JPS6221729B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an improved method for producing a composite copper-arsenic compound as an intermediate product of a chromium-copper-arsenic compound wood preservative from a smelting intermediate containing copper and arsenic. Conventionally, chromium-copper-arsenic compound preservatives (hereinafter referred to as
CCA (abbreviated as CCA) uses chromium trioxide or potassium dichromate, copper sulfate or copper oxide, and arsenic acid or pyroarsenic acid. For example, in Japan, the addition ratio of these compounds is shown in Table 1. It is stipulated in the Japanese Industrial Standards (JISK-1554), and each wood preservative treatment company prepares its own mixture according to this standard.

[Table] However, when CCA drugs are prepared according to Item 1A above, water-soluble K ⁺
_This is not preferable because ions and SO ^2-4 ions are mixed in as impurities. In this respect, among the CCA drugs, No. 1 B drug, which does not contain the above-mentioned impurities, is superior. However, when preparing No. 1B drug, cupric oxide is used as the copper compound, and this must be dissolved in chromium trioxide and arsenic or pyroarsenic acid. However, cupric oxide is not an easily soluble substance, so the required amount of chromium trioxide and cupric oxide are added to an extremely concentrated aqueous solution such as arsenic acid, kneaded, and reacted.
It must first be made into a highly viscous aqueous solution. Moreover, this dissolution operation is not easy because it generates heat. In addition, the raw materials for the above-mentioned drugs with few impurities have many problems, such as being expensive. The applicant of the present application has separately applied for a method for producing a composite copper-arsenic compound as an intermediate product for CCA-based drugs, which does not have the problems of the conventional methods described above. (Tokukai Akira
56-14421) This method for producing a composite copper-arsenic compound uses smelting intermediates such as sulfides, arsenides, and oxides containing copper and arsenic as raw materials, and adds a water-soluble copper salt to the raw materials. After autoclave treatment and adding sulfuric acid to extract copper and arsenic respectively to obtain an acidic aqueous solution in which the concentration ratio of copper to arsenic (Cu/As) in the extract was 1.0 or more,
This is cooled to a predetermined temperature, held at that temperature, and separated into solid and liquid to achieve the desired concentration ratio of copper and arsenic (Cu/
An acidic aqueous solution of As) is obtained, then an alkali is added to the solution to adjust the pH to 6 to 7, and the entire amount of copper and arsenic in the aqueous solution is separated as a precipitate. However, the above method ensures that the desired
A product with a Cu/As ratio can be obtained, but the sulfide, arsenide, and/or oxide are treated separately, and each extract obtained has an excess or deficiency in copper and arsenic content due to the characteristics of raw material generation. Therefore, in order to achieve the desired concentration ratio of copper and arsenic (Cu/As), the process is complicated, such as adding copper separately to the extract, cooling it to a specified temperature, and holding it at that temperature for solid-liquid separation. There is also danpan (CuSO ₄ ,
There were problems such as 5H ₂ O) adhering to the flexible pipe and clogging the outlet pipe. The object of the present invention is to solve the above-mentioned problems using composite copper.
An object of the present invention is to provide a method for producing an arsenic compound. In order to achieve this objective, the inventors of the present application improved the method for producing the above-mentioned composite copper-arsenic compound,
The desired copper and arsenic concentration ratio (Cu/Arsenic) can be achieved by separately processing various smelting intermediates containing copper and arsenic, and simply mixing the resulting extracts in appropriate proportions.
The method of the present invention was achieved by discovering a method for producing a composite copper-arsenic compound in which an aqueous solution of As) is obtained, then an alkali is added to the solution, and the entire amount of copper and arsenic is separated as a precipitate. The present invention will be explained in detail below. The raw materials used in the method of the present invention are of two types: smelting intermediates consisting of one or both of arsenides and oxides containing copper and arsenic, and smelting intermediates consisting of sulfides containing copper and arsenic. However, its characteristics are as follows. Although the arsenide and oxide mentioned above vary depending on operating conditions, the content of copper is usually considerably higher than the content of arsenic. This raw material is made into a slurry by adding water, and when sulfuric acid is added while blowing air, both copper and arsenic are extracted. On the other hand, the above sulfide contains both copper and arsenic,
Although this varies depending on operating conditions, the arsenic content is usually higher than the copper content. Similarly, water is added to this raw material to form a slurry, and when alkali is added while blowing air and treated while maintaining the pH at 5 to 8, only arsenic is extracted as acidic arsenate. This treatment method follows the first step of Japanese Patent Application Laid-open No. 160590/1983, which was previously filed by the applicant. The applicant et al. obtained the desired copper to arsenic concentration ratio (Cu/As) by mixing both extracts in an appropriate ratio based on the characteristics of the extracts obtained from these two different types of raw materials. I tried. However, although this method is the simplest, when both extracts are mixed in a predetermined ratio and then neutralized by adding alkali, some copper forms sulfides, resulting in so-called black precipitation. The product obtained by separating this product as a precipitate of a composite copper-arsenic compound, which involves a reaction, is an undesirable product that does not dissolve when used to manufacture CCA drugs. Ta. It is unclear why copper sulfide is produced when the two types of extracts described above are mixed. When the slurry of smelting intermediates made of sulfides is treated while adding alkali, which corresponds to the second step of the method of the present invention, most of the sulfur content in the sulfide substances becomes elemental sulfur, but some of this sulfur content contains ionized sulfur compounds that are not oxidized to sulfate ions but are unstable, and when this aqueous solution is mixed with a sulfate solution containing copper, the sulfur ions and copper ions combine. I thought that it might generate CuS. The inventors of the present application made the above hypothesis in researching an improved method for producing a composite copper arsenic compound, and conducted intensive studies on a method for treating the sulfide based on the hypothesis. As a result, water is added to a smelting intermediate consisting of arsenic or copper and sulfide containing arsenic to form a slurry, and water is added to a soluble alkali to adjust the pH value to 5-8 and the temperature to 50℃ or higher. After extracting at normal pressure until the oxidation-reduction potential (hereinafter abbreviated as ORP value) becomes positive by blowing air into the extract, the extract from the first step, sulfuric acid, and an acidic aqueous solution containing copper are added to the extract. Add one or more of the following:
Hold for a period of time to obtain an extract with a pH of 4 or less, and use this extract to add sulfuric acid to another extract, a smelting intermediate consisting of arsenide and/or oxide containing copper and arsenic. When this method was treated and mixed with the resulting aqueous solution in an appropriate ratio, results beyond expectations were obtained; if this method was followed, the formation of the black precipitate mainly consisting of copper sulfide as described above was not observed at all. We experimentally discovered that there is no
We established a method to prepare an aqueous solution with a Cu/As ratio. In the method of the present invention, in the first step, a slurry prepared by adding at least an equivalent amount of sulfuric acid and water to the amount of copper in the arsenide or oxide containing copper and arsenic is blown with air at a temperature of 50°C or higher, preferably 60°C or higher. The extraction process is carried out at normal pressure for 3 hours or more while blowing. The reason why the extraction conditions are set as above is to efficiently extract the copper and arsenic contained therein. In the second step, water is added to the smelting intermediate of the sulfide described above to form a slurry, and an aqueous solution of a water-soluble alkali, preferably an alkali hydroxide, is added to this slurry to reduce the pH value to 5. ~8. Hold the temperature at 50℃ or above, preferably 80℃ or above, and extract at normal pressure for 3 hours or more. When the ORP value becomes positive, extract from the first step, arsenide containing copper and arsenic, oxidation. thing,
At least one of an acidic aqueous solution containing copper and sulfuric acid is added to adjust the pH of the extract to 4.0 or less, and the extraction is continued for 2 hours or more, after which the extract is separated. The reason why the pH value is maintained at 5 to 8 in the second step is that if the pH value is lower than this, the extraction rate of arsenic will decrease, and iron, zinc, etc. in the raw materials will be extracted at the same time, which is undesirable. This is because the oxidation rate of the sulfur content in the raw material increases at this value, resulting in an increase in the amount of sulfuric acid produced. Next, the reason why the treatment temperature is set to 50° C. or higher, preferably 80° C. or higher is to efficiently extract arsenic. Next, in the middle of the extraction operation, that is, when the ORP value becomes positive, add additives such as sulfuric acid to lower the pH to below 4.0, continue the extraction operation, and then separate the insoluble materials. Although it is not clear, some unstable sulfur ions are generated during the extraction operation in the second step, and this sulfur content reacts with copper ions etc. eluted from sulfuric acid or arsenide, etc., resulting in a stable form. It is assumed that this is to prevent the formation of black precipitate in the subsequent third step. Each extract that has undergone the above first and second steps is
Next, copper and arsenic are mixed so that the concentration ratio becomes a predetermined value, but this is done by setting the pH to 6 to 7 in the final step, so that both copper and arsenic are precipitated quantitatively, and then dried. This is because a desired composite copper-arsenic compound can be obtained. As explained above, according to the method of the present invention, smelting intermediates containing copper and arsenic, which have been difficult to recover in conventional nonferrous metal refining, are used as raw materials.
This method produces a composite copper-arsenic compound as an intermediate product for CCA-based drugs using extremely simple operations.
The copper-arsenic compound obtained by the method of the present invention is Cu _n H (3n-2m) (AsO ₄ ) _o・XH ₂ O (m=1~
7, n=1-6, x=1-5) and hydroxide, and this product provides the following excellent advantages. 1 When this product is dissolved in an aqueous chromium trioxide solution, almost no undissolved residue remains and a product equivalent to JIS No. 1 B is obtained. 2. A product can be obtained that easily dissolves in dilute or concentrated chromium trioxide aqueous solutions without significant heat generation. 3. The ratio of copper and arsenic contained can be freely selected. Examples to be explained below First step: 554 g of arsenide (slime) generated during decopper electrolysis containing 8.3% by weight of arsenic, 42.7% by weight of copper, and 20.5% by weight of attached water and 3.6% of water and concentrated sulfuric acid
371g (1.0 equivalent to Cu) was added to form a slurry, and this was placed in an extraction reaction tank with a capacity of 5, heated to 70℃, and the air blow rate set to 5.2/min at normal pressure for 3 hours. After treatment for a period of time, the undissolved residue was separated by suction filtration. The results are shown in Table 2.

[Table] As shown in Table 2, when treated by adding sulfuric acid equivalent to copper, about 99% of copper and about 96% of arsenic are extracted, and the Cu/As concentration ratio is 5.3, which is an extract with a high copper content. was gotten. This extract can be used as is as a copper source in the method of the present invention. Second step Arsenic 11.0% by weight, Copper 4.4% by weight, Moisture 65.0% by weight
1143g of sulfide generated from the cleaning process of copper smelting furnace exhaust gas, containing the balance sulfur, was placed in an extraction reaction tank with a capacity of 6, and water from 4 was added to form a slurry, which was then heated to a temperature of 80 °C, air blowing amount 3.5
/min, and then add a 20% by weight aqueous sodium hydroxide solution to bring the pH inside the reaction tank to 6.8.
When the ORP value reached +100 mv, the pH was adjusted to 3.5 by adding 400 ml of the extract obtained in the first step, and after that, air blowing was stopped and the temperature was further increased to 50°C or higher. After treatment for 3 hours with stirring, the insoluble residue was separated by suction filtration. The results are shown in Table 3.

[Table] As is clear from Table 3, almost no copper is extracted in this process, and only arsenic is extracted.
This extract can be used as it is as an arsenic source in the method of the present invention. Although not specifically indicated, the extraction of other impurities such as sb and Bi in the first and second steps is 0.01~0.01~
It was a trace amount of about 0.03g/. In addition, undissolved residues from each step can be treated separately together with other smelting intermediates. Third step Extract 3.46 of the first step shown in Table 2 and the third
Mix the extract 5.02 of the second step shown in the table,
An aqueous solution of 17.5 g/As, 24.5 g/Cu, and 1.40 Cu/As was prepared. Next, transfer the above aqueous solution 5.0 to a neutralization tank, heat it to 50℃, and add 20% by weight aqueous sodium hydroxide solution while stirring with a propeller type stirrer to reach a pH of 6.5. The resulting precipitate was filtered and washed using a suction filtration method and separated. The results are shown in Table 4.

[Table] Next, weigh 500g of the sediment from Table 4, and
When added to and dissolved in 12.7g/29.0g of chromium trioxide aqueous solution, no undissolved residue was observed.
An aqueous solution containing 6.56 g/Cr, 2.85 g/Cu, and 2.03 g/As was obtained. In this dissolution operation, almost no heat generation phenomenon was observed. The aqueous solution obtained in the third step can be used as is.
It has the same composition as a 2% aqueous solution of CA-based No. 1 B wood preservative, and can be used as a wood preservative. Example 2 First step The arsenide (slime) used in Example 1 was
The sample was weighed and treated in the same manner as in Example 1 to obtain 4.0 g of an extract containing 11.0 g of As and 58.5 g of Cu. This extract has a high copper content with a Cu/As concentration ratio of 5.3.
This can be used as is as a copper source in the method of the present invention. Second step: 1143 g of the sulfide used in the second step of Example 1 was placed in an extraction reaction tank with a capacity of 6, and the water from step 4 was added to make a slurry, which was then heated to a temperature of 80°C and an air flow rate of 3.5. /min, then 20 wt%
of the reaction tank by adding an aqueous sodium hydroxide solution of
Processed for 5 hours while maintaining pH at 6.0
Since the ORP value has become plus 80 mv, add 47 ml of concentrated sulfuric acid.
The mixture was added to adjust the pH to 3.5, after which air blowing was stopped and treatment was continued for 3 hours with stirring at the same treatment temperature, followed by suction filtration to separate undissolved residues. The results are shown in Table 5.

[Table] In Table 5, as in Table 3 above, almost no copper was extracted, and only arsenic was extracted. This extract can be used as it is as an arsenic source in the method of the present invention. Third step: When 3.0 of the extract from the first step and 4.7 of the extract from the second step shown in Table 5 were mixed, As17.59g/
, Cu22.79g/, and an aqueous solution with a Cu/As concentration ratio of 1.3 was obtained. This aqueous solution was used to precipitate a Cu/As composite copper arsenic compound of 1.30 by adding an alkali as in Example 1, but no black precipitate was observed during the precipitate formation.

Claims (1)

[Scope of Claims] 1 A smelting intermediate consisting of one or both of arsenide and oxide containing copper and arsenic is made into a slurry with water, and the slurry contains at least an equivalent amount of copper with respect to the amount of copper in the smelting intermediate. sulfuric acid was added to extract copper and arsenic at normal pressure, and the concentration ratio of copper and arsenic (Cu/As) in the extract was determined.
The first step is to obtain an extract with a pH of 1.0 or higher, and the smelting intermediate consisting of arsenic or copper and sulfide containing arsenic is made into a slurry with water, and an alkali is added to the slurry to adjust the pH.
After extracting at normal pressure while maintaining the temperature between 5 and 8 until the redox potential becomes positive, one or more of the extract from the first step, an acidic aqueous solution containing copper, and sulfuric acid is added to the extract. In the second step, the pH of the treated solution is set to 4.0 or less, and the extraction process is continued to obtain an extract, and each extract obtained in the first step and the second step is adjusted to Cu/As) is mixed to a desired value, and then an alkali is added to the mixed solution to adjust the pH to 6 to 7, and a third step is to separate copper and arsenic as precipitates. -Production method for arsenic compounds. 2. The method for producing a composite copper-arsenic compound according to claim 1, wherein in the first step, extraction is carried out at a temperature of 50° C. or higher for 3 hours or more while blowing air. 3. The composite according to claim 1, wherein in the second step, the first half of the extraction is carried out at a temperature of 50°C or higher while blowing air for 3 hours or more, and the latter half of the extraction is carried out at a temperature of 50°C or higher and for 2 hours or more while stirring. A method for producing a copper-arsenic compound.