JPS6059175B2 - Arsenous acid manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing arsenous acid from electrolytically precipitated copper produced during smelting of arsenic-containing copper concentrate.

For the production of arsenous acid, there is an old method based on the reaction formula shown by Mellor [A Compreh
intensiveTreatiseonInorganic
andTlleoretical Chemistry V
ol, 99p, 319 (1933)].

3CUS04+AS2S3+4H20 →3CuS+string AsO2+311250, and in recent years, arsenic sulfide (As) has been used as a wet purification method for arsenic oxide.

s. A method in which copper sulfate is added to a slurry of A and AS2S5) to remove copper by a substitution reaction, and arsenic oxide dissolved in the resulting solution is reduced with 502 and then crystallized as arsenous acid (As.O0) 52-5469 hours) is proposed. Incidentally, there are almost no reports other than those mentioned above regarding the production of arsenous acid using copper sulfate. The method proposed above also uses AS2S5 as the arsenic sulfide, resulting in highly pure As.

It is difficult to obtain 03, and moreover, As is produced in the process of copper removal reaction.

O. There are drawbacks such as the fact that it is impossible to obtain AS2O3 in high yield due to loss due to early crystallization of AS2O3. An object of the present invention is to provide a method for producing highly pure (99.4% or more) arsenous acid in high yield and economically. The present inventor basically used the electrolytically precipitated copper produced during the smelting of arsenic copper concentrate as a starting material to produce the Mel
By applying lor's reaction formula, the above object was successfully achieved and the present invention was completed.

The present invention will be explained in detail below. The present invention involves adding and mixing an aqueous hydrogen peroxide solution and arsenic sulfide (Asβ3) to a leachate obtained by leaching electrolytically precipitated copper with a low-concentration sulfuric acid solution, separating and removing the produced copper sulfide, and Sulfur dioxide gas is introduced into the liquid to remove arsenic from the liquid.
) is characterized by being crystallized as

The electrolytically precipitated copper used as a starting material in the present invention is produced by removing copper from the electrolytic solution produced during electrolytic refining of blister copper in the process of producing electrolytic copper by smelting arsenic copper concentrate. It is a slime-like substance produced during arsenic electrolysis, and is usually used in the smelting process of copper concentrate (e.g. flash furnace).
It is circulated to

For reference, an example of the composition of electrolytically precipitated copper is as follows. In the present invention, first, electrolytically precipitated copper is leached with a low concentration sulfuric acid solution to prepare a leaching solution mainly containing Cu2+ and As5+.

When preparing this leachate, it is necessary to prevent the elution of antimony (Sb) as much as possible in order to obtain high-purity arsenous acid as the target product. PHL ~ 1 at a concentration below /'
．． Use the sulfuric acid solution in step 5. During this leaching, a sulfuric acid solution is added so that the slurry concentration of electrolytically precipitated copper becomes 100 to 250 y/e, and air is added to this at a rate of 1 to 5 e/min/e.
It is preferable to perform the leaching for 6 to 8 hours with stirring at room temperature to 90° C. while blowing at a level of e. By this leaching, the impurities in the electrolytically precipitated copper are leached into the solution at a leaching rate of 75 to 85%. Next, arsenic sulfide (AS2S3) was added to the leachate obtained as described above, and a copper removal reaction (3CUS04+, AS2S3+4H20
+3CUS+2HAS02+3H2S04), but in the present invention, excess A is removed during this copper removal reaction.
An aqueous solution of hydrogen peroxide is added in advance to the leachate in order to increase the actual yield of arsenic by minimizing the early precipitation of S2O3.

In addition, a considerable amount of antimony (
65 to 80%) is separated and removed from the system together with copper sulfide as a decoppered residue that precipitates at the same time when a part of arsenic precipitates as A>203 and is generated by the decoppered reaction. The As/Sb ratio in the reaction solution increases significantly, and as a result, it becomes possible to reduce the contamination of the AS2O3 crystals as the target product by antimony to 0.6% or less. In addition, in order to efficiently remove antimony during the copper removal reaction, the arsenic sulfide added to the leachate should be AS2O.
3, and if AS2O3 is used, the desired high purity arsenous acid cannot be obtained.

In the present invention, the arsenic sulfide (AS2S3) may be one in which arsenic in the exhaust gas generated in the smelting process (for example, a flash furnace) during the smelting of copper concentrate is fixed as sulfide. Arsenic in the exhaust gas is fixed by washing the gas with water to elute the arsenic into the water, and sulfurizing the resulting aqueous solution with a sulfurizing agent such as hydrogen sulfide gas or sodium hydrogen sulfide. Since the arsenic sulfide obtained in this manner is in the form of a cake, it is preferably added to the above-mentioned leachate in the form of a slurry. Incidentally, an example of the composition (dry weight basis) of the arsenic sulfide obtained by fixing is as follows.
Add hydrogen peroxide aqueous solution and arsenic sulfide (AS2) to the above leachate.
When adding the slurry in S3) to carry out the copper removal reaction, hydrogen peroxide is added in an amount of 0.5 to 3.0 equivalents as H2O2 to the As3+ generated in the leachate, and then hydrogen peroxide is added to the Cu2+ in the solution. About equivalent amount of AS2S3 is added to
The reaction may be carried out at a temperature of 60 to 90°C with stirring for about 0.5 to 1 hour. Note that if the amount of hydrogen peroxide added becomes excessive, a portion of the copper removal residue (CuS) generated by the copper removal reaction will be redissolved, so care must be taken. In addition, AS2S3
It is advantageous to add the slurry in parts, rather than adding it all at once, in order to reduce the loss of M. In the present invention, the copper removal reaction using AS2S3 of the electrolytically precipitated copper leachate is carried out in the presence of hydrogen peroxide, so as mentioned above, the early crystallization of AS2O3 (HAsO2 generated by the copper removal reaction) is accompanied by the copper removal reaction. (occurring due to low saturation solubility) can be suppressed to a minimum.

That is, hydrogen peroxide is HAs produced by the above reaction.
At least a part of O2 is oxidized to highly soluble As5+ to suppress the crystallization of excess AS2O3 and finally to A.
Helps increase the yield of S2O3. Also, this means that
The concentration of arsenic in the copper removal reaction solution will increase due to the arsenic acid produced by the copper removal reaction and the As5+ already present in the leachate, so the solution is directly reduced with SO2 without concentrating the solution to remove arsenic acid. Enables crystallization. Furthermore, in the present invention, arsenic in the exhaust gas is used in the decopper removal reaction.
Since fixed arsenic sulfide is used as S2S3, it is different from ordinary electrolytic copper (9 to 101) used as a copper electrolyte purification method.
]Terama) and the freezing method (2 to 3 hours), the reaction time is shorter (4). 5 to 1 hour) and with virtually 100% efficiency.

Sulfur dioxide gas (SO2) is introduced into the reaction solution obtained by performing a copper removal reaction on the leaching solution of electrolytically precipitated copper as described above by blowing, etc. to remove arsenic ions (As3+, As
5+) is crystallized as AS2O3.

The introduction of SO2 into the reaction solution is preferably carried out at a temperature of room temperature to 80° C. for 1 to 3 hours at a rate of about 0.5'/Min/'. By introducing this SO2, the amount of arsenic in the reaction solution is 82~
85% crystallizes as AS2O3. The crystallized AS2O3 thus obtained is of high quality with a high purity of 99.4% or more and an extremely low antimony content, so gallium arsenide, which has been attracting attention as a material for various semiconductor devices in recent years, It can be said that it is suitable as a raw material for producing metal arsenic for producing aluminum arsenic and the like. Further, according to the present invention, electrolytically precipitated copper obtained in the electrolytic refining process in the smelting process of arsenic copper concentrate and sulfide obtained by fixing arsenic in exhaust gas generated in the smelting process of the copper concentrate described above Since the above-mentioned high-grade arsenous acid can be produced from arsenic (AS2S3), the method for producing arsenous acid according to the present invention can be applied to, for example, the flash smelting method, which is a typical copper smelting method currently in use. When used in combination, it becomes easy to smelt copper ore with a high arsenic content, and in addition, the scale of equipment for arsenic removal treatment can be reduced, which has the advantage of being very economically advantageous.

EXAMPLES The present invention will be explained in more detail with reference to Examples below.

Example 1 As a starting material, electrolytically precipitated copper having the following composition produced in the process of self-smelting was used.

Electrolytically precipitated copper slurry with the above composition (concentration 160v/e)
A sulfuric acid solution with a concentration of 32f/e was added dropwise to the leaching solution while blowing air at a ratio of '/Mln/' into the solution to maintain the pH of the leachate at 1.5, and leaching was carried out at a temperature of 80'C for 8 hours. Then, this leachate was filtered out.

The Fuchibetsu residue was returned to the flash furnace and subjected to the smelting process. Next, the post-leaching solution obtained as described above (CU2+67
．． 14f/E. ．． AS3+0.5y/E,. AS5+1
8.4v/e and Sb+0.61f/e)
At 2.6f, hydrogen peroxide aqueous solution (formed A in the solution after leaching)
1.5 equivalents as H2O2 with respect to s3+ ion concentration)
was added, and then 1.2 equivalents of As? was added to the Cu2+ ion concentration in the leached solution. 3 was added in the form of a slurry and reacted for 1 hour. The AS2S3 slurry was added in six equal amounts at intervals of one millimeter. Table 1 shows the results of analyzing the amounts of As3+, AS5+ and Sb in the solution after the reaction was completed.
Also, as a reference, when the reaction was carried out without adding hydrogen peroxide to the solution after leaching, and when hydrogen peroxide was added to the As3+ ion concentration in the solution after leaching, the concentration was 0.5, 1.0, 2. .0
, 2.5, and 3.0 equivalents of each reaction solution were analyzed in the same manner, and the results are also shown in Table 1. As shown in Table 1, an increase in the amount of hydrogen peroxide added increases the M oxidation rate in the post-leaching solution and improves the actual yield of As, but on the contrary, the removal rate of Sb decreases. Note that if the amount of hydrogen peroxide added exceeds 3.0 equivalents, CuS in the decoppered residue precipitated by the decoppering reaction will be redissolved by H2O2 under acidic sulfuric acid, reducing the quality of the target AS2O3. This should be kept in mind as it may cause Next, the post-reaction liquid was separated with P to remove the decoppered residue mainly consisting of CuS (the decoppered residue was returned to the flash furnace and subjected to the smelting process), and then SO2 was added to the furnace liquid at a temperature of 70°C. Arsenous acid (.AS2O3
) was crystallized.

The quality of the crystallized AS2O3 obtained was 99.77%. For reference, the respective post-copper removal solutions obtained when no hydrogen peroxide was added and when the above amounts of hydrogen peroxide were added were also reduced by blowing SO2 gas in the same manner. Table 2 shows the results of crystallizing AS2O3 and analyzing the quality of each crystallized AS2O3.
Shown below.

As shown in Table 2, the amount of FI2O2 added was 3.0 equivalents. When the amount approaches, crystallization occurs for the reasons mentioned above. AS2O
The quality of 3 will begin to deteriorate.

Example 2 Electrolytically precipitated copper with the following composition produced in the process of another copper smelting method was used as a starting material, and the amount of hydrogen peroxide added to the leachate was changed to 1.0 equivalent instead of 1.5 equivalent. The procedure was similar to that described in Example 1.

Composition of electrolytically precipitated copper: The composition of the electrolytically precipitated copper solution after leaching and the composition of the reaction solution obtained by subjecting the leaching solution to a copper removal reaction are as follows.

Furthermore, the quality of the crystallized AS2O3 obtained by reducing the above reaction liquid by introducing SO2 gas is 99.5%, and the reduced liquid is ASl4. O9/E. ．． CUOy/ElsbO
．． O6y/e and H? The composition was 04161y/e.

From the above results, a 100% copper removal rate was achieved through the copper removal reaction of the solution after leaching electrolytically precipitated copper, and As was crystallized at an actual yield of 82% without concentrating the solution after the reaction. I understand.

It can also be seen that As3+ remaining in the solution after reduction is quite low at 14y/e.

Note that in this example, the time required from the start of the leaching operation to the crystallization of AS2O3 was approximately 11 hours, and it can be said that the method for producing arsenous acid according to the present invention is extremely efficient.

Claims (1)

[Claims] 1. Hydrogen peroxide aqueous solution and arsenic sulfide are added to and mixed with the leachate obtained by leaching electrolytically precipitated copper with a low-concentration sulfuric acid solution, and the produced copper sulfide is separated and removed. A method for producing arsenous acid, which comprises introducing sulfur dioxide gas into a liquid to crystallize arsenic in the liquid as arsenous acid. 2. The manufacturing method according to claim 1, wherein the electrolytically precipitated copper is obtained from an electrolytic refining step in the smelting process of arsenic-containing copper concentrate. 3. The production method according to claim 1 or 2, wherein the arsenic sulfide is obtained by fixing arsenic in exhaust gas generated during smelting of arsenic-containing copper concentrate as sulfide and making it into a slurry form. 4. The manufacturing method according to claim 1, wherein the sulfuric acid concentration of the sulfuric acid solution is 10 g/l or less. 5. The manufacturing method according to claim 4, wherein the pH of the sulfuric acid solution is 1 to 1.5.