JP2893160B2 - Melting method of copper or copper alloy with low sulfur content - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copper or copper alloy smelting method capable of supplying copper or a copper alloy having an extremely low sulfur concentration at a low cost while enabling a large amount of scrap materials to be used. is there.

[0002]

[Prior art and its problems] When copper is extracted from ore, the current mainstream “dry refining process” is applied, and the sulfur present in the ore is reduced to about 0.02 wt% by oxidation in the smelting process. To be reduced. Then, the sulfur concentration can be further reduced by the subsequent electrolysis process.However, since the copper sulfate bath is used as the electrolytic solution, it cannot be prevented that sulfur is inevitably mixed into the precipitated copper. Even if it does, the refining limit is to reduce the sulfur concentration to about 0.001% by weight. However, as a means of reducing the sulfur concentration in copper to less than this, there is a method of re-electrolysis using a copper nitrate bath, etc., but in this case, the production cost is remarkably increased, and the obtained product is as good as gold. Price will be added.

In the production of copper or copper alloy materials such as sheet materials, wires, rods, etc., raw materials such as refined electrolytic copper, alloy components and scrap are remelted and cast into ingots of a predetermined shape. Processing this is a generally adopted process. In this case, it is desirable to use a large amount of scrap in order to reduce the manufacturing cost. However, if the amount of used scrap increases, mixing of impurities becomes a problem. In particular, the sulfur easily mixes in from the oil and the like adhering to the scrap, so that the amount of scrap used has to be naturally restricted.

[0004] In view of the above, an object of the present invention is to make it possible to use a large amount of scrap raw materials in producing copper or copper alloy materials, and to reduce materials having a sulfur concentration lower than the ordinary refining limit at low cost. Is to establish a "copper or copper alloy smelting process" that can be manufactured by

[0005]

Means for Solving the Problems The present inventors have conducted various studies in order to achieve the above object, and have stated that "for realization of a copper or copper alloy material having a sulfur concentration as low as possible, desulfurization treatment is performed at the time of remelting. Is the most practical means, "and the following findings were obtained. First, we examined the use of the “oxidative desulfurization method (desulfurization method using oxygen blowing) that is used in ordinary copper refining processes” as a desulfurization process when re-dissolving raw materials. It took a long time to lower the copper content, and it was found that copper and copper alloy components as raw materials were significantly lost by oxidation.

[0006] Therefore, this time, focusing on “desulfurization refining using slag”, in which oxidation loss that is applied to the desulfurization of hot metal is considered to be not so problematic, this method is applied to desulfurization of copper or copper alloy. As a result of diligent research on the feasibility of the application and on the slag to be used, "When re-dissolving the copper or copper alloy raw material, the treatment of the molten metal using Na ₂ O, Na ₂ CO ₃ or NaOH as a desulfurizing agent is particularly important. Then, desulfurization proceeds remarkably without fear of oxidation loss of the raw material, and the above-mentioned object is sufficiently achieved. "

In the field of hot metal processing, CaC ₂ and CaO
Although -CaF ₂ based flux is often used as a desulfurizing agent, CaC _2, there is a possibility of generating explosive substance called acetylene copper With the copper, safety of use thereof is difficult. As for the CaO-CaF ₂ flux, CaF ₂ itself has no desulfurizing power, which is added for the purpose of lowering the melting point of CaO and improving the desulfurization rate. The effect of CaF ₂ was not exhibited because of the lower temperature of iron compared to iron, and the desulfurization rate of CaO—CaF ₂ to copper or copper alloy was extremely slow. In recent years, Na ₂ CO ₃ flux has also been studied as a simultaneous desulfurization and dephosphorization agent for hot metal.
Problems have been pointed out, such as generation of fumes due to the reaction with the bon and damage to the smelting vessel due to the reaction with the refractory.

However, Na-based fluxes such as Na ₂ CO ₃ , Na ₂ O, and NaOH, which are considered to be difficult to use as desulfurizing agents in hot metal refining, are also intended for copper or copper alloys. In these cases, the melting temperature was low and the molten metal itself did not contain carbon, indicating that "generation of fumes" and "reaction with refractories" were not significant. . In addition, it has been clarified that when a Na-based flux having a low melting point and a high sulfur distribution value is used as a desulfurizing agent for molten copper or copper alloy, an extremely effective desulfurizing power works. In addition, Na ₂ CO ₃ or NaO
H dissociates into Na ₂ O at the melting temperature of copper or a copper alloy, and therefore exhibits the same desulfurization power as Na ₂ O.

[0009] Further, in the case of a Na-based desulfurizing agent, particularly when the treatment temperature is high or the amount of the desulfurizing agent added is small, a phenomenon (sulfur concentration once decreases to a low value and then increases again) (resulfurization) is recognized. However, CaO, CaCO ₃ , Ca
It has also been found that when a basic oxide having a high melting point such as (OH) ₂ , MgO, MgCO ₃ or Mg (OH) ₂ is mixed, the “resulfurization” is effectively suppressed.

Of course, because of the desulfurization of copper or copper alloy in the past,
There is no example of applying slag refining with Na ₂ O, Na ₂ CO ₃ or NaOH, and the inventors of the present invention have stated that “Na ₂ O, Na ₂ CO ₃ is used for desulfurization of copper or a copper alloy aiming at an extremely low sulfur concentration.
Or slag refining using NaOH is the best. "

[0011] In addition, the desulfurization treatment may be carried out using a reducing gas or an inert gas.
Performed in a gas atmosphere , mixed carbon powder with a desulfurizing agent, performed desulfurization treatment after coating the surface of the treated molten metal with charcoal or carbonaceous material, or contained carbon. It has also been found that when a desulfurization treatment is performed using a melting furnace or a crucible made of a refractory, the desulfurization efficiency is further improved.

The present invention has been completed as a result of further research conducted on the basis of the above findings, and is described below. To provide a low-cost and stable method of smelting copper alloys. 1) Dissolve copper or copper or copper alloy smelting raw materials to which alloy elements, scraps, etc. are added, and melt the copper or copper alloy. After the temperature is raised to a temperature higher by 50 to 500 ° C. than the liquidus temperature, the molten metal is mixed with “Na” in a reducing gas or inert gas atmosphere.
CaO, CaCO ₃ , C in an amount of at least one of ₂ O, Na ₂ CO ₃ or NaOH and a ratio of 0 to 50% by weight based on the total amount thereof
a (OH) ₂ , MgO, MgCO ₃ and one or more of Mg (OH) ₂ mixed with at least one of desulfurizing agents “Na ₂ O, Na ₂ CO ₃ and NaO
H and H are added and maintained so that the total weight of H is within the range of 0.1 to 10% of the weight of the molten metal, and then the desulfurizing agent after the reaction is removed. Melting method of copper alloy containing more than 10% by weight. 2) After melting the raw material for copper or copper alloy smelting and raising the temperature to a temperature 50 to 500 ° C. higher than the melting point or liquidus temperature,
At least one of Na ₂ O, Na ₂ CO ₃ or NaOH
Desulfurizing agent "and" desulfurizing agent by weight of less than 10% Ca consisting - 0.1% to 10% of the melt weight at desulfurizing agent by weight of a mixture of carbon powder "
, And then removing the desulfurizing agent after the reaction.
Melting method of copper alloy containing more than 10% by weight. 3) The raw material for melting copper or copper alloy is melted and heated to a temperature 50 to 500 ° C. higher than the melting point or the liquidus temperature, and the surface of this molten metal is made up of 50% by weight or more of charcoal or carbon. Containing material ”, and then add“ Na ₂ O, Na ₂ CO
₃ or desulfurizing agent "consisting of one or more NaOH Na ₂ O, N
The total weight of a ₂ CO ₃ and NaOH is 0.1-10% of the melt weight
A method for producing a copper alloy containing 60% by weight or more of copper or Cu having a low sulfur content, characterized by adding and maintaining the content within the range described above and then removing the desulfurizing agent after the reaction. 4) The raw material for copper or copper alloy smelting is melted and heated to a temperature 50 to 500 ° C. higher than the melting point or liquidus temperature, and the surface of the molten metal is made up of 50% by weight or more of charcoal or carbon. Containing material ”, and then add“ Na ₂ O, Na ₂ CO
₃ or one or more from the consisting desulfurizing agent "and" desulfurizing agent by weight of less than 10% mosquito NaOH - held is added in a range from 0.1 to 10% of the melt weight mixture at desulfurization agent by weight of the carbon powder " And then removing the desulfurizing agent after the reaction.5) A method for melting copper or a copper alloy containing 60% by weight or more of copper having a low sulfur content, 5) Na ₂ O, Na ₂ 1 of CO ₃ or NaOH
50% by weight of the total amount in addition to the seeds
% Or less of CaO, CaCO ₃ , Ca (OH) ₂ , MgO, MgCO
With ₃ and Mg (OH) those comprising a mixture of one or more ₂
According to any one of the above items 1) to 4),
Copper with low sulfur content or copper containing at least 60% by weight of Cu
How to make alloys. 6) The melting and subsequent treatment of the raw materials should be performed in a furnace built with a refractory containing 10% by weight or more of carbon or in a crucible containing 10% by weight or more of carbon. The method for melting a copper alloy containing 60% by weight or more of copper or Cu having a low sulfur content according to any one of the above items 1) to 5) . Here, in the present invention, the reason why the Cu content of the copper alloy which is one of the objects of smelting is set to 60% by weight or more is that "the property as a molten copper" appears in the molten metal at 60% by weight or more. This is because Cu is contained.

In the present invention, the reason why the copper content of the copper alloy, which is one of the objects of smelting, is set to 60% by weight or more is that the "characteristics of copper as a molten metal" appears in the molten metal at 60% by weight. % Of Cu or more.

Next, the reason why the conditions for smelting copper or copper alloy in the present invention are limited as described above will be described in detail together with the operation thereof.

[Operation] First, the operation of the Na-based desulfurizing agent will be described. As mentioned earlier, Na-based desulfurizing agents such as Na ₂ CO ₃ and NaOH dissociate into Na ₂ O at the melting temperature of copper or copper alloy.
It exhibits the same effect as Na ₂ O, but this Na-based desulfurizing agent (Na ₂
The desulfurization reaction of copper or copper alloy by O) is represented by the following equation (1). Na ₂ O + S = Na ₂ S + O (1) The standard free energy change (ΔG ⁰ ), equilibrium constant (K) and sulfur distribution ratio at this time are as follows (2) to (2), respectively.
It is expressed by equation (4). ΔG ⁰ = 6111-1.56T (cal / mol) …… (2)

[0014]

(Equation 1)

[0015]

(Equation 2)

Incidentally, the above-mentioned Na-based desulfurizing agent exerts an effect of desiliconization and dephosphorization other than desulfurization. P ₂ O ₅ and SiO ₂ generated by these reactions are strong acidic oxides, and reduce the “Na ₂ O activity in the slag” in the above formula (4) to lower the distribution ratio of sulfur. Further, the Na-based desulfurizing agent is decomposed by the reaction with carbon. At this time, Na is vaporized and lost along with the flame and white smoke, and the distribution ratio of sulfur decreases. It is presumed that these phenomena are the cause of "resulfurization". Therefore, preventing a decrease in “Na ₂ O activity in slag” leads to suppression of “resulfurization”. Where CaO,
Oxides such as CaCO ₃ , Ca (OH) ₂ , MgO, MgCO ₃ , and Mg (OH) _{2 by} themselves have very low desulfurization capacity for copper or copper alloys. The effect of increasing the ratio and desulfurization rate is hardly recognized,
When the desiliconization reaction or dephosphorization reaction proceeds, P ₂ O ₅ or SiO ₂
And an effect of preventing a decrease in “Na ₂ O activity in slag”, that is, an effect of suppressing “resulfurization”. Also,
Even if the Na is vaporized lost, since the fact that Ca ²⁺ and Mg ²⁺ is present in the slag when the oxide is added to the desulfurizing agent, the Ca ²⁺ and Mg ²⁺ is S ² "Resulfurization" can be mitigated by having affinity with ⁺ .

In the present invention, "CaO, CaCO
_{3, Ca (OH) 2,} MgO, the amount also MgCO ₃ and Mg (OH) desulfurizing agent comprising a mixture of one or more ₂ 'Na ₂
It is defined by the total weight of O, Na ₂ CO ₃ and NaOH, because the reason is CaO, CaCO ₃ , Ca (OH) ₂ , MgO, MgC
This is because O ₃ and Mg (OH) ₂ themselves do not have the effect of improving the desulfurization power, but show only the effect of suppressing “desulfurization”. In this case, the sulfur concentration of the molten metal can be reduced as the added weight of Na ₂ O, Na ₂ CO ₃ or NaOH increases, but it is not practical to add more than 10% of the weight of the molten metal in view of the production cost. On the other hand, if the amount of the desulfurizing agent is less than 0.1% of the weight of the molten metal, an effective desulfurizing effect cannot be secured. Therefore, the added amount of the desulfurizing agent is Na ₂ O, Na ₂ CO ₃
And the total weight of NaOH is limited to the range of 0.1 to 10% of the weight of the molten metal.

[0018] In addition, CaO, CaC
Contains O ₃ , Ca (OH) ₂ , MgO, MgCO ₃ or Mg (OH) ₂
When performing , CaO, CaCO ₃ , Ca (OH) ₂ , MgO, MgCO
_The reason why the amount of one or more of Mg ₃ and Mg (OH) ₂ is limited to “50% by weight or less based on the total amount of Na ₂ O, Na ₂ CO ₃ and NaOH” is as follows. % Is a sufficient amount to suppress "resulfurization", and even if the compounding amount exceeds 50% by weight, the production cost increases, and the descaling operation (removing the desulfurizing agent after desulfurization treatment) This is because it only increases the load of (work). Note that these CaO, CaCO ₃ , C
The reason for not setting a lower limit on the amount of a (OH) ₂ , MgO, MgCO ₃ or Mg (OH) ₂ is that when the sulfur concentration shows the lowest value, the debris is removed immediately (before resulfurization starts). by applying the processes such as to work, the amount is extremely small amount der
This is because “resulfurization” can be prevented by only Na ₂ O, Na ₂ CO ₃ or NaOH alone.

Next, the reason why the desulfurization treatment temperature is limited to "a temperature 50 to 500 ° C. higher than the melting point or liquidus temperature of the molten metal" is as follows. That is, when the treatment temperature is lower than the melting point or liquidus temperature of the molten metal plus 50 ° C., the surface temperature of the molten metal is rapidly lowered when the desulfurizing agent is added, and the molten metal is solidified, and the desulfurization rate is significantly reduced. On the other hand, the higher the processing temperature, the higher the reaction rate. However, when the temperature exceeds “the temperature higher than the melting point of the molten metal or the liquidus temperature by 500 ° C.”, the vaporization loss of Na increases, and the sulfur concentration after desulfurization increases. And the amount of resulfurization increases. In addition, there also arises a problem that operating costs such as power costs increase.

In this case, as expected from equation (4), the lower the oxygen partial pressure at the molten metal / slag interface, the higher the equilibrium distribution ratio of sulfur. In order to lower the interfacial oxygen partial pressure in the melting of copper or copper alloy usually performed in the atmosphere, carbon powder is mixed with a desulfurizing agent, or the surface of the treated molten metal is treated with “charcoal” or “carbon”. It is effective to coat with a carbonaceous substance (for example, a carbon-based refractory or a crushed crucible). Here, if the carbon content of the carbonaceous substance is less than 50% by weight, the desired effect cannot be obtained.

When carbon powder is mixed with the desulfurizing agent, the amount of the carbon powder to be mixed is preferably limited to less than 10% of the weight of the desulfurizing agent. This is because when the amount of carbon powder to be mixed exceeds 10% of the weight of the desulfurizing agent, Na ₂ O, Na ₂ CO 3
_This is because the loss of decomposition of Na due to the reaction of ₃ or NaOH with carbon is increased, and the desulfurization efficiency is rather reduced.

Further, melting of the above-mentioned copper or copper alloy raw material
In the desulfurization treatment, the use of a melting furnace or a crucible made of "a refractory containing carbon" is also effective in reducing the interfacial oxygen partial pressure to promote desulfurization. However,
Also in this case, if the carbon content in the refractory is less than 10% by weight, the desired effect cannot be obtained.

By the way, as described above, Na ₂ O, Na ₂ C
When desulfurization efficiency is improved by bringing O ₃ or NaOH into contact with a carbonaceous substance, some fumes are generated even in the treatment of copper or copper alloy having a relatively low melting temperature. It is difficult to control. Therefore, installation of exhaust gas equipment is recommended. In addition, in the dissolution / desulfurization treatment according to the present invention, it is important to remove the slag as much as possible and to clean the inside of the furnace or the crucible before adding the desulfurizing agent. This is because CuO and Cu ₂ O have high oxidizing power.
This is because if oxygen is mixed in the desulfurizing agent, the oxygen partial pressure at the interface increases.

In order to reduce the oxygen partial pressure at the molten metal / slag interface, it is placed in an atmosphere of a reducing gas or an inert gas.
That is, the melting of the molten metal with an inert gas or an inert gas.
Gas, reducing gas or inert gas into the molten metal
It is carried out and the like are also effective. Moreover, when this method is applied, a reaction promoting effect by stirring can be expected, and the reaction efficiency is further improved by simultaneously blowing a desulfurizing agent. However,
Due to the large cost increase, its application can be said to be limited to high-grade materials. As a melting furnace for melting the raw materials, it can be said that an electromagnetic induction furnace is more preferable than a resistance heating furnace. This is because in the case of an electromagnetic induction furnace, a stirring effect is generated by the movement of hot water, and the reaction efficiency is increased.

Further, in order to lower the sulfur concentration to a lower value with the same amount of desulfurizing agent, it is effective to add the desulfurizing agent in portions. This is proved as shown below. The weight of the molten metal is W (kg), the amount of the desulfurizing agent added is V (kg), the sulfur distribution ratio is L _S , and the sulfur concentrations in the molten metal and the desulfurizing agent before desulfurization are [% S] ₀ and (% S) _{0, respectively.} , The sulfur concentration in the molten metal after desulfurization and in the desulfurization agent are [% S] and (% S), respectively.
Then, the material balance of sulfur in the molten metal / desulfurizer is
Equation (5) holds. V {(% S) - ( % S) 0} = W {[% S] 0 - [% S]} ...... (5) In addition, L the definition of _{L S S = (% S)} / [% S ] ... (6) holds. Therefore, substituting equation (6) into equation (5) gives (%
S) When it is transformed as ₀ = 0, the following equation (7) is obtained.

[0026]

(Equation 3)

On the other hand, after the Jokasu desulfurized by adding for example _^1/2 of the amount of flux in processing such perform a desulfurized by adding the remaining _^1/2 the amount of flux Jokasu, after treatment Is given by the following equation (8).

[0028]

(Equation 4)

Comparing the above equations (7) and (8), it can be seen that the sulfur concentration is reduced to a lower concentration by adding the desulfurizing agent in two parts.

Next, the effects of the present invention will be specifically described with reference to examples.

【Example】

[Example 1] 5 kg of commercially available pure copper having an impurity level was prepared, charged into an alumina crucible, and melted in a high-frequency melting furnace.
The temperature was raised to 200 ° C. Then, in a state of covering the surface of the melt with charcoal were desulfurization test of Na ₂ O, and 100g added CaO or Na ₂ O-CaO-based desulfurizing agent in the total weight of Na ₂ O and CaO melt.

FIG. 1 shows the results obtained in this test, “when Na ₂ O was simply added”, “when CaO was simply added”, and
For "case of adding Na ₂ O-CaO-based desulfurizing agent obtained by changing the weight ratio of Na ₂ O and CaO" is a graph showing the investigation results on the sulfur concentration change in the melt. From the results shown in FIG. 1, it can be seen that the minimum sulfur concentration was increased by mixing CaO with Na ₂ O, and desulfurization did not progress at all with CaO alone. That is, the desulfurizing power of Na ₂ O against copper is CaO
It is evident that it is significantly larger. Na ₂ O
With simple addition, it was also confirmed that the sulfur concentration reached about 0.0005%, a value lower than that of electrolytic copper.

[0032] Instead of Na ₂ O Na ₂ CO ₃ or Na
Similar results were obtained when OH was used. Also, Ca
Similarly to O, it was also confirmed that CaCO ₃ , Ca (OH) ₂ , MgO, MgCO ₃ or Mg (OH) ₂ did not show a desulfurizing ability for copper.

Example 2 Commercially available pure copper and Cu-P alloy were
It was prepared so as to have a composition of -0.03 wt% P. Next, this was charged into an alumina crucible and melted in a high-frequency melting furnace to obtain 13
The temperature was raised to 50 ° C., and the surface of the molten metal was covered with charcoal. And “20g Na ₂ O”, “20g Na ₂ O + 8g CaO”, “20g N
A desulfurization test of the molten copper alloy was performed on four types of desulfurizing agents, namely, “a ₂ O + 4 g CaO” and “10 g Na ₂ O + 4 g CaO”. It is known that “resulfurization” easily proceeds under such a condition that a molten metal containing P is treated at a high temperature with a small amount of a desulfurizing agent.

FIG. 2 is a graph showing the results of comparing the sulfur concentration change in the molten metal for each of the above desulfurizing agents. From the results shown in FIG. 2, but significant "resulfurization" is in progress with Na ₂ O plain, when mixing CaO and a constant addition weight of Na ₂ O "resulfurization" is suppressed You can see that it is. In addition, when the mixing amount of CaO increases, "resulfurization"
In this test, the mixing amount of CaO was sufficient at 40% based on the weight of Na ₂ O.

Focusing on the sulfur concentration after a lapse of 10 minutes, “20 g of Na ₂ O added simply” and “10 g of
When 4 g of CaO is mixed and added to Na ₂ O ”, the desulfurization effect is equal. That is why it has been possible to reduce the Na ₂ O amount to _^1/2 by mixing CaO. This, considering "that can reduce damage to the smoke generator and refractories by decomposition of Na ₂ O by reduction of Na ₂ O amount""CaO inexpensive be compared to Na ₂ O" and, this effect Is very large.

Example 3 Commercially produced pure copper, pure tin, Cu-P alloy and phosphor bronze scrap were melted in a 3 ton low frequency induction furnace (actual operation furnace) built with an alumina-based furnace material (refractory). Then, 3 tons of phosphor bronze (Cu-0.1% P-6% Sn alloy) melt was obtained, and then the temperature was raised to 1250 ° C. ± 50 ° C. And
Various amounts of Na ₂ CO ₃ were added to the melt, and a desulfurization test of the melt was performed.

FIG. 3 is a graph showing the results of an investigation on the amount of added Na ₂ CO ₃ and the change in the sulfur concentration in the molten metal in this test. According to the results shown in FIG. 3, effective desulfurization does not progress when the amount of Na ₂ CO ₃ added is 2.5 kg (0.08% by weight of the molten metal), but the minimum sulfur concentration decreases as the amount of Na ₂ CO ₃ increases. You can confirm that. When the amount of Na ₂ CO ₃ added was 0.1% by weight or more of the weight of the molten metal, the initial reaction rate was extremely high, and it was confirmed that desulfurization treatment in normal operation was sufficiently possible.

[Example 4] 5 kg of commercially available pure copper having an impurity level was charged into a carbon crucible and melted in a high-frequency melting furnace.
The CuS reagent was added so that the S concentration was 0.007 to 0.008% by weight. Then, after raising the temperature to various temperatures and holding it, “25 g Na ₂ CO ₃ +25 g NaOH mixture” and “25 g
A mixture of “Na ₂ CO ₃ +25 g NaOH + 10 g CaCO ₃ +10 g MgO” was added to perform a desulfurization test of the molten metal.

FIG. 4 is a graph showing the results of an investigation on the desulfurization treatment temperature and the change in the sulfur concentration in the molten metal when “25 g Na ₂ CO ₃ +25 g NaOH mixture” was added. This figure 4
The graph shows that the higher the temperature of the molten metal, the higher the desulfurization rate and the shorter the time until the minimum sulfur concentration is shown, but the higher the minimum sulfur concentration itself and the greater the resulfurization amount. At 1600 ° C. (the melting point of pure copper + 517 ° C.), which exceeds the specified range of the present invention, this effect was more remarkable, and the desulfurization efficiency was significantly reduced. Further, when a desulfurizing agent was added at 1120 ° C. (the melting point of pure copper + 37 ° C.), which was below the specified range of the present invention, the surface of the molten metal was solidified, and desulfurization did not progress at all for 5 minutes until it re-yang.

Next, FIG. 5 shows "25 g Na ₂ CO ₃ +25 g Na
OH + 10gCaCO ₃ + 10gMgO mixture "is a graph showing the investigation results on the sulfur concentration change desulfurization treatment temperature and the melt when added. From FIG. 5, the desulfurization rate increases as the temperature of the molten metal increases, but the CaCO ₃ and MgO
It can be seen that the increase in the minimum sulfur concentration and the resulfurization amount is small as compared with the results of FIG. However, 160
At 0 ° C., the power consumption of the melting furnace was about twice that at 1150 ° C., and it became clear that the operating cost increased. In addition, similar to the result of FIG.
, The desulfurization rate is significantly reduced.

[Example 5] [Example 5] 5 kg of a Corson alloy having a composition of Cu-1.6 wt% Ni-0.4 wt% Si was prepared and charged into an alumina crucible or a carbon crucible, and a high-frequency melting furnace was prepared. And heated to 1250 ° C. And 10 g of Na ₂ O, 20 g of Na ₂ CO ₃
And a mixture of 20 g of NaOH as a desulfurizing agent, and adding this “desulfurizing agent” or “mixture of desulfurizing agent and 5 g of carbon powder” (both 50 g of desulfurizing agent) to conduct desulfurization test of molten metal. went. In some cases, the desulfurizing agent was added under the condition that the surface of the molten metal was covered with charcoal.

FIG. 6 is a graph showing the results of an investigation on "sulfur concentration change in molten metal" in this test. As is clear from the results shown in FIG. 6, it can be seen that good desulfurization can be performed in any case. However, from the test results, the desulfurization effect when the carbon crucible was used was most remarkable. The desulfurizing agent contains more than 10% by weight of car
It was also confirmed that the desulfurization effect was not further improved even if the bon powder was mixed.

[0043]

As described above, according to the present invention, copper and copper alloys can be desulfurized at low cost by ordinary melting operation, and copper and copper alloys having extremely low sulfur concentrations can be obtained by using a lot of scrap materials. Industrially extremely useful effects are obtained, such as mass production of materials at low cost.

[Brief description of the drawings]

FIG. 1 shows a case where “Na ₂ O is simply added”, “a case where CaO is simply added”, and “a Na ₂ O—CaO desulfurizing agent in which the weight ratio of Na ₂ O and CaO is changed. 6 is a graph showing the results of an investigation regarding a change in sulfur concentration in a molten metal when “added”.

[Figure 2] “20g Na ₂ O”, “20g Na ₂ O + 8g CaO”, “20g Na ₂ O”
g is a Na ₂ O + 4g CaO "and" graph showing the investigation results on the sulfur concentration change in the melt in the case of adding four types of desulfurizing agent 10g Na ₂ O + 4g CaO ".

FIG. 3 is a graph showing the results of an investigation on the amount of added Na ₂ CO ₃ and a change in sulfur concentration in a molten metal.

FIG. 4 is a graph showing the results of an investigation on the desulfurization treatment temperature and the change in sulfur concentration in the molten metal when “a mixture of 25 g Na ₂ CO ₃ +25 g NaOH” was added.

FIG. 5: “25 g Na ₂ CO ₃ +25 g NaOH + 10 g CaCO ₃
10 is a graph showing the results of an investigation regarding the desulfurization treatment temperature and the change in the sulfur concentration in the molten metal when “+10 g MgO mixture” was added.

FIG. 6 is a graph showing the results of an investigation on “sulfur concentration change in molten metal” under various desulfurization treatment conditions.

Claims (6)

(57) [Claims] After melting a raw material for producing copper or a copper alloy and raising the temperature to a temperature higher by 50 to 500 ° C. than a melting point or a liquidus temperature, a reducing gas or an inert gas atmosphere is added to the molten metal. Enclosure
Under care _{"Na 2 O, Na 2 CO} 3 or desulfurizing agent comprising <br/> of one or more NaOH" Na ₂ O, the total weight of Na ₂ CO ₃ and NaOH of 0.1% to 10% of the melt weight A method for producing a copper alloy having a low sulfur content of copper or Cu of 60% by weight or more, characterized by adding and maintaining the content within the range and then removing the desulfurizing agent after the reaction. 2. A material for melting copper or a copper alloy is melted and heated to a temperature 50 to 500 ° C. higher than the melting point or liquidus temperature, and then “Na ₂ O, Na ₂ CO ₃ ” is added to the melt. Or NaOH
Mosquito less than 10% of the desulfurizing agent by weight "and" desulfurizing agent consisting of one or more - of the melt weight mixture at desulfurization agent by weight of the carbon powder "
A method for melting a copper alloy containing 60% by weight or more of copper or Cu having a low sulfur content, characterized by adding and holding in the range of 0.1 to 10% and then removing the desulfurizing agent after the reaction. 3. A material for melting copper or a copper alloy is melted and heated to a temperature 50 to 500 ° C. higher than the melting point or liquidus temperature, and the surface of the molten metal is heated with 50% charcoal or carbon. weight%
After covering with the “substances contained above,”
₂ O, and adding a desulfurizing agent "consisting of one or more Na ₂ CO ₃ or NaOH Na ₂ O, such that the total weight of Na ₂ CO ₃ and NaOH is in the range of 0.1% to 10% of the melt weight A method for producing a copper alloy containing 60% by weight or more of copper or Cu having a low sulfur content, wherein the desulfurizing agent after the reaction is retained and then the desulfurizing agent after the reaction is removed. 4. A material for melting copper or a copper alloy is melted and heated to a temperature 50 to 500 ° C. higher than the melting point or liquidus temperature, and the surface of the molten metal is heated with 50% charcoal or carbon. weight%
After covering with the “substances contained above,”
₂ O, less than 10% of the desulfurizing agent by weight "and" desulfurizing agent consisting of one or more Na ₂ CO ₃ or NaOH force - by desulfurizing agent by weight of a mixture of carbon powder "of molten metal by weight 0.1% to 10% of A method for melting a copper alloy containing 60% by weight or more of copper or Cu having a low sulfur content, characterized by adding and holding in a range and then removing a desulfurizing agent after the reaction. 5. A desulfurizing agent comprising Na ₂ O, Na ₂ CO ₃ or
In addition to one or more types of NaOH, their proportion to the total amount
Is less than 50% by weight of CaO, CaCO ₃ , Ca (OH) ₂ , Mg
A mixture of at least one of O, MgCO ₃ and Mg (OH) ₂
5. The method according to claim 1, wherein:
60% by weight or more of copper or Cu with low sulfur content described in
Melting method of contained copper alloy. 6. The melting of the raw materials and the subsequent treatment are carried out in a furnace constructed of a refractory containing 10% by weight or more of carbon or in a crucible containing 10% by weight or more of carbon. 6. The method for producing a copper alloy having a low sulfur content of copper or Cu of 60% by weight or more according to any one of claims 1 to 5 , which is performed.