Method for operating copper smelting furnace

Abstract

To provide a method capable of appropriately adjusting a treatment amount when treating a recycled raw material in a copper smelting furnace.SOLUTION: In a method for operating a copper smelting furnace, when a copper smelting raw material containing copper concentrate and a recycled raw material containing metallic Cu is melted and treated in the copper smelting furnace, a transfer amount of Fe contained in the copper smelting raw material to slag is estimated, and a treatment amount of the recycled raw material is adjusted according to the transfer amount.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for operating a copper smelting furnace. [Background technology]

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

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-363659 [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 proportion of recycled materials in smelting raw materials has been increasing. In copper smelting furnaces, a problem that arises when increasing the amount of recycled materials processed is when the solubility of the metallic Cu (copper or copper alloy) contained in the recycled materials in the matte exceeds the limit, resulting in the coexistence of metallic Cu phases in the Cu matte. In this situation, metal accumulates at the bottom of the copper smelting furnace, causing operational problems and must be avoided.

[0005] The recycled materials processed in copper smelting furnaces contain a large amount of metallic Cu or copper alloys, but the behavior of Fe (iron) in the matte when they are dissolved in the matte is unknown. Furthermore, when the recycled materials contain metallic Fe or Fe alloys, the behavior of the Fe contained in the recycled materials after melting in the furnace is unknown. Therefore, it is difficult to suppress the coexistence of metallic Cu phases in the matte.

[0006] The present invention has been made in view of the above-mentioned problems, and aims to provide a method capable of suppressing the coexistence of metallic Cu phase in matte when treating recycled raw materials in a copper smelting furnace. [Means for solving the problem]

[0007] The copper smelting operation method according to the present invention involves melting and processing a copper smelting raw material containing copper concentrate and a recycled raw material containing metallic Cu in a copper smelting furnace, estimating the amount of Fe contained in the copper smelting raw material that has migrated to slag, and adjusting the processing amount of the recycled raw material in accordance with the estimated amount of Fe.

[0008] In the copper smelting operation method, the copper smelting furnace may be a copper smelting furnace, and when adjusting the throughput of the recycled material, the copper smelting furnace may calculate an estimated matte composition assuming that the copper smelting material excluding the recycled material is melted together with the copper concentrate to reach equilibrium, thereby determining a first Fe content in the estimated matte composition, determining a second Fe content in the recycled material, estimating a proportion of a third Fe content, which is the sum of the first Fe content and the second Fe content, that transfers to slag, and adjusting the throughput of the recycled material according to the proportion.If the throughput of the metallic Cu contained in the recycled material exceeds the Cu solubility in the matte when equilibrium is reached in the copper smelting furnace, the throughput of the recycled material may be adjusted based on the Fe content remaining after subtracting the Fe content transferred to the slag from the third Fe content, and the contents of Cu and S in the matte (including metallic Cu phases present in the matte), so as not to exceed the Cu solubility in the matte.

[0009] Another copper smelting operation method according to the present invention includes, when a copper smelting raw material containing copper concentrate and a recycled raw material containing metallic Cu is melted and processed in a copper smelting furnace, estimating the amount of Fe contained in the copper smelting raw material that migrates to slag, and adjusting the amount of a S source added to the copper smelting furnace in accordance with the estimated amount of Fe.

[0010] In the copper smelting operation method, the copper smelting furnace may be a copper smelting furnace, and when adjusting the throughput of the recycled raw material, the copper smelting furnace may calculate an estimated matte composition assuming that the copper smelting raw materials excluding the recycled raw material are melted together with the copper concentrate to reach equilibrium, thereby determining a first Fe content in the estimated matte composition, determining a second Fe content in the recycled raw material, estimating a proportion of a third Fe content, which is the sum of the first Fe content and the second Fe content, that transfers to slag, and adjusting the amount of a sulfur source added to the copper smelting furnace based on the proportion.When the throughput of the metallic Cu contained in the recycled raw material exceeds the Cu solubility in the matte when equilibrium is reached in the copper smelting furnace, the amount of a sulfur source added to the copper smelting furnace may be adjusted based on the Fe content obtained by subtracting the amount of Fe transferred to the slag from the third Fe content and the contents of Cu and S in the matte (including a metallic Cu phase present in the matte) so as not to exceed the Cu solubility in the matte. [Effects of the Invention]

[0011] According to the present invention, when recycled raw materials are treated in a copper smelting furnace, the coexistence of a metallic Cu phase in the matte can be suppressed. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a diagram illustrating a schematic configuration of a flash furnace for copper smelting according to an embodiment. [Figure 2] FIG. 2 is a diagram illustrating the details of a concentrate burner 4. [Figure 3] FIG. 1 is a phase diagram showing the solubility of Cu in the matte. [Figure 4] FIG. 1 is an enlarged view of a portion of the phase diagram. DETAILED DESCRIPTION OF THE INVENTION

[0013] (First embodiment) FIG. 1 is a diagram schematically illustrating the configuration of a flash smelting furnace 100, which is a type of copper smelting furnace. 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 copper concentrate, solvent, recycled raw materials, etc. (hereinafter, these solid raw materials will be referred to as copper smelting raw materials) into the reaction shaft 1, as well as a main reaction blast gas, an auxiliary reaction gas, and a dispersion gas (which also contributes to the reaction). For example, the main reaction blast gas and the auxiliary reaction gas are oxygen-enriched air, and the dispersion gas is air or oxygen-enriched air.

[0014] FIG. 2 is a diagram illustrating the details of the concentrate burner 4, and is an explanatory diagram showing the input section 10 through which the copper smelting raw material, the main reaction gas, the auxiliary reaction gas, and the dispersion gas are input to the reaction shaft 1.

[0015] The input section 10 of the concentrate burner 4 is equipped with a lance 16, which is provided with a first passage 11 through which a dispersion gas passes and a fourth passage 14 through which a reaction auxiliary gas passes. 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 also has a second passage 12 as a raw material flow path provided outside the lance 16, more specifically, on the outer periphery of the lance 16. The input section 10 further has a third passage 13 provided outside the second passage 12, more specifically, on the outer periphery of the second passage 12, through which a reaction main blast gas passes. The third passage 13 is formed by a tubular portion provided 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.

[0016] The first passage 11 supplies dispersion gas into the reaction shaft 1. The second passage 12 supplies concentrate into the reaction shaft 1. The third passage 13 supplies main reaction gas from the air chamber 17 into the reaction shaft 1. The fourth passage 14 supplies auxiliary reaction gas into the reaction shaft 1.

[0017] 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 part 151 of the side surface 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 arranged so that the gas is discharged in the normal direction to the bottom circle of the dispersion cone 15.

[0018] When copper 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 (slag solution) 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. Silicate ore is used as the solvent. CuFeS2+SiO2+O2→Cu2S·FeS+FeO·SiO2+SO2+ Reaction heat (1)

[0019] The recycled raw material may contain metallic components. If the amount of metallic components is small, the metallic components are sulfidized to form matte 5 during the process of falling from the concentrate burner 4. Therefore, no metal phase is generated.

[0020] However, as the amount of recycled raw materials processed increases, the proportion of metallic Cu (copper or copper alloy) in copper smelting raw materials tends to increase. In recent years, the proportion of metallic Cu in copper smelting raw materials has sometimes been 6.0 mass% or more and 28.0 mass% or less, or 9.0 mass% or more and 18.0 mass% or less, or 9.0 mass% or more and 12.0 mass% or less.

[0021] As the proportion of metallic Cu in the smelting raw material increases, metallic Cu is not completely sulfidized during the process of falling from the concentrate burner 4 and falls as metallic Cu. While 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 formed. The phase diagram in Figure 3 is based on "Report of the Selection and Research Institute, Takazai and Yazawa, 1983."

[0022] Incidentally, recycled raw materials contain a large amount of metallic Fe (iron and iron alloys) in addition to metallic Cu. It is thought that metallic Fe also consumes sulfur components and is sulfided, but it was unclear how much of it is transferred to matte 5. Therefore, it is conceivable to adjust the amount of recycled raw materials contained in the copper smelting raw materials so that the entire amount of metallic Cu and metallic Fe is sulfided by consuming the sulfur components contained in the copper smelting raw materials and transferred to matte 5.

[0023] Recycled materials processed in copper smelting furnaces contain a large amount of metallic Cu, but the behavior of Fe (iron) in the matte when metallic Cu dissolves in the matte is unknown. Furthermore, when metallic Fe or Fe alloys are included in recycled materials, the behavior of the metallic Fe contained in the recycled materials after melting in the furnace is unknown. For example, the maximum recycled material throughput that does not result in the formation of metallic Cu phase in the matte is unknown. Therefore, it has been difficult to maximize the recycled material throughput while suppressing the coexistence of metallic Cu phase.

[0024] Through intensive research by the present inventors, it has been found that a portion of the Fe contained in the recycled raw material does not transfer to matte 5 but to slag 6. Furthermore, it has been found that a portion of the Fe in matte 5 also transfers to slag 6. Therefore, it is not necessary to assume that all of the Cu and Fe are sulfidized by consuming the sulfur component contained in the copper smelting raw material, and it is therefore thought that it is possible to increase the processing amount of the recycled raw material while suppressing the generation of a metal phase in matte 5.

[0025] Therefore, in this embodiment, the amount of Fe contained in the copper smelting raw material that migrates to the slag 6 is estimated, and the processing amount of the recycled material is adjusted according to the estimated amount. In this way, when the recycled material is processed in a copper smelting furnace, the coexistence of the metallic Cu phase in the matte 5 can be suppressed. For example, the processing amount of the recycled material can be maximized while suppressing the coexistence of the metallic Cu phase in the matte 5.

[0026] For example, the first Fe content in the estimated matte composition is calculated by assuming that copper smelting raw materials, excluding recycled materials, are melted together with copper concentrate and reach equilibrium. Figure 4 shows the Fe content ratio corresponding to the first Fe content. Next, the second Fe content in the recycled material is calculated. The third Fe content is then calculated by summing the first Fe content and the second Fe content. Figure 4 shows the Fe content ratio corresponding to the third Fe content. The proportion of this third Fe content that transfers to the slag can be estimated, and the amount of recycled material processed can be adjusted accordingly. For example, as described below, the proportion of the third Fe content that transfers to the slag can be estimated by conducting tests under simulated operating conditions using matte from an actual operation, slag from an actual operation, and a sample with a composition similar to the Cu, Fe, and S of the expected recycled material. Note that the term "content" here refers to the amount processed per unit time in the case of continuous operation, and the amount processed per batch in the case of batch operation.

[0027] For example, if the amount of metallic Cu contained in the recycled material exceeds the Cu solubility in matte 5 when the equilibrium state is reached in the flash smelting furnace 100, the Fe content (minus the amount of Fe transferred to slag 6) of the third Fe content and the Cu and S contents in matte 5 (including the metallic Cu phase present in the matte) are plotted based on the Fe content (minus the amount of Fe transferred to slag 6) and the Cu and S contents in matte 5 (including the metallic Cu phase present in the matte). Specifically, the amount of recycled material processed is preferably adjusted so that the amount of recycled material is in the single-phase matte region, so as not to exceed the Cu solubility in matte 5. Figure 4 shows the "Fe content ratio (minus the amount of Fe transferred to slag) of the third Fe content." This point is the boundary between the two-liquid-phase region and the homogeneous matte region, and corresponds to the point where the recycled material processing volume is maximized while still remaining in the homogeneous matte region. Therefore, by comparing this point with the "Fe content ratio (minus the amount of Fe transferred to slag)," it is possible to determine how much the recycled material processing volume can be increased while maintaining the homogeneous matte region.

[0028] It is considered that the amount of Fe contained in the copper smelting raw material that migrates to slag 6 varies depending on the quantitative ratio of slag 6 to matte 5. Therefore, the amount of recycled material contained in the copper smelting raw material may be adjusted depending on the quantitative ratio of slag 6 to matte 5. Specifically, as the proportion of slag 6 in the quantitative ratio of slag 6 to matte 5 increases, the amount of recycled material contained in the copper smelting raw material may be increased, thereby increasing the processing amount of recycled material. This makes it possible to appropriately adjust the processing amount of recycled material.

[0029] Furthermore, it is considered that the amount of Fe contained in the copper smelting raw material that migrates to the slag 6 varies depending on the oxygen potential in the flash smelting furnace 100. Therefore, the amount of recycled material contained in the copper smelting raw material may be adjusted depending on the oxygen potential in the flash smelting furnace 100. Specifically, the higher the oxygen potential in the flash smelting furnace 100, the greater the amount of recycled material contained in the copper smelting raw material, thereby increasing the processing amount of recycled material. This makes it possible to appropriately adjust the processing amount of recycled material.

[0030] (Second embodiment) In the second embodiment, differences from the first embodiment will be described. In the second embodiment, the amount of Fe contained in the copper smelting raw material that migrates to the slag 6 is estimated, and the amount of S source added to the flash smelting furnace 100 is adjusted according to this amount so that the processing amount of metallic Cu contained in the recycled material does not exceed the Cu solubility in matte 5. In this way, the coexistence of metallic Cu phases can be suppressed when the recycled material is processed in the copper smelting furnace. The S source is not particularly limited as long as it contains sulfur, and for example, S-containing waste slag generated in the ore dressing process of non-ferrous metal raw materials can be used.

[0031] For example, it is possible to estimate the proportion of the third Fe content explained in FIG. 4 that transfers to the slag, and adjust the amount of the S source added to the flash smelting furnace 100 according to this proportion.

[0032] For example, when the amount of metallic Cu contained in the recycled raw material exceeds the Cu solubility in matte 5 when the equilibrium state is reached in the flash smelting furnace 100, it is preferable to adjust the amount of the S source added to the flash smelting furnace 100 so that the Cu solubility in matte 5 is not exceeded, based on the Fe content ratio obtained by subtracting the amount of Fe transferred to the slag 6 from the third Fe content ratio and the Cu and S content ratios in matte 5 (including the metallic Cu phase present in the matte). Specifically, the content ratios of each element are plotted on a Cu-Fe-S ternary phase diagram, and the amount of the S source added to the flash smelting furnace 100 is adjusted so that the matte 5 is in the single-phase region of matte.

[0033] For example, in actual operation, it is difficult to make the amount of metallic Cu contained in the recycled raw material uniform, and since it fluctuates, it is preferable to add a S source as a preventative measure in case the solubility is momentarily exceeded.

[0034] In the above-described embodiments, a flash smelting furnace has been described as an example of a copper smelting furnace, but the copper smelting operation method according to the above-described embodiments can also be applied to copper smelting furnaces other than flash smelting furnaces. In particular, the copper smelting furnace operation method according to the above-described embodiments is preferably applied to a copper smelting furnace.

[0035] Experiments were carried out in which metallic Cu and metallic Fe were added to the slag-matte two-phase coexistence state.

[0036] The crucible was filled with the metal sample, matte, and slag in that order. The metal sample was prepared by mixing weighed amounts of metallic Cu and weighed amounts of metallic Fe in a predetermined ratio. The crucible was heated and maintained at a high temperature to melt the sample in the crucible.

[0037] The crucible was cooled, and the presence or absence of metallic components in the matte was confirmed. Specifically, the presence or absence of metallic components in the matte was evaluated by taking out the cooled matte sample and observing its cross section from the edge, using the presence of metallic components of a certain size or larger and including impurities as an indicator. The composition of the matte was analyzed using inductively coupled plasma (ICP). The distribution of elements was evaluated by converting the amount of elements present by weight from the composition and weight of each phase and comparing it with a sample without added metal samples.

[0038] Table 1 shows the mass percentage of each component in the matte before melting, the metal sample before melting, and the matte after melting. Table 2 shows the weight conversion results for each component. In Tables 1 and 2, the Fe content ratio in the matte before melting corresponds to the first Fe content ratio in Figure 4. The Fe content ratio in the metal sample before melting corresponds to the second Fe content ratio. The third Fe content ratio corresponds to the subtotal in Table 2. The Fe content in the matte after melting corresponds to the Fe content obtained by subtracting the amount of Fe that migrated to the slag from the third Fe content. [Table 1] [Table 2]

[0039] After this experiment, no metallic components were found in the matte, confirming a uniform matte composition. The critical amount of metal sample (the minimum amount at which metallic components do not coexist in the matte) estimated from the phase diagram, assuming that all metal elements capable of sulfidation dissolve in the matte, was 4.1 mass% of the matte weight before the metal sample was added. However, in this experiment, 8.6 mass% (= 0.69 g ÷ 8.13 g) of the metal sample dissolved in the matte, which means that a larger amount of metal sample dissolved than would be expected if all metal elements capable of sulfidation were dissolved in the matte. This result indicates that a portion of the metal sample was transferred to the slag.

[0040] Next, assuming that all of the added metal samples dissolved in the matte, the amounts of Cu and S present in the matte remained almost unchanged. On the other hand, assuming that all of the added metal samples dissolved in the matte, the amount of Fe present in the matte decreased by approximately 30%. This is thought to be because the composition of the matte changed as the metal samples reacted, which changed the distribution ratio between the slag and matte, resulting in the distribution of Fe from the matte to the slag.

[0041] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and variations are possible within the scope of the gist of the present invention as described in the claims.

[0042] According to one embodiment of the present invention, by contributing to technological innovation in copper smelting, it is possible to contribute to Goal 9 of the United Nations' Sustainable Development Goals (SDGs), "Build resilient infrastructure, promote inclusive and sustainable industrialization, and foster innovation." Furthermore, according to one embodiment of the present invention, by promoting the use of recycled materials, it is possible to contribute to Goal 12 of the United Nations' Sustainable Development Goals (SDGs), "Ensure sustainable consumption and production patterns." [Explanation of symbols]

[0043] 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 100 Flash furnace

Claims

1. A method for operating a copper smelting furnace, comprising: estimating an amount of Fe contained in the copper smelting raw material that migrates to slag; and adjusting a processing amount of the recycled material in accordance with the amount of Fe that migrates; and, when melting and processing a copper smelting raw material containing copper concentrate and a recycled material containing metallic Cu in the copper smelting furnace, estimating an amount of Fe contained in the copper smelting raw material that migrates to slag; and adjusting a processing amount of the recycled material in accordance with the amount of Fe that migrates.

2. The copper smelting furnace is a copper smelting furnace, When adjusting the processing amount of the recycled raw material, a first Fe content in the estimated matte composition is calculated by assuming that raw materials excluding the recycled raw material from the copper smelting raw materials are melted together with the copper concentrate and reach an equilibrium state; A second Fe content contained in the recycled raw material is determined; Estimating a ratio of a third Fe content, which is the sum of the first Fe content and the second Fe content, that transfers to slag; The method for operating a copper smelting furnace according to claim 1 , further comprising adjusting the amount of the recycled raw material to be processed in accordance with the ratio.

3. 3. The method for operating a copper smelting furnace according to claim 2, wherein, when a processing amount of the metallic Cu contained in the recycled raw materials exceeds the Cu solubility in the matte when an equilibrium state is reached in the copper smelting furnace, the processing amount of the recycled raw materials is adjusted based on the Fe content obtained by subtracting the amount of Fe transferred to the slag from the third Fe content and the Cu and S contents in the matte (including a metallic Cu phase present in the matte) so as not to exceed the Cu solubility in the matte.

4. A method for operating a copper smelting furnace, comprising: estimating an amount of Fe contained in the copper smelting raw material that migrates to slag; and adjusting an amount of a S source to be added to the copper smelting furnace in accordance with the amount of Fe that migrates; and, when melting and processing a copper smelting raw material containing copper concentrate and a recycled material containing metallic Cu in the copper smelting furnace, said method comprising estimating an amount of Fe contained in the copper smelting raw material that migrates to slag; and adjusting an amount of a S source to be added to the copper smelting furnace in accordance with the amount of Fe that migrates.

5. The copper smelting furnace is a copper smelting furnace, When adjusting the processing amount of the recycled raw material, a first Fe content in the estimated matte composition is calculated by assuming that raw materials excluding the recycled raw material from the copper smelting raw materials are melted together with the copper concentrate and reach an equilibrium state; A second Fe content contained in the recycled raw material is determined; Estimating a ratio of a third Fe content, which is the sum of the first Fe content and the second Fe content, that transfers to slag; The method for operating a copper smelting furnace according to claim 4, further comprising adjusting the amount of the S source added to the copper smelting furnace in accordance with the ratio.

6. 6. The method for operating a copper smelting furnace according to claim 5, wherein, when a processing amount of the metallic Cu contained in the recycled raw material exceeds the Cu solubility in the matte when an equilibrium state is reached in the copper smelting furnace, an amount of a S source added to the copper smelting furnace is adjusted based on the Fe content obtained by subtracting the amount of Fe transferred to the slag from the third Fe content and the Cu and S contents in the matte (including a metallic Cu phase present in the matte) so that the Cu solubility in the matte is not exceeded.

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