JP2001226120A - Method for manufacturing ferric sulfate solution - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a ferric sulfate solution having an extremely low content of manganese by removing the manganese in the ferric sulfate solution obtained by dissolving an iron ore consisting essentially of FeOOH in sulfuric acid. SOLUTION: The iron ore consisting essentially of FeOOH is dissolved in sulfuric acid to obtain a ferric sulfate solution, a permanganate is added so as to obtain the solution in >=0.667 molar ratio of MnO4-/Mn as the permanganate to manganese in the solution, the solution is heated to insolubilize manganese, and the insolubilized component is separated from liquid to manufacture the ferric sulfate solution.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a ferric sulfate solution having an extremely low manganese concentration in the production of a ferric sulfate solution which has been attracting attention as a chemical for treating various wastewaters and also as a flocculant for water purification in recent years. And a method for producing the same.

[0002]

2. Description of the Related Art Ferric sulfate solution has conventionally been used as a flocculant for treating sewage, human waste or various industrial wastewater, or sludge.
Widely used, such as sludge dewatering aids. Aluminum salts such as aluminum sulfate and polyaluminum chloride are also used for similar applications.However, ferric sulfate solutions are superior to aluminum salts in removing organic substances in wastewater, have a wide flocculation pH, It is excellent in that it has a high sedimentation speed and has a deodorizing effect on odors, especially sulfur-based odors. In addition, there is an advantage that the corrosion to the equipment is small as compared with the ferric chloride solution of the same iron salt solution.

[0003] Recent tap water sources tend to gradually deteriorate due to the effects of environmental pollution, and problems such as trihalomethane and off-flavors have become apparent. One of these causes is due to organic substances present in a tap water source, and iron-based flocculants such as a ferric sulfate solution which is excellent in removing these substances have recently been reviewed in place of aluminum salts. However, most iron salts, such as a ferric sulfate solution currently on the market, have various problems when they are used for water purification. One of the reasons is that the manganese concentration in the product solution is high. Therefore, if manganese is contained in the coagulant used in the treatment of raw tap water, the manganese is gradually oxidized by chlorine injected in the subsequent treatment process, and the problem of black precipitate formation in the water distribution pipe, In addition, peeling off them causes "black water".

[0004] Such ferric sulfate solution is generally used to oxidize pickling waste solution of steel, to dissolve and oxidize metallic iron such as scrap iron in sulfuric acid, and to produce by-product ferrous sulfate discharged during titanium production. However, these methods mainly use ferrous iron as a raw material, so that an oxidation step was necessary to produce a ferric sulfate solution. Under such circumstances, the present inventors have found that FeOOH containing 30% or more as ferric iron is easily soluble in sulfuric acid, and the oxidation step is almost unnecessary. I found an application that I could do.
(Japanese Patent Application No. 11-309058) In addition, those in which manganese is reduced from a ferric sulfate solution obtained by dissolving iron ore containing FeOOH as Fe ^{3+ by} 30% or more with sulfuric acid have excellent turbidity removing effect. Filed an application where they found it. However, the manganese concentration in the ferric sulfate solution thus produced may be about 50 to 1000 mg / kg when the Fe3 ⁺ concentration is approximately 11%. Many. Since iron and manganese in the ferric sulfate solution have very similar properties, and the iron concentration is about 100 times as large as manganese, it is very difficult to selectively remove only manganese. It was difficult.

[0005] From the above, in order to produce a product having a low manganese concentration, it is necessary to use raw materials having a very low manganese content. It was difficult to produce a ferric sulfate solution having a low manganese concentration. As described above, although there is a demand for a ferric sulfate solution having a low manganese concentration, there has been almost no research on manganese removal in the ferric sulfate solution so far, with almost no results.

[0006] Many manganese removal methods are generally used in water treatment, wastewater treatment and the like. For example, Japanese Patent Application Laid-Open No. 9-29267 discloses a method in which permanganate is added to wastewater containing manganese to remove manganese in the wastewater. However, such wastewater is generally neutral and has a low concentration of other contaminants, so that it is generally easy to remove it.However, such wastewater coexists with a high-concentration iron salt such as a ferric sulfate solution. Moreover, it is extremely difficult to remove manganese from the solution under strongly acidic conditions. Therefore, as a method of removing impurities from an iron salt solution containing impurities such as manganese, a method of concentrating and cooling the solution to crystallize and separate the iron salt (Japanese Patent Application Laid-Open No. 10-273326), etc. Although it must be noted that such a method can reduce the concentration of manganese to a very low level, but the process is very complicated and not economical.

[0007]

In view of such a situation, the present inventors selectively remove only manganese from a ferric sulfate solution obtained by dissolving iron ore containing FeOOH as a main component with sulfuric acid. Further, the present inventors have conducted intensive studies on a method for producing a ferric sulfate solution having a low manganese content that can be used in water purification treatment and the like. As a result, a specific amount or more of permanganate is added to a ferric sulfate solution obtained by dissolving iron ore containing FeOOH as a main component with sulfuric acid, and this solution is heated to insolubilize manganese. By separating and removing the insolubilized component, it was found that a ferric sulfate solution having a low manganese concentration can be stably produced even in a raw material in which the manganese concentration in the solution changes. Based on this, the present invention has been completed.

[0008]

That is, the present invention relates to a ferric sulfate solution obtained by dissolving iron ore containing FeOOH as a main component with sulfuric acid, a permanganate relative to the amount of manganese in the solution. Permanganate is added so that the amount becomes 0.667 or more as MnO ₄ ⁻ / Mn (molar ratio), and the solution is heated to insolubilize manganese, and then the insoluble matter is subjected to solid-liquid separation. And a method for producing a ferric sulfate solution comprising:

[0009] In the production method of the present invention, a permanganate salt is added in a theoretical amount or more to a ferric sulfate solution containing manganese obtained by dissolving iron ore containing FeOOH as a main component with sulfuric acid; By heating, it is a method of insolubilizing the manganese in the ferric sulfate solution and the excess permanganate, and efficiently producing a low manganese ferric sulfate solution by filtering it out. . Therefore, even if the permanganate is added in a larger amount than the theoretical amount or the manganese content in the ferric sulfate solution changes, it is possible to stably produce a ferric sulfate solution having a low manganese concentration. it can. Also,
When there is a reducing inorganic substance such as Fe ²⁺ or an organic substance that consumes permanganate in the solution, it becomes difficult to calculate the amount of permanganate to be added. To produce a ferric sulfate solution having a low manganese content.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The iron ore containing FeOOH as a main component used in the present invention is a naturally occurring iron ore containing FeOOH as a main component, and the naturally occurring iron ore includes limonite, Examples include iron hydroxide minerals called goethite and lepite, but are not limited thereto. The present invention uses a ferric sulfate solution obtained by dissolving such iron ore with sulfuric acid. Such a ferric sulfate solution contains not only a normal salt but also a free acid or a basic acid. It may be a salt.

[0011] The method for producing a ferric sulfate solution of the present invention comprises:
Dissolve iron ore containing FeOOH as a main component with sulfuric acid
To the resulting ferric sulfate solution, add permanganate and add
Manganese is insolubilized by heating the solution
You. The type of permanganate used is
Potassium phosphate, sodium permanganate, permanganate
Ammonium and the like can be exemplified. Addition amount of permanganate
Is the Fe present in the solution²⁺There are reducing inorganic substances, such as
Or the amount of organic substances that consume permanganate
More specifically, it is contained in ferric sulfate solution
The amount of permanganate added to the amount of manganese is MnO_Four ^-/ Mn
(Molar ratio) as 0.667 or more, more preferably 0.667 to 6.00
The permanganate is added so as to be within the range.

Regarding the heating temperature, if the temperature is 70 ° C. or higher, manganese can be removed, and the higher the temperature, the higher the manganese insolubilization efficiency. However, if the temperature is lower, the heating time is longer, so it is preferable. Is 80 ° C. or higher.
The heating time varies depending on the heating temperature, the target removal rate of manganese, and the like, but is generally about 30 minutes to 6 hours. Also, the method of adding permanganate, even if it is added as a solution,
Alternatively, it may be added as a powder. Further, the necessary amount of addition may be added all at once, or may be added in portions.
In addition, the timing of addition may be before the start of heating, after the solution has reached the target heating temperature, or at the temperature raising stage. Further, as a method of adding a permanganate, when the iron ore containing FeOOH as a main component is dissolved in sulfuric acid to produce a ferric sulfate solution, the permanganate is added in advance to form a sulfated iron ore. An addition method for producing an iron solution can also be adopted.

By performing the above treatment, manganese contained in the ferric sulfate solution becomes insoluble MnO ₂ or a hydrate thereof, and an excess amount of permanganate is similarly decomposed by autolysis. It becomes insoluble MnO ₂ or its hydrate.

Next, by separating the insolubilized manganese from the solution, the ferric sulfate solution having a low manganese concentration, which is the object of the present invention, can be obtained. As the separation means, any method such as a method of filtering after sedimentation and separation, and a method of centrifugation may be used.

[0015]

The present invention will be further described below with reference to examples of the present invention. In the examples, all percentages are by weight unless otherwise specified.

Example 1, Comparative Example 1
267.2 g of 70% sulfuric acid and 148.4 g of water were added to a 3 L four-necked flask, and 120 g of iron ore (mainly FeOOH, total Fe concentration of 63.9%) was gradually added while stirring at 300 rpm. The solution was heated to 105 ° C. with continued stirring, and heating was continued at this temperature for 3 hours. After heating, the solution was cooled, and thereto was added 90 g of water and 5 g of diatomaceous earth (trade name: Rashiolite # 2000, manufactured by Showa Chemical Industry Co., Ltd.), and the mixture was stirred and filtered with No. 5C filter paper to obtain a ferric sulfate solution. Was. The composition of the ferric sulfate ^{solution, Fe 3+ 11.62%, Fe 2+} 0.01% or less, SO ₄
30.0% and Mn was 56 mg / kg.

200 g of the ferric sulfate solution was placed in a 500 ml four-necked flask equipped with a reflux condenser, and potassium permanganate (Kanto Chemical Co., Ltd., special grade reagent) was added with 5% ion-exchanged water.
1.94 g of a solution dissolved in (MnO ₄ ⁻ / Mn molar ratio = 3.01) was added, and 20
The solution was heated while stirring at 0 rpm, and heating was continued for 3 hours while maintaining the boiling state (103 ° C.). After heating, cool
Diatomaceous earth (manufactured by Showa Chemical Industry Co., Ltd.)
1 g of trade name (Rashiolite Special Flow) was added, and the mixture was stirred and filtered with No. 5C filter paper to obtain a ferric sulfate solution from which manganese had been removed.
[Example 1] Separately, a ferric sulfate solution containing 56 mg / kg of Mn obtained from the iron ore was used.
In a 0 ml four-necked flask, 1.94 g of the 5% potassium permanganate solution and manganese sand (manufactured by Tochem Co., Ltd., trade name: MC-2)
Was added and the solution was left for 3 hours without heating. After 3 hours, diatomaceous earth (manufactured by Showa Chemical Co., Ltd., trade name: Rashiolite # 2
000), and the mixture was stirred and filtered with No. 5C filter paper. Comparative Example 1 The iron and manganese concentrations of the ferric sulfate solutions obtained in Example 1 and Comparative Example 1 were measured. The results are shown in Table 1.

[0018]

[Table 1]

Example 2 and Comparative Example 2 With a reflux cooler
To a 5 L three-necked flask, 519.6 g of 70% sulfuric acid and 288.8 g of water were added, and while stirring at 300 rpm, 240 g of iron ore (having FeOOH as a main component and a total Fe concentration of 63.9%) was gradually added. The solution was heated to 105 ° C. with continued stirring, and heating was continued at this temperature for 3 hours. After heating, the solution was cooled, and 180 g of water and 8 g of diatomaceous earth (manufactured by Showa Chemical Industry Co., Ltd., trade name: Rashiolite # 2000) were added.After stirring, the solution was filtered through a No. 5C filter paper, and the basic ferric sulfate solution was added. I got
The composition of this basic ferric sulfate solution is Fe ³⁺ 11.57%, Fe ²⁺
The results were 0.01%, SO ₄ 29.0%, and Mn 63 mg / kg.

400 g of this basic ferric sulfate solution was placed in a 1 L four-necked flask equipped with a reflux condenser, and 193.5 mg of potassium permanganate (Kanto Chemical Co., Ltd., reagent grade) was added.
The solution was heated at 90 ° C. for 5 hours with stirring. After completion of heating, the solution was cooled, 1 g of diatomaceous earth (manufactured by Showa Chemical Industry Co., Ltd., trade name: Rashiolite Special Flow) was added to this solution as a filter aid, and the mixture was stirred and filtered with No. 5C filter paper to remove manganese. A ferric sulfate solution was obtained. [Example 2] Separately, a basic ferric sulfate solution containing 63 mg / kg of Mn obtained from the iron ore was used, and 400 g of the basic ferric sulfate solution was supplied to a four-hole with a reflux condenser. Take the flask and add potassium permanganate (Kanto Chemical Co., Ltd., reagent grade) 4
3.6 mg was added and the solution was heated at 90 ° C. for 5 hours with stirring. After heating, the mixture was cooled, 1 g of diatomaceous earth (trade name: Rashiolite Special Flow, manufactured by Showa Chemical Industry Co., Ltd.) was added, and the mixture was stirred and filtered with No. 5C filter paper. Comparative Example 2 The iron concentration and the manganese concentration of the basic ferric sulfate solutions obtained in Example 2 and Comparative Example 2 were measured. The results are shown in Table 2.

[0021]

[Table 2]

Example 3 and Comparative Example 3 With a reflux condenser
To a 5 L three-necked flask, 519.6 g of 70% sulfuric acid and 288.8 g of water were added, and while stirring at 300 rpm, 240 g of iron ore (having FeOOH as a main component and a total Fe concentration of 63.9%) was gradually added. The solution was heated to 105 ° C. with continued stirring, and heating was continued at this temperature for 3 hours. After heating, the solution was cooled, and 180 g of water and 8 g of diatomaceous earth (manufactured by Showa Chemical Industry Co., Ltd., trade name: Rashiolite # 2000) were added.After stirring, the solution was filtered through a No. 5C filter paper, and the basic ferric sulfate solution was added. I got
The composition of this basic ferric sulfate solution is Fe3 ⁺ 11.20%, Fe2 ⁺
It was 0.01%, SO ₄ 28.2%, and Mn 55 mg / kg.

300 g of the basic ferric sulfate solution is placed in a 1 L four-necked flask equipped with a reflux condenser, and a 40% aqueous solution of sodium permanganate (Nippon Chemical Industry Co., Ltd., SPM-40) is used.
Was added and heating of the solution was continued at 95 ° C. for 4 hours. After the heating was completed, the solution was cooled, 1.5 g of diatomaceous earth (trade name: Rashiolite Special Flow, manufactured by Showa Chemical Industry Co., Ltd.) was added to the solution, and the mixture was stirred and filtered with No. 5C filter paper to remove manganese. A basic ferric sulfate solution was obtained. [Example 3] Separately, a basic ferric sulfate solution containing 55 mg / kg of Mn obtained from the iron ore was used, and 300 g of the basic ferric sulfate solution was supplied to a four-hole with a reflux condenser. 40 in a flask
% Sodium permanganate aqueous solution (Nippon Chemical Industry Co., Ltd., S
0.34 g of PM-40) was added, and heating of the solution was continued at 50 ° C. for 4 hours. After completion of the heating, the mixture was cooled, 1.5 g of diatomaceous earth (trade name: Radiolite Special Flow, manufactured by Showa Chemical Industry Co., Ltd.) was added to the solution, and the mixture was stirred and filtered with No. 5C filter paper. Comparative Example 3 The iron concentration and the manganese concentration of the basic ferric sulfate solutions obtained in Example 3 and Comparative Example 3 were measured. The results are shown in Table 3.

[0024]

[Table 3]

[0025]

The method for producing a ferric sulfate solution of the present invention comprises:
A ferric sulfate solution obtained by dissolving iron ore containing FeOOH as the main component with sulfuric acid selectively removes only manganese from the ferric sulfate solution, and has a low manganese content of ferric sulfate that can be used in water purification treatment etc. This is a method for producing a solution. Further, the method of the present invention can stably obtain a ferric sulfate solution having a low manganese concentration even when the manganese concentration in the ferric sulfate solution changes. Furthermore, even if there are reducing inorganic substances such as Fe ²⁺ or organic substances consuming permanganate in the solution,
Not only is it easy to calculate the amount of permanganate added,
It is also effective in removing these impurities from the ferric sulfate solution. Therefore, the ferric sulfate solution obtained by the method of the present invention is particularly useful as a flocculant for water purification instead of an aluminum salt.

Claims (2)

[Claims] 1. A ferric sulfate solution obtained by dissolving iron ore containing FeOOH as a main component with sulfuric acid, the amount of permanganate relative to the amount of manganese in the solution is MnO ₄ ⁻ / Mn (mol Ratio) is 0.667 or more as permanganate is added, and the solution is heated to insolubilize the manganese, and then the ferrous sulfate solution is produced by solid-liquid separation of the insoluble matter. Method. 2. The method for producing a ferric sulfate solution according to claim 1, wherein the heat treatment of the solution is performed at a temperature of 70 ° C. or more for 30 minutes or more.