JP6665693B2 - Reduction method in copper refining furnace - Google Patents

Description

  The present invention relates to a method for reducing blister copper performed in a refining furnace of a copper smelting facility.

  In copper smelting and refining equipment, copper concentrate as a raw material is oxidized in a flash furnace, etc., to separate Kawa mainly composed of copper sulfide from slag composed of iron oxide, silica, etc. Oxidation treatment is performed in a furnace to obtain a blister copper in a molten state having a purity of about 98%. The obtained molten copper is then subjected to a reduction treatment in a refining furnace to adjust the concentration of impurities such as oxygen and sulfur in the molten copper, and then supplied to a casting machine to be cast on a copper anode for electrolytic refining.

  In the refining furnace, generally, fluid hydrocarbons such as heavy oil, natural gas, and butane gas are used as a reducing agent. Although these fluid reducing agents are rich in fluidity, they can be efficiently mixed with molten blister copper, but since fluid hydrocarbons generally have high volatility, they act as reducing agents. However, it is easy to dissipate directly from the surface of the molten blister copper without increasing the consumption cost. As a countermeasure, Patent Document 1 discloses a method in which a solid carbonaceous reducing agent such as powdered coke or coal is charged into a furnace so as to cover a molten copper surface in a refining furnace and then a gaseous state. A technique of blowing a reducing agent below the surface of a bath has been proposed.

JP-A-59-205428

  However, the solid carbonaceous reducing agent such as coke or coal described above tends to float locally as a large mountain-like lump on the surface of the molten metal, and in this case, it does not contribute much to saving of the fluidic reducing agent. However, there is a problem in that it remains without being burned out and becomes an impurity, and the furnace port and the tap port are clogged. As a countermeasure, attempts have been made to finely pulverize the solid carbonaceous reducing agent into powder and then charge it, or charge it little by little. However, the above problem still occurs. In particular, in a refining furnace operated in batch, molten blister copper which is easily oxidized due to an operational balance with a converter in the preceding stage which is also operated in batch, and an operational balance with a casting machine in the subsequent stage. Is often kept in a refining furnace for a long time as it is. In order to prevent the oxidation of the molten blister copper during the holding, an excessive reducing agent may be introduced into the refining furnace, so that the above problem is more likely to occur.

  The present invention has been made in view of the above-described problems of the conventional method for reducing a refining furnace, and reduces the amount of a fluid reducing agent used in a reduction step and waits for blister copper in a refining furnace for a long time. It is intended to suppress the oxidation of the blister copper during the standby when a case occurs.

  The present inventors have conducted intensive studies to achieve the above object, and as a result, before charging the molten blister copper treated in the converter into the refining furnace and filling it to the usual liquid level, coke was introduced into the refining furnace. By charging, it becomes possible to cover the charged coke almost uniformly while floating on the surface of the molten blister copper, thereby reducing the amount of the fluid reducing agent used during the reduction, and in the refining furnace. The inventors have found that oxidation of blister copper during standby can be suppressed, and have completed the present invention.

  That is, the copper smelting method of the present invention comprises: a first blister loading step in which the molten blister treated in the converter is charged so as to partially fill the effective capacity of the refining furnace; and the first blister loading step. Before or after the reducing agent charging step of charging the solid carbonaceous reducing agent into the refining furnace, and after waiting until the behavior of the solid carbonaceous reducing agent charged in the reducing agent charging step becomes steady A second blister charging step of charging the molten blister copper into the refining furnace from above the solid carbonaceous reducing agent; and blowing the fluid bleaching agent under the molten blister copper surface in the refining furnace to remove the molten blister copper. A reducing step for reducing, a reducing agent discharging step for tilting the refining furnace in one direction and discharging the solid carbonaceous reducing agent from the furnace port, and an anode casting from the tap port for tilting the refining furnace in the other direction To discharge the molten blister copper for use and charge the discharged solid carbonaceous reducing agent into a converter. It is characterized by comprising a copper discharge step.

  According to the present invention, the amount of the fluid reducing agent used can be reduced as compared with the conventional copper refining method in the refining furnace, and when the blister copper is kept in the refining furnace for a long time, its oxidation is suppressed. Can be.

It is an outline sectional view of general equipment used for smelting of copper smelting. It is a schematic front view of the refinery furnace of copper smelting.

  In the dry smelting of copper, copper concentrate as a raw material is sequentially processed in a flash smelting furnace 10, a converter 20 and a refining furnace 30 as shown in FIG. 1 to produce a molten crude copper for anode casting. Specifically, first, oxygen-enriched air is blown into the copper concentrate in the flash smelting furnace 10 to oxidize the copper concentrate. And separated into Karami is extracted from the flash smelting furnace 10, left in a kneading furnace (not shown), and then cooled with water to obtain granulated slag. On the other hand, the Kawa separated in the flash smelting furnace 10 is extracted from an outlet different from Karami and then transferred to the converter 20 by a Kawa transfer means such as a ladle or a gutter.

  The converter 20 is formed of a cylindrical container having a central axis extending in a horizontal direction, and is supported by a plurality of rollers 21 so as to be rotatable about the central axis. At a substantially central portion in the axial direction of the cylindrical container, there is provided a furnace port 22 serving as an inlet and outlet of the raw material before and after the treatment. The oxidation treatment is performed by blowing oxygen-enriched air from the tuyere 23 provided on the side. Thereby, it is separated into slag and molten blister copper having a copper grade of about 98%. After the separation, the converter 20 is tilted on the rollers 21, the slag in the upper layer is first discharged from the furnace port 22, and then the molten blister copper is discharged. The discharged blister copper is transferred to the refining furnace 30 by a blister transfer means such as a ladle or a gutter.

  The refining furnace 30 is also formed of a cylindrical container whose central axis extends in the horizontal direction, and is supported by a plurality of rollers 31 so as to be rotatable about the central axis. A furnace port 32 serving as a loading port for the molten blister copper and a solid carbonaceous reducing agent described later, and a tap port 33 serving as an outlet for the treated molten blister copper are provided at a substantially central portion in the axial direction of the cylindrical container. . In addition, a tuyere 34 for blowing air or a fluid reducing agent is provided at a position below the surface of the molten metal.

  In the refining furnace 30 having such a structure, a first blister copper charging step of charging the molten blister copper treated in the converter 20 so as to fill a part of the effective capacity of the refining furnace, and before the first charging step. Or, after a reducing agent charging step of charging the solid carbonaceous reducing agent into the refining furnace, and waiting until the behavior of the solid carbonaceous reducing agent charged in the reducing agent charging step becomes steady, A second blister loading step in which the blister copper is loaded into the refining furnace 30 from above the solid carbonaceous reducing agent, and a fluid reducing agent is blown under the molten blister copper surface in the refining furnace 30 to melt the blister copper. A reducing step of reducing, purifying the refining furnace 30 in one direction and discharging a solid carbonaceous reducing agent from the furnace port 32, and a refining furnace 30 moving the refining furnace 30 to the other side (in the case of the reducing agent discharging step). (The direction opposite to the turning direction) and discharge the molten blister copper for anode casting from the tap hole 33. Together, by performing a series of processes consisting of a melt blister copper discharged step of loading the solid carbonaceous reducing agent discharged above the converter 20, the reduction of the molten blister copper is performed.

  More specifically, in the first blister copper charging step, first, in the first blister copper charging step, the molten blister copper containing oxygen and sulfur, which has been treated in the converter 20 in the preceding stage, is subjected to an effective capacity in the refining furnace 30 (that is, the refining furnace 30). Inside the container, the molten blister copper is charged so as to fill a part of the maximum volume. It is preferable that the amount of molten blister copper charged into the refining furnace 30 in the first blister copper charging step is not less than の and not more than 有効 of the effective capacity of the refining furnace 30. If the amount is 1/5 or more, the surface of the molten blister copper charged into the refining furnace 30 can be sufficiently widened, so that the solid carbon charged into the refining furnace 30 in the reducing agent charging step can be used. The quality reducing agent can be spread well on the surface of the molten metal.

  On the other hand, when the content is set to 以下 or less, a large amount of molten blister copper can be charged in the second blister charging step in the subsequent step, so that the stirring effect by the charging can be enhanced. In addition, the solid carbonaceous reducing agent temporarily submerged under the surface of the molten metal by the charging can be retained deeper than the surface of the molten metal, and therefore, can remain under the surface of the molten metal for a longer time. As a result, the contact efficiency between the solid carbonaceous reducing agent and the molten blister copper can be increased, so that a more efficient reduction treatment can be performed. In addition, as mentioned above, since the furnace port 32 which becomes the discharge port of the gas produced from the molten blister copper is provided in the substantially central part of the axial direction in the purification furnace 30 which consists of a container with the cylindrical body laid down. , It is necessary to provide a gas phase for the horizontal flow of gas. Therefore, the above-mentioned effective capacity is usually about 45 to 70% of the total volume in the refining furnace 30 (that is, the sum of the volume of the effective capacity and the volume of the gas phase above the surface of the molten metal).

  Next, in the reducing agent charging step, a solid carbonaceous reducing agent is charged into the refining furnace 30 into which the molten blister copper has been charged. The amount of the solid carbonaceous reducing agent to be charged is preferably 1/1000 to 1/300 of the mass of the molten blister copper charged in the first blister copper charging step. By setting this amount to 1/1000 or more, almost half or more of the molten copper surface in the refining furnace 30 can be covered with the solid carbonaceous reducing agent. The consumption can be significantly reduced. On the other hand, even if the charge exceeds 1/300, the effect of the charge cannot be improved so much, and the cost of the reducing agent is rather increased, which is not preferable. The reducing agent charging step may be performed before the first blister copper charging step. In this case, it is possible to reduce the thermal shock to the furnace wall when charging the molten blister copper. Depending on the type and concentration of the impurities contained in the solid carbonaceous reducing agent, the impurities may adhere to the furnace wall of the refining furnace 30. Therefore, the reducing agent is charged before the first blister copper charging step. When performing the process, it is desirable to pay attention to the above-mentioned adverse effects due to impurities.

  Next, in the second blister copper charging step, after waiting until the behavior of the charged solid carbonaceous reducing agent becomes steady, the liquid level in the effective volume of the refining furnace 30 is set to an upper limit and The molten blister copper is charged into the refining furnace 30 so as to satisfy the level. In general, it is preferable that the above-mentioned waiting time be longer as the temperature difference between the molten crude copper and the solid carbonaceous reducing agent is larger, and it is longer as the water content of the solid carbonaceous reducing agent is higher. Usually, this waiting time is about 10 minutes to 10 hours, preferably about 1 hour to 3 hours. If the waiting time is less than 10 minutes, there is a possibility that the solid carbonaceous reducing agent cannot be broken down by loosening the mountain-like mass of the solid carbonaceous reducing agent formed on the molten metal surface when the solid carbonaceous reducing agent is charged into the refining furnace 30. is there. By setting the time to 1 hour or more, even if the solid carbonaceous reducing agent is in a wet state or wet, it can be dried by the heat of the molten crude copper, and the solid carbonaceous reducing agent can be reliably removed from the hot water. Can be spread on the surface. On the other hand, if the waiting time exceeds 10 hours, the amount of heat released from the refining furnace may be too large, and casting may be difficult. Can be enhanced.

  In the second blister loading step, molten blister copper is poured over the solid carbonaceous reducing agent. As a result, the solid carbonaceous reducing agent is stirred, so that the above-mentioned mountain-like mass can be easily broken. That is, by pouring molten blister copper from above, the solid carbonaceous reducing agent can be submerged in the molten metal, and a pressure difference corresponding to the depth from the molten metal surface occurs in the voids of the solid carbonaceous reducing agent, and It is believed that the reducing agent is crushed. In the second blister loading step, the molten blister may be charged a plurality of times. In this case, it is preferable to perform the next charging after the carbonaceous reducing agent that has settled in the molten metal by the charging of the molten blister copper rises to the surface of the molten metal. Can be efficiently dispersed, and the reduction reaction can be promoted.

  Next, in the reduction step, a fluid reducing agent such as heavy oil, natural gas, or butane gas is blown from a tuyere 34 provided below the molten copper surface in the refining furnace 30 to reduce the molten copper. . In this reduction step, air may be blown from the tuyere 34 as needed, thereby generating carbon monoxide from the fluid reducing agent to increase the reduction efficiency or cooling the tuyere with air. In this reduction step, a part of the solid carbonaceous reducing agent remains as unburned residue. However, as described above, since the gas generated from the molten blister copper flows in the gaseous phase portion of the purification furnace 30 in the horizontal direction, Along with the flow of the gas, the solid carbonaceous reducing agent floating near the furnace wall or at both ends in the axial direction of the furnace is collected below the furnace port 32 located at substantially the center of the molten metal surface.

  Next, in the reducing agent discharging step, the unburned solid carbonaceous reducing agent collected below the furnace port 32 is discharged from the furnace port 32 by tilting the purification furnace 30 in one direction. Since the solid carbonaceous reducing agent discharged from the furnace port 32 is charged into the converter 20 as described later, it is temporarily held by a transfer means such as a ladle.

  Next, in the molten blister copper discharging step, the refining furnace 30 is tilted in the other direction to discharge the molten blister copper from the tap port 33, and the unburned solid carbonaceous reducing agent discharged in the reducing agent discharging step is discharged. The converter 20 is charged. The molten blister copper discharged from the tap opening 33 is sent to a casting machine directly or through a gutter, and is cast as an anode. In some cases, the fluid reducing agent is not blown in the above reduction step. In this case, the molten blister may be discharged after the fluid reducing agent is blown in the molten blister discharging step. The solid carbonaceous reducing agent charged into the converter 20 is used for keeping the temperature of the molten blister copper in the converter 20, becomes ash derived from the solid carbonaceous reducing agent by combustion, and is collected together with the slag.

[Example 1]
The river consisting mainly of copper sulfide obtained by oxidizing copper concentrate in a flash furnace was further oxidized in a converter at a later stage to obtain molten crude copper having a copper grade of 99%. Most of the impurities contained in the molten blister copper were oxygen, and the remaining impurities were sulfur. After charging 200 tons of the obtained molten blister copper into the refining furnace, 200 kg of coke having a moisture content of 1% was charged into the refining furnace, and after the mountain-like lumps of coke were loosened, the behavior of the coke on the molten metal surface was changed. Waited 1 hour until steady. At this time, the height from the molten metal surface to the upper end of the coke was almost constant. Thereafter, 400 tons of molten blister copper were charged into the refining furnace from above the coke in 10 steps of about 40 tons so as to satisfy about 94% of the effective capacity of the refining furnace. At that time, a waiting time of 10 minutes is provided between each charging and the next charging, and the molten blister copper is charged after the coke sinking in the molten metal by the charging of the molten blister floats on the surface of the molten metal. I did it.

  While periodically sampling the molten blister copper, propane gas was blown from the tuyere until the oxygen grade of the molten blister copper became 0.5% or less to perform a reduction treatment. At that time, the coke flowed while floating on the surface of the molten metal, and gathered below the furnace opening located at the center of the refining furnace, away from the furnace wall. Next, the refining furnace was tilted in one direction, so that the coke collected under the furnace port was discharged from the furnace port together with a small amount of molten blister copper, and held in a ladle.

  Subsequently, the refining furnace was tilted in the direction opposite to the above one direction, so that the molten blister copper remaining in the refining furnace was discharged from the tap opening. The molten blister copper discharged from the tap opening was supplied to a casting machine through a gutter to cast an anode. The obtained anode had little surface swelling and copper quality was 99% or more. On the other hand, the coke discharged from the furnace port was charged into a converter via a ladle and used for keeping the temperature of the molten blister copper in the converter. This coke finally burned off in the converter, leaving the ash of non-combustible components, and was recovered together with the slag.

[Example 2]
An anode and a slag were produced in the same manner as in Example 1 except that the amount of the molten blister copper charged into the refining furnace before charging the coke was 100 t. The flow condition of coke and the quality of anode and slag were the same as in Example 1.

[Example 3]
Example 1 except that the charging amount of the molten blister to the refining furnace before charging the coke was 320 t, the charging amount of the coke was 96 kg, and the charging amount of the molten blister copper after the charging of the coke was 320 t. An anode and a slag were produced in the same manner as in Example 1. The flow condition of coke and the quality of anode and slag were the same as in Example 1.

[Example 4]
An anode and a slag were produced in the same manner as in Example 1, except that the amount of the molten blister copper charged into the refining furnace before charging the coke was 100 t, and the amount of the coke charged was 300 kg. The flow condition of coke and the quality of anode and slag were the same as in Example 1.

[Comparative Example 1]
An anode and a slag were produced in the same manner as in Example 1, except that the entire amount (600 t) of the molten blister copper was charged into the refining furnace and then coke was charged. Part of the coke remained in a mountain shape in the furnace, and it took more time to discharge from the furnace port than in Example 1. Further, a large amount of molten blister copper was discharged from the furnace port with the discharge of coke.

[Evaluation]
In Examples 1 to 4, the amount of propane used was 3.20 × 10 ^{−3 to} 3.30 × 10 ⁻³ times the total amount of molten blister copper charged into the refining furnace in terms of mass. In particular, in Example 4, it was 3.21 × 10 ⁻³ times. On the other hand, in Comparative Example 1, the amount of propane used was 3.40 × 10 ⁻³ times in terms of mass with respect to the total amount of molten blister copper charged into the refining furnace.

The propane that binds to 0.5 mass% of oxygen contained in the molten blister copper (that is, a value obtained by subtracting 0.5% of oxygen grade after reduction from 1% of oxygen grade before reduction) is stoichiometrically molten. In consideration of the fact that the mass of blister copper is 1.38 × 10 ⁻³ times, the amount of propane consumed by the dissipated or foreign air is 1.82 × 10 ⁻³ to 1.82 × 10 ⁻³ of the mass of molten blister copper in Examples 1 to 4. It is 1.92 × 10 ⁻³ times, which means that a maximum reduction of 10% has been achieved compared to 2.02 × 10 ⁻³ times of Comparative Example 1. If the waiting time for the molten blister copper is long (for example, when the construction of related facilities or the restoration work at the time of failure of the casting machine occurs), a further reduction can be expected.

DESCRIPTION OF SYMBOLS 10 Flash furnace 20 Converter 21 Roller 22 Furnace port 23 Tuyere 30 Refining furnace 31 Roller 32 Furnace port 33 Tap port 34 Tuyere

Claims (2)

A first blister charging step of charging the molten blister copper treated in the converter to fill a part of the effective capacity of the refining furnace;
A reducing agent charging step of charging the solid carbonaceous reducing agent into the purification furnace before or after the first blister copper charging step;
After waiting until the behavior of the solid carbonaceous reducing agent charged in the reducing agent charging step becomes steady, the second blister copper charging the molten blister copper into the refining furnace from above the solid carbonaceous reducing agent. Input process,
A reduction step of reducing the molten blister by blowing a fluid reducing agent below the surface of the molten blister in the refining furnace,
A reducing agent discharging step of tilting the refining furnace in one direction and discharging a solid carbonaceous reducing agent from the furnace port;
Tilting the refining furnace in the other direction, discharging molten blister copper for anode casting from the tap opening thereof, and discharging the molten blister copper into the converter with the discharged solid carbonaceous reducing agent. Of blister copper. In the second blister copper charging step, the molten blister copper is charged in a plurality of times, and the next charging is performed after the carbonaceous reducing agent sinking in the molten metal by the charging floats. , reduction method of the crude copper according to claim 1.

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