JP5209249B2 - Copper manufacturing method - Google Patents

Description

  The present invention relates to a novel method for producing electrolytic copper using crude copper powder obtained by pulverizing crude copper.

Conventionally, as an electrolytic purification process for converting crude copper to electrolytic copper, for example, as shown in FIG. 1, in a copper electrolyte 3 in an electrolytic cell 4, an anode 1 made of crude copper to a cathode 2 made of a high-purity copper plate. When a direct current is passed through, the copper content in the anode 1 dissolves and moves to the cathode 2 and deposits as electrolytic copper (pure copper) on the surface of the cathode plate.
The crude copper usually contains noble metals and the like, and these noble metals settle and deposit on the bottom of the electrolytic cell as slime during the electrolytic purification process. Precious metals and impurities are recovered by separately treating the sedimented and accumulated slime.

However, in the conventional method, the distance between the anode and the cathode is preferably short in order to improve the productivity per unit area. However, if the distance is too short, a short circuit is likely to occur. When a short circuit occurs, current efficiency is reduced, and generation of nodules or the like causes an increase in impurities due to deterioration of the external shape of the cathode, entrainment of slime, and the like.
In addition, since the amount of copper deposited by electrolysis is proportional to the magnitude of the current, increasing the current density increases the production capacity, but the inclusion of slime and copper electrolyte increases the level of impurities in the electrolytic copper, and Quality deteriorates. In addition, Cu ions are saturated in the electrolyte solution adjacent to the anode, non-conductive CuSO ₄ · 5H ₂ O crystals are precipitated, and a passive state phenomenon in which Cu cannot be eluted occurs, resulting in restrictions on electrolytic efficiency. Arise. Furthermore, there is a problem in that the noble metal contained in a trace amount in the crude copper cannot be recovered unless the final process is reached, and the recovery of the noble metal is delayed.

As a method for directly producing high-purity copper having a high copper quality, for example, a method described in Patent Document 1 is disclosed. In this method, an insoluble anode composed of a sulfuric acid acidic copper electrolyte having a copper concentration of 25 g / L or more obtained after electrolytic purification of copper using a copper anode is coated with a noble metal based metal oxide. Used to obtain electrolytic copper by electrowinning. Preferably, the insoluble anode is a titanium plate coated with iridium oxide. Preferably, the copper electrolyte is made to flow in parallel with the anode and the cathode.
However, in this method, since a cast anode plate is used, a large melting facility is required, noble metals cannot be recovered early, and impurities are difficult to remove before electrolysis. Is the actual situation.

JP-A-9-316679

The present invention can recover a noble metal early, can effectively use the noble metal early, can remove impurities before electrolysis, and can efficiently use high-purity electrolytic copper by repeatedly using sulfuric acid (copper solution). It aims at providing the manufacturing method of the copper which can be manufactured.
Another object of the present invention is to provide a copper manufacturing method that can improve the copper melting efficiency without using a so-called cast anode plate without using a large melting equipment.

Means for solving the problems are as follows. That is,
<1> A copper powder dissolving step in which a crude copper powder is dissolved in a liquid containing an oxidizing agent and sulfuric acid to prepare a copper solution,
Filtering the copper solution to obtain a primary residue containing the filtrate and noble metal;
And an electrolytic process of producing electrolytic copper by electrolyzing the copper electrolyte and using the filtrate as a copper electrolyte.
<2> The method for producing copper according to <1>, including a desilvering substitution step between the copper powder dissolution step and the filtration step.
<3> The above-mentioned <1> to <2 including a secondary leaching step of adding an oxidizing agent to a leachate obtained by leaching a primary residue with a spent copper electrolyte to obtain a secondary residue having a noble metal concentration higher than that of the primary residue. > The method for producing copper according to any one of the above.
<4> The method for producing copper according to any one of <1> to <3>, further including a liquid purification step in which the free sulfuric acid concentration of the filtrate in the filtration step is reduced to remove impurities to obtain a copper electrolyte.
<5> The method for producing copper according to any one of <3> to <4>, including a noble metal recovery step of recovering noble metal from the secondary residue.
<6> The method for producing copper according to <5>, wherein the noble metal is any one of silver, gold, platinum, palladium, rhodium, and ruthenium.
<7> The method for producing copper according to any one of <1> to <6>, wherein the crude copper powder is obtained by pulverizing crude copper.
<8> The copper production method according to <7>, wherein the pulverization treatment is an atomization method.
<9> The method for producing copper according to <8>, wherein the atomizing method is a water atomizing method.
<10> The method for producing copper according to any one of <1> to <9>, wherein in the particle size distribution of the coarse copper powder, a mass ratio of the coarse copper powder having a particle size of 250 μm or less is 90% or more.
<11> The method for producing copper according to any one of <7> to <10>, wherein the raw material of the crude copper is a recycled raw material selected from a waste printed board, a waste electronic component, and a waste electrical component.
<12> The copper production method according to any one of <7> to <11>, wherein the copper concentration in the crude copper is 80% by mass to 99% by mass.

  According to the present invention, conventional problems can be solved, precious metals can be recovered early, their effective use can be achieved, impurities can be removed before electrolysis, and the copper dissolution efficiency can be improved by using crude copper powder. It can improve and can provide the manufacturing method of copper which can manufacture electrolytic copper efficiently using sulfuric acid (copper solution) repeatedly. Moreover, according to the present invention, even if the quality of crude copper is low, high-purity electrolytic copper can be produced efficiently.

  The method for producing copper of the present invention includes at least a copper powder dissolving step, a filtration step, and an electrolysis step, and preferably a crude copper powdering step, a desilvering replacement step, a secondary leaching step, and a liquid purification step. , Including a noble metal recovery step, and further including other steps as necessary. In addition, a copper powder melt | dissolution process and a filtration process may be collectively called a primary leaching process.

  Here, FIG. 2 is a figure which shows each process of the manufacturing method of the copper of this invention. Hereafter, with reference to FIG. 2, each process of the manufacturing method of the copper of this invention is demonstrated.

<Powdering process of crude copper>
-Crude copper-
There is no restriction | limiting in particular as a raw material of the said rough copper, For example, the copper concentrate which selected the copper ore of the copper grade 0.5%-2.0% excavated from the mine, and raised it to the copper grade 20%-40% is used. However, in the present invention, it is preferable to use a recycled material selected from a waste printed circuit board, a waste electronic component, and a waste electrical component from the viewpoint of effective utilization of resources.

The recycled material is crushed, sieved, concentrated and recovered copper and precious metals, etc. by specific gravity difference, magnetic force, eddy current sorting, electrostatic sorting, and dry smelted into crude copper. Manufacture. The dry smelting typically includes the process shown in FIG. 1 described above, but is not limited thereto.
In addition to Cu, the crude copper usually contains trace amounts of As, Ni, Pb, Sn, Zn, Fe, Sb, Bi, S, Te, Se, Au, Ag, Pt, Pd and the like. Among these, those containing a large amount of noble metals such as Au, Ag, Pt, and Pd are particularly preferable.

  There is no restriction | limiting in particular in the copper concentration in the said crude copper, According to the objective, it can select suitably, 80 mass%-99 mass% are preferable, 90 mass%-99 mass% are more preferable, 93 mass%-95 mass% More preferred is mass%. According to the method for producing copper of the present invention, high-purity electrolytic copper can be efficiently obtained even from crude copper having a low copper concentration.

-Powdering treatment-
There is no restriction | limiting in particular as said powdering process, According to the objective, it can select suitably, For example, a wet reduction method, a vapor phase reduction method, an atomization method etc. are mentioned. Among these, the atomizing method is particularly preferable because it can be produced in large quantities at a low cost.

The atomizing method is a method of producing a crude copper powder by injecting a high-pressure gas or water as a grinding medium into a molten metal stream, grinding the metal stream, cooling and solidifying it.
In the gas atomization method using a gas for the grinding medium, the obtained crude copper powder has a spherical shape, and an inert gas can be used to produce a crude copper powder having a low oxygen content, but the particle size is relatively small. It becomes rough. This is because the cooling rate of molten copper is low in the gas atomization method.

  In contrast, the water atomization method using water as the pulverizing medium can produce a product having a large shear energy and a small particle size because the mass of water is heavier than the gas even when shearing at the same flow rate as the gas. . In addition, the cooling rate can be increased, and a powder having an irregular grain shape and many irregularities on the surface is often produced. Moreover, since it becomes a particle | grain with a large surface area for said reason, the powder with comparatively high oxygen content is manufactured under the influence of the water vapor | steam which generate | occur | produces at the time of molten metal cooling, and the oxygen in atmosphere.

  In the present invention, in the water atomization method, a molten metal flow is caused to flow substantially in the center, and a water jet is jetted from its periphery so as to have an inverted conical shape, or a V-shaped water jet is opposed to the molten metal flow. The molten metal is crushed at the point (line) where the water jet converges or in the vicinity thereof by injecting it into a shape. In atomization, the angle between the molten metal and the water jet greatly affects the crushing force and also greatly affects the rebound phenomenon of the molten metal (molten metal). It is more preferable to inject so that it may become a letter shape from the point of freedom, such as adjustment of an injection angle.

Here, as an example of the atomizing apparatus used for the atomizing process, as shown in FIG. 3, the molten copper flow is retained by holding a molten iron flow from a holding furnace capable of holding and tilting molten copper. The molten copper flow is made to flow down from the tundish 10 and the nozzle 11 at the bottom of the tundish 10, and the molten copper flow is pulverized by discharging high-pressure water or air to the flowing molten copper flow. The spraying part 12 to be used, and the storage part 13 which is below the spraying part 12 and cools, stores and carries out the powdered crude copper powder. In FIG. 3, 14 is a stopper, 15 is a burner for keeping the molten copper in the tundish 10 warm, and 17 is a baffle plate bar.
As another example of the apparatus, a molten metal nozzle hole may be formed at the bottom of the crucible in the furnace having the crucible, and the hot water may be discharged from the nozzle in the same manner as described above.

Further, the water atomization method will be described in detail. First, the crude copper is melted, and the molten crude copper is flowed down from the bottom nozzle 11 of the tundish 10 to form a molten copper flow, and a water jet is injected into the molten copper flow. The temperature of the molten copper is preferably 50 ° C. or higher and more preferably 150 ° C. or higher with respect to the copper melting temperature (about 1083 ° C.). When the melting temperature is less than 150 ° C., the viscosity of the molten copper stream containing many impurities may be too high to smoothly flow. In addition, when the molten copper flow is caused to flow down from the tundish 10, a nozzle 11 is generally provided at the bottom thereof, and the molten copper flow is caused to flow down from the nozzle 11, but the nozzle diameter is 0.5 mm in diameter. -30 mm is preferable, 0.5 mm to 20 mm is more preferable, 3 mm to 15 mm is still more preferable, and 3 mm to 10 mm is particularly preferable. Further, the nozzle shape may not be circular, but the area thereof is preferably in a range equivalent to the area in the case of the circular shape. Outside this range, it becomes difficult to adjust the flow rate of the molten copper flow, and the molten copper flow may be clogged. Further, if the nozzle diameter is too large, it is difficult to produce fine granular powder.
Moreover, there may be a plurality of nozzles, and the molten copper flow rate is preferably 10 kg / min to 60 kg / min, more preferably 20 kg / min to 50 kg / min per nozzle.
The injection flow rate (pressure) of the molten copper is a factor that determines the discharge water flow rate, and the flow rate of the discharge water flow is preferably 100 m / s or more, and more preferably 200 m / s or more.
The amount of water is preferably 2 or more, more preferably 3 or more, and still more preferably 4 or more in terms of water / solution ratio. If the water / solution ratio is insufficient, a sufficient pulverization effect cannot be obtained, and a coarse powder tends to be obtained. Moreover, the amount of water vapor | steam generated can be reduced by making water solution ratio high.
The total solution flow rate is not particularly limited as long as the above relationship is balanced, and can be appropriately selected according to the purpose, and is preferably about 60 kg / min to 80 kg / min, for example.

  As the injection conditions of the water jet, the water pressure is preferably 10 MPa to 100 MPa, more preferably 20 MPa to 50 MPa. If the water pressure is less than 10 MPa, the particle size of the coarse copper powder may not be refined, and if the water pressure is 10 MPa or more, the particle size can be refined and the surface smoothed. At a high pressure such that the water pressure exceeds 100 MPa, the spraying apparatus becomes large and unrealistic. Moreover, in addition to making the said water pressure into the said range, 50 L / min-1,000 L / min are preferable, and 300 L / min-600 L / min are more preferable. When the water flow rate is less than 50 L / min, the generated water vapor is wound up, and the oxidation of the crude copper powder is promoted to increase the oxygen content. Cooling occurs and the apparatus becomes difficult.

As the shape of the water jet flow ejected from the spray nozzle of the spray section 12, it is sprayed in a fan shape and in a planar shape, and as shown in FIG. 4, an inverted triangular pyramid shape using three spray nozzles 100, 100, 100, or As shown in FIG. 5, an inverted quadrangular pyramid shape using four injection nozzles 100, 100, 100, 100 is preferable.
In FIG. 4, water is sprayed in three directions from three spray nozzles 100, 100, 100 in a fan shape and a flat shape, and an inverted trigonal pyramid shape is formed by the water spray. Flow down 101 and grind.
In FIG. 5, water is sprayed in four directions from the four spray nozzles 100, 100, 100, 100 in a fan-like and flat shape, and an inverted quadrangular pyramid shape is formed by the water spray, and is melted at a substantially central portion thereof. The copper stream 101 flows down and is crushed.
Further, as shown in FIG. 6, the fan-like apex angle θ of the water jet flow ejected from the ejection nozzle 100 is preferably 10 ° to 30 °, and more preferably 15 ° to 25 °. When the apex angle θ is less than 10 °, the molten copper flow may deviate from the water jet flow, and it is necessary to spread the molten copper flow at a certain angle so that the molten copper flow and the water jet collide with each other. Moreover, even if the angle is too wide, the water jet flow unnecessarily spreads, so that there is an ineffective water flow.

  In the particle size distribution of the crude copper powder obtained by the powdering treatment, the mass ratio of the coarse copper powder having a particle size of 250 μm or less is preferably 90% or more, and the mass ratio of the crude copper powder having a particle size of 106 μm or less is 90% or more. More preferred. If the particle size is too large, the dissolution rate of the coarse copper powder may be slowed in the copper powder dissolving step described later, resulting in poor efficiency.

<Primary leaching process>
The primary leaching step includes a copper powder dissolution step and a filtration step, and may include a desilvering replacement step as necessary.

-Copper powder dissolution process-
The copper powder dissolving step is a step of preparing a copper solution by dissolving the crude copper powder obtained in the powdering step in a liquid containing an oxidizing agent and sulfuric acid. As the oxidizing agent, for example, oxygen gas, Air, hydrogen peroxide, etc. are mentioned.
The copper concentration of the copper solution obtained in the copper powder dissolving step is preferably 50 g / L to 150 g / L, and more preferably 70 g / L to 140 g / L. When the copper concentration is less than 50 g / L, the concentration may be too low when the copper electrolyte is prepared in a later step, and when it exceeds 150 g / L, copper sulfate may be precipitated depending on the temperature. May occur.

  There is no restriction | limiting in particular in the said copper powder melt | dissolution process, Although it can select suitably according to the objective, For example, a crude copper powder is melt | dissolved using the dissolution tank which melt | dissolves the crude copper powder demonstrated below. Further, if necessary, the precipitation may be carried out using a precipitation tank in which the remaining crude copper powder remaining after dissolution in the dissolution tank is precipitated and returned to the dissolution tank again.

  Here, as shown in FIG. 7, the dissolution tank 30 for preparing the copper dissolution liquid has a dissolution tank main body 31 for storing the copper dissolution liquid, and a baffle plate 32 is disposed inside the main body. A stirrer 33 is disposed for stirring. The stirrer 33 can control the number of rotations, and four turbine blades are in one stage. In addition, the temperature of the stored liquid can be raised and lowered and controlled at a constant temperature. In the dissolution tank, there is a pipe 34 through which a part of the liquid flows out to the side wall and is sent to the precipitation tank 35. The settling tank 35 is provided with a pump 36 into which the remaining coarse copper powder that has been dissolved in the dissolving tank 30 flows in together with the liquid, precipitates the remaining coarse copper powder, and returns it to the dissolving tank 30. In FIG. 7, reference numeral 37 denotes a coarse copper powder supply hopper, and 38 denotes an air ejector as an oxidant supply.

  In addition, in order to improve the melt | dissolution efficiency of rough copper powder, you may promote melt | dissolution using a precipitation tank as needed. After several minutes from the start of dissolution, the remaining copper powder that is in the middle of dissolution floats, and is sent to the precipitation tank 35 together with the liquid. Therefore, the opening on the side of the dissolution tank 30 of the pipe 34 is preferably near the copper solution liquid surface. In the settling tank 35, since there is no stirrer, the remaining coarse copper powder begins to settle immediately after the liquid is fed and is deposited around the bottom of the settling tank. This is extracted together with the liquid from the bottom, and the liquid and the remaining coarse copper powder are put into the dissolution tank 30 via the pump 36. At this time, it is preferable to return to the bottom of the dissolution tank 30.

  As shown in FIG. 7, the precipitation tank 35 is arrange | positioned in the dissolution tank 30, and the coarse copper powder precipitated in the precipitation tank is sent to the dissolution tank 30, and a dissolution reaction is carried out again. When the crude copper powder is dissolved while circulating the undissolved crude copper powder in this manner, the copper dissolution efficiency is remarkably improved, the dissolution time can be shortened, and the manufacturing cost can be greatly reduced. The copper solution is sent to the subsequent filtration step.

-Filtration process-
The said filtration process is a process of filtering the copper solution containing the copper powder melt | dissolution slurry of a copper powder melt | dissolution tank. Here, what is not dissolved in the copper solution in which copper is dissolved but remains as a precipitate is filtered to obtain a primary residue.

-Desilvering substitution process-
A desilvering substitution step may be included between the copper powder dissolution step and the filtration step. This desilvering and replacing step is a step in which a solution containing the copper powder dissolving slurry in the copper dissolving tank is fed from the copper powder dissolving tank to the desilvering and replacing tank and processed in the desilvering and replacing tank.
Here, in the copper solution in which copper is dissolved, silver dissolved in a trace amount and other noble metals are cemented with undissolved copper powder in the copper powder dissolution slurry, and the dissolved silver, This is a step of solidifying the noble metal. When oxidized by applying a temperature in a copper powder dissolution tank, silver and the like dissolve in a very small amount in addition to copper, and have the role of returning it. The desilvering / replacement tank performs cementation with a constant residence time without blowing oxygen with only low stirring. Thereafter, the precipitate resulting from the cementation is filtered to obtain a primary residue containing a noble metal.
The filtration method is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include a filter press and vacuum filtration.

  Since a large amount of silver is dissolved in the filtrate of the secondary leaching tank (residue dissolution tank) and the filtrate of the purification liquid dissolution tank, which will be described later, these filtrates are put in a desilvering and replacement tank, and the above copper powder Perform cementation with the dissolved slurry. In addition, since the dissolved silver is electrodeposited prior to copper in electrolysis and causes deterioration of the quality of electrolytic copper, it is taken out as a residue in the primary leaching process and the secondary leaching process, and collected in a noble metal recovery process described later.

<Secondary leaching process (residue dissolution process)>
The secondary leaching step is a step of adding an oxidant to a leaching solution obtained by leaching the primary residue with a used copper electrolyte solution to obtain a secondary residue having a noble metal concentration higher than that of the primary residue. Performed to increase the concentration of noble metals.
That is, the primary residue of the primary leaching step is immersed and dissolved in the used copper solution, but a secondary residue (insoluble precipitate) remains. This is filtered to remove insoluble precipitates. At this time, the concentration of noble metal in the secondary residue (insoluble precipitate) is higher than that of the primary residue.
Examples of the oxidizing agent include oxygen gas, air, and hydrogen peroxide.

  In the secondary leaching step, the primary residue (dissolved residue) from the primary leaching step is preferably leached using a copper electrolyte solution (electrolytic tail solution) that has been used in an electrolysis step described later. This electrolytic tail solution is an acid having a high concentration of free sulfuric acid and a strong leachability since metal ions such as copper are collected from the solution during electrolysis. Most of the copper in the primary residue is leached into the liquid, but noble metals that are hardly soluble in sulfuric acid are transferred into the secondary residue. The secondary residue is obtained by filtration or the like and used as a raw material for the precious metal recovery step.

<Precious metal recovery process>
The noble metal recovery step is a step of recovering noble metal from the secondary residue.
Examples of the noble metal include silver, gold, platinum, palladium, rhodium, and ruthenium.
There is no restriction | limiting in particular as a method of collect | recovering noble metals from the said secondary residue, Although it can select suitably according to the objective, For example, electrolytic purification, electrowinning, etc. are mentioned.

<Purification process>
The said liquid purification process is a process of reducing the free sulfuric acid concentration of the said copper solution which is a filtrate in the said filtration process, and removing the impurity in a copper solution, It is preferable to implement before an electrolysis process.
In the liquid purification step, the copper solution was put into a liquid solution dissolution tank, the copper powder was dissolved, and the free sulfuric acid concentration was brought close to 0 (zero), so that impurities such as arsenic, antimony and tin exceeded the solubility. Falls as a minute precipitate. By separating this from solid and liquid, impurities in the solution can be efficiently removed.
Moreover, although what fell as this deposit is isolate | separated by filtration, since there exists a small amount of undissolved copper powder and a noble metal in it, it is preferable to collect | recover. In this process, after filtration with a filter press, backwashing is performed with a post-electrolysis solution, so that impurities can be redissolved and recovered while leaving undissolved copper powder and noble metal in the filter press. The solution in which the impurities are redissolved is copper removal electrolysis, and after copper is recovered, it is preferably treated as waste water as waste water.
In the liquid purification step, impurities (for example, As and Sb) in the copper solution are reduced. For example, crude copper powder was added to the copper solution, air was blown into the liquid, and the crude copper powder was dissolved in the copper solution while stirring to reduce the free sulfuric acid concentration. After the reaction, the solution is filtered, and the copper concentration of the filtrate is adjusted for electrolysis to obtain an electrolytic solution for copper electrolysis. By using the crude copper powder in this manner, it is possible to remove arsenic, which is an inhibitory element, particularly in copper electrolysis, and it is possible to suppress an increase in cost because a new chemical agent such as hydrogen sulfide is not used.

<Electrolysis process>
The electrolysis step is a step of obtaining electrolytic copper by electrolyzing a copper solution (filtrate) obtained in the primary leaching step or the liquid purification step with a copper electrolyte adjusted for electrolysis.
The copper concentration in the primary leaching step or the liquid purification step is adjusted with, for example, a used copper electrolytic solution to obtain a copper electrolytic solution. The copper electrolytic solution is preferably a copper sulfate solution having a copper concentration of 70 g / L to 100 g / L and a free sulfuric acid concentration of 5 g / L or less, particularly 1 g / L or less, and the liquid temperature is adjusted to 10 ° C. to 40 ° C. ing.
There is no restriction | limiting in particular as electrolysis conditions in the said electrolysis process, Although it can select suitably according to the objective, It is preferable as follows.
[Electrolysis conditions]
Current ^density: Preferably ^{20A / m 2 ~700A / m 2} , 30A / m 2 ~400A / m 2 is more preferable.
・ Bath voltage: 0.5V-3V
-Bath temperature: 30 to 80 degreeC is preferable and 40 to 70 degreeC is more preferable.
As the anode, for example, Pb, Pb alloy or the like is used.
For example, copper or stainless steel is used as the cathode.

  In addition, the higher the liquid temperature, the lower the power intensity, which is preferable. However, the decomposition rate of glue added for the purpose of smoothing the surface increases, the temperature constraint on the equipment, working atmosphere, heating cost, etc. For this reason, it is preferable to set an upper limit.

Specifically, as shown in FIG. 8, in the electrolytic process, the electrolysis process is performed by applying a direct current from a lead-based anode 1 to a cathode 2 made of a high-purity copper plate through a rectifier in a copper electrolyte 3 in an electrolytic cell 4. By flowing, water is electrolyzed at the anode 1, electrons move to the cathode 2, and deposit as electrolytic copper (pure copper) on the surface of the cathode plate.
In the electrolysis step, the anode is not passivated as compared with the prior art, and is less susceptible to the slime generated from the anode, so that the quality of electrolytic copper is improved.

  The copper produced by the copper production method of the present invention has a high purity and high purity because it contains less impurities (including noble metals) in the copper electrolyte than in the past. It is suitably used in various fields such as equipment materials, LSI wiring, and electric wires.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

Example 1
<Powdering process of crude copper>
-Preparation of crude copper-
As raw materials for crude copper, waste printed circuit boards, waste electronic components, and waste electrical components are collected, crushed and sieved, and sorted by specific gravity difference, magnetic force, eddy current sorting, and electrostatic sorting to concentrate copper. It collect | recovered and it was set as the copper concentrate, this was processed with the converter, and crude copper was obtained. The composition of this crude copper is shown in Table 1. In addition to the elements described in Table 1, the crude copper contained trace amounts of Bi, S, Te, Se, Au, Ag, Pt, and the like.

-Powdering treatment-
Next, the crude copper having the above composition was melted in a melting furnace, and an atomizing process for obtaining a coarse copper powder was performed.
As shown in FIG. 3, the atomizing apparatus used for this atomizing process holds molten copper, receives and stores molten copper melted from a tiltable holding furnace, and molten copper from the bottom of the tundish. A spraying part 12 for pulverizing molten copper by discharging high-pressure water into the flowing molten copper stream and cooling the pulverized coarse copper powder below the spraying part And a storage unit 13 for storing and unloading.
Using this atomizing device, 100 kg of the crude copper was received in a tundish from a holding furnace in which molten copper was stored at 1150 ° C., and while keeping the temperature, 10 kg / min to 13 kg / min from a downstream outlet having a diameter of 13 mm. Then, the molten copper flow was flown down and sprayed at a water pressure of 20 MPa and a flow rate of 68 L / min by three-way blowing on the flow of molten copper flow to obtain 50 kg of crude copper powder. At this time, an inverted triangular pyramid shape was formed by the water ejected from the nozzle, and the molten copper flow was allowed to flow down to its substantially central portion.

The obtained coarse copper powder was sieved with a sieve having an opening of 106 μm, and the fine particle side was obtained as 106 μm under powder. At this time, the mass of the coarse copper powder that passed through the sieve was divided by the total mass of the coarse copper powder that had been sieved, and the percentage was obtained as a percentage, and it was 98 mass%. Further, when the particle size distribution was measured by sieving, 60% by mass was less than 25 μm, 22% by mass was 25 μm or more and less than 45 μm, 16% by mass was 45 μm or more but less than 106 μm, and the remainder was 106 μm or more.
The composition of the obtained 106 μm under powder of Example 1 was as shown in Table 2 below.

<Primary leaching process>
-Copper powder dissolution process-
Using the crude copper powder under the sieve shown in Table 2 above, dissolution was performed as follows to prepare a copper solution.
As shown in FIG. 7, the dissolution tank 30 for producing the copper dissolution liquid includes a dissolution tank body 31 for storing the copper dissolution liquid, and a baffle plate 32 disposed inside the dissolution tank body, and stirring of the copper dissolution liquid. A stirrer 33 is arranged. The stirrer 33 can control the number of rotations, and four turbine blades are in one stage. In addition, the temperature of the stored liquid can be raised and lowered and controlled at a constant temperature. In the dissolution tank, there is a pipe 34 through which a part of the liquid flows out to the side wall and is sent to the precipitation tank 35. The settling tank 35 is provided with a pump 36 into which the remaining coarse copper powder that has been dissolved in the dissolving tank 30 flows in together with the liquid, precipitates the remaining coarse copper powder, and returns it to the dissolving tank 30. In FIG. 7, 37 represents a coarse copper powder supply hopper, and 38 represents an air jet.

In the dissolution tank 30, 100 L of a liquid having a copper concentration of 40 g / L and a free sulfuric acid concentration of 10 g / L in a copper sulfate solution is prepared. To this, 4.4 kg of crude copper powder is added, and the crude copper powder is stirred and stirred. Dissolved. The set liquid temperature of the dissolution tank was 60 ° C., and the dissolution reaction was performed for 1 hour.
After several minutes from the start of dissolution, the remaining copper powder that is in the middle of dissolution floats, and is sent to the precipitation tank 35 together with the liquid. Therefore, the opening on the side of the dissolution tank 30 of the pipe 34 is preferably near the copper solution liquid surface. In the settling tank 35, since there is no stirrer, the remaining coarse copper powder begins to settle immediately after the liquid is fed and is deposited around the bottom of the settling tank. This is extracted together with the liquid from the bottom, and the liquid and the remaining coarse copper powder are put into the dissolution tank 30 via the pump 36. At this time, it is returned to the bottom of the dissolution tank 30.
As shown in FIG. 7, the precipitation tank 35 is arrange | positioned in the dissolution tank 30, the coarse copper powder precipitated in this precipitation tank 30 is sent to a dissolution tank, and a dissolution reaction is made again. When the crude copper powder is dissolved while circulating the undissolved crude copper powder in this manner, the copper dissolution efficiency is remarkably improved, the dissolution time can be shortened, and the manufacturing cost can be greatly reduced.
And the melt | dissolution rate of the copper solution in a melt | dissolution tank at the time of 30 minutes from a melt | dissolution start was calculated | required as follows. The results are shown in Table 3. In addition, Table 4 shows the composition of the remaining crude copper powder at 30 minutes.

[Evaluation of solubility of crude copper powder]
The copper solution in the dissolution tank at 30 minutes from the start of dissolution was sampled, and the copper concentration in the copper solution was analyzed by an ICP emission spectroscopic analyzer (manufactured by Shimadzu Corporation).
The dissolution rate (% by mass) is obtained by dividing the dissolved copper amount (g) obtained by calculation based on the copper concentration value obtained by ICP analysis as a numerator and the copper mass (g) in the added crude copper powder as the denominator. Expressed in

  For comparison, in Example 1, the crude copper powder was dissolved only in the dissolution tank without providing a precipitation tank. The dissolution rate at 30 minutes after the start of dissolution was determined in the same manner as in Example 1. The results are shown in Table 3.

  From the results in Table 3, when a precipitation tank is placed in the dissolution tank, and the crude copper powder precipitated in the precipitation tank is sent to the dissolution tank, dissolved again, and dissolved while circulating, the efficiency of copper dissolution is significantly improved. I understood. As a result, the process time can be shortened, and the manufacturing cost can be greatly reduced. In addition, the copper concentration in the copper solution at this time was about 80 g / L.

-Filtration process-
After 100 L of the obtained copper solution was gently stirred, the produced precipitate was subjected to solid-liquid separation by filtration to obtain a primary residue. The composition of this primary residue is shown in Table 5.

<Secondary leaching process>
Next, the primary residue was leached with a used copper electrolyte (copper concentration of about 40 g / L), and air was added to the leaching solution as an oxidizing agent to obtain a secondary residue having an increased precious metal concentration. The composition of this secondary residue is shown in Table 6.

  From the results of Tables 4 to 6, the concentration of Au, Pd and Ag is increased by the primary leaching process (copper powder dissolution process and filtration process) and the secondary leaching process, and the recovery of precious metals can be performed using this secondary residue. It turns out that it can do efficiently. It was also found that impurities Sb, Ni, and Pb were also removed.

Thus, in the copper powder dissolution step, the crude copper powder is dissolved in sulfuric acid, the copper concentration of the copper solution is adjusted to a desired concentration, and the process proceeds to the subsequent step in order to obtain a copper electrolyte. Since it manages by copper concentration, the whole quantity of coarse copper powder may not be melt | dissolved, and the residue which is an undissolved substance generate | occur | produces. Since these residues contain valuable metals, they are treated in a primary leaching process and a secondary leaching process for treating the residues. In the secondary leaching step, the residue is further dissolved in an acid to obtain a metal solution, and at the same time, an undissolved secondary residue is generated.
In the secondary leaching step, the liquid from the primary leaching step is filtered, and the remaining secondary residue is leached using the electrolytic tail solution that has been used in the electrolysis step described later. The electrolytic tail solution is an acid having a high concentration of free sulfuric acid and a strong leachability since metal ions such as copper are collected from the solution during electrolysis. Most of the copper in the residue is leached into the liquid, but noble metals that are hardly soluble in sulfuric acid migrate into the secondary residue. The secondary residue is obtained by filtration and can be used as a raw material for the precious metal recovery step.

<Purification process>
A copper electrolyte was prepared by reducing impurities in the copper solution. In addition, you may use the filtrate obtained through the said primary leaching process as a copper solution. Table 7 shows the composition of the copper solution.

<Experiment 1>
Next, experimentally, 2 g, 4 g, 12 g, and 24 g of crude copper powder are added to 0.7 L of the above copper solution by dry mass, air is blown into the liquid, and the copper solution is stirred into the copper solution. Was dissolved to reduce the free sulfuric acid (FA) concentration. The results are shown in Table 8. The liquid temperature was 75 ° C. and the reaction time was 4 hours. After the reaction, the solution was filtered, and the copper concentration of the filtrate was adjusted for electrolysis to obtain a copper electrolyte for copper electrolysis.

From the results of Table 8, it is possible to remove arsenic, which is an inhibitory element in copper electrolysis, by adding 12 g or more of coarse copper powder, and a copper electrolyte solution suitable for copper electrolysis when the arsenic concentration is 500 mg / L or less. Fabrication is now possible. Moreover, since a new chemical | medical agent, such as hydrogen sulfide, is not used, the increase in cost can be suppressed.

<Electrolysis process>
The obtained copper electrolyte was electrolyzed under the following electrolysis conditions using the electrolytic cell shown in FIG. 8 to obtain electrolytic copper. That is, in the copper electrolyte 3 in the electrolytic cell 4, a direct current is passed from the lead-based anode 1 to the cathode 2 made of a high-purity copper plate through a rectifier, whereby water is electrolyzed at the anode 1 and electrons are converted into the cathode. 2 and deposited as electrolytic copper (pure copper) on the surface of the cathode plate.
-Electrolysis conditions-
・ Current density: 100 A / m ²
・ Bath voltage: 1.5V
・ Bath temperature: 60 ° C
Pb was used as the anode.
Copper was used as the cathode.

  Analysis of the obtained electrolytic copper confirmed that it was 99.99% by mass or more and that high-purity electrolytic copper (purified copper) could be produced from low-grade crude copper.

  The copper production method of the present invention can recover a noble metal at an early stage, can effectively use the noble metal, can remove impurities before electrolysis, improves the copper dissolution efficiency by using crude copper powder, Can be used repeatedly, and is an efficient method for producing high-quality electrical copper, and the copper produced by this method is suitably used in various fields such as electronic component materials, electronic equipment materials, LSI wiring, electric wires, etc. .

FIG. 1 is a schematic diagram showing a conventional copper electrolysis process. FIG. 2 is a schematic view showing an example of a copper electrolysis process of the copper production method of the present invention. FIG. 3 is a schematic view showing an example of an atomizing apparatus used for the pulverization process. FIG. 4 is a diagram showing water injection in a three-way system (inverted triangular pyramid). FIG. 5 is a diagram showing water injection in a four-way system (inverted quadrangular pyramid). FIG. 6 is a diagram illustrating an example of a horizontal fan-type spray nozzle. FIG. 7 is a schematic view showing an example of a dissolution tank and a precipitation tank used in the copper powder dissolution step. FIG. 8 is a schematic view showing an example of an electrolytic cell used in the electrolysis process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Copper anode 2 Cathode 3 Copper electrolyte 4 Electrolysis tank 10 Tundish 11 Bottom nozzle 12 Spraying part 13 Storage part 30 Dissolution tank 31 Dissolution tank main body 32 Baffle plate 33 Stirrer 35 Precipitation tank 100 Injection nozzle 101 Molten copper flow

Claims (11)

A copper powder dissolving step of preparing a copper solution by dissolving the crude copper powder in a solution containing an oxidizing agent and sulfuric acid;
Filtering the copper solution to obtain a primary residue containing the filtrate and noble metal;
A secondary leaching step of adding an oxidant to a leachate obtained by leaching the primary residue with a spent copper electrolyte, and obtaining a secondary residue having a higher precious metal concentration than the primary residue;
An electrolytic process for producing electrolytic copper by using the filtrate as a copper electrolyte and electrolyzing the copper electrolyte to produce copper.   The manufacturing method of copper of Claim 1 including a desilvering substitution process between a copper powder melt | dissolution process and a filtration process. The manufacturing method of copper in any one of Claim 1 to 2 including the liquid purification process which lowers | hangs the free sulfuric acid density | concentration of the filtrate in a filtration process, removes an impurity, and obtains a copper electrolyte solution. The method for producing copper according to any one of claims 1 to 3, further comprising a precious metal recovery step of recovering the precious metal from the secondary residue. The method for producing copper according to claim 4, wherein the noble metal is any one of silver, gold, platinum, palladium, rhodium, and ruthenium. The method for producing copper according to any one of claims 1 to 5, wherein the crude copper powder is obtained by pulverizing crude copper. The method for producing copper according to claim 6, wherein the powdering treatment is an atomizing method. The method for producing copper according to claim 7, wherein the atomizing method is a water atomizing method. The method for producing copper according to any one of claims 1 to 8, wherein in the particle size distribution of the coarse copper powder, a mass ratio of the coarse copper powder having a particle size of 250 µm or less is 90% or more. The method for producing copper according to any one of claims 6 to 9, wherein the raw material of the crude copper is a recycled raw material selected from a waste printed circuit board, a waste electronic component, and a waste electrical component. The copper concentration in crude copper is 80 mass%-99 mass%, The manufacturing method of copper in any one of Claim 6 to 10.