KR0119001B1 - Process for iron chloride utilizing the ferrite iron oxide - Google Patents

Abstract

A process for producing ferric chloride by recycling waste acid produced from acid rinsing line of ironworks comprises the steps of: refining the waste acid by filtrating Si of colloidal sludge with a cover of filter membrane so that the remaining Si may be up to 65% of the whole Si; crystallizing ferric chloride by heating the refined solution at boiling point, condensing and chilling, subsequently; cleaning the ferric chloride crystal with Fe solution of which concentration is 4 M or more.

Description

Method for preparing iron chloride solution for the production of soft ferrite iron oxide

The present invention relates to a method for producing an iron chloride solution for producing high purity iron oxide for soft ferrite raw materials used in magnetic materials, and more particularly, other impurities other than iron, especially SiO ₂ , Ca, A method for producing a high purity iron chloride solution suitable for the production of iron oxide for advanced soft ferrite raw materials having an Al content of less than 0.005%.

Cold mill pickling process in iron works is carried out with 18% hydrochloric acid solution to remove iron oxide layer formed on the surface of hot rolled steel sheet, and is equipped with an acid recovery facility for recovering and regenerating hydrochloric acid from by-product waste acid. In addition to the 18% hydrochloric acid regeneration, ferric oxide is produced as a by-product. This by-product ferric oxide is currently supplied as an important basic raw material, accounting for 70-90% of the ferrite raw material.

In general, waste acid produced by the cold rolling process in steel mills is supplemented with 18% of 36% hydrochloric acid in fresh water to replenish the hydrochloric acid and wastewater absorbed by fresh water. Pickled. Waste acid emitted during this pickling process contains about 25% FeCl ₂ and other impurities such as SO ₄ −, Si, Al, Na, K, Ca, Mn, etc. The chemical composition of the waste acid is shown in Table 1 below.

Acid recovery equipment for recovering hydrochloric acid from the pickling waste liquid as shown in Table 1 is classified into a spray roasting method and a fluid roasting furnace method according to the recovery method of iron oxide produced by-product. In general, iron oxide produced by the spray roasting method is supplied as a raw material of hard ferrite or pigment, and iron oxide produced by the flow roasting method is supplied as the raw material of soft ferrite. The quality of the iron oxide supplied as hard ferrite or pigment depends greatly on the content of various impurities, in particular, Si, Al, Ca, Mn and the like. Iron oxide produced by pickling waste of steel has many problems in terms of quality, especially when used as a raw material for soft ferrite. That is, the waste acid solution contains a large amount of metal impurities such as Si, Al, Ca, Na, and Mn, and is naturally contained in iron byproducts by spraying or flowing roasting. Therefore, in the final product manufactured by using iron byproducts, ie, soft ferrite product, a large amount of SiO and metal impurities are contained, and the most important influence on the characteristics of soft ferrite product among these impurities is SiO. It is becoming. Table 2 shows the quality standards of the ferrite iron oxide prescribed in JIS K1462.

In general, iron oxide produced in the cold rolling process of steelworks contains about 0.05% by weight of SiO with respect to FeO, and is mixed with these byproducts such as iron, Zn, Mn, Ni, Mg, and Cu compounds to perform heating, firing, and grinding processes. After the soft ferrite powder is produced.

However, SiO powder contained in iron oxide acts as a cause of lowering the permeability (u), electrical resistance value, and quality factor (Q) characteristics of soft ferrite. As the soft ferrite magnetic material becomes smaller, the high performance of the soft ferrite magnetic material is required, that is, the permeability (u) and the electrical resistance value are increasing every year. Development is strongly demanded. Purification of such impurities is possible only for extremely limited components in a state made of iron oxide, so it is preferable to remove them in a solution state in a waste acid state.

The impurity reduction method in pickling waste liquid which has been carried out or proposed so far is a method of removing the pickling waste liquid by using an ultrafiltration membrane (Japanese Patent Laid-Open No. 61-289). The pickling waste liquid is brought into contact with silica gel to adsorb SiO onto the surface of the silica gel. , Separation method (Japanese Laid-Open Patent Publication No. 59-111930), a method of adding a polymer flocculant to the pickling waste liquid to coagulate SiO in the pickling waste solution, and separating and separating it (JP-A-58-151335). Physical removal methods, such as a method of adsorbing and separating SiO by passing an adsorbent medium by adding an activator (Japanese Patent Publication No. 60-122087), and a method of heating and concentrating a pickling waste liquid to precipitate iron crystals (Japanese Patent Laid-Open Publication No. SO 53-62797, SO 62-59532, WO 1-215725, WO 1-261236, WO 3-12325) A method of separating the flocculation dates by heating and concentrating the pickling waste liquid and then aging (JP-A-61-53123 ), Mountain Iron scrap is administered to the waste liquid to adjust to a predetermined pH and then filtered (Japanese Patent Laid-Open Publication No. Hei 2-302325), a method of contacting an acid-containing waste liquid with an oxygen-containing gas and filtering it (Japanese Patent Laid-Open No. 59-162139) In addition, there is a chemical removal method such as a method of administering an alkaline substance to the pickling waste liquid, adjusting the pH, and then filtering (JP-A-63-49294).

The above-mentioned filtration and the physical removal method using various adsorption media reduce only the colloidal particles, i.e., SiO particles, generated in the waste acid, and are effective in removing Si ions and other impurities in the form of dissolved ions. Almost no manufacturing method. In addition, the method of generating and filtering precipitates by adjusting the pH of the solution by adding a neutralizing agent such as iron scrap or alkaline solution among the chemical removal methods, there is an additional problem that the recovery of iron ions is reduced, on the other hand, In order to reduce impurities due to the precipitation of iron chloride crystals by heating and concentrating waste acid, the proposed method requires not only several crystallization processes but also removal of impurities adsorbed on the surface of precipitated crystals. There is a problem that it is difficult to do.

Accordingly, the present invention has been proposed to solve the above problems, and in addition to the insoluble Si particles generated as colloidal sludge particles, as well as for the advanced soft ferrite raw material by effectively removing the impurity ions such as Si and other Ca, Al An object of the present invention is to provide a method for preparing a high purity iron chloride solution for producing iron oxide.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated.

The present invention relates to a method for producing an iron chloride solution for producing iron oxide for soft ferrite raw material from pickling waste liquid, wherein the Si component in the colloidal sludge produced in the waste acid is separated by a filtration membrane, and the remaining amount of Si component is 65% relative to the total amount of Si component. Purifying to below%; A crystallization step of heating, concentrating, and cooling the purified iron chloride solution to boiling point temperature to precipitate iron chloride crystals; And it relates to a method for producing a ferric chloride solution for the production of soft ferrite iron oxide, characterized in that it comprises a step of washing the iron chloride crystals with 4M or more Fe solution.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

The present invention is characterized in that the Si component generated as colloidal sludge particles in the waste acid is filtered off by a filtration membrane, precipitated with iron chloride crystals after heating and concentration, and then washed.

Usually, the Si component coexisting in the waste acid is largely composed of an insoluble Si component, that is, a colloidal particle and a dissolved Si component, and their abundance is present at approximately a ratio. Therefore, if the insoluble Si components are not controlled to the proper concentration or less by using the filtration membrane, these insoluble Si components are very likely to be occluded inside the precipitated iron chloride crystals in the subsequent crystallization process, and thus cannot be removed by the cleaning process. . If the crystallization process is repeated, the reduction effect can be expected, but it is not economical because the problem of having to repeat the crystallization process in order to prepare a high-purity iron chloride solution for high-quality soft ferrite.

Therefore, after filtering the Si component generated as colloidal sludge particles in the waste acid by the filtration membrane, the residual Si component amount (hereinafter referred to as 'Si component coexistence amount') to the total amount of the Si component in the waste acid is 65% or more. In the case of coexistence, it is impossible to prepare a high purity iron chloride solution by the first crystallization process and the cleaning process.Since the second and third crystallization processes are repeated, the high purity iron chloride solution can be manufactured. It is more preferable to control so that it may be below.

In addition, in the process of washing the iron chloride crystals precipitated in the present invention, distilled water or the like may be used. However, since the precipitated iron chloride crystals may be reused during washing, it is preferable to use a Fe concentration solution of 4 M or more. As such, when Fe concentration of 4M or higher is used as the washing liquid, the precipitated iron chloride crystals are not re-dissolved during washing, and thus impurities can be removed while maintaining a high recovery rate.

The iron chloride solution prepared according to the present invention exhibits a composition suitable for the production of iron oxide for ferrite raw materials, in particular iron oxide for soft ferrite, in particular high-quality soft ferrite oxide, whose electromagnetic properties are also influenced by trace impurities. In other words, when the iron oxide is manufactured using the high purity iron chloride solution prepared according to the present invention, not only the SiO component which acts as the most important impurity in soft ferrite manufacturing but also the Ca and Al components can be produced at 50 ppm or less based on the FeO weight. Will be displayed.

Hereinafter, the present invention will be described in more detail with reference to Examples.

Example 1

Invention Example 1-4

The chemical composition of the spent acid produced in the cold rolling mill is shown in Table 3 in terms of the coexistence of the other components in g, based on the case where the total Fe component contains 100g / L. 2 L of waste acid having the chemical composition shown in Table 3 was separated by a filtration membrane to remove colloidal insoluble Si component particles, thereby controlling each solution in which the coexistence amount of the Si component in the waste acid was controlled to 65%, 59%, 55%, and 51%, respectively. The mixture was heated to a boiling point temperature, concentrated to about 50%, cooled, precipitated with iron chloride crystals, and dissolved in distilled water to prepare a purified iron chloride solution. Each of these purified iron chloride solutions was wet analyzed and the results are shown in Table 4 below.

[Prior Example 1]

The colloidal insoluble Si particles by the filtration membrane are not filtered out, that is, 2 L of waste acid having the chemical composition shown in Table 3 below, which does not control the coexistence amount of Si in the waste acid below the optimum concentration, is heated to a boiling point temperature and concentrated to about 50%. Precipitated with iron chloride crystals, dissolved in distilled water to prepare a purified iron chloride solution. This purified iron chloride solution was wet analyzed and the results are shown in Table 4 below.

Comparative Example 1-3

The colloidal Si component produced in the waste acid was filtered by a filtration membrane, and the Si component coexistence was controlled to 85%, 80%, and 75%, respectively. 4 is shown.

Example 2

Invention Example 5-8

2L of waste acid having the chemical composition as a by-product of cold mill in steel mill was separated by filtration membrane to remove colloidal insoluble Si component particles to reduce the amount of Si component in waste acid to 65%, 59%, 55% and 51%, respectively. The controlled solution was heated to a boiling point temperature, concentrated about 50%, cooled, precipitated with iron chloride crystals, the precipitated iron chloride crystals were washed with 4M Fe concentration solution, and dissolved in distilled water to prepare iron chloride crystals. The solution was wet analyzed and shown in Table 5 below.

[Conventional Example 2]

The colloidal insoluble Si particles by the filtration membrane are not filtered out, that is, 2 L of waste acid, which shows the chemical composition of Table 3 above, which does not control the coexistence amount of Si in the waste acid below the optimum concentration, is heated to a boiling point temperature and concentrated by about 50%. The precipitated iron chloride crystals were washed with 18% hydrochloric acid solution, and the resulting iron chloride crystals were dissolved in distilled water to prepare an iron chloride solution. The solution was wet-analyzed and shown in Table 5 below.

[Comparative Example 4-6]

The colloidal Si component produced in the waste acid was separated by a filtration membrane, and the Si component coexistence was controlled to 85%, 80% and 75%, respectively. The results are shown in Table 5 below.

Example 3

[Comparative Example 7-11]

2 L of waste acid having the chemical composition of Table 3, which does not filter colloidal insoluble Si particles by the filtration membrane, was heated to a boiling point temperature, concentrated to about 50%, cooled to obtain primary crystals, and dissolved in distilled water to prepare an iron chloride solution. These solutions were wet analyzed and shown in Table 6 below. In addition, the iron chloride crystals prepared by washing the primary crystals with 4M Fe concentration solution were dissolved in distilled water to prepare an iron chloride solution, and these solutions were shown in Table 6 by wet analysis. In addition, the solution obtained by washing the primary crystals was heated and concentrated again to obtain secondary crystals, and the secondary crystals were washed with 4M Fe concentration solution to prepare an iron chloride solution, and these solutions were wet analyzed and shown in Table 6 below. In addition, the solution obtained by washing the secondary crystals was heated and concentrated again to obtain tertiary crystals, which were dissolved in distilled water to prepare an iron chloride solution, and wet analysis was shown in Table 6 below.

[Comparative Example 12-16]

The purified iron chloride solution prepared by using 1 L, 2 times, 4 times, 8 times, 10 times the filtration frequency of the waste acid 2L having the chemical composition of Table 3 using only the filtration membrane was analyzed by wet analysis and the results are shown in Table 6 below. Shown in

[Prior Example 3-4]

2L of waste acid having the chemical composition shown in Table 3 was introduced into the top of the packing tower at an inflow rate of 100 ml / min in a packing tower filled with silica gel and activated carbon (inner capacity 660 cm 3: H = 20 cm, 0 = 6.5 cm) and the bottom of the packing tower. Purified iron chloride solution obtained from was analyzed by wet analysis and the results are shown in Table 6 below.

Example 4

Invention Example 9-10

Table 3 above, which is a by-product of cold mill in steel mill, separates 2 L of waste acid having a chemical composition by a filtration membrane to remove colloidal insoluble Si component particles, and controls a solution in which the amount of Si component in waste acid is controlled to 51% is heated to a boiling point temperature. Concentrated about%, cooled and precipitated as iron chloride crystals. The chemical composition of the purified iron chloride solution prepared by washing 50 g of precipitated iron chloride crystals with 20 ml of Fe solution of 4M and 4.5M concentration and the recovery rate of iron chloride crystals were shown in Table 7 below.

[Comparative Example 17-20]

50 g of iron chloride crystals precipitated in Inventive Example (9-10) were washed with 2M, 3M Fe concentration solution and 20 ml of distilled water 18% hydrochloric acid solution, in the same manner as in Inventive Example (9-10). The chemical composition of the prepared iron chloride solution and the recovery rate of iron chloride crystals were investigated and the results are shown in Table 7 below.

Although the method of the conventional examples (3,4) shown in Table 6 above, that is, an adsorption medium, has a certain effect on the removal of insoluble Si particles generated as colloidal sludge particles in waste acid, the dissolved impurity ions (Ca) , Al, Mn) is not expected to reduce the effect, but rather the contact of the waste acid containing unreacted hydrochloric acid elutes the components of the adsorption medium to increase the incorporation of impurities, so high purity iron chloride It was judged that it was not suitable for the method of preparing a solution. In particular, when the purified iron chloride solution of the conventional example (3) prepared by using silica gel as an adsorption medium with iron oxide, Ca and Al components of about 170ppm, Mn component of about 1700ppm, SiO component of about 130ppm It showed a medium purity iron oxide quality.

In addition, in the method of the conventional example (1) shown in Table 4 above, that is, when precipitated as iron chloride crystals by crystallization without removing the colloidal Si component generated in the waste acid by the filtration membrane, the soluble components (Ca, Al Although the Si component including, Mn) and the like have an effect of reducing, it can be seen that the Si component can only be expected to have an effect similar to that of using an adsorption medium. When the purified iron chloride solution prepared by the method of the prior art (1) was made of iron oxide, the iron oxide quality was about 40 ppm, 70 ppm, 1100 ppm of Mn component, and 130 ppm SiO component, respectively, based on FeO weight. That is, the Ca, Al, Mn components, etc. correspond to the high purity iron oxide quality, while the SiO component corresponds to the medium purity iron oxide quality. Therefore, it can be seen that the subsequent crystallization process can be repeated several times as shown in Comparative Example (7-11) of Table 6 in order to prepare a high-purity iron chloride solution suitable for producing high-purity iron oxide by the conventional method 1.

However, in the present invention, as shown in Inventive Example (1-4) of Table 4, after controlling the colloidal sludge Si component generated in the waste acid by the filtration membrane primarily, the Si coexistence amount was controlled to 65% or less. When only the first crystallization process is performed, not only the SiO component but also Ca and Al components are removed to about Table 4, wherein impurities are adsorbed on the surface of the precipitated crystal. In order to remove even the adsorbed impurities as described above, when washed with 4M concentration Fe liquid as shown in Inventive Example (5-8) of Table 5, the purity of the iron chloride solution is as shown in Table 5 above. The component is hardly detected and it can be seen that the Ca component is also greatly improved to 10 ppm or less based on the FeO weight. In particular, it can be seen that the use of the Fe liquid of 4M concentration or more during cleaning can improve the recovery rate of precipitated iron chloride crystals by 95% or more.

As described above, the present invention effectively removes impurity ions such as Si and other Ca and Al in dissolved ions, as well as insoluble Si particles generated from colloidal sludge particles, thereby providing a high-purity iron chloride solution. There is an effect that can produce iron oxide for advanced soft ferrite raw material.

Claims (1)

In the manufacturing method of the iron chloride solution for manufacturing iron oxide for soft ferrite raw material from pickling waste liquid, the Si component in colloidal sludge produced in waste acid is separated by a filtration film, and the amount of residual Si component is 65% or less with respect to the total amount of Si component. To purify if possible; A crystallization step of heating, concentrating, and cooling the purified iron chloride solution to a boiling point temperature to precipitate iron chloride crystals; And washing the iron chloride crystals with a Fe solution of 4M or higher concentration.