KR100293197B1 - Method for eliminating aluminium from waste pickling solution - Google Patents

Abstract

PURPOSE: A method for eliminating aluminium from waste pickling solution is provided to selectively remove dissolved ionic impurities contained in waste pickling solution, especially to separate aluminium that affects magnetic characteristics and thermal expansion coefficient during the manufacture of soft ferrite. CONSTITUTION: The method for eliminating aluminium from waste pickling solution includes the steps of (i) adding tartaric acid or EDTA to waste pickling solution, and then reacting the waste pickling solution added with tartaric acid or EDTA at a temperature below boiling point thereof, wherein the amount of EDTA or tartaric acid is 1.5x10¬-3 to 5x10¬-3 mol; and (ii) by filtration, separating colloidal particle containing aluminium that is generated in the 1st step.

Description

[Name of invention]

How to remove aluminum from pickling waste

Detailed description of the invention

[Purpose of invention]

[Technical field to which the invention belongs and the prior art in that field]

The present invention relates to a method for removing an aluminum component in a pickling waste liquid, and more particularly, to a method for removing an aluminum component among impurities contained in a hydrochloric acid pickling waste liquid discharged from a steel pickling process.

Iron oxide, the main component of ferrite raw materials, is mostly produced by pyrolysis of hydrochloric acid pickling waste liquid discharged from the steel pickling process in a reaction with high temperature roasting. The hydrochloric acid pickling liquid discharged from the pickling process contains various impurities such as Mn, Al, Ca, and Si, which are eluted from the constituents of the steel to be pickled, in addition to about 25% of iron chloride (FeCl ₂ ) as a main component. Iron oxide produced from the pickling waste liquid composed of these components is supplied as a raw material for manufacturing such as soft ferrite, hard ferrite and pigment.

In the case of iron oxide used as a raw material for producing hard ferrites or pigments, there is almost no restriction on the component content of the trace impurities mentioned above, but the quality is classified according to the chlorine ion content and color.

Soft ferrites, on the other hand, are mainly used in the information industry, such as magnetic heads, antennas, deflection yokes, and other components of ultra-precision electronic communication devices. The content of impurities has a significant impact on quality.

In particular, recent advances in communication equipment, high performance of electronic device components, and light and small shortening have made it necessary to improve the performance of waste light, that is, increase the permeability, increase the electric resistance value, and reduce the loss. Is very important.

Among the impurity components contained in the hydrochloric acid pickling liquor used in the production of iron oxide, in particular, the silica component is the most strictly controlled because it acts as a major cause of lowering the electromagnetic properties of ferrite products. In addition, aluminum is also a component that affects the saturation flux density, Curie temperature, temperature characteristics, coefficient of thermal expansion, etc., so the demand for content management is gradually increasing.

In line with the recent miniaturization and weight reduction of electronic devices, the demand for high performance soft ferrite products, that is, increased permeability and electrical resistance, as well as products requiring miniaturization (Mn-Zn ferrite, Mn-Mg ferrite) Increasingly, there is a strong demand for the development of high quality of iron by-product iron oxide, which is the main raw material of soft ferrite, that is, precise control and purification of impurities.

Among impurities contained in iron oxides, calcium, sodium, chlorine and the like are components which can be substantially removed by washing with water (wet method) as soluble components in water. However, since the manganese, aluminum, and the like, such as silica, are almost impossible to remove in a state made of iron oxide, it is preferable to use a physical and chemical method in a waste solution state in a solution state.

Conventional methods for purifying impurities in pickling solutions include removing pickling liquor using an ultrafiltration membrane (Japanese Patent Publication No. 61-289), and separating the filtrate by adding a polymer flocculant (Japanese Patent Laid-Open Publication 58-151335), a method of physical removal such as a method of adding a surfactant to pass through the adsorption medium (Japanese Patent Publication No. 60-122087), and an iron scrap to the pickling waste liquid to control filtered to a predetermined basicity. There is a chemical removal method such as a method (Japanese Patent Laid-Open No. Hei 2-302325), a method of controlling the basicity by administering an alkaline substance to the pickling waste liquid (Japanese Patent Laid-Open No. 63-49294).

Such physical methods are used to remove insoluble substances in waste acid, and a reduction effect cannot be expected for components existing in the form of dissolved ions.

Meanwhile, the method of purifying impurities by adding iron scrap or alkaline agent in waste acid and consuming free acid to control the basicity above a certain basicity uses coprecipitation effect due to precipitation of ferric ions (Fe ³⁺ ). In addition, there is a limit in removing impurity ions on the dissolved ions, as well as a problem that the recovery rate of iron ions, which is a raw material of iron oxide, is reduced.

In order to solve the above problems, studies and experiments were conducted, and based on the results, the silica removal method in waste acid was disclosed in Patent Application No. 95-41929, but only the silica component was removed, but the aluminum component was not removed.

[Technical problem to be achieved]

Accordingly, an object of the present invention is to provide a method for effectively removing impurities in dissolved ions present in waste acid, in particular, aluminum components affecting magnetic properties, thermal expansion coefficient, and the like in the manufacture of soft ferrite.

Another object of the present invention is to produce a high-purity iron oxide having excellent magnetic and temperature characteristics, containing 22 ppm or less of aluminum components by weight of iron oxide.

[Configuration and Function of Invention]

In the method for removing aluminum component of waste acid for producing high purity iron oxide according to the present invention, tartaric acid or EDTA is added to pickling liquor at 1.5 × 10 ⁻³ mole (iron concentration reference ratio of 5.8 × 10 ⁻⁴ ) or more and the temperature is lower than the boiling point. Reacting with; Filtering the reaction solution by the reaction to remove the aluminum component-containing colloidal particles formed by the reaction; It includes.

Hereinafter, the present invention will be described in detail.

According to the present invention, tartaric acid or EDTA is added to the pickling waste solution at least 1.5 × 10 ⁻³ mol (iron concentration reference ratio of 5.8 × 10 ⁻⁴ ), stirred at a boiling point temperature or lower, and then the resulting impurity-containing colloidal particles are filtered. By removing the aluminum component of the pickling waste liquid.

Generally, sulfuric acid or hydrochloric acid solution is used as the pickling solution. The present invention is a method of removing impurities in the pickling waste used during pickling, and it is preferable to add tartaric acid or EDTA to the pickling waste in a range of 1.5 × 10 ⁻³ mol or more.

When the amount of tartaric acid or EDTA added is less than the above range, a significant reduction effect of the aluminum component cannot be expected. In addition, when tartaric acid or EDTA is added in excess, aluminum removal effect is not expected as much as adding tartaric acid or EDTA. Therefore, it is preferable to add tartaric acid or EDTA in 1.5 * 10 <^{-3> -5} * 10 <^-3> mol (iron concentration component reference concentration ratio 5.8 * 10 <^-4> -1.9 * 10 <^-3> ).

The temperature at the time of adding tartaric acid or EDTA to the waste acid and reacting is not particularly limited as long as it is below the boiling point temperature. The boiling point temperature here is about 100 ° C. considering both waste acid and tartaric acid or waste acid and EDTA. If the reaction is at a temperature above the boiling point, the tartaric acid or EDTA will be volatilized before the reaction.

Thus, by adding tartaric acid or EDTA to the pickling waste acid and reacting, colloidal particles containing impurities, particularly colloidal particles containing aluminum, are formed, which can be removed by a common filtration method such as a filter.

When iron oxide is prepared from purified waste acid in which dissolved impurities in dissolved ions, especially aluminum components, are removed by the method according to the present invention, the aluminum component content is 22 ppm or less, and the aluminum component affecting the saturation flux density, the Curie temperature, the coefficient of thermal expansion, etc. is remarkable. By being reduced, it is possible to expect excellent magnetic properties, temperature characteristics, etc. in the production of soft ferrite.

Hereinafter, the present invention will be described through examples.

Example 1

Effect of Removal of Aluminum Components by Addition of Tartaric Acid in Pickling Waste

Invention Example 1-5

The chemical composition of the waste acid discharged from the steel mill pickling process is shown in Table 1 in terms of the content of co-existing impurities in g, based on the case where 100 g / L of the total iron component is contained.

＊ Total Fe concentration = 2.58M

In the chemical composition of the pickling liquor shown in the above table, the total Fe 144.2 ppm was calculated as the ppm of Fe ₂ O ₃ , and the Al component contained about 180 ppm based on the weight of iron oxide.

15 ml (1.5 × 10 ^-3 mol), 20 ml (2 × 10 ^-3 mol), 30 ml (3 × 10 ^-3 mol), 40 ml (4 × 10) of 0.1 mol concentration tartaric acid solution in 1 L of waste acid having the chemical composition shown in Table 1 above ^-3 mol) and 50 ml (5x10 ^-3 mol) were added, respectively, and stirred for 10 minutes at the reaction temperature of 25 ° C.

The colloidal particles were suspended in the pickling liquor after the agitation, and the purified pickling liquor solution was recovered and wet analyzed to investigate the aluminum content, and the test results are shown in Table 2 below.

Comparative Example 1-2

Except that 5 ml (5 × 10 ^-4 mol) and 10 ml (1 × 10 ^-3 mol) of 0.1 M tartaric acid solution were added, the same method as in the above-described invention was conducted. The results are shown in Table 2 below.

[Prior Example 1]

Crystallization Method

1 L of the pickling waste liquid having the chemical composition of Table 1 was concentrated by heating to a boiling point temperature to precipitate iron chloride crystals, which were then dissolved in distilled water to prepare a purified iron chloride solution, and the wetted aluminum content was analyzed. The results are shown in Table 2 below. .

[Conventional Example 2]

[filtration]

Purified iron chloride solution was prepared by passing 1 L of an acid wash liquid having a chemical composition of Table 1 through an ultrafiltration membrane, and wet analysis of the aluminum component content is shown in Table 2 below.

In the above Table 1, the crystallization method in which the pickling liquor is heated and concentrated to precipitate into iron chloride crystals is about 60 ppm based on the weight of iron oxide, and about 130 ppm in the case of the prior art 2 which passed an ultrafiltration membrane. Contains Al component.

The crystallization method, which is mainly used to manufacture high-purity iron oxide, shows a significant reduction effect, but only the Al component adhering to the surface of insoluble fine particles is removed when passing through the filtration membrane. Can be.

On the other hand, in the examples in which tartaric acid was added at 1.5 × 10 ⁻³ to 3 × 10 ⁻³ moles, the aluminum content was reduced to 13-22 ppm, and if it was out of the above range, the remaining content was 70-97 ppm as shown in Comparative Examples 1 and 2 Relatively poor aluminum removal effect.

Example 2

Effect of Removal of Aluminum Components by Addition of EDTA in Pickling Waste

Invention Example 6-10

15 ml (1.5 × 10 ^-3 mol), 20 ml (2 × 10 ^-3 mol), 30 ml (2 × 10 ^-3 mol), 40 ml (4) of 0.1 mol EDTA solution in 1 L of waste acid showing the chemical composition shown in Table 1 above X10 ^-3 moles) and 50 ml (5 x 10 ^-3 moles) were added respectively, followed by stirring for 10 minutes at a reaction temperature of 25 ° C.

After the agitation, the colloidal particles were suspended in the pickling liquor, and the suspended solids were filtered to recover the purified waste acid solution, and they were analyzed by wet analysis for the aluminum content and the wet analysis of the aluminum component is shown in Table 3 below. .

Comparative Example 3-4

Except that 5 ml (5 × 10 ^-4 mol) and 10 ml (1 × 10 ^-3 mol) of 0.1 M EDTA solution were added, the same procedure as in the above example was conducted. It is shown in Table 3 below.

As shown in the table above, in the example in which EDTA was added at 1.5 × 10 ⁻³ to 3 × 10 ⁻³ moles, the aluminum content was reduced to 16-22 ppm, and the content remaining as shown in Comparative Examples 1 and 2 was outside the above range. The removal effect was relatively poor at 112-119 ppm.

Example 3

Effect of removing aluminum component by stirring temperature

Invention Example 11-12

30 ml (3 × 10 ⁻³ mol) of a 0.1 mol concentration tartaric acid solution was added to 1 L of the pickling waste liquid having the chemical composition shown in Table 1, followed by stirring at 50 ° C. and 90 ° C. for 10 minutes.

After the agitation, the colloidal particles were suspended in the pickling liquor, and the suspended solids were filtered to recover the purified pickling liquor and subjected to wet analysis. The results are shown in Table 4 below.

The temperature at which tartaric acid is added to the waste acid to react is preferably 50 ° C or 90 ° C. Since the boiling point considering waste acid and tartaric acid is about 100 ° C., it is not considered to be greatly restricted if it is below the temperature.

Meanwhile, when the purified pickling waste liquid prepared according to Inventive Example 1-5 in Table 2, Inventive Example 6-10 in Table 3 and Inventive Example 11-12 in Table 4 is made of iron oxide, the aluminum component is based on the iron oxide weight. It is 22 ppm or less and therefore the present invention is very efficient as a method of removing aluminum components.

[Effects of the Invention]

As described above, the present invention can effectively remove the aluminum components present in the waste acid, and in particular, excellent magnetic properties, temperature characteristics, and the like can be expected in manufacturing soft ferrite.

Claims (2)

To prepare a high-purity iron oxide, adding tartaric acid or EDTA to the pickling liquor in an amount of 1.5 × 10 ⁻³ mol or more (5.8 × 10 ⁻⁴ based on iron component concentration ratio) and reacting at a temperature below the boiling point; and the reaction by the reaction Filtering the liquid to remove the aluminum component-containing colloidal particles formed by the reaction; aluminum component in the pickling waste liquid comprising a. The method of claim 1, wherein the tartaric acid or EDTA is added at 1.5 × 10 ⁻³ to 5 × 10 ⁻³ mol (iron concentration component reference concentration ratio of 5.8 × 10 ⁻⁴ to 1.9 × 10 ⁻³ ).