JP2007169135A - Basic copper carbonate, copper oxide, and method for producing copper oxide - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide basic copper carbonate capable of producing copper oxide readily dispersing into primary particles at the time of mixing, with high productivity, and copper oxide and to provide a method for producing copper oxide. <P>SOLUTION: This basic copper carbonate is produced by adding an aqueous copper nitrate solution to an aqueous solution of an ammonium salt, to cause a reverse neutralization reaction. The copper oxide is obtained by washing the basic copper carbonate with warm pure water, followed by drying and firing. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to basic copper carbonate and copper oxide, and a method for producing copper oxide, and in particular, when a copper oxide produced from the basic copper carbonate is used as a raw material for producing a superconducting material, a perovskite type effective as a superconducting material. It is related with the copper oxide which is easy to obtain the structure of this, and the manufacturing method of the copper oxide.

  Conventionally, for example, a method described in Patent Document 1 is known as a method for producing copper oxide having fine primary particles. The production method includes adding an aqueous solution containing an ammonium salt as a neutralizing agent to an aqueous copper nitrate solution, neutralizing the aqueous copper nitrate solution to produce basic copper carbonate particles, washing the basic copper carbonate particles with water, This is a method for producing copper oxide by drying in the air after drying.

Japanese Patent Publication No. 5-59845

  The copper oxide powder according to Patent Document 1 is manufactured for the purpose of obtaining a perovskite structure effective as a superconducting material when the copper oxide powder is used as a raw material for the superconducting material. For this purpose, the copper oxide powder is required to be easily dispersed in primary particles when mixed with other superconducting substances. However, since the secondary particles contained in the copper oxide powder produced by the copper oxide production method according to Patent Document 1 are not easily dispersed into primary particles, a large number of man-hours are required for the mixing and dispersing step. There was a problem to do.

  Furthermore, the manufacturing method of the copper oxide powder which concerns on patent document 1 changed the primary and secondary particle diameter of the obtained copper oxide powder with aqueous solution temperature, aqueous solution density | concentration, and reaction temperature. For this reason, in manufacturing copper oxide powder, it is necessary to precisely control the aqueous solution temperature, the aqueous solution concentration, and the reaction temperature within specific conditions, and the manufacturing method is complicated and the productivity is low. Furthermore, the secondary particles of the basic copper carbonate particles produced by the production method are coarse. For this reason, in order to remove impurities existing between the primary particles constituting the secondary particles, the generated basic copper carbonate particles must be washed with a large amount of pure water, and the oxidation is performed. It took a lot of time and labor when mass-producing copper.

  Therefore, the problem to be solved by the present invention is to have a primary particle size suitable as a raw material for producing a superconducting substance, and as a raw material for producing a superconducting substance, it is easily dispersed in the primary particles when the raw materials are mixed It is providing the basic copper carbonate which can manufacture copper oxide with high productivity, the copper oxide manufactured from the said basic copper carbonate, and the manufacturing method of the said copper oxide.

  As a result of studies conducted by the present inventors to solve the above-mentioned problems, an ammonium salt is contained, contrary to the neutralization method according to the prior art, in which an aqueous solution containing an ammonium salt is added to an aqueous copper nitrate solution. The inventors came up with a reverse neutralization reaction method in which an aqueous copper nitrate solution was added to the aqueous solution. And according to the reverse neutralization reaction method of adding the copper nitrate aqueous solution to the aqueous solution containing the ammonium salt, it is unnecessary to strictly control the reaction conditions. Furthermore, since the secondary particles of the basic copper carbonate particles produced after the reaction are not coarse, it is possible to quickly and easily perform pure water cleaning for removing impurities existing between the primary particles constituting the secondary particles. The idea was that copper oxide could be produced with high productivity.

  Further, the manufactured copper oxide is easily dispersed in primary particles by quantitative mixing with a predetermined substance in a wet mixing method, and has a primary particle size of 100 to 600 liters and is effective as a superconducting substance. It was easy to obtain a kite type structure.

That is, the first means for solving the above-described problem is:
A copper nitrate aqueous solution is added to an aqueous solution of an ammonium salt to perform a reverse neutralization reaction, basic copper carbonate is generated by the reverse neutralization reaction, and the basic copper carbonate is baked to generate copper oxide. It is a manufacturing method of the copper oxide made into.

The second means is
The basic copper carbonate produced by the reverse neutralization reaction is subjected to solid-liquid separation, and the solid copper-separated basic copper carbonate is washed with pure water, and then calcined in air at 200 ° C. to 300 ° C. to obtain copper oxide. The method for producing copper oxide according to the first means, wherein

The third means is
Residual ammonia produced by adding a copper nitrate aqueous solution to an aqueous ammonium salt solution to perform a reverse neutralization reaction, and washing the basic copper carbonate produced by the reverse neutralization reaction with pure water using a centrifuge It is basic copper carbonate characterized by having a concentration of 0.6% or less.

The fourth means is
A copper oxide produced by firing the basic copper carbonate described in the third means.

  According to the method for producing copper oxide according to the first or second means, it was possible to produce copper oxide that can easily obtain a perovskite structure effective as a superconducting substance with high productivity.

  The basic copper carbonate according to the third means becomes copper oxide that easily obtains a perovskite structure effective as a superconducting material by firing the basic copper carbonate in the atmosphere.

  The superconducting material using copper oxide as a raw material according to the fourth means can easily obtain a perovskite structure effective as a superconducting material.

The copper oxide produced by the production method according to the present invention has an average primary particle size of 300 to 500 あ り, an average secondary particle size of 1 to 3 µm, and a specific surface area of 40 m ² / g or more. , Copper oxide having a powder characteristic of 70 m ² / g or less. And since the copper oxide manufactured by the manufacturing method which concerns on this invention has few impurities which exist between the primary particles which comprise the secondary particle, a secondary particle disperse | distributes to a primary particle easily. Therefore, when the copper oxide is used as a raw material for producing a superconducting material, it is easily dispersed into primary particles in the mixing and dispersing step of the raw material. As a result, it is considered that when the copper oxide is used as a raw material for producing a superconducting material, a perovskite structure effective as a superconducting material can be easily obtained.

Furthermore, since the primary particle diameter of the copper oxide having the powder characteristics is in the range of 100 to 600 mm, the specific surface area of the powder is very large and at least 40 m ² / g or more. The large specific surface area can greatly increase the reactivity during calcination in the production of a superconducting material using the copper oxide as a raw material powder.

Next, a method for producing copper oxide according to the present invention will be described.
The production method includes a first step of performing a reverse neutralization reaction of an aqueous ammonium salt solution with an aqueous copper nitrate solution, and a solid-liquid separation of the reaction product obtained in the first step, followed by washing with pure warm water, And a second step of performing drying.
Hereinafter, the manufacturing method is described below for each process.

(First step: reverse neutralization reaction step)
Copper nitrate (Cu (NO ₃ ) ₂ ) with a copper concentration of 99.0% or more was put into pure water with a conductivity of 1 μs or less, and stirred and dissolved for about 10 minutes with a stirrer to obtain a Cu concentration of around 200 g / L. An aqueous copper nitrate solution is obtained. In addition, as for the melting temperature at this time, it is desirable that it is 10 to 30 degreeC.
On the other hand, ammonium hydrogen carbonate (NH ₄ HCO ₃ ) having a purity of 95% or more is put into pure water having a conductivity of 1 μs or less, and stirred and dissolved with a stirrer to obtain an ammonium hydrogen carbonate aqueous solution having a concentration of around 100 g / L. At this time, the dissolution time is not specified, and stirring is performed until the ammonium hydrogen carbonate is completely dissolved. In addition, as for the melting temperature at this time, it is desirable that it is 10 to 30 degreeC. Since ammonium hydrogen carbonate as an ammonium salt does not contain a metal element, copper oxide finally produced is preferably not contaminated with the metal element.

  While stirring the dissolved ammonium hydrogen carbonate aqueous solution, the copper nitrate aqueous solution is continuously added to the ammonium hydrogen carbonate aqueous solution to perform a reverse neutralization reaction. In the reverse neutralization reaction, the copper nitrate aqueous solution is added at a rate in the range of 2.5 L / min to 3.5 L / min, for example, when the amount of the dissolved ammonium hydrogen carbonate aqueous solution is 150 L. The rate at which is continuously added is preferred.

  The stirring at this time is, for example, when using a 200 L tank and three sheets / one stage blade, installed at a position of 5 cm to 10 cm from the center of the bottom of the tank, and the rotation speed of the stirrer is set to 100 rpm to 200 rpm. Weak stirring is preferred. By performing the weak stirring, aggregates having an average secondary particle diameter of about 1 μm to 10 μm are mixed, as in the case of performing strong stirring at a rotational speed of 300 rpm or more using a baffle plate in a reaction vessel or beaker. This is because basic copper carbonate particles having a uniform secondary particle size can be obtained.

  The time for the reverse neutralization reaction is preferably about 10 to 30 minutes, and it is desirable to terminate the reaction after rapidly nucleating. By setting the reaction time to 30 minutes or less and the aging time after reaction to 30 minutes or less, the primary particle diameter of the produced basic copper carbonate is 100 to 600 mm, and the secondary particle average diameter is 1 to 3 μm. A certain uniform aggregate can be obtained.

  More preferably, since the reaction temperature may be in the range of 10 ° C. to 30 ° C. during the reverse neutralization reaction, there is no need to control the reaction liquid temperature with special equipment, and the reverse temperature is high. It became possible to carry out a neutralization reaction. In addition, since the said reverse neutralization reaction and stirring are endothermic reactions, the liquid temperature at the time of the said reverse neutralization reaction and stirring will be 10 to 20 degreeC.

(Second step: washing and drying step)
Subsequent to the first step, a second step of washing and drying the product generated by the reverse neutralization reaction is performed.
First, the product is subjected to solid-liquid separation, and basic copper carbonate (CuCO ₃ · Cu (OH) ₂ · nH ₂ O) is collected. At this time, when the liquid is separated from the basic copper carbonate and the filtrate is no longer discharged from the remaining basic copper carbonate, about 3000 L of hot pure water at 55 ° C. to 65 ° C. is added, and the basic copper carbonate is slurried. Then, washing is performed for 40 minutes to 60 minutes.

  In the production of copper oxide according to the conventional technology, the secondary particles of the basic copper carbonate to be produced are coarsened to about 10 μm. For this reason, in order to remove impurities such as ammonium salts existing between primary particles constituting the coarsened secondary particles, the generated basic copper carbonate is used for a long time using a large amount of pure water. It was necessary to wash, and even after the washing, impurities such as ammonium salt remained between the primary particles.

  On the other hand, in the production of the copper oxide according to the present invention, the secondary particles of the basic copper carbonate to be produced have a particle size of about 1 μm to 3 μm and do not become coarse. In order to remove impurities such as an ammonium salt existing between the particles, it is possible to perform a single cleaning with pure water. Here, it is preferable that the liquid temperature of the pure water is 50 ° C. or higher because the cleaning time is shortened and uniform cleaning can be performed. On the other hand, when the liquid temperature is 70 ° C. or lower, the surface of the basic copper carbonate being washed does not start to be oxidized, which is preferable.

Here, the solid-liquid separation operation of the slurry-like basic copper carbonate (CuCO ₃ · Cu (OH) ₂ · nH ₂ O) in the warm pure water cleaning will be described.
As the method and apparatus for solid-liquid separation, a centrifugal method using a centrifuge is desirable. This is because the slurry contains a lot of H ₂ O molecules, so that when the H ₂ O molecules are released during solid-liquid separation to form a cake, the volume contracts. For example, when the suction filtration method using Nutsche is used in the solid-liquid separation, cracks occur in the cake being separated during the warm pure water cleaning due to the volume shrinkage of the slurry described above. Then, the washing water does not pass through the cake, but passes through the cracked portion and reaches the filter paper, so-called short pass is caused, so that the washing efficiency is remarkably deteriorated. In addition, for example, in the case of a solid-liquid separation method using a filter press, as in the case of the suction filtration method, cracking occurs in the cake and a short pass is caused, which is not preferable.

On the other hand, when a centrifuge is used as the method and apparatus for solid-liquid separation, even if volume shrinkage of the cake occurs, the space of the cracked portion of the cake is reduced due to the strong centrifugal force acting. Immediately filled. As a result, the washing water always passes through the cake efficiently.
As a result, since the secondary particle average diameter is 1 μm to 3 μm, the handling of the powder is easy, and since there are few impurities between the primary particles constituting the secondary particles, they can be easily dispersed in the primary particles. Copper oxide powder could be obtained.

The thus obtained basic copper carbonate (CuCO ₃ · Cu (OH) ₂ · nH ₂ O) after washing with warm pure water was dried in a temperature range of 100 ° C. to 120 ° C. for 17 hours or more. At this time, it was confirmed that the primary copper carbonate primary particles had a uniform particle size of 100 to 600Å and the secondary particles had an average particle size of about 2.0 µm. And since there is very little ammonium salt which remains as an impurity between the primary particles which comprise the said secondary particle, and the said ammonium salt does not crystallize and become a lump, the crushing of the said basic copper carbonate after drying is carried out. Easy.

Next, the obtained dried product of basic copper carbonate is baked for 10 hours to 20 hours in a temperature range of 200 ° C. to 300 ° C. in an oxidizing atmosphere including air, and the copper oxide according to the present invention is baked. A powder was obtained. The copper oxide powder had a primary particle size of 100 to 600 and a specific surface area of 40 m ² / g or more and 70 m ² / g or less.

  When the copper oxide according to the present invention and an oxide or carbonate such as Bi, Sr, or Ca are used as raw materials for production of a superconducting material, superconductivity is obtained by quantitatively mixing various oxides or carbonates by a wet mixing method. Materials can be manufactured. And at the time of the said quantitative mixing, since the said secondary particle disperse | distributes to a primary particle (100 to 600 Å) easily, the said copper oxide exhibits the desirable mixing characteristic as an ultrafine powder. As a result, it was easy to obtain an effective perovskite structure in the superconducting material produced using the copper oxide as a raw material powder.

Example 1
Copper nitrate (Cu (NO ₃ ) ₂ ) having a purity of 99.0% or more and ammonium hydrogen carbonate (NH ₄ HCO ₃ ) having a purity of 95% or more were prepared.
20 kg of copper nitrate was put into a tank with an internal volume of 60 L, 35 L of pure water having a conductivity of 1 μs was added and dissolved with a stirrer for 10 minutes to obtain a copper nitrate aqueous solution with a Cu concentration of 200 g / L. The melting temperature at this time was 20 ° C.
On the other hand, 15 kg of ammonium hydrogen carbonate was put into a 200 L tank, 150 L of pure water having a conductivity of 1 μs was added, and then dissolved with a stirrer to obtain an aqueous ammonium hydrogen carbonate solution having a concentration of 100 g / L. At this time, when the dissolution temperature was 20 ° C., the ammonium bicarbonate was completely dissolved in 60 minutes.

The dissolved aqueous ammonium hydrogen carbonate solution was stirred, and the aqueous copper nitrate solution was continuously added thereto at a rate of 3 L / min to carry out a reverse neutralization reaction. At this time, as the stirrer, a three-stage, one-stage blade was used, and was installed at a position 5 cm from the center of the bottom of the 200 L tank. The rotational speed of the stirrer was 150 rpm.
The reverse neutralization reaction time nucleated in 20 minutes to complete the reaction, and a slurry-like reaction solution was obtained. The reaction liquid temperature at this time was 15 degreeC.

Subsequently, the slurry-like reaction liquid is placed in an upper discharge centrifuge to perform solid-liquid separation. And after carrying out solid-liquid separation of the whole reaction liquid, when the filtrate was no longer discharged | emitted, the pure warm water of 60 degreeC was supplied from the said top discharge | emission type centrifuge inlet, and the washing | cleaning for 50 minutes was performed. The amount of warm pure water used was about 3000 L. The residual ammonia concentration of the slurry-like basic copper carbonate after the washing was 500 ppm.
The analysis of the residual ammonia concentration is performed by eluting the residual ammonia of the slurry-like basic copper carbonate into pure water and measuring the ammonia concentration in the pure water with an ion chromatograph (Dionex). It was.

The washed slurry-like basic copper carbonate thus obtained was dried for 17 hours at a temperature of 110 ° C. in a forced exhaust dryer to obtain basic copper carbonate particles. When the obtained primary copper carbonate primary particles were confirmed with a transmission electron microscope (TEM), the primary particles were confirmed to have an average particle diameter of 400 mm, and the secondary particle diameter was confirmed with a laser diffraction particle size distribution analyzer. It was a uniform aggregate having an average particle diameter of 2 μm.
Subsequently, the dried product of the basic copper carbonate was subdivided into about 10 stainless steel vats, and baked in the temperature range of 250 ° C. for 15 hours in the atmosphere to obtain the copper oxide according to this example.

Here, the quality of the copper oxide according to this example is shown in Table 1, and the powder characteristics are shown in Table 2.
In the measurement of the quality, Fe, Ni, Al, and Si were measured with an ICP analyzer, and the Cu content was calculated by the difference method. The specific surface area is a value determined by the BET method. The average particle diameter is a value measured using a HELD & RODOS dry laser diffraction particle size distribution analyzer manufactured by WINDOX at a dispersion pressure of 3.00 bar and a suction pressure of 125.00 mbar.

  When copper oxide according to this example and Bi, Sr, Ca oxide or carbonate are used as raw materials for producing a superconducting material, by quantitative mixing of various oxides or carbonates by a wet mixing method, We were able to manufacture superconducting materials. And since the said copper oxide is easily disperse | distributed to a primary particle (100 ~ 600 ~) at the time of the said quantitative mixing, it exhibits the desirable mixing characteristic as an ultrafine powder, and has a perovskite type structure effective as a superconducting substance. It turned out to be easy to obtain.

(Example 2)
Basic copper carbonate according to Example 2 was produced in the same manner as in Example 1 except that the temperature of pure water at the time of washing with pure warm water was 20 ° C. The residual ammonia concentration of the basic copper carbonate according to Example 2 was 0.1%. This slurry-like basic copper carbonate was dried at a temperature of 110 ° C. for 17 hours with a forced exhaust dryer to obtain basic copper carbonate particles. When the obtained primary copper carbonate primary particles were confirmed with a transmission electron microscope (TEM), the primary particles were confirmed to have an average particle size of 500 mm, and the secondary particle size was confirmed with a laser diffraction particle size distribution analyzer. It was a uniform aggregate having an average particle size of 3 μm.
When the copper oxide according to Example 2 and the oxides or carbonates of Bi, Sr, and Ca are used as raw materials for producing a superconducting material, various oxides or carbonates are quantitatively mixed by a wet mixing method. We were able to produce superconducting materials. And since the said copper oxide is easily disperse | distributed to a primary particle (100 ~ 600 ~) at the time of the said quantitative mixing, it exhibits the desirable mixing characteristic as an ultrafine powder, and has a perovskite type structure effective as a superconducting substance It turned out to be easy to obtain.

(Comparative Example 1)
The same copper nitrate and ammonium hydrogen carbonate as in Example 1 were prepared.
20 kg of the copper nitrate is put into a 200 L tank, 35 L of pure water having a conductivity of 1 μs is added and dissolved with a stirrer for 10 minutes to obtain a copper nitrate aqueous solution with a Cu concentration of 200 g / L, and the liquid temperature of the copper nitrate aqueous solution Was controlled at 26 ° C.
On the other hand, 15 kg of ammonium hydrogen carbonate was put into a 200 L tank, 150 L of pure water having a conductivity of 1 μs was added, and then dissolved with a stirrer to obtain an aqueous ammonium hydrogen carbonate solution having a concentration of 100 g / L. At this time, when the dissolution temperature was controlled at 26 ° C., the ammonium hydrogen carbonate was completely dissolved in a stirring time of 60 minutes. Therefore, the liquid temperature of the aqueous ammonium hydrogen carbonate solution was directly controlled at 26 ° C. to obtain a neutralizing agent.

  Next, a 200 L tank containing the aqueous solution of copper nitrate is used as a neutralizing agent with a small amount of an aqueous ammonium hydrogen carbonate solution whose liquid temperature is controlled at 26 ° C. from a 200 L tank containing the neutralizing agent solution. Each was continuously injected. During the injection, the temperature in the 200 L tank containing the copper nitrate aqueous solution was adjusted using a temperature controller so that the reaction temperature was around 26 ° C. (± 1 ° C.). And using the same stirring apparatus as Example 1, the said copper nitrate aqueous solution was neutralized over 45 minutes on the same stirring conditions, and the slurry-like reaction liquid was obtained.

Subsequently, the slurry-like reaction liquid is placed in an upper discharge centrifuge to perform solid-liquid separation. And after carrying out solid-liquid separation of the reaction liquid whole quantity, when the filtrate was no longer discharged | emitted, 20 degreeC pure water was supplied from the said top discharge | emission type centrifuge inlet, and it wash | cleaned for 3 hours. The amount of pure water used was about 9000 L. And the said pure water washing | cleaning was implemented twice. The residual ammonia concentration of the basic copper carbonate according to Comparative Example 1 after washing was 0.6%.
The washed slurry-like basic copper carbonate (CuCO ₃ · Cu (OH) ₂ · nH ₂ O) thus obtained was dried at a temperature of 110 ° C. for 24 hours in a forced exhaust dryer.
The primary particles of the obtained dried basic copper carbonate were 600Å, and the secondary particles were non-uniform aggregates having an average particle diameter of 1 µm to 10 µm.
Subsequently, the dried product of the basic copper carbonate was subdivided into about 10 stainless steel bats, and baked in the temperature range of 250 ° C. for 15 hours in the atmosphere to obtain copper oxide according to this comparative example.

Here, the quality of the copper oxide according to this comparative example is shown in Table 3, and the powder characteristics are shown in Table 4.
In the same manner as in Example 1, the quality was measured for Fe, Ni, Al, and Si using an ICP analyzer, and the Cu content was calculated by the difference method. The specific surface area is a value determined by the BET method. The average particle diameter is a value measured using a HELD & RODOS dry laser diffraction particle size distribution analyzer manufactured by WINDOX at a dispersion pressure of 3.00 bar and a suction pressure of 125.00 mbar.

  When the copper oxide according to this comparative example and the oxide or carbonate of Bi, Sr, Ca are used as raw materials for producing a superconducting material, the superconductivity is obtained by quantitatively mixing various oxides or carbonates by a wet mixing method. We were able to manufacture the necessary materials. However, since the copper oxide according to this comparative example uses pure water having a liquid temperature of about 20 ° C. at the time of slurry cleaning in the production stage, the slurry cleaning becomes uneven, and the aggregated particles of primary particles after drying It became enlarged secondary particles. The enlarged secondary particles were not easily dispersed into primary particles when the superconducting material was mixed. As a result, it has been found that it is difficult to obtain a perovskite structure that is effective as a superconducting material as compared with the case of using the copper oxide according to this example.

Claims (4)

  A copper nitrate aqueous solution is added to an aqueous solution of an ammonium salt to perform a reverse neutralization reaction, basic copper carbonate is generated by the reverse neutralization reaction, and the basic copper carbonate is baked to generate copper oxide. A method for producing copper oxide.   The basic copper carbonate produced by the reverse neutralization reaction is subjected to solid-liquid separation, and the solid copper-separated basic copper carbonate is washed with pure water, and then calcined in air at 200 ° C. to 300 ° C. to obtain copper oxide. The method for producing copper oxide according to claim 1, wherein:   Residual ammonia produced by adding a copper nitrate aqueous solution to an aqueous ammonium salt solution to perform a reverse neutralization reaction, and washing the basic copper carbonate produced by the reverse neutralization reaction with pure water using a centrifuge A basic copper carbonate characterized by having a concentration of 0.6% or less.   A copper oxide produced by firing the basic copper carbonate according to claim 3.