Method of operating copper smelting

Abstract

To provide a method of operating copper smelting by which it is possible to inhibit generation of a metallic Cu phase.SOLUTION: With a method of operating copper smelting, under conditions where a metallic phase of metallic Cu is generated in a mat generated from copper concentrate and a smelting raw material including the metallic Cu in a smelting furnace, the smelting raw material is loaded into the smelting furnace to obtain the mat in a state where a metallic phase generated by melting of the metallic Cu is dispersed.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a copper smelting operation. [Background technology]

[0002] In the reaction shaft of a copper smelting flash furnace, a reaction gas is fed from a concentrate burner together with smelting raw materials such as copper concentrate and solvent. The copper concentrate undergoes an oxidation reaction due to the reaction gas, producing matte and slag at the bottom of the reaction shaft (see, for example, Patent Documents 1 to 3). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2002-363659 A [Patent Document 2] Japanese Patent Application Publication No. 11-140554 [Patent Document 3] Special Publication No. 01-036539 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, the ratio of recycled raw materials as smelting raw materials has been increasing. However, recycled raw materials may contain metallic Cu. As the amount of recycled raw materials processed increases, the ratio of metallic Cu supplied to smelting furnaces such as flash smelting furnaces increases. When the amount of metallic Cu supplied to a smelting furnace increases and exceeds the solubility of metallic Cu in matte, three phases, slag, matte, and metal, coexist in the furnace. When metal accumulates at the bottom of a smelting furnace, it promotes the concentration of impurity elements in the metal phase, the penetration of low-melting-point metal into the joints of the hearth bricks, and the impregnation of the bricks themselves, increasing the risk of molten metal leaking from the bottom of the hearth. In addition, when the amount of metal exceeds a certain amount and reaches the matte tap hole level, metal is suddenly discharged from the matte hole, which may cause the risk of melting the metal matte trough, and may also cause operations to be disrupted by the supply of high-impurity metal to the converter.

[0005] The present invention has been made in consideration of the above problems, and aims to provide a copper smelting operation method that can reduce the formation of a metallic Cu phase at the bottom of a melting furnace. [Means for solving the problem]

[0006] The copper smelting operation method according to the present invention is characterized in that the smelting raw material containing metallic Cu is charged into the smelting furnace under conditions in which a metal phase of the metallic Cu is generated in the matte produced from the copper concentrate and the smelting raw material, and the matte in a state in which the metallic phase is dispersed by melting the metallic Cu is obtained. The maximum particle size of the metallic Cu contained in the smelting raw material may be 1 mm or less in terms of a sphere equivalent diameter. When the metallic Cu is contained in the smelting raw material in an amount exceeding the solubility in the matte, the metallic Cu may be finely pulverized before the smelting raw material is charged into the smelting furnace, and the maximum particle size when the metal phase is melted in the matte and forms spheres may be 1 mm or less. When the metallic phase of the metallic Cu is confirmed in the matte by sampling the matte, the metallic Cu may be finely pulverized before the smelting raw material is charged into the smelting furnace, and the maximum particle size when the metal phase is melted in the matte and forms spheres may be 1 mm or less. The smelting raw material may be charged into a smelting furnace, and the maximum particle size of the metal phase generated by melting the metallic Cu may be controlled to 1 mm or less. When the weight of the matte is taken as 100, the supply weight of the metallic Cu may be 5 or less in excess of the solubility of the metallic Cu in the matte. After obtaining the matte in a state in which the metal phase generated by melting the metallic Cu is suspended, the matte in a state in which the metal phase is suspended may be charged into a subsequent copper smelting furnace for processing. The composition of the matte and the amount of copper in the metal phase suspended in the matte may be analyzed to determine the operating conditions of the copper smelting furnace. Effect of the Invention

[0007] According to the present invention, it is possible to provide a copper smelting operation method capable of reducing the formation of a metallic Cu phase in the hearth of a melting furnace. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram illustrating a schematic configuration of a flash furnace for copper smelting according to an embodiment. [Diagram 2]FIG. 2 is a diagram illustrating the details of a concentrate burner 4. [Diagram 3] FIG. 2 is a phase diagram showing the solubility of Cu in the matte. [Figure 4] FIG. 1 illustrates an experimental setup. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] (Embodiment) FIG. 1 is a diagram showing a schematic configuration of a flash smelting furnace 100 for copper smelting according to an embodiment. As shown in FIG. 1, the flash smelting furnace 100 includes a reaction shaft 1 in which concentrate and reaction gas are mixed, a settler 2, and an uptake 3. A concentrate burner 4 is provided on the ceiling of the reaction shaft 1. The concentrate burner 4 supplies a reaction main blast gas, a reaction auxiliary gas, and a dispersion gas (which also contributes to the reaction) into the reaction shaft 1 together with copper concentrate, solvent, recycled raw materials, etc. (hereinafter, these solid raw materials are referred to as smelting raw materials). For example, the reaction main blast gas and the reaction auxiliary gas are oxygen-enriched air, and the dispersion gas is air or oxygen-enriched air.

[0010] FIG. 2 is a diagram illustrating the details of the concentrate burner 4, and is an explanatory diagram showing the input section 10 that inputs the smelting raw material, the main reaction blast gas, the auxiliary reaction gas, and the dispersion gas into the reaction shaft 1.

[0011] The input section 10 of the concentrate burner 4 is provided with a lance 16, and a first passage 11 through which the dispersion gas passes and a fourth passage 14 through which the reaction auxiliary gas passes are formed in the lance 16. The fourth passage 14 is provided in the center of the lance 16, and the first passage 11 is provided around the fourth passage 14. The input section 10 is also provided with a second passage 12 as a raw material flow path provided on the outside of the lance 16, more specifically on the outer periphery of the lance 16. The input section 10 further includes a third passage 13 provided on the outside of the second passage 12, more specifically on the outer periphery of the second passage 12, through which the reaction main blast gas passes. The third passage 13 is formed by a tubular portion provided so as to surround the second passage 12, and communicates with a funnel-shaped air chamber 17 provided above it. The second passage 12 and the third passage 13 are separated by a cylindrical partition wall 21.

[0012] The first passage 11 supplies the dispersion gas into the reaction shaft 1. The second passage 12 supplies the concentrate into the reaction shaft 1. The third passage 13 supplies the main reaction blast gas from the air chamber 17 into the reaction shaft 1. The fourth passage 14 supplies the auxiliary reaction gas into the reaction shaft 1.

[0013] A hollow truncated cone-shaped dispersion cone 15 is formed at the tip (lower end) of the lance 16. A plurality of supply holes 152 are formed in a lower side portion 151 of the dispersion cone 15 to discharge the dispersion gas that has passed through the first passage 11 into the reaction shaft 1. The supply holes 152 are provided so that the gas is discharged in the normal direction to the bottom circle of the dispersion cone 15.

[0014] When the smelting raw materials are fed into the reaction shaft 1 from the concentrate burner 4, the copper concentrate containing sulfides undergoes an oxidation reaction according to the following reaction formula (1) and separates into matte 5 and slag 6 at the bottom of the reaction shaft 1, as shown in Figure 1. In the following reaction formula (1), Cu2S·FeS corresponds to the main component of matte 5, and FeO·SiO2 corresponds to the main component of slag 6. Silica ore is used as the solvent. CuFeS2+SiO2+O2→Cu2S·FeS+FeO·SiO2+SO2+ Reaction heat (1)

[0015] The recycled raw material may contain metallic Cu. If the amount of metallic Cu is small, the metallic Cu is sulfidized during the process of falling from the concentrate burner 4 to become matte 5. Therefore, no metal phase is generated.

[0016] However, as the amount of recycled raw materials processed increases, the proportion of metallic Cu in the smelting raw materials tends to increase. In recent years, the proportion of metallic Cu in the Cu component of the smelting raw materials can be 9.0 mass% or more and 30.0 mass% or less, or 12.0 mass% or more and 27.0 mass% or less, or 18.0 mass% or more and 20.0 mass% or less.

[0017] When the ratio of metallic Cu in the smelting raw material becomes high, metallic Cu is not completely sulfidized during the process of falling from the concentrate burner 4 and falls as metallic Cu. Although metallic Cu dissolves in matte 5 to a certain extent, there is a solubility limit. Figure 3 is a phase diagram showing the solubility of Cu in matte at 1250°C. In Figure 3, "matte(l)" indicates the range in which metallic Cu can dissolve in matte. "matte(l)+Cu(l)" indicates the range in which metallic Cu cannot dissolve in matte and a metal phase is generated. The phase diagram in Figure 3 is taken from "Takazaietsu, Yazawa Akira, 1983, Senkeniho."

[0018] In this embodiment, the smelting raw material is charged into the flash smelting furnace 100 under conditions in which a metal phase of metallic Cu is generated in matte 5 generated from copper concentrate and a smelting raw material containing metallic Cu, and the metallic Cu is melted to obtain matte 5 in a state in which the metal phase generated is suspended. By dispersing and suspending metallic Cu in the matte 5 in this manner, it is possible to suppress the generation of a metal phase separately from the matte 5 at the bottom of the furnace.

[0019] In order to disperse metallic Cu more in the matte 5, it is preferable that the particle size of the metal phase generated by melting metallic Cu is small. When each metallic Cu melts in the matte 5, it tends to become a metal phase with a substantially spherical shape. Therefore, the particle size of metallic Cu contained in the smelting raw material can be specified by the sphere-equivalent diameter, and in this embodiment, the maximum particle size of metallic Cu contained in the smelting raw material is preferably 1 mm or less as the sphere-equivalent diameter. The sphere-equivalent diameter of metallic Cu contained in the smelting raw material may be calculated after measuring the volume by a method utilizing Archimedes' principle. Alternatively, the particle size of multiple metallic coppers can be measured using an apparatus that measures particle size on a volume basis, such as a laser diffraction type particle size distribution meter.

[0020] When the smelting raw material contains metallic Cu in an amount exceeding the solubility in the matte 5, it is preferable to subject the metallic Cu to a fine pulverization process before the smelting raw material is charged into the flash smelting furnace 100 so that the maximum particle size of the metallic Cu charged is 1 mm or less in terms of spherical equivalent diameter.

[0021] When the metal phase of metallic Cu is confirmed in the matte 5 by sampling the matte 5, it is preferable to perform a fine pulverization process on the metallic Cu before feeding the smelting raw material into the flash smelting furnace 100, and to set the maximum particle size of the metallic Cu at this time to 1 mm or less in terms of spherical equivalent diameter.

[0022] In order to disperse the metal phase more in the matte 5, it is preferable that the average particle size of the metal phase when it melts and becomes a sphere in the matte 5 is small. In this embodiment, the average particle size of metallic Cu contained in the smelting raw material is preferably 41 μm or less, more preferably 35 μm or less, as a volume average diameter.

[0023] In addition, if the metallic Cu contains some excessively large particles, the large particles may not be suspended in the mat 5. Therefore, it is preferable that the metallic Cu has a sharp particle size distribution. In this embodiment, when the particle size distribution of the metallic Cu contained in the smelting raw material is measured, the standard deviation of the particle size is preferably 17 μm or less, more preferably 15 μm or less, and even more preferably 13 μm or less. When measuring the particle size distribution of the metallic Cu contained in the smelting raw material, a sample is taken by reducing the metallic Cu only before mixing with the smelting raw material, and the particle size distribution can be measured using a laser diffraction particle size distribution meter.

[0024] Furthermore, by setting a maximum diameter in the metallic Cu or the metal phase in the matte 5, it is possible to suppress the inclusion of large particles. Therefore, it is preferable to set a maximum diameter in the metallic Cu or the metal phase in the matte 5. In this embodiment, the maximum diameter of the metallic Cu contained in the smelting raw material is preferably 1 mm or less, more preferably 170 μm or less, and even more preferably 150 μm or less, as a sphere-equivalent diameter. The maximum particle diameter of the metal phase in the matte 5 is preferably 1 mm or less, more preferably 170 μm or less, and even more preferably 150 μm or less.

[0025] The metal phase suspended in the matte 5 is discharged together with the matte 5 when it is discharged from the flash smelting furnace 100, and is therefore charged into the copper smelting furnace for processing in the next process. In this case, the matte 5 with the metal phase suspended therein is charged directly into the next copper smelting furnace. In the next copper smelting furnace, the concentrations of Cu, Fe, and S in the total molten metal, which is the sum of the Cu component in the matte 5 and the Cu in the metal phase, are used as a standard, and the operating conditions, including the blast conditions, are adjusted for processing. The next copper smelting furnace here may be a smelting furnace that produces blister copper from matte, such as a converter.

[0026] When the amount of metallic Cu contained in the smelting raw material is equal to or less than the solubility in matte 5, the metallic Cu dissolves in matte 5 without being pulverized, and the generation of the metallic phase is suppressed. In this case, no operational problems due to the generation of the metallic phase occur. Therefore, when the amount of metallic Cu contained in the smelting raw material is equal to or less than the solubility in matte 5, the pulverization process of the recycled raw material may be omitted.

[0027] Even if the average particle size of the metal phase in the matte 5 is reduced, if the amount of metallic Cu in the smelting raw material is too large, metallic Cu particles having small particle sizes may come into contact with each other and become coarse, which may result in the metallic Cu not being sufficiently suspended in the matte 5. Therefore, it is preferable to set an upper limit on the supply amount of metallic Cu. In this embodiment, when the weight of the matte 5 is taken as 100, the supply weight of metallic Cu that exceeds the solubility of metallic Cu in the matte 5 is preferably set to 5 or less, more preferably 4 or less, and even more preferably 3 or less.

[0028] Whether or not the supply amount of metallic Cu exceeds the solubility in matte 5 can be determined by sampling the smelting raw material and measuring the composition ratio. Alternatively, it may be determined that the supply amount of metallic Cu exceeds the solubility in matte 5 when a metal phase is confirmed by sampling the matte 5 of the reaction shaft 1.

[0029] In the above embodiment, a flash smelting furnace has been described as an example of a smelting furnace, but the present invention is not limited thereto. As long as the smelting furnace produces matte mainly composed of copper sulfide from a smelting raw material containing copper concentrate and a raw material containing metallic Cu, the smelting raw material can be charged into the smelting furnace under conditions in which a metal phase of metallic Cu is produced in the matte produced from the copper concentrate and the smelting raw material containing metallic Cu, and the metallic Cu can be melted to obtain matte in a state in which the metal phase produced is suspended. EXAMPLES

[0030] (Example) The matte was filled in the quartz Tammann tube 51 in advance, and Cu powder with a purity of 99.6% or more was mixed therein, and the quartz Tammann tube 51 was fixed to the alumina crucible. The average particle size of the Cu powder was 41 μm as the volume average diameter. The amount of Cu powder added was the amount that exceeded the solubility in the molten matte on the phase diagram. Specifically, the weight of the Cu powder was 5 when the weight of the matte was 100. Next, the alumina crucible was set in an electric furnace, and the temperature was raised to a molten metal temperature of 1250° C. The retention time in the electric furnace was changed in the range of 2 hours to 10 hours, and multiple experiments were performed. At this time, as illustrated in FIG. 4, the solution in the quartz Tammann tube 51 had a two-liquid phase coexistence composition of matte-Cu, in which a Cu phase 53 was suspended in matte 52. Next, in order to prevent Cu precipitation during the cooling process, the alumina crucible was removed from the electric furnace and immersed together with the quartz Tammann tube 51 in ice water for rapid cooling.

[0031] The compositions of the matte and Cu powder used in the test are shown in Table 1. [Table 1]

[0032] (analysis) The presence or absence of residual Cu phase (metallic Cu) in the sample after quenching was confirmed for the sample of the embodiment. The residual Cu phase was evaluated by CT scanning and microscopic observation of the sample cross section (observation magnification was 100 to 2000 times). The sample cross section was observed by polishing the sample with a diameter of 17.0 mm in 0.5 mm increments, and the observation was repeated to confirm the presence or absence of Cu phase. The evaluation accuracy was improved by using CT in combination.

[0033] In the sample of the embodiment, it was confirmed that metallic Cu was in a phase-separated state in the matte. In other words, it was confirmed that metallic Cu did not settle to the bottom of the furnace and maintained dispersion stability. The largest Cu particle dispersed in the matte was observed to be approximately circular, with a diameter of about 500 μm.

[0034] From these results, it is considered that when metallic Cu is additionally supplied at 7.3 t / h under the operating conditions where matte is produced at 70 t / h in the flash smelting furnace, 5.4 t / h of metallic Cu will be in a phase-separated state in the matte. It was clarified that the metallic Cu in the phase-separated state does not settle to the bottom of the furnace and maintains dispersion stability.

[0035] The above-described embodiment is a preferred example of the present invention, but the present invention is not limited to this embodiment and can be modified in various ways without departing from the scope of the present invention. [Explanation of symbols]

[0036] 1 Reaction shaft 2 Setra 3. Uptake 4 Concentrate burner 5. Matt 6. Slug 10 Input section 11 1st aisle 12 2nd aisle 13 3rd aisle 14 4th aisle 16. Lance 51 Quartz Tammann tube 52 Matt 53 Metallic Cu 100 Flash furnace

Claims

1. Under conditions in which a metallic phase of metallic Cu is formed in the matte produced from copper concentrate and smelting raw materials containing metallic Cu in a smelting furnace, A method for copper smelting, characterized by introducing the smelting raw materials into a smelting furnace and obtaining a mat in which the metallic phase, produced by the melting of the metallic Cu, is dispersed.

2. The copper smelting operation method according to claim 1, characterized in that the maximum particle size of metallic Cu contained in the smelting raw material is 1 mm or less in terms of the diameter equivalent to a sphere.

3. The copper smelting method according to claim 1, characterized in that, when the amount of metallic Cu in the mat exceeds the solubility of the metallic Cu contained in the smelting raw material, the metallic Cu is subjected to a fine grinding treatment before the smelting raw material is introduced into the smelting furnace, thereby reducing the maximum particle size of the metallic Cu to 1 mm or less in terms of the diameter of a sphere.

4. The copper smelting method according to claim 1, characterized in that, when the metallic phase of the metallic Cu is confirmed in the mat by sampling the mat, the metallic Cu is subjected to a fine grinding treatment before the smelting raw material is introduced into the smelting furnace, and the maximum particle size of the metallic Cu at that time is 1 mm or less in terms of the diameter equivalent to a sphere.

5. The copper smelting operation method according to claim 1, wherein the smelting raw material is introduced into a smelting furnace and the maximum particle size of the metal phase produced by the melting of the metallic Cu is controlled to be 1 mm or less.

6. The copper smelting operation method according to claim 1, characterized in that, when the weight of the mat is 100, the amount supplied of metallic Cu is such that the amount exceeding the solubility of metallic Cu in the mat is 5 or less.

7. The copper smelting method according to claim 1, wherein after obtaining the mat in which the metal phase produced by the melting of the metallic Cu is suspended, the mat in which the metal phase is suspended is charged into the next copper smelting furnace for processing.

8. The method for operating a copper smelting furnace according to claim 7, comprising analyzing the composition of the mat and the amount of copper in the metal phase suspended in the mat to determine the operating conditions of the copper smelting furnace.

Images