JP2022109497A - Method for producing aqueous solution of copper sulfate - Google Patents

Abstract

To provide a method for simply and economically producing an aqueous copper sulfate solution containing little unreacted sulfuric acid from a copper material using sulfuric acid in an air atmosphere.SOLUTION: A method for producing an aqueous copper sulfate solution, characterized in that a copper material and sulfuric acid are fed into a container and heated at a predetermined ambient temperature to allow them to react in an oxygen-containing atmosphere; the reaction mixture is dried almost completely; water is added thereto to dissolve the copper sulfate so formed; and the resulting mixture is subjected to solid-liquid separation to remove remaining copper material.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a method for producing an aqueous copper sulfate solution with little unreacted sulfuric acid from a copper material such as a copper foil simply and economically using sulfuric acid in an oxygen-containing atmosphere.

For example, copper foil, which is a copper material, is widely used in lithium-ion batteries, flexible printed wiring boards, PDP electromagnetic wave shielding film members, and substrates with built-in resistors.

Aqueous copper sulfate solutions are used as raw materials for copper plating solutions, pigments, disinfectants, and antiseptics, and can also be used as raw materials for synthesizing copper oxide and copper hydroxide.

Conventionally, the method of dissolving metallic copper directly with hot concentrated sulfuric acid is known for the production of copper sulfate. Since processing facilities are also required, there is a disadvantage that the facility costs are too high.

Also known is a method of burning metallic copper to form copper oxide and dissolving it in sulfuric acid.

A method of adding hydrogen peroxide as an oxidizing agent to dissolve metallic copper in sulfuric acid is also known. According to this method, since the oxidation reaction proceeds efficiently, no heating operation is required, but hydrogen peroxide is expensive and economically difficult. In addition, it is difficult to manage because it easily self-decomposes, and there was also a problem with safety in terms of gas generation and heat generation at the time of injection. Furthermore, hydrogen peroxide tends to remain in the aqueous solution of copper sulfate produced, and it was necessary to provide a step for removing it.

As a method using sulfuric acid and air as an oxidizing agent, Patent Document 1 describes a method in which a large amount of fine air bubbles are introduced into a metal copper powder suspension of 40 to 120 meshes maintained at a liquid temperature of 65 to 85 ° C. A method for producing an aqueous copper sulfate solution is disclosed in which sulfuric acid is added to oxidize and dissolve metallic copper powder. (Patent Document 1: JP-A-5-262523)
Furthermore, in Patent Document 2, a metal dissolving tower is filled with metallic copper lumps, heated sulfuric acid is supplied from the upper part of the metal dissolving tower, and an oxidizing agent is supplied from the upper or lower part of the metal dissolving tower. is disclosed. (Patent Document 2: JP-A-2011-32126)

JP-A-5-262523 Japanese Unexamined Patent Application Publication No. 2011-32126

However, both of Patent Documents 1 and 2 require a heating facility and a solution bath having a liquid temperature control, so that the facility becomes a large-scale facility, and there is a problem that the facility cost is large.

The present invention has been made to solve the above-mentioned problems, and does not require large-scale equipment, and is capable of producing an aqueous copper sulfate solution with little unreacted sulfuric acid from a copper material simply and economically. The purpose is to provide a method.

The above objects are achieved by the following means.
(1) The copper material and sulfuric acid put into a container are heated in an atmosphere containing oxygen, and the molar ratio (M _Cu ) of the number of moles of the copper material (M _Cu ) and the number of moles of sulfuric acid (M _s ) is /(M _s ) is more than 1, and after almost completely drying, water is added to dissolve the generated copper sulfate, and solid-liquid separation from the residual copper material is performed. A method for producing an aqueous copper solution.
(2) The above item 1, wherein the molar ratio (M _Cu )/(M _S ) of the number of moles (M _Cu ) of the copper material and the number of moles (M _S ) of the sulfuric acid is 2 or more. A method for producing an aqueous solution of copper sulfate.
(3) The method for producing an aqueous copper sulfate solution according to (1) or (2) above, wherein the concentration of the sulfuric acid is in the range of 10 to 70% by weight.
(4) The method for producing an aqueous copper sulfate solution according to any one of (1) to (3) above, wherein the heating is carried out at a temperature of 40 to 280°C in an oxygen-containing atmosphere.
(5) The copper sulfate aqueous solution according to any one of the preceding items 1 to 4, wherein the copper material is composed of a large number of divided bodies in at least one of the form of flakes, granules, powder, and chips. Production method.
(6) The molar ratio (M _CuP )/(M _SP ) between the number of moles of copper (M _CuP ) and the number of moles of sulfuric acid (M _SP ) in the copper sulfate aqueous solution obtained is in the range of 0.93 to 1.00. 6. The method for producing an aqueous copper sulfate solution according to any one of items 1 to 5, wherein the concentration of the copper sulfate is in the range of 1 to 50% by weight.

According to the invention described in the preceding item (1), a copper sulfate solution containing little free sulfuric acid can be easily produced without the need for large-scale equipment, as long as there is a container, a copper material, sulfuric acid, and general-purpose heating and drying equipment. .

According to the invention described in the preceding item (2), since the copper material is excessive, the contact efficiency with oxygen in the atmosphere is improved, the reaction is facilitated, and free sulfuric acid is contained in the copper sulfate solution after the reaction. less.

According to the invention described in the preceding item (3), if the sulfuric acid concentration is less than 10% by weight, the concentration of sulfuric acid is low and the dissolution rate may be slow, and if it exceeds 70% by weight, the concentration of sulfuric acid is high and safety is impaired. Since there is a risk of being disadvantageous, the reaction can be efficiently and safely carried out in the range of 10 to 70% by weight.

According to the invention described in the preceding item (4), the heating in the atmosphere containing oxygen is performed at a temperature in the range of 40 to 280° C., so that the reaction can be carried out efficiently and safely.

According to the invention described in the preceding item (5), since the copper material is composed of a large number of split bodies in at least one of flake, granular, powder, and chip shapes, the unit weight of the copper material is Increased surface area. As a result, the efficiency of contact with oxygen in the atmosphere increases and the reaction proceeds.

According to the invention described in the preceding item (6), a copper sulfate solution containing little free sulfuric acid and having a molar ratio (M _CuP )/(M _SP ) in the range of 0.93 to 1.00 can be obtained.

FIG. 1 is a flow chart showing a schematic procedure of a method for producing an aqueous copper sulfate solution according to one embodiment of the present invention. It is sectional drawing which shows typically the state of the copper material and sulfuric acid which were thrown into the container. 1 is a photographic image of copper foil and sulfuric acid before reaction in Example 1. FIG.

As shown in FIG. 1, in the embodiment of the method for producing a copper sulfate solution according to the present invention, copper foil as an example of a copper material and sulfuric acid are prepared as raw materials, and the copper foil is pulverized into a large number of small pieces. (Step S1), pulverized copper foil and sulfuric acid are placed in a container, heated and dried in an oxygen-containing atmosphere to react (Step S2), and copper sulfate is produced. Next, water is added to the generated copper sulfate and dissolved by stirring (step S3), and unreacted residual copper foil is removed by solid-liquid separation (step S4) to obtain an aqueous solution of copper sulfate.

As shown in FIG. 2, the material of the container 1 into which the copper material 2 and the sulfuric acid 3 are charged should be resistant to sulfuric acid and heat-resistant. ), fluororesin and the like are used. A metal container coated with glass or fluorine resin may be used. Further, the shape of the container 1 is desirably a tray-like one with a shallow bottom. Since the container 1 with a shallow bottom has a large opening area, the efficiency of contact with oxygen in the atmosphere is high, and the reaction tends to progress rapidly. A deep-bottomed vessel can also be used, but the reaction takes longer.

The type of heating and drying equipment for heating and drying the copper material 2 and sulfuric acid 3 put into the container 1 is not particularly limited as long as it can be used in an atmosphere containing oxygen. The atmosphere containing oxygen includes, but is not limited to, an air atmosphere (in the air). As specific heating and drying equipment, a constant temperature constant temperature oven, a constant temperature dryer, an electric furnace, etc. that can be used in an air atmosphere are used, and those that have an air blowing function to positively contact the air to promote dissolution of the copper material. desirable.

The amount of the copper material 2 should be more than 1 with respect to the number of moles of the sulfuric acid 3, desirably at least twice the amount. The excess is recovered as residual copper foil and can be reused as a raw material.

In order to obtain a copper sulfate solution containing less unreacted sulfuric acid in a short period of time, an excessive amount of the copper material 2 should be used, but the size of the container 1 is increased. The volume can be reduced by pulverizing the copper material 2 as small as possible.
copper material
The copper material 2 used in this embodiment is, for example, a copper foil. As described above, the copper foil is desirably pulverized into a large number of split pieces. Since the surface area per unit weight of the copper foil is small in rolls and sheets, the efficiency of contact with the sulfuric acid 3 and air decreases, and unreacted sulfuric acid tends to remain. As the copper foil, a surface-treated foil or a foil to which carbon or the like is adhered can be used by subjecting it to an appropriate pretreatment.

Also, as the copper material 2, a large number of split bodies in the form of granules or powder may be used. Furthermore, other than copper foil, copper wires, coils, etc. can be used by shaving them into flakes or chips as a pretreatment. Note that the term "chip-like" refers to all small lumps having a thickness greater than that of flakes, excluding flakes, granules, and powders, and includes copper chips, copper shavings, and the like. Moreover, only one kind of form of the divided bodies constituting the copper material 2 may be used, or a mixture of two or more forms of the copper material may be used. Copper powder, copper turning powder, copper chips, copper shavings, and the like can be added in an amount greater than twice the molar amount of sulfuric acid, thereby forming copper sulfate with better reactivity. In short, it is desirable that the copper material 2 is divided into pieces of small size such as flakes, powders, granules, chips, etc., and the copper material is composed of an assembly of these divided bodies.

Although the size of the divided body is not particularly limited, for example, when a piece of copper foil is used, it is preferable to pulverize it to a size of 20 mm square or less. If the size of one piece is too large, the efficiency of contact with the sulfuric acid 3 and oxygen in the atmosphere will be low, so the treatment will take a long time. The method of pulverizing the copper foil into flakes is not particularly limited, and may be any method such as shearing pulverization, grinding pulverization, impact pulverization, or a combination of two or more methods.
sulfuric acid
The sulfuric acid 3 used in this embodiment preferably has a concentration of 10 to 70% by weight, more preferably 30% by weight or more.

If the concentration of sulfuric acid 3 is less than 10% by weight, the dissolution rate may become slow, and a large container is required. Moreover, the amount of copper sulfate to be produced is also reduced, so there is a possibility that the productivity will be disadvantageous.

If the concentration of the sulfuric acid 3 exceeds 70% by weight and is too high, there is a possibility that water will evaporate before reacting with the copper material 2, resulting in concentrated sulfuric acid, which is disadvantageous in terms of safety.
Reaction mechanism
The reaction formula of the copper material 2 and the sulfuric acid 3 is as follows.
Reaction formula: Cu + H2SO4 + ₁ / _2O2 → _{CuSO4 + H2O}
Since the copper material 2 exists in excess of the sulfuric acid 3, as shown in the partially enlarged view of the lower part of FIG. There are parts. Since the copper material 2 exposed from the liquid surface 31 is in contact with an atmosphere containing oxygen such as air, the oxygen concentration is high. A work to keep the oxygen concentration constant occurs between the two, and the copper material is oxidized according to the principle of the oxygen concentration cell.

Based on the above principle, as the water in the sulfuric acid 3 evaporates, the copper material 2 is exposed from the liquid surface, and oxidation of the copper material 2 occurs from the exposed portion, and reacts with the sulfuric acid 3 to produce copper sulfate. be done.

The heating temperature of the copper material 2 and the sulfuric acid 3 in an oxygen-containing atmosphere, in other words, the reaction temperature of the copper material 2 and the sulfuric acid 3 is preferably in the range of 40 to 280.degree. Within this range, the reaction is completed quickly, and the container 1 made of plastic can be used, which is economically advantageous. In particular, it is preferably in the range of 75 to 100°C. If priority is given to the reaction rate, the reaction should be carried out at a high temperature range of 100 to 200°C.

The amount of water for eluting the generated copper sulfate depends on the desired concentration of the copper sulfate aqueous solution. Since the same amount of copper sulfate is produced as the number of moles of sulfuric acid added, the amount of water to be added is determined by calculating from that. At this time, if the concentration of the aqueous solution of copper sulfate exceeds the solubility, there will be undissolved portions.

The generated copper sulfate adheres to the residual copper material and forms lumps, so it is eluted by stirring in water. If a small amount of water is added to the container after the reaction and allowed to stand still, it will soften and become easier to pour into water.

Residual copper material is removed by solid-liquid separation. The separation method is not limited, and a method suitable for the grain size of the residual copper material may be used. There are no particular restrictions on the solid-liquid separation method, and vacuum filtration, pressurized filtration, and centrifugation are usually used.

The obtained copper sulfate aqueous solution has a molar ratio (M _CuP )/(M _SP ) of the number of moles of copper (M _CuP ) to the number of moles of sulfuric acid (M _SP ) in the range of 0.93 to 1.00. A copper sulfate concentration in the range of 1 to 50% by weight is desirable because a copper sulfate solution with less free sulfuric acid, which is in the range of 0.93 to 1.00, can be obtained.

Examples of the present invention are shown below, but the present invention is not limited to the examples.
(Example 1)
Production of copper sulfate aqueous solution (1)
A PP container 1 (shape: square, size: 195 mm×133 mm×40 mm) was charged with 120 g of copper foil pulverized to a maximum piece of 2 mm or less and 100 mL of sulfuric acid having a concentration of 65% by weight. At this time, since the amount of the sulfuric acid 3 is small, it does not stay at the bottom of the container, but adheres to the copper foil. FIG. 3 shows a photographic image of the copper material (copper foil) 2 and the sulfuric acid 3 before the reaction which are put into the container 1 .

Next, the container 1 was allowed to stand still for 7 hours in a dryer set at 75° C. to dry substantially completely. Since copper sulfate is deposited on the surface of the residual copper foil, dissolve it in a beaker containing 1,000 mL of water while stirring for 10 minutes, filter with Advantec's 5-type C filter paper, and remove the copper sulfate aqueous solution (1). manufactured. At this time, the molar ratio (M _Cu /M _s ) of the copper material (copper foil) 2 and sulfuric acid 3 used in the reaction was 2.12.

The resulting copper sulfate aqueous solution (1) has a copper sulfate concentration of 25.2% by weight, a pH of 2.59, a molar ratio (M _CuP )/(M _SP ) of 0.990, and almost no free sulfuric acid. It was a copper sulfate solution.
(Example 2)
Production of copper sulfate aqueous solution (2)
Into a magnetic evaporating dish (shape: flat dish, size: φ15 mm×41 mm) as the container 1, 30 g of copper foil pulverized to a maximum piece of 2 mm or less and 25 mL of sulfuric acid having a concentration of 65% by weight were put. At this time, since the amount of the sulfuric acid 3 is small, it does not stay at the bottom of the container, but adheres to the copper foil.

Next, the container 1 was allowed to stand still for 4 hours in an electric furnace set at 50° C. to dry substantially completely. Since copper sulfate is precipitated on the surface of the residual copper foil, dissolve it in a beaker containing 250 mL of water while stirring for 10 minutes, filter with Advantec 5 type C filter paper, and remove the copper sulfate aqueous solution (2). manufactured. At this time, the molar ratio (M _Cu /M _s ) of the copper material (copper foil) 2 and sulfuric acid 3 used in the reaction was 2.12.

The copper sulfate aqueous solution (2) thus obtained had a copper sulfate concentration of 23.3% by weight, a pH of 1.42, a molar ratio (M _CuP )/(M _SP ) of 0.987, and almost no free sulfuric acid. It was a copper sulfate solution.
(Example 3)
Production of copper sulfate aqueous solution (3)
In a PP container 1 (shape: square, size: 167 mm x 117 mm x 36 mm), 65 g of copper foil pulverized to a maximum piece of 2 mm or less and 50 mL of sulfuric acid having a concentration of 65% by weight were put. At this time, since the amount of the sulfuric acid 3 is small, it does not stay at the bottom of the container, but adheres to the copper foil.

Next, the container 1 was allowed to stand in an electric furnace set at 100° C. for 4 hours to dry substantially completely. Since copper sulfate is precipitated on the surface of the residual copper foil, dissolve it in a beaker containing 500 mL of water while stirring for 10 minutes, filter with Advantec 5 type C filter paper, and remove the copper sulfate aqueous solution (3). manufactured. At this time, the molar ratio (M _Cu /M _s ) of the copper material (copper foil) 2 and sulfuric acid 3 used in the reaction was 2.09.

The resulting copper sulfate aqueous solution (3) has a copper sulfate concentration of 22.9% by weight, a pH of 1.94, a molar ratio (M _CuP )/(M _SP ) of 0.972, and almost no free sulfuric acid. It was a copper sulfate solution.
(Example 4)
Production of copper sulfate aqueous solution (4)
Into a magnetic evaporating dish (shape: flat plate, size: φ15 mm×41 mm) as the container 1, 30 g of copper foil pulverized to a maximum piece of 2 mm or less and 25 mL of sulfuric acid having a concentration of 65% by weight were put. At this time, since the amount of the sulfuric acid 3 is small, it does not stay at the bottom of the container, but adheres to the copper foil.

Next, the container 1 was allowed to stand in an electric furnace set at 40° C. for 8 hours to dry substantially completely. Since copper sulfate is precipitated on the surface of the residual copper foil, dissolve it in a beaker containing 250 mL of water while stirring for 10 minutes, filter with Advantec 5 type C filter paper, and remove the copper sulfate aqueous solution (4). manufactured. At this time, the molar ratio (M _Cu /M _s ) of the copper material (copper foil) 2 and sulfuric acid 3 used in the reaction was 2.12.

The resulting copper sulfate aqueous solution (4) had a copper sulfate concentration of 23.0% by weight, a pH of 1.43, a molar ratio (M _CuP )/(M _SP ) of 0.989, and almost no free sulfuric acid. It was a copper sulfate solution.
(Example 5)
Production of copper sulfate aqueous solution (5)
In a PP container 1 (shape: square, size: 195 mm x 133 mm x 40 mm), 40 g of copper foil pulverized to a maximum piece of 2 mm or less and 200 mL of sulfuric acid having a concentration of 10% by weight were put. At this time, the copper foil is completely immersed in the liquid.

Next, the container 1 was allowed to stand still for 16 hours in a dryer set at 100° C. to dry substantially completely. Since copper sulfate is precipitated on the surface of the residual copper foil, dissolve it in a beaker containing 160 mL of water while stirring for 10 minutes, filter with Advantec 5-C filter paper, and remove the copper sulfate aqueous solution (5). manufactured. At this time, the molar ratio (M _Cu /M _s ) of the copper material (copper foil) 2 and sulfuric acid 3 used in the reaction was 3.23.

The resulting copper sulfate aqueous solution (5) has a copper sulfate concentration of 28.7% by weight, a pH of 2.50, a molar ratio (M _CuP )/(M _SP ) of 0.991, and almost no free sulfuric acid. It was a copper sulfate solution.
(Example 6)
Production of copper sulfate aqueous solution (6)
Into a 500 mL glass beaker (manufactured by PYREX, outer diameter x height: 90 x 124 mm) as a container 1, 30 g of copper foil pulverized to a maximum piece of 2 mm or less and 25 mL of sulfuric acid having a concentration of 65% by weight were added. At this time, since the amount of the sulfuric acid 3 is small, it does not stay at the bottom of the container, but adheres to the copper foil.

Next, the container 1 was allowed to stand still for 16 hours in a dryer set at 100° C. to dry substantially completely. Since copper sulfate is deposited on the surface of the residual copper foil, dissolve it in a beaker containing 200 mL of water while stirring for 10 minutes, filter with Advantec 5 type C filter paper, and remove the copper sulfate aqueous solution (6). manufactured. At this time, the molar ratio (M _Cu /M _s ) of the copper material (copper foil) 2 and sulfuric acid 3 used in the reaction was 2.12.

The resulting copper sulfate aqueous solution (6) had a copper sulfate concentration of 26.0% by weight, a pH of 1.41, a molar ratio (M _CuP )/(M _SP ) of 0.974, and a sulfuric acid solution containing little free sulfuric acid. A copper solution was obtained.
(Example 7)
Production of copper sulfate aqueous solution (7)
Into a PP container 1 (shape: square, size: 195 mm×133 mm×40 mm), 22 g of copper foil pulverized to a maximum piece of 2 mm or less and 200 mL of sulfuric acid having a concentration of 10% by weight were put. At this time, the copper foil is completely immersed in the liquid.

Next, the container 1 was allowed to stand still for 16 hours in a dryer set at 100° C. to dry substantially completely. Since copper sulfate is precipitated on the surface of the residual copper foil, dissolve it in a beaker containing 160 mL of water while stirring for 10 minutes, filter with Advantec 5 type C filter paper, and remove the copper sulfate aqueous solution (7). manufactured. At this time, the molar ratio (M _Cu /M _s ) of the copper material (copper foil) 2 and the sulfuric acid 3 used in the reaction was 1.78.

The resulting copper sulfate aqueous solution (7) had a copper sulfate concentration of 26% by weight, a pH of 0.92, a molar ratio (M _CuP )/(M _SP ) of 0.897, and a small amount of free sulfuric acid remained. However, a copper sulfate solution could be obtained.

1 container 2 copper material 3 sulfuric acid

Claims (6)

The _{copper material and sulfuric acid put into the container are heated in an atmosphere containing oxygen, and the molar ratio (M Cu ) /} (M After reacting so that _s ) exceeds 1 and drying almost completely, water is added to dissolve the generated copper sulfate, and solid-liquid separation is performed from the residual copper material. Production method. 2. The sulfuric acid according to claim 1, wherein the molar ratio (M _Cu )/(M _S ) of the number of moles (M _Cu ) of the copper material and the number of moles (M _S ) of the sulfuric acid is 2 or more. A method for producing an aqueous copper solution. 3. The method for producing an aqueous copper sulfate solution according to claim 1, wherein the concentration of said sulfuric acid is in the range of 10 to 70% by weight. 4. The method for producing an aqueous copper sulfate solution according to any one of claims 1 to 3, wherein the heating is performed at a temperature of 40 to 280°C in an atmosphere containing oxygen. The method for producing an aqueous copper sulfate solution according to any one of claims 1 to 4, wherein the copper material is composed of a large number of divided bodies in at least one of the form of flakes, granules, powder and chips. . The molar ratio (M _CuP )/(M _SP ) between the number of moles of copper (M _CuP ) and the number of moles of sulfuric acid (M _SP ) in the copper sulfate aqueous solution obtained is in the range of 0.93 to 1.00, and the The method for producing an aqueous copper sulfate solution according to any one of claims 1 to 5, wherein the concentration of copper sulfate is in the range of 1 to 50% by weight.

Images