JPH01208331A - Production of iron oxide for ferrite - Google Patents

Abstract

PURPOSE:To increase the yield of the iron component by recovering iron of low purity from the blow solution in which the impurities of by-products is concentrated in the recovery process, when iron oxide of high purity is recovered by removing impurities in the waste from the steel pickling. CONSTITUTION:The waste solution from steel pickling is concentrated, the impurities are filtered off, and the filtrate is fed to the installation for producing iron oxide of high purity such as a calcination furnace to give iron oxide of high purity. In the meantime, a part of the residue on the filtration is recycled to the concentration process, the remaining is fed together with the blow solution in which the impurities from the concentration process is concentrated to the installation for producing iron oxide of low purity to produce iron oxide of low purity. The concentration operation is carried out by the evaporation or vacuum concentration or the flocculation using a flocculent such as a cationic polyacrylamide. The high-purity iron oxide is used in a toner ferrite, while the low-purity iron oxide is in Indian red coating.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is directed to the production of iron oxide for ferrite from the pickling waste liquid generated after pickling steel materials such as steel sheets, shapes, rods, and wires with hydrochloric acid or sulfuric acid. It's about how to get it.

[Conventional technology]

Generally, there are two types of iron oxide obtained from pickling waste: high-purity iron oxide and low-purity iron oxide. High-purity iron oxide is used for toner ferrite and soft ferrite (high-grade products), while low-purity iron oxide is used for hard ferrite, red iron paint, soft ferrite (low-grade products), etc. The standards (JISK1462) for iron oxide for soft ferrite are shown in Table 1.

It is desirable for high purity iron oxide to pass Type 1 in the table above.
Furthermore, recently, many products require SiO□ of 0.005% by weight or less. On the other hand, for low-purity iron oxide, there are only a few impurities that significantly impede magnetic properties or cause corrosion (there are few limiting conditions).

Because of the difference in required quality between such low-purity and high-purity iron oxides, -II has been manufactured by the following steps. In other words, low-purity iron oxide can only be obtained by directly heating the concentrated liquid obtained through the pickling waste liquid concentration process to 600 to 800°C in a roasting furnace (spray type, fluidized type, kiln type, etc.) to remove the acid content. Iron oxide is obtained by

High-purity iron oxide was produced by removing impurities through a combination of the following steps. That is, (1) the waste liquid from pickling steel materials with low impurity content is used as a raw material; (2) Impurities in the pickling waste liquid are removed by coagulation-sedimentation filtration (including aging filtration), pressure flotation removal, crystallization, solvent extraction, etc. - A method of removing impurities by further treating the separated iron oxide with water, chemical cleaning, high-temperature vaporization, etc.
These are various processes such as.

Example of component analysis of low-purity iron oxide obtained in this way (A
, B, and C) are shown in Table 2.

As mentioned above, conventionally, the above-mentioned low-purity and high-purity iron oxides have been produced from pickling waste liquid through separate dedicated processes.

[Problem to be solved by the invention]

However, when obtaining high-purity iron oxide using the above conventional method, the entire amount of iron cannot be recovered, and a liquid (blow liquid) containing a part of the iron and concentrated impurities remains, which is then subjected to neutralization treatment. After that, it had to be filtered and drained. For this reason, the recovery yield (production yield) of iron in the pickling waste liquid decreases, resulting in higher costs.

In addition, if the blowing liquid is small, it is sometimes recycled into the original pickling waste liquid, but this results in an early increase in the concentration of impurities in the entire system and a deterioration in the purity of the iron oxide.

Furthermore, when obtaining low-purity iron oxide and attempting to directly remove impurities from the pickling waste liquid by the above-mentioned roasting method, the iron concentration in the pickling waste liquid must be lower than the acid concentration used in the pickling process (usually 18%). before and after), usually 14g/100
Since it was low at less than cc, the efficiency of removing impurities was extremely poor.

Therefore, the main object of the present invention is to improve the iron production yield while maintaining the purity of high-purity iron oxide.

[Means to solve the problem]

To solve the above-mentioned problems, the present invention is a method for recovering iron oxide from a steel pickling waste solution, in which impurities in the pickling waste solution are removed to recover high-purity iron oxide, and as well as by-products in the recovery process. This method is characterized by recovering low-purity iron oxide from the resulting impurity-concentrated blowing liquid.

[For production]

In the present invention, the blowing fluid discharged from the manufacturing process of high-purity iron oxide is not disposed of or recycled, but is allocated to the production of low-purity iron oxide, so the iron production yield is reduced. This improves the overall performance while avoiding the contamination of impurities.
High purity iron oxide of desired quality can be produced.

In addition, in the production of low-purity iron oxide,
Since the raw material is not the pickling waste liquid, but the blow liquid with concentrated iron and impurities as the raw material, impurities can be easily removed using conventional techniques such as crystallization purification and solvent extraction of iron ions. It can be carried out.

Furthermore, since the ratio of the blowing liquid can be controlled, it is also possible to separate the pickling waste liquid for producing high-purity and low-purity iron oxides, which reduces costs and allows for the production of It is possible to adjust the quality and improve the overall production yield.

[Specific structure of the invention]

The present invention will be explained in more detail below.

1 and 2 are processing flow diagrams according to the present invention. First, in Figure 1, pickling waste liquid (hereinafter referred to as "waste acid")
) 1 is concentrated 2 and then filtered 3 to remove impurities,
The filtrate 4 is supplied to a high purity iron oxide production facility 5 such as a roasting furnace. A part of the residue from the filtration 3 is circulated to the concentration step 2, and the remaining portion (residue containing impurities) 7 is sent to the low-purity iron oxide production facility 8 together with the blow liquid 6 discharged from the concentration step 2.
supplied to

In addition, in the method shown in Figure 2, after the waste acid 1 is concentrated 2,
It is characterized in that it is filtered 3 and the obtained furnace liquid is crystallized. Pure iron oxide crystals 9 obtained by this crystallization are supplied to high purity iron oxide manufacturing equipment 5. On the other hand, a part of the impurity-containing residue 7 generated after filtration is circulated to the concentration step 2, and is supplied to the low-purity iron oxide production facility 8 together with the blow liquid 6 discharged after the concentration 2.

The above-mentioned concentration 2 refers to a means for concentrating the iron content and impurities in the pickling waste liquid. Specifically, for example, a coagulation precipitation method, an evaporative concentration method, a reduced pressure concentration method, etc. can be applied.

〔Example〕

Next, the effects of the present invention will be clarified through examples.

<Example 1> In this example, the processing flow shown in FIG. 3 was used. That is, the hydrochloric acid pickling waste liquid (referred to as "waste acid" in the figure) 11 is coagulated and precipitated 12, and then a portion of the residue obtained by filtration 13 is returned to the coagulated precipitate 2, and the filtrate 14 is sent to the roasting furnace. 5, and this produces high-purity iron oxide (for soft ferrite) 1
6 was obtained.

On the other hand, the blow liquid 17 discharged after the coagulation and precipitation 12 is mixed and dissolved with the residue 18 discharged by the filtration 13, and then
Low-purity iron oxide (for hard ferrite) 19 was used. In addition, as shown by the broken line, the blow liquid 17 and the residue 18 were conventionally disposed of 20, but in the present invention, they are effectively utilized.

The specifications in the above processing flow are as follows.

Waste acid; l (C1 concentration 5%, FeC1, concentration 15% flocculant; cationic polyacrylamide (chemical name set C
200) 11000pp, static filtration for 1 day after addition stirring; 0.1μ microfilter, filtrate production rate 5
1/min Circulating fluid; 5001/min (?! Reduction ratio is 10
(When it doubles, blow out the remaining liquid and replenish with new liquid.) The results are as shown in Table 3. Note that the quantitative ratio refers to the ratio of the filtrate, etc. when the amount of waste acid is set to 10.

Table 3 <Example 2> The experiment was carried out under the same conditions as in Example 1, except for the quantitative ratio.

The results are shown in Table 4.

Table 4 <Example 3> The experiment was carried out under the same conditions as in Example 1, except for the quantitative ratio.

The results are shown in Table 5.

Table 5 [Effects of the Invention] As described above, according to the present invention, it is possible to improve the iron production yield while maintaining high purity iron oxide.

[Brief explanation of the drawing]

1 and 2 are process flow diagrams according to the present invention, and FIG. 3 is a flow diagram showing an embodiment. Patent applicant: Sumitomo Metal Industries, Ltd. Zen, j, B, j Figure 1 Figure 2

Claims (1)

[Claims] (1) In a method for recovering iron oxide from pickling waste liquid of steel materials, impurities in the pickling waste liquid are removed to recover high-purity iron oxide, and at the same time, the impurities concentrated by-product in the recovery process are A method for producing iron oxide for ferrite, characterized by recovering low-purity iron oxide from a liquid.