for tyulite magnets.

Indicates the range of components.

Table 1 (%) When the mill scale is iron oxide for oxide permanent magnets, most of the Ft shown in Table 1 needs to be I"a. Now, the Ft in the mill scale is oxidized and reduced. The degree of oxidation is defined by the following formula.

p′e2+m)′″YI in mill scale before Xli conversion
Ft (%) in mill scale after oxidation (α+weight increase due to oxidation) The present invention will be described in detail below.

Example 2 Mill scale was crushed so that 90% or more passed through a 000 sieve (74 μm) and was made into pellets with a thickness of 5 cm.

Table 2 shows the degree of oxidation and weight change when oxidized in the air at a temperature of 650υ.

・ 6 ・ The oxidation degrees obtained in this way are 61.5% and 82.6% (7
) K material and Ba(,'US) were blended at a molar ratio of 5.3, rapidly heated at 1200 vK, held for 1 hour, and subjected to a turite reaction. The X-ray diffraction images are shown in Figure 1 and , as shown in Figure 2.As shown in the figure, even -0 oxidation degree of about 65% can be used to produce the desired M type ferrite (B
aU・.

6Fa205) was obtained, but there were some monophrases.

- Light (BaU・7i'g203) was detected.

That's true.

However, about 80% of them are made from ordinary iron oxide.

It was possible to obtain M-type fullite similar to that used as a material. Further, in an atmosphere in which oxygen was added to the normal atmospheric atmosphere, samples with an oxidation degree of 80% or more could be easily obtained even at 500 V by holding for one hour.

As explained above, when mill scale is used as an iron oxide raw material for oxide permanent magnets, oxidation treatment for more than 2 hours as specified in known publications is not necessary, and it can be done in a short time not exceeding 2 hours. It is possible to carry out necessary and sufficient oxidation treatment.

・　4、

[Brief explanation of drawings]

Figure 1 shows the starting material from mill school with an oxidation degree of 61.5%. FIG. 2 is an X-ray diffraction image after the tuulitic reaction using mill scale with an oxidation degree of 82.6% as a starting material. .

Claims (1)

[Claims] The iron oxide film generated during the hot rolling process of iron is treated with acid. In the manufacturing process of oxide permanent magnets, which are used as raw materials for iron oxides. Then, apply an iron oxide coating in advance at 600V or more for 2 hours. 1. A method for producing iron oxide for use in tetraoxide permanent magnets, characterized by carrying out oxidation treatment for a time not exceeding .