JPS63182390A - Chelate agent for removing transition metal element and removal of transition metal element using the same - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a chelating agent for removing transition metal elements and a method for removing transition metal elements using the same. The present invention relates to a chelating agent suitable for separating and removing transition metal elements mixed in an aluminum acid salt aqueous solution obtained by treatment, and a method for removing the transition metal elements using the same.

[Prior Art] There are generally two methods for extracting aluminum components from natural aluminum ore. That is,
The alkaline extraction method uses an aqueous sodium hydroxide solution or sodium carbonate aqueous solution, and the acid extraction method uses an inorganic solution such as sulfuric acid or hydrochloric acid. Of these extraction methods, the alkaline extraction method is the most common. Among the alkaline extraction methods, the Bayer method, which uses sodium hydroxide to finally obtain alumina from bauxite, is widely adopted.

The reason why the acid extraction method has not been widely used as a method for extracting aluminum components from natural aluminum ores is that when the acid extraction method is applied, compared to when the alkaline extraction method is applied, the aluminum content is This is because a large amount of impurities are extracted together with the aluminum component, and it is difficult to separate this large amount of impurities and the aluminum component in a subsequent step. The type and amount of these impurities vary depending on the type of aluminum ore. For example, in the case of bauxite, alumina CAl2O5
) 52.57%, iron oxide (Fe203) lxlO% and silica (Sif□) 5-20%, and also contains small amounts of alkali metals such as sodium and alkaline earth metals such as calcium, as well as titanium. , contains trace amounts of heavy metals such as copper, nickel, and zinc, and in the case of high peaks, it also contains 35-39% alumina and 40-5% silica.
It contains 0% and 2-3% iron oxide, as well as small amounts of sodium, potassium and calcium, as well as trace amounts of titanium, chromium and manganese. Therefore, in this bauxite and kaolin, all impurities other than alumina are subject to removal, but among these impurities, the presence of transition metal elements such as iron, titanium, chromium, manganese, copper, and nickel affects the purity of the product. Not only does it reduce the quality of the product, but it also severely limits its uses, and the presence of iron is a particularly big problem because it causes undesirable coloration in the product. therefore,
When the acid extraction method is applied, it is important to separate and remove transition metal elements such as iron, which are impurities mixed with the aluminum component.

As a method for separating and removing impurities such as iron from the extract obtained by applying the acid extraction method from aluminum minerals,
Solvent precipitation methods, solvent extraction methods, and precipitation methods are known, but
Both methods are difficult to industrialize due to technical and economical problems, and have not yet been put into practical use.

Among the methods for separating and removing such impurities, as a solvent precipitation method, for example, a method has been proposed in which ethanol is added to an aqueous solution of aluminum sulfate to crystallize aluminum sulfate, and iron as an impurity remains in the mother liquor ( (Belgium Patent No. 423.079, 1937) However, this method has the problem that iron cannot be removed to a sufficiently satisfactory extent and that it is difficult to recover the expensive ethanol used. be.

In addition, as a solvent extraction method, iron ions present in aluminum sulfate are oxidized using an oxidizing agent.
A method has been proposed in which the valence is changed from +2 to +3 and then extracted and purified with an amine solvent such as LA-1 (trade name: Rohm and Haas) [U.S. No. 3.479.136 (1936) and British Patent No. 1,037,869 (1966)
], However, this method involves - separation of the aqueous phase and amine solvent phase, recovery of high purity amine solvent from the separated amine solvent phase, and treatment of the final sulfuric acid waste containing iron. There are problems in that these methods are technically difficult and that expensive oxidizing agents are required.

Furthermore, the precipitation method depends on the type of precipitant used.
Thorium ferrocyanide (Na, s [Fe (C
N)s ]) Law [U.S. Pat. No. 3,141,733 (1
964]], ferricyanide salt CK3 [Fe (
CN)s] ) method [U.S. Pat. No. 837,280 (1)
930)] and the xanthate method [U.S. Pat. No. 2.416,
No. 508 (1947)] and the like are known.

However, when applying the precipitation method using these precipitants, pre-precipitation using an oxidizing agent is required, similar to the solvent extraction method.
The divalent iron ion must be made +trivalent, and
Since the precipitate produced is in a fine colloidal state, it is difficult to apply the simplest separation method or the proper method, and this problem cannot be solved on an industrial scale even if a flocculant is used. is difficult.

[Problems to be solved by the invention] Conventionally, when applying the acid extraction method as a method for separating and recovering aluminum components from aluminum ore, its practical use has been hampered due to the technical and economic problems described above. It is difficult to

Therefore, the present invention solves these problems and removes transition metal elements such as iron and chromium mixed in an aluminum acid salt aqueous solution obtained by applying an acid extraction method in a simple manner and at a low cost. The object of the present invention is to provide a chelating agent that can be separated and removed, and a method using the same to remove transition metal elements present in an aqueous aluminum acid salt solution.

[Means for Solving the Problems 1] As a result of intensive studies to achieve the above object, the present inventors found that by using a dithiocarbamate-based compound as a chelating agent.

■ React selectively and quantitatively with transition metal elements such as iron and chromium in an aqueous aluminum acid salt solution with a pH of 0.5 to 3.0 to form a stable crystalline precipitate. ) The precipitate consists of large particles (especially).

Since the precipitate containing iron is non-colloidal, it is easy to separate it by filtration.
The present invention was completed based on the following discoveries: It is easy to collect and can be reused.

That is, the present invention provides - General formula (I): ゝNC3,-M (I) (wherein R and R1 may be the same or different and each represents a hydrogen atom or an alkyl group; M represents an alkali metal or ammonium) Alkyldithiocarbamate represented by the general formula (■): (wherein 1M has the above meaning and n is an integer from 2 to 4) The present invention relates to a chelating agent for removing transition metal elements present in an aluminum acid salt aqueous solution, which is characterized by being a bisdithiocarbamine molten salt, and a method for removing transition metal elements present in an aluminum acid salt aqueous solution using the same.

The chelating agent of the present invention has the above formula (I) or formula (II).
), but the alkyl group represented by R or l (1) in formula (I) is.

For example, methyl group, ethyl group, n-propyl group and 1s
Mention may be made of the o-propyl group. Also, formula (I)
Examples of the alkali metal represented by M in formula (II) include sodium and potassium.

Examples of the compound represented by the formula (I) include sodium dimethyldithiocarbamate, ammonium dimethyldithiocarbamate, sodium diethyldithiocarbamate, potassium di-n-propyldithiocarbamate, sodium di-1so-propyldithiocarbamate, and sodium methylethyldithiocarbamate. , sodium methylhydrodithiocarbamate, sodium ethylhydrodithiocarbamate, sodium igo-propylhydrodithiocarbamate, etc. Examples of the compound represented by the formula (!■) include 1, for example, sodium ethylene bisdithiocarbamate, ethylene Examples include ammonium bisdithiocarbamate, potassium propylene bisdithiocarbamate, and sodium hexamethylene bisdithiocarbamate.

The dithiocarbamate represented by formula (I) or formula (II), which is the chelating agent of the present invention, reacts selectively and quantitatively with transition metal elements such as iron and chromium to form a chelate compound. The chelating agent of the present invention is extremely useful in separating useful components from transition metal elements present as impurities. It is very useful for removing transition metal elements that are mixed as a metal.

The aluminum acid salt aqueous solution obtained by applying the acid extraction method referred to here is 1.For example, an aluminum acid salt aqueous solution obtained by applying the acid extraction method is a It is an aqueous solution.

Examples of such aluminum-containing clay minerals include bauxite, kaolin, alunite, montmorillonite, and cloudy soil minerals, and examples of aS-free clay minerals include 1.
For example, sulfuric acid, chlorinated acid, nitric acid, etc. can be mentioned.

Therefore, the aluminum resistant salt aqueous solution is an aqueous solution of aluminum sulfate, aluminum chloride, and aluminum nitrate corresponding to the inorganic acid used, and in these aqueous solutions, transition metal elements derived from aluminum-containing clay minerals, for example, In the case of bauxite, iron.

Titanium, copper and nickel are mixed as impurities.

Removal of the transition metal element mixed in the aluminum acid salt aqueous solution can be carried out by using the transition metal element 1, for example, expressed by formula (I) or formula (II) in an amount of 1.0 to 2.0 times equivalent to iron. By this treatment, the transition metal element forms a chelate compound with the dithiocarbamate represented by formula (I) or formula (■), This precipitate has large particles, and especially those containing iron are non-colloidal and can be easily separated by filtration. Therefore, only the transition metal elements can be easily separated from the aluminum acid salt aqueous solution in this way.

In addition, the precipitate separated by filtration can be treated with a dilute alkaline aqueous solution to obtain formula (I) or formula (II).
) can be separated into a dithiocarbamate and a transition metal element.

In other words, wash the collected precipitate with water 2 to 3 times? 'll
After that, the precipitate was converted to the formula (I) or the formula (r
1.0 to 2.0 of the dithiocarbamate represented by l)
It is added to an aqueous solution of 1 to 5% of sodium hydroxide, potassium hydroxide, or ammonium hydroxide corresponding to twice the amount and stirred. By this treatment, formula (I) or formula (II)
) is eluted in an alkaline aqueous solution, but transition metal elements are not eluted; for example, in the case of iron, insoluble iron oxide (Fe20s ・nH20)
It precipitates as The formula separated and recovered in this way (
I) or the dithiocarbamate represented by formula (H),
It can be reused as a chelating agent in the present invention.

[Examples] Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples.

Example 1 While vigorously stirring 100 g of an aqueous aluminum sulfate solution with a concentration of 20% and an iron content of 2050 ppm (3,0 mmol) obtained by treating kaolin with sulfuric acid, 30% sodium dimethyldithiocarbamate [(CH3) 2
After gradually adding 6.0 g (12.6 mmol) of NC52-Nal aqueous solution, the mixture was further stirred for 5 minutes to form a precipitate.Then, the formed black iron precipitate was filtered and separated. A pure purified aluminum sulfate aqueous solution with an iron content of 39PP■ was obtained. After washing the collected iron precipitate three times with water, 30g of 2% sodium hydroxide aqueous solution was added.
(15.0 mmol) and stirred slowly. As a result, the black precipitate decomposed and turned into a brown catalyzed iron precipitate. The iron oxide precipitate thus formed was filtered and the filtrate obtained was subjected to a standard method (Official Me
thods of analysis of theA
association of official An
analytic chemists 12th Ed,
(1975) e, 310-8, 313), 1.6 g of sodium dimethyldithiocarbamate was recovered (90% recovery rate).

Examples 2 to 8 The same process as in Example 1 was carried out except that the alkyldithiocarbamates shown in Table 1 were used as chelating agents and added at the addition ratios shown in Table 1. The results are shown in Table 1.

Example 9 30% ammonium dimethyldithiocarbamate [(CH3)
2NC3.NH4] aqueous solution (6.2 g (13.5 mmol)) was gradually added in a nitrogen atmosphere, and the mixture was further stirred for 5 minutes to form a precipitate.Then, the formed iron pile precipitate was filtered. , to obtain a purified aluminum sulfate solution of the iron-containing SPP layer. After washing the collected iron pile precipitate three times with water, it was placed in 28 g of a 2% ammonium hydroxide aqueous solution and slowly stirred at 35°C. As a result, the black iron pile precipitate decomposed and turned into reddish brown iron oxide precipitate. When the filtrate obtained by filtering the iron oxide precipitate thus produced was analyzed in the same manner as in Example 1, 1.7 g of ammonium dimethyldithiocarbamate was recovered (recovery rate 91%).

Example 10 Iron content 1 at a concentration of 22% obtained by treating kaolin with hydrochloric acid
680ppm (3.0 mmol), manganese content 42ppm, copper content 33ppm+, zinc content! 1)
45 pp layer and 100 g of a 135 ppm aluminum chloride aqueous solution containing chromium was mixed with 8.5 g of a 20% sodium dimethyldithiocarbamate aqueous solution (11
, 9 mmol) in a nitrogen atmosphere,
Stir for a further 5 minutes to form a precipitate.The resulting precipitate is then filtered and separated to give an iron content of 41 pp.
A pure aluminum chloride aqueous solution containing 318 ppm manganese, 5 ppm copper, 7 ppm zinc and fi 3 ppm+ chromium was obtained. The iron precipitate taken at tP was washed three times with water, then placed in 30 g of 2% sodium hydroxide and gradually stirred at room temperature. As a result, the black precipitate changed to a reddish brown iron oxide precipitate. When the filtrate obtained by filtering the iron oxide precipitate thus produced was analyzed in the same manner as in Example 1, 1.5 g of sodium dimethyldithiocarbamate was recovered (
recovery rate 88%).

Example 11 Kaolin treated with nitric acid, concentration 35%, iron content 1
While vigorously stirring 100 g of a 510 ppm (2,70 mmol) aqueous aluminum nitrate solution, 5.0 g (10 g) of a 30% aqueous sodium dimethyldithiocarbamate solution was added.
, 5 mmol) in a nitrogen atmosphere, and then an additional 5 mmol
The mixture was stirred for a minute to form a precipitate. The black precipitate formed was then filtered to obtain a pure aqueous aluminum nitrate solution with an iron content of 23 pp-. The collected iron pile precipitate was washed three times with water, then placed in 25 g of a 2% aqueous sodium hydroxide solution and slowly stirred at room temperature, and the black precipitate turned into a brown iron oxide precipitate. When the filtrate obtained by filtering the iron oxide precipitate thus produced was analyzed in the same manner as in Example 1, 1.3 g of sodium dimethyldithiocarbamine was recovered (recovery rate 8
7%).

Example 12 Barium sulfide Ig was added to 100 g of an aluminum sulfate aqueous solution with a concentration of 21% and an iron content of 2085 ppm (3.73 mmol) obtained by treating bauxite with sulfuric acid.
React at 05°C for 1 hour.

After all Fe3+ ions were reduced to Fe2+, the mixture was allowed to cool at room temperature. While stirring the aluminum sulfate aqueous solution reduced in this way in a nitrogen atmosphere, 30% sodium ethylene bisdithiocarbamate [(CH2NHC52
After gradually adding 3.9 g (4.56 mmol) of Na)2] aqueous solution, the mixture was further stirred for 5 minutes to form a precipitate.Next, the formed black iron pile precipitate was separated by filtration. A purified aluminum sulfate aqueous solution with an iron content of 81 pp was obtained. After washing the collected iron pile sediment with water three times,
2% sodium hydroxide aqueous solution 2〇- put it in, room temperature,
When slowly stirred in a nitrogen atmosphere, the iron pile precipitate decomposed and turned into a reddish brown iron oxide precipitate. When the filtrate obtained by filtering the iron oxide precipitate thus produced was analyzed in the same manner as in Example 1, 0.94 g of sodium ethylene bisdithiocarbamate was recovered (recovery rate 80%).

Examples 13 to 15 The same procedure as in Example 12 was carried out except that alkylene dithiocarbamates shown in Table 2 were used as chelating agents and added at the addition ratios shown in Table 2.

The results are shown in Table 2.

Example 16 Alunite treated with sulfuric acid, concentration 18%, iron content 1
While vigorously stirring 100 g of an 800 ppm (3.22 mmol) aluminum sulfate aqueous solution, 6.99 g (13
, 0 mmol) was gradually added and stirred for another 5 minutes to form a precipitate.Then, the black iron precipitate formed was filtered and separated to obtain a pure product with an iron content of 2PP. An aluminum sulfate aqueous solution was obtained. Thereafter, the collected iron precipitate was washed three times with water, and then added to 45 g of a 2% aqueous potassium hydroxide solution and slowly stirred, and the black precipitate turned into a reddish brown iron oxide precipitate. When the filtrate obtained by filtering and separating the iron oxide precipitate thus produced was analyzed in the same manner as in Example 1, 1.8 g of dimethyldithiocarbamine-ugly potassium was recovered (recovery rate 87%). .

Example 17 While vigorously stirring 100 g of an aluminum sulfate aqueous solution with a concentration of 10% and an iron content of 11,020 pp (1,83 mmol) obtained by treating montmorillonite with sulfuric acid, a 20%
Sodium dimethyldithiocarbamate aqueous solution 5.0g
(8.98 mmol) was added slowly and stirred for an additional 5 minutes to form a precipitate.Then, the black iron precipitate formed was filtered to obtain pure sulfuric acid with an iron content of 12 ppm. An aqueous aluminum solution was obtained.・Then, the iron precipitate was washed three times with water, and then added to 20 g of a 2% aqueous sodium hydroxide solution and stirred, and the black precipitate changed to a reddish-brown iron oxide precipitate. When the filtrate obtained by filtering this iron oxide precipitate was analyzed in the same manner as in Example 1, 0.9 g of sodium dimethyldithiocarbamate was recovered (recovery rate 90%).

Example 18 Industrial solid aluminum sulfate 10 with alumina (AC 203) content of 15.6% and iron content of 120 ppm
After dissolving 0 g in 200 - of water, while stirring, 10
% sodium dimethyldithiocarbamate aqueous solution 1.2
g was added thereto, and the mixture was further stirred with W2 for 5 minutes to form a precipitate. Next, the produced black precipitate is filtered and separated, and then heated to evaporate the water to obtain iron-containing m 1 pp.
A pure sulfur-like aluminum having a size of less than m was obtained.

[Effects of the Invention] The chelating agent of the present invention has the following excellent effects.

In an aqueous aluminum acid salt solution of rpHo, 5 to 3, it reacts selectively and quantitatively with transition metal elements such as iron to produce a precipitate consisting of a stable chelate compound. Further, the precipitate formed from the generated chelate compound has large particles, and in the case of iron in particular, is non-colloidal, so it can be easily separated by filtration.

・Conventionally, when removing iron present in an aluminum acid salt aqueous solution using a known chelating agent, all of the iron components coexisting in the Fe2+ and Fe3+ ionic states in the aqueous solution are changed to the Fez+ ionic state. A pretreatment step is essential, such as reduction or, in most cases, oxidation to the Fe3+ ionic state. On the other hand, the chelating agent of the present invention can form a resistant and stable chelate compound with either Fe2+ ion or Fe"+ ion, so there is no need for a pretreatment process as in the past, and there is no need for an expensive oxidizing agent. or reducing agent is not required.

■ In addition to iron ions, the aluminum acid salt aqueous solution obtained by acid extraction of aluminum-containing clay minerals contains
Although transition metal ions such as manganese, chromium, and nickel are present, when known chelating agents such as ferrocyanate are used, or when known methods such as solvent extraction or alcohol salting out are applied, Although it is possible to remove iron to a certain extent, it is not possible to remove iron to a satisfactory extent, and transition metal elements other than iron can hardly be removed.In contrast, the chelating agent of the present invention When used, not only iron ions but also other transition metal elements can be removed to a fully satisfactory extent.

■ As mentioned above, the chelating agent of the present invention forms a stable chelate compound with transition metal elements such as iron, but the chelating agent can be easily recovered by treating this chelate compound with a dilute aqueous alkaline solution. Furthermore, the recovered chelating agent can be reused.

Claims (4)

[Claims] (1) General formula (I): ▲Mathematical formula, chemical formula, table, etc.▼(I) (In the formula, R and R^1 may be the same or different, and both are hydrogen atoms or alkyl (M represents an alkali metal or ammonium) or general formula (II): ▲There are numerical formulas, chemical formulas, tables, etc.▼ (In the formula, M has the above meaning , n is an integer of 2 to 4. (2) The chelate for removing transition metal elements according to claim 1, wherein the aqueous aluminum acid salt solution is an aqueous aluminum sulfate solution, an aqueous aluminum chloride solution, or an aqueous aluminum nitrate solution obtained by treating an aluminum-containing clay mineral with an inorganic acid. agent. (3) The chelating agent for removing transition metal elements according to claim 2, wherein the aluminum-containing clay mineral is bauxite, kaolin, alunite, montmorillonite, or slagstone. (4) In the method of removing transition metal elements present in an aluminum acid salt aqueous solution using a chelating agent, general formula (I): ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) (in the formula, R and R^1 may be the same or different, each represents a hydrogen atom or an alkyl group; M represents an alkali metal or ammonium) or an alkyl dithiocarbamate represented by the general formula (II): ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (II) (In the formula, M has the above meaning, and n is an integer from 2 to 4.) After adding and mixing to precipitate the transition metal element as a chelate compound with a dithiocarbamate represented by formula (I) or formula (II),
A step of separating and removing the chelate compound, and a step of separating and recovering the carbamate represented by formula (I) or formula (II) from the chelate compound by treating the separated and removed chelate compound with an alkaline aqueous solution. A method for removing transition metal elements mixed in an aluminum acid salt aqueous solution.