JPS59162140A - Purification of aqueous solution of ferrous chloride - Google Patents

Abstract

PURPOSE:To prepare a solution of ferrous chloride free from SiO2 and other impurities, by adding a specific amount of a solution of aluminum hydroxide colloid to an aqueous solution of ferrous chloride, thereby coagulating and adsorbing SiO2 to the surface of the colloid particle. CONSTITUTION:An aqueous solution of ferrous chloride obtained as a by-product of the process for pickling a steel plate with hydrochloric acid, is adjusted to 4-5pH with ammonia water, and is added with a solution of aluminum hydroxide colloid (25-60wt% in terms of Al2O3 based on SiO2 in the aqueous solution) and if necessary with negatively charged cellulose (10-20pts.wt. per 1pt.wt. of the colloidal solution). After the adsorption and coagulation of SiO2 in the aqueous solution to the surface of the colloid particles or the surface of the cellulose, the mixture is subjected to ultrafiltration.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the purification of an aqueous ferrous chloride solution produced as a by-product from the hydrochloric acid pickling process of steel sheets.

In recent years, the method of pickling steel plates, etc. has shifted from the conventional sulfuric acid pickling method to the hydrochloric acid pickling method, and with this, a method has been adopted to recover expensive hydrochloric acid and reuse it for pickling steel plates. There is. As a means for recovering hydrochloric acid from an aqueous solution for washing steel sheets with hydrochloric acid, as is well known in the industry, a typical method is a spray roasting method.
Iron oxide is produced as a by-product (hereinafter referred to as by-product iron oxide).

This by-product iron oxide is widely used as the main raw material for soerite, but there are many problems in terms of quality characteristics, especially when it is used as the main raw material for soft ferrite.

That is, in the ferrous chloride aqueous solution which is the starting material, SiO
It also contains a large amount of metal impurities such as AI, Ca, and Na, and these impurities are contained in the by-product iron oxide during spray roasting and the like.

However, the soft ferrite product, which is the final product manufactured using this by-product iron oxide as the main raw material, contains a large amount of 5i02 and metal impurities, and these impurities deteriorate the characteristics of the soft ferrite product. It is the cause of this.

Among these impurities, attention will be paid to 5inQ, which is said to have the most adverse effect on soft ferrite products, and will be described below.

For by-product iron oxide, SiO□ is usually 0.0% compared to Fe2O.
It contains about 5% by weight (hereinafter simply referred to as 0.05% by weight), and this by-product iron oxide and Zn, Mn+ N+
+ Mg + Soft ferrite powder obtained by a manufacturing method of mixing ferrite auxiliary raw materials such as Cu compounds, heating, firing, and pulverizing (hereinafter simply referred to as dry method) is as follows:
In the manufacturing process, Si02 is further mixed in, resulting in a product containing a large amount of 5iO9.

It is known that 5i02 contained in soft ferrite powder causes a decrease in properties such as magnetic permeability (μ) and electrical resistance value. This fact, for example,
Publication No. 15360 states, “...in ferric oxide...
Due to the accumulation of impurities, it cannot be used at all for magnetic materials that require high performance and miniaturization, especially soft composite ferrites such as manganese/zinc or manganese/magnesium.The main cause of this is secondary oxidation. Trace amount of silica M contained in iron
This is clear from the statement that "the crystals of C and ferrite particles become coarser and the (electrical) resistance value and μ/Q characteristics decrease due to the action of (Si02)."

In recent years, as electric devices have become smaller and lighter, the soft ferrite magnetic materials incorporated in these devices have also become smaller. There is a strong demand for the development of a method for purifying and removing Sioa contained in by-product iron oxide, which is the main raw material for soft ferrite.

In view of the above, the present inventor has determined that S in the by-product iron oxide
Take care of i02! In order to remove the by-product iron oxide, the existence form of Sim2 and Sins in each step of the manufacturing process are
As a result of various studies on purification and removal methods, the present invention was achieved.

That is, the present invention adds 25 to 60% by weight of aluminum hydroxide colloidal particles at ρ114 to 5 to a ferrous chloride aqueous solution, calculated as 1□08 to SiO□ in the aqueous solution, or further adds negative It is added to the cellulose whole aluminum hydroxide 304 particles which are electrically charged to adsorb and aggregate the Si02 in the aqueous solution on the surface of the aluminum hydroxide colloidal particles by adding 10 to 20 times the amount by weight, or on the surface of the cellulose. This is a method for purifying a ferrous chloride aqueous solution, which comprises adsorbing and aggregating SiO□ in the aqueous solution through aluminum hydroxide colloid particles, and then filtering it.

Next, the technical background that led to the completion of the present invention and the configuration of the present invention will be described.

First, the inventors of the present invention first conducted a study to determine at which step in the production process of by-product iron oxide SiOQ can be purified and removed, and in order to find out whether the purpose can be easily achieved,
We investigated the existence form of t02.

Conventionally, methods have been attempted to remove Si02 by subjecting the by-product iron oxide to various treatments. The inventor is
By-product iron oxide is obtained by spraying an aqueous ferrous chloride solution into a heating furnace body at about 600 to 800°C and decomposing and oxidizing it. Therefore, it was thought that it would be extremely difficult to purify and remove Si02 at the stage when by-product iron oxide was generated.

The inventor of the present invention has found that it is necessary to perform some kind of treatment in advance to purify and remove SiO□ before the by-product iron oxide is produced, that is, at the stage of the ferrous chloride aqueous solution. Knew.

Furthermore, the present inventor has discovered that S contained in the ferrous chloride aqueous solution
After repeated studies to purify and remove ioQ, we focused on the fact that SiO□ contained in an aqueous ferrous chloride solution exists in the form of Si02 colloidal particles. This S
i02 colloidal particles are very fine particles and can be removed not only by normal filtration means such as filter presses, vacuum suction filtration machines, and pre-recorded pressure filtration machines, but also by using special filtration machines, such as ultrafilters. It was something that could not be done. The present inventor has further investigated the method of efficiently removing these fine SiO2 colloidal particles, and has developed a method for efficiently removing the fine SiO2 colloid particles. The idea was to form colloidal particles into coarse aggregates with good filterability. When aluminum hydroxide colloid particles are added to a ferrous chloride aqueous solution at pH 4 to 5, the aluminum hydroxide colloid particles adsorb and aggregate Si02 colloid particles on the particle surface, forming coarse aggregates with good filterability. We obtained the knowledge that it is possible to generate aggregates. This aggregate forms a negative (Wj
It is thought that it is formed by electrically adsorbing and aggregating electrically charged Si02 colloidal particles.

The coarse aggregates thus produced can be separated by filtration using a conventional filtration means such as the above-mentioned filter press, vacuum suction filtration machine, and precoat pressure filtration machine.

Ultrafiltration allows more efficient filtration and separation.

When positively charged cellulose is present when adding aluminum hydroxide colloidal particles to a ferrous chloride aqueous solution, it is possible to make the aggregates even coarser. Because the state forms a network structure,
Since the filterability can be improved, -H1 can be efficiently separated by filtration.

Aggregates in this phenomenon are formed by adsorbing and aggregating positively charged Si02 through positively charged aluminum hydroxide colloid particles on the surface of positively charged cellulose. It is thought that it will become coarser. In addition, this aggregate forms a network structure in which the cellulose molecules are entangled with each other, so it is thought that the filterability is greatly impaired.

Next, various conditions for implementing the present invention will be described.

The ferrous chloride aqueous solution in the present invention is used for pickling steel plates with hydrochloric acid.
[The ferrous chloride aqueous solution produced as a by-product from the process is used. Another source of the ferrous chloride aqueous solution is the ferrous chloride aqueous solution discharged from the titanium white manufacturing process, and this ferrous chloride aqueous solution can also be used as a starting material in the present invention.

The pl+ of the ferrous chloride aqueous solution in the present invention needs to be adjusted to 4 to 5 by adding aqueous ammonia. In this case, in order to recover IIcI normally, it is practically preferable to neutralize it mainly with scrap iron or the like, and then adjust the pH to 4 to 5 with aqueous ammonia.

If ρ is less than 114, the added aluminum hydroxide colloidal particles will dissolve, and if pl is more than 5, a large amount of iron in the ferrous chloride aqueous solution will precipitate, so a purified ferrous chloride aqueous solution can be obtained. However, the intended purpose of the present invention cannot be achieved.

As the aluminum hydroxide colloidal particles in the present invention, aluminum hydroxide colloidal particles produced by mixing an aqueous aluminum salt solution and an alkali can be used as they are, or those that have been further washed with water can be used. The amount of aluminum hydroxide colloid particles added is ^120 for SiO□
It is 25 to 60% by weight when converted to 3. If it is less than 25% by weight, the effect of purifying and removing Si02 is not sufficient. It is possible to carry out the present invention even when the amount is 60% by weight or more, and even when the aluminum hydroxide colloidal particles are present in excess of the SiO2 colloidal particles in the ferrous chloride aqueous solution, it is possible to separate them by filtration. Although it can be separated, there is no point in adding more than necessary - and it is not economical.

For the filtration in the present invention, ordinary filtration means such as the above-mentioned filter press, vacuum suction filtration machine, pre-pressure filtration machine, etc. may be used. Ultrafiltration allows efficient filtration and separation.

As the positively charged cellulose in the present invention, filter cotton available from Yamahan may be used as is.

Moreover, shredded cotton thread can also be used. The amount of positively charged cellulose added is 10 to 20 times the weight of the aluminum hydroxide:10oid particles.

If the amount is less than 10 times the amount, further improvement in filtration efficiency cannot be expected. Although the present invention can be practiced even when the amount is 20 times or more by weight, it is meaningless and uneconomical to add more than necessary.

The order of addition of cellulose and aluminum hydroxide colloidal particles in the present invention may be either first or simultaneous. After dispersing cellulose in an aluminum salt aqueous solution and adding an alkali, cellulose is added. A material with aluminum hydroxide colloidal particles adsorbed on the surface can also be used.

The present invention configured as described above has the following effects.

That is, according to the method of adding aluminum hydroxide colloidal particles in the present invention, SiO□ colloidal particles can be adsorbed and aggregated on the surface of aluminum hydroxide colloidal particles to produce coarse aggregates with good filterability. Si02 in an aqueous ferrous chloride solution can be easily removed.

Further, according to the method of adding aluminum hydroxide colloidal particles and cellulose according to the present invention, the aggregates can be made even coarser, and since the aggregates form a network structure, the filtration Since the properties can be improved, SiO□ in the ferrous chloride aqueous solution can be purified and removed more efficiently.

That is, according to the present invention, as is clear from the examples described later, the SiO2 content in the ferrous chloride aqueous solution is reduced to 0゜oo.
Since it can be purified and removed to less than Sii%, the content of Si02 in the by-product iron oxide obtained by performing 111i mist roasting using the ferrous chloride aqueous solution as a starting material becomes extremely small. Therefore, even if SiO2 is unavoidably mixed in during the production process of soft ferrite powder using the dry method described above, the SiO□ content in the final product can be suppressed as a whole, and the SiO2 content is extremely low. Soft I Ferrai 1 ~ products can be obtained.

Furthermore, according to the method of the present invention, S in the ferrous chloride aqueous solution
Not only iO3 but also metal impurities such as the aforementioned AI, Ca, and Na can be removed at the same time.

In addition to the above-mentioned dry method, methods for producing the soft ferrite magnetic material include ferrite auxiliary raw materials Zn, Mn, Ni,
There is a so-called wet method in which a spinel type oxide produced by adding an alkali to an aqueous ferrous chloride solution containing an aqueous Mg and Cu salt solution and performing an oxidation reaction is heated and calcined.

Even when using this wet method, 5iO9 can be obtained by the method of the present invention.
Of course, it is possible to use an aqueous ferrous chloride solution in which metal impurities such as AI, Ca, and Na have been purified and removed.

Next, the present invention will be explained by examples.

In addition, the amount of Fe'+ in the following examples is JIS K 1
462 5.2.2. By potassium dichromate titration method, the amount of 5i02 was determined as 5.4.3 of JIS K 1462. Eight l+ca+Na was measured gravimetrically using atomic absorption spectrophotometry.

Example I Fe I]7.2sif, 5i020.085M (F
This corresponds to 0.051% by weight based on e20B. ), ^I
O,023%, CaO,017% and NaO,0
) A steel plate hydrochloric acid pickling ferrous chloride aqueous solution 1β containing 2% was prepared, and aqueous ammonia was added to the aqueous solution to adjust the pH to 4.5. Separately, aluminum sulfate (8Iz(S(L)a・1
71120) 0.3g was dissolved in 0.2N water to make an aluminum sulfate aqueous solution containing AI 0.02554, and 0.5ml of ammonia water was added to this to make p
.

After producing aluminum hydroxide 9173041 particles in step 9.5, the product was washed with water until pH'H was reached.

Aluminum hydroxide colloid particles after washing with water 0.07
g was added to the ferrous chloride aqueous solution, which corresponds to 52% by weight based on SiO□. ) After stirring for 5 minutes, the mixture was separated by filtration using a filter press.

He” remaining in the filtrate is 11.2.(l HlS i
02 is 0.00589J (0.00 for Fe*Os
This corresponds to 36% by weight. ) and 11110.008
M, CaO, 008M and Na 0.005M.

Examples 2 to 7 Ferrous chloride aqueous solution, amount of aluminum hydroxide mucolloid particles added, type and amount of cellulose added, and filtration means were varied, and ferrous chloride was prepared in the same manner as in Example 1. The iron aqueous solution was purified.

The main purification conditions and purification results are shown in Table 1.

Comparative example 1 Water Mated y-luminium! An attempt was made to purify a ferrous chloride aqueous solution in the same manner as in Example 5, except that iron particles were not added. Fe2' remaining in the filtrate is 113°0ry6.
5in2 is 0.077 M (0.0 for Pe203
This corresponds to 48% by weight. ) and ^I 0.0215
4, CaO,017M and NaO,012M, and impurities in the ferrous chloride aqueous solution were hardly removed.

Claims (1)

[Claims] 1. To a ferrous chloride aqueous solution, aluminum hydroxide colloidal particles with al14 to 5 are added in an amount of 25 to 60i in terms of 1□02 to SiO□ in the aqueous solution. 510 in the above aqueous solution on the surface of the aluminum colloid particles.
1. A method for purifying an aqueous ferrous chloride solution, which comprises adsorbing and filtering ferrous chloride. 2. In p114-5, aluminum hydroxide colloidal particles were added to a ferrous chloride aqueous solution at an AI ratio of 0 to 5iO9 in the aqueous solution. Si in the water Ig liquid is added to the surface of the aluminum hydroxide colloid particles in an amount of 25 to 60% by weight.
1. A method for purifying an aqueous ferrous chloride solution, which comprises adsorbing and aggregating ferrous chloride, followed by ultrafiltration. 3. Add 25 to 60% by weight of aluminum hydroxide colloidal particles to SiO2 in the aqueous solution and negatively charged cellulose to a solution of ferrous chloride/iron chloride/8 at pH 4 to 5. By adding 10 to 20 times the weight of aluminum hydroxide colloidal particles, Si in the above aqueous solution is applied to the cellulose surface via aluminum hydroxide colloidal particles.
A method for purifying an aqueous ferrous chloride solution, which comprises adsorbing and coagulating 02 and then filtering it.