JPS59232241A - Refining method of crude copper by caustic soda - Google Patents

Abstract

PURPOSE:To refine product electric copper having high quality by a large volume treatment of copper concentrate having a high impurity content with an extremely simple method and device by passing molten crude copper by a stream droplet method through the inside of a molten NaOH layer and recovering said copper. CONSTITUTION:A channel type induction furnace 11 is provided with a recovering chamber 14 which holds an NaOH bath 13 in a molten state and rises after extending horizontally from the bottom end of the bath in the upright part 12 thereof. An induction coil 15 is provided in the horizontal part between the perpendicular parts at both ends. The coil 15 generates the quantity of heat required for maintaining refined crude copper 19 in an adequate fluid state. The crude copper produced from a converter or refining furnace is dropped from a dropping device 18 such as a ladle, tray or the like onto the bath 13 and is accumulated through the bath in the chamber 14. A dischrging port 16 is provided to the chamber 14 so that the refined crude copper is discharged through said port at a suitable interval and is sent for an anode casting stage. Impurities such as As, Sb, Bi, Pb or the like in the crude copper are efficiently removed during the passage through the bath 13 according to the above-mentioned method.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for refining blister copper discharged from a converter or refining furnace, and in particular, by dropping molten blister copper into a layer of molten caustic soda, impurities such as Am and Sb are removed from the blister copper. It relates to a method of removal.

In copper smelting, copper concentrate basically goes through the steps of smelting in a flash furnace and wrought copper in a converter, then refined in a refining furnace and cast as an anode for electrolysis. The refining furnace, which plays the final role in the smelting process, processes the sulfur and oxygen in blister copper,
This is a furnace installed in the younger sister to reduce oxygen, and As exists in blister copper.

It is not suitable for removing impurities such as Sb, Bj SPb, etc. In order to improve the removal rate of these impurities, a method has been proposed in which slaked lime, quicklime or soda ash is added in a converter or refining furnace to remove impurities as lime slag or soda slag. However, the problem with this method is how closely the additives and molten steel can be brought into contact. For example, attempts have been made to improve the contact effect by various methods such as injecting powdered additives into the bath on a gas or creating a stirring effect by blowing inert gas, but there are still many ways to improve the contact effect. Contact between the material and the molten steel is insufficient, and a high removal rate cannot be expected.
In addition, the separation between the generated slag and molten steel is poor, and metal loss cannot be ignored. Besides this, fi? A technology has also been reported in which impurities are removed by vacuum treating blister copper from a converter, but there is still room for further investigation in terms of equipment, reaction efficiency, and other aspects.

In any case, the removal of impurities, especially heavy metals, by conventional processes has not always been achieved satisfactorily.

Particularly when there are many impurities in the raw material, the amount of impurities remaining after purification becomes unacceptably high. As18bsBiSPb
Impurities such as these have a serious negative impact on the subsequent electrolytic process, so it is necessary not only to reduce them as much as possible, but also to reduce the tolerance of impurities at smelters in view of the recent decline in high-quality copper concentrate. It is hoped that by increasing the capacity, it will be possible to use large amounts of ore with many impurities.

In response to these demands, the present inventor conducted extensive research on a new crude silver refining method to replace the conventional method, and as a result, impurities in blister copper were removed by a so-called droplet method in which molten crude silver was dropped into a molten caustic soda layer. was found to be able to be removed efficiently. By using caustic soda as the 7 lux layer to remove impurities in blister copper and by dropping molten steel into the 7 lux layer as a contact method, we can remove impurities such as A8 and Sb, which are particularly problematic in blister copper. Sulfur and oxygen can also be removed very efficiently. The blister copper to be treated is blister copper from a converter or a refining furnace, but since the effect of removing impurities is very high, it is also possible to treat blister copper for converters according to the present invention and cast it as an anode as it is. This allows the refining furnace step to be omitted.

Thus, the present invention provides a method for refining blister copper, which comprises dropping molten crude silver into a molten caustic soda layer and recovering purified blister copper that has passed through the caustic soda layer.

The present invention will be explained in detail below.

As mentioned above, the converter blister copper produced in the converter is
It still contains significant amounts of impurities and sulfur and oxygen. Impurities vary depending on operating conditions and raw material conditions, but include 0.03 to 008% Bi, 0.03 to 0.0
4% Sb, 0.2-0.3% As.

0,015~0.030%pb,o,001~0.00
2% Zn is a typical example. Sulfur is 0.01-0.02%
Oxygen is contained in an amount of about 0.50 to 0.60%.

If the proportion of ore with many impurities is high, the amount of impurities can further increase.

According to the conventional method, blister copper for converters is processed in a tilting type refining furnace, where sulfur and impurities are removed by adding air or cooperating if necessary [11], and then the oxides floating on the surface are removed from the furnace. A scraping operation 5 was performed to remove the material from the outside, and then a reduction treatment, that is, deoxidation, was performed using a reducing agent such as ammonia. However, as mentioned above, impurities could not be sufficiently removed by this method.

Therefore, according to the present invention, blister copper from a converter or blister copper from a refining furnace is purified by a droplet method using a layer of molten caustic soda. Conventionally, flux or slag called soda-based flux or soda slag is used. Research has been conducted on the refining of blister copper, but the mainstream is soda ash (N
a2CO3).

There has been no attempt to commercialize blister copper refining using caustic soda (NaOH). caustic soda! Masota.

As a salt, it is relatively stable at high temperatures, and as shown in Examples later, it can remove impurities more effectively than soda ash. For example, it is assumed that AI and sb are caused by the following reaction.

2 As -1-6NaOH→ 2Na3AsOs +
3H22Sb + 6 NaOR- + 2Nas
Sb Oa + 5Hz FIG. 1 shows a test setup illustrating the basic principle of the method of the invention. A layer of caustic soda 3 is placed in an alumina crucible 1, and a layer of molten blister copper (7 layers) is heated from above the caustic soda bath.
dripped. The eluted blister copper drops pass through a caustic soda bath [the impurities contained in it in the river are removed]. The impurities in the blister copper are effectively removed by passing through the bath in droplet form and by the high reactivity of the caustic soda and impurities. Refined crude lead 9 accumulates under the bath. The bath floats on the refined coarse brocade due to the J-seven claw difference, and good separation of the metal is maintained.

FIG. 2 shows an example of an industrialized refining device. The ζ-type induction furnace 11 has a caustic miso soda bath 13 in its upright part 12.
is maintained in a molten state. It is equipped with a recovery chamber 14 that extends horizontally from the lower end of the furnace 11 and the bath and rises later, and a circular induction coil 15 is installed in the horizontal portion between the vertical portions on both sides. The induction coil 15 generates the amount of heat necessary to maintain the caustic soda bath in a molten state and to maintain the refined crude slag 19 in a moderately fluid state. The blister copper from the converter or from the refining furnace 11 is dripped onto the caustic soda bath from a dripping device 18 such as a ladle or tray, passes through the bath, and collects in the recovery chamber 14.

A spout 16 is provided in the recovery chamber 14, and refined blister copper is extracted at an appropriate opening and subjected to an anode spinning process. The inner wall of the upright portion 12 that accommodates and holds the caustic soda bath is coated with, for example, fused magnesia brick. The caustic soda bath is periodically withdrawn from the outlet 20, purified in the slag wet treatment process, and used repeatedly.

The use of a caustic soda bath is determined depending on the blister copper temperature, the dropping state, the bath passing time of the blister copper droplets, the bath temperature, etc.
: Sufficient M for caustic soda 2Rffl ratio up to about 30o:1! You can increase the effect. The production temperature of blister copper for converters is 1100 to 1200°C, and if necessary, it may be preheated to a temperature of up to 1350°C. Since the temperature of the melt pot decreases during the refining process, it is preferable to control the converter temperature at a high level. Conveniently, the caustic soda bath is maintained at around 1100°C.

Example 1 and Comparative Example 1 As test blister copper, the grade shown in the table below was obtained by melting blister copper produced at a copper wire cutting site in a graphite crucible. 1 kg of this test blister copper was heated at 1200°C in a graphite crucible. The solution was subjected to droplet treatment in an apparatus as shown in FIG. A caustic soda bath and a soda ash bath 5002 were dissolved in an alumina crucible and maintained at 1100°C hh. The height of the bath is 12
It was 0 fights. After the blister copper was poured, it was allowed to cool, and the treated refined blister copper was sampled and the quality of impurities was analyzed. The results are shown in the table below.

Example 2 and Comparative Example 2 The same treatment as Example 1 was carried out, except that a 500v caustic soda and soda ash bath was treated with coarse @10 to 9. The results are shown in the table below.

As can be seen from the above examples, a caustic soda bath is much better at removing impurities than a soda ash bath. Regarding the cause of this, impurity removal by soda ash CI4
Taking AI as an example, M't is AAs +502 +
It is thought that this is due to a reaction such as 6Na20-+4Na3As03, and the most important factor that determines the rate of the reaction is the supply of 02, and it seems that it is difficult to satisfy this condition. In any case, the present invention very efficiently removes As, Sb% Bi, etc., which are particularly problematic in blister copper, as well as sulfur and acid accumulations.

The present invention enables the production of copper iI'i with a high impurity content by an extremely simple method and by a simple device without using means such as gas blowing or vacuum treatment. This will make a significant contribution to the field of copper smelting and refining in that it will be possible to manufacture high-quality electrical steel products through mass processing of seven ores. In addition, the refining furnace process can be omitted in some cases, and a new copper smelting flow sheet can be established.

[Brief explanation of drawings]

FIG. 1 shows a test device illustrating the principle of the method of the present invention, and FIG. 2 is a sectional view showing a specific example of the device for carrying out the present invention. 1: / L / pot 2: caustic soda bath 5: fill 7: blister copper 9: purified blister copper 11: groove induction furnace 12: upright part 13: caustic soda bath 14: recovery chamber 15: induction coil 16: spout 17 2 coarse m 18 Two dropping device 19: Refined blister copper 20; Bath outlet ゛・2. −

Claims (1)

[Scope of Claims] 1) A method for refining blister copper, which comprises dropping molten blister copper into a molten caustic soda layer and recovering the refined blister copper that has passed through the caustic soda layer. 2) The method according to claim 1, wherein the molten blister copper is blister copper extracted from a converter.