Flash furnace operation method, and concentrate burner

Abstract

In this flash furnace operation method, a bulk material containing sulfur and having an average particle diameter of 5 mm or more is introduced into a flash furnace.　

Description

Flash smelting furnace operation method and concentrate burner

[0001] The present invention relates to a method for operating a flash smelting furnace and a concentrate burner.

[0002] In a copper smelting furnace, reactant gas is introduced into the furnace along with raw materials such as copper concentrate and solvent from a concentrate burner. The raw materials are oxidized by the reactant gas, producing matte and slag.

[0003] JP 2007-092133 A JP 51-047410 A

[0004] In recent years, the proportion of recycled raw materials as smelting raw materials has been increasing. However, recycled raw materials contain metallic elements such as Cu, Fe, Sn, Zn, Pb, and Al present as pure metals or alloys, largely without being oxidized or sulfurized. In the present invention, these elements are defined as metallic components. Therefore, when increasing the amount of recycled raw material processed in a copper smelting furnace, a sulfur source is required to convert the metallic components into matte. When this sulfur source is introduced into a flash smelting furnace, a measure is required to allow the sulfur source to react with the metallic components in the matte phase.

[0005] The present invention has been made in view of the above problems, and has as its object to provide a method for operating a flash smelting furnace and a concentrate burner that can react a sulfur source with a metallic component in the matte phase.

[0006] In a method for operating a flash smelting furnace according to the present invention, lumps containing sulfur and having an average particle size of 5 mm or more are charged into the flash smelting furnace. The lumps may be charged through a flow path of a concentrate burner provided on the ceiling of the flash smelting furnace. The lumps may be granulated material obtained by mixing a sulfur-containing material and a recycled raw material. The concentrate burner may include a vertically extending middle lance in the center, the middle lance having at least two paths, and a gas for oxidizing the smelting raw material may be flowed through one of the two paths, and the lumps may be charged into the other of the two paths. The middle lance may include a double pipe constituting the two paths. A gas for oxidizing the smelting raw material may be flowed through the outer path of the double pipe, and the lumps may be charged into the inner path of the double pipe. Gas may be injected into the flash smelting furnace through the path for charging the lumps to prevent gas in the flash smelting furnace from flowing back from the concentrate burner. The gas flowing through the path for introducing the lumps may be an inert gas, air, or oxygen-enriched air.

[0007] The concentrate burner according to the present invention is a concentrate burner provided on the ceiling of a flash smelting furnace, and includes a middle lance extending vertically at its center, the middle lance having a plurality of passages. The middle lance may include a double pipe extending vertically. At least one of the plurality of passages may be provided with a ceramic lining.

[0008] According to the present invention, it is possible to provide a method for operating a flash smelting furnace and a concentrate burner that can react a sulfur source with metallic Cu in the matte phase.

[0009] It is a diagram showing the schematic configuration of a flash smelting furnace for copper smelting according to an embodiment. It is a phase diagram showing the solubility of Cu in matte. It is a diagram showing an example of a concentrate burner. It is a diagram showing an example of a concentrate burner. It is a diagram showing an example of a briquetting machine. It is a diagram for explaining an example.

[0010] (Embodiment) Fig. 1 is a diagram schematically illustrating the configuration of a flash smelting furnace 100. As illustrated in Fig. 1, the flash smelting furnace 100 includes a reaction shaft 1 in which copper concentrate and a reaction gas are mixed and reacted, 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, along with copper concentrate, solvent, recycled raw materials, etc. (hereinafter, these solid raw materials will be 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.

[0011] When the smelting raw material is 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 as shown in FIG. 1, it separates into matte 5 and slag 6 (slag solution) at the bottom of the reaction shaft 1. In the following reaction formula (1), Cu ２ S.FeS corresponds to the main component of Mat 5, and FeO.SiO ２ The main component of slag 6 is silica ore. CuFeS ２ +SiO ２ +O ２ → Cu ２ S・FeS+FeO・SiO ２ +SO ２ + Reaction heat (1)

[0012] The recycled raw material may contain metallic components. If the amount of metallic components is small, the metallic components are sulfided to form matte 5 during the process of dropping from the concentrate burner 4. Therefore, no metal phase is generated.

[0013] However, as the amount of recycled raw materials processed increases, the proportion of metallic components (e.g., metallic Cu) in the smelting raw material tends to increase. In recent years, the proportion of metallic Cu in the Cu component of the smelting raw material may be 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. The following description will focus on metallic Cu contained in the recycled raw material, but the same can be applied to other metallic components.

[0014] 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. Although metallic Cu dissolves in matte 5 to a certain extent, there is a solubility limit. Figure 2 is a phase diagram showing the solubility of Cu in matte at 1250°C. In Figure 2, "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 2 is based on "Report of the Selection and Research Project, Takazai and Yazawa, 1983."

[0015] Therefore, it is conceivable to introduce a powdered sulfur-containing material into the reaction shaft 1 to sulfurize the metallic Cu contained in the matte 5 and turn it into matte. However, there is a risk that the powdered sulfur-containing material will be oxidized when introduced into the reaction shaft 1. In addition, there is a risk that the powdered sulfur-containing material will be captured by the slag 6 floating on the matte 5 and will not reach the matte 5. Therefore, it is conceivable to supply the sulfur-containing material by injection using an inert gas as a carrier. However, this method is difficult to operate and has many issues.

[0016] Therefore, in this embodiment, sulfur-containing aggregates containing sulfur and having an average particle size (average equivalent spherical diameter) of 5 mm or more are supplied from the concentrate burner 4 into the reaction shaft 1. The equivalent spherical diameter refers to the diameter of each aggregate measured as a sphere. The volume of the aggregate is measured by submerging the aggregate in pure water or ethanol in a measuring cylinder and observing the change in the liquid level. The use of sulfur-containing aggregates reduces the specific surface area of ​​sulfur in contact with the atmosphere in the reaction shaft 1, thereby suppressing sulfur oxidation. Furthermore, the use of aggregates makes them more likely to sink in the slag 6 and reach the metallic Cu in the matte 5 than powdered sulfur-containing aggregates. This facilitates sulfurization of the metallic Cu contained in the matte 5 to form matte.

[0017] Furthermore, directly below the reaction shaft 1, molten droplets generated in the reaction shaft 1 rain down, forming a mixed layer where matte 5 and slag 6 are mixed. Therefore, a relatively thin layer of slag 6 is formed directly below the reaction shaft 1. By supplying sulfur-containing agglomerates from the concentrate burner 4 directly below the reaction shaft 1, the granulated material can easily penetrate the slag 6 and reach the matte 5. As described above, when the recycled raw material processing in the copper smelting furnace is increased, the sulfur source can be reacted with metallic Cu in the matte 5.

[0018] The larger the sulfur-containing agglomerates, the more easily they can reach the mat 5, so the average particle size of the sulfur-containing agglomerates is preferably 10 mm or more, and more preferably 20 mm or more.

[0019] The sulfur-containing materials contained in the sulfur-containing mass include FeS minerals (pyrrhotite), FeS ２ Mineral (pyrite), CuFeS ２ Minerals (chalcopyrite), FeS and FeS ２ Minerals containing FeS, copper concentrate containing sulfur, etc. can be used. ２ When comparing minerals, FeS is said to contain more sulfur, which is necessary for matte formation. ２It is preferable to use minerals. Alternatively, the sulfur-containing material may be sulfur-containing tailings generated in the ore-dressing process of non-ferrous metal raw materials. For example, tailings generated in the flotation process are an example of sulfur-containing tailings. For example, the sulfur content of the powdered sulfur-containing material is about 20 mass% or more and 55 mass% or less.

[0020] The configuration of the concentrate burner 4 is not particularly limited as long as it can supply sulfur-containing agglomerates from the concentrate burner 4 into the reaction shaft 1, but an example of the configuration of the concentrate burner 4 will be described below.

[0021] 3 is a diagram illustrating the details of the concentrate burner 4. As illustrated in FIG. 3, the concentrate burner 4 has a dispersion cone 10 in the center extending vertically from the outside to the inside of the reaction shaft 1 of FIG. 1. An inner cylinder 20 is provided outside the dispersion cone 10, covering the dispersion cone 10 while being spaced apart from it. An outer cylinder 30 is provided outside the inner cylinder 20, covering the inner cylinder 20 while being spaced apart from it. The upper part of the outer cylinder 30 is funnel-shaped and functions as an air chamber. The dispersion cone 10, the inner cylinder 20, and the outer cylinder 30 are arranged approximately concentrically. The space between the dispersion cone 10 and the inner cylinder 20 functions as a raw material passage 21 through which the smelting raw material passes. The space between the inner cylinder 20 and the outer cylinder 30 functions as a reaction main blast gas passage 31 through which the reaction main blast gas passes.

[0022] The dispersion cone 10 includes an inner cylinder 11, a middle cylinder 12 that covers the inner cylinder 11 while being spaced apart from the inner cylinder 11, and an outer cylinder 13 that covers the middle cylinder 12 while being spaced apart from the middle cylinder 12. The inner cylinder 11, the middle cylinder 12, and the outer cylinder 13 are arranged approximately concentrically. Therefore, the inner cylinder 11 and the middle cylinder 12 form a double pipe. This double pipe is a middle lance. The middle lance (the inner cylinder 11 and the middle cylinder 12) and the outer cylinder 13 form a triple pipe. The space inside the inner cylinder 11 functions as a lump passage 14 through which the sulfur-containing lump passes. The space between the inner cylinder 11 and the middle cylinder 12 functions as a reaction auxiliary gas passage 15 through which the reaction auxiliary gas passes. The space between the middle cylinder 12 and the outer cylinder 13 functions as a dispersion gas passage 16 through which the dispersion gas passes. In the present invention, the middle lance is defined as a portion that exists inside the dispersion cone and that constitutes two or more paths other than the dispersion gas path, the path through which the sulfur-containing aggregates pass and the path through which the reaction assisting gas passes. Also, in the present invention, the dispersion cone is defined as a portion that exists in the center of the concentrate burner, that is a cylinder with a truncated cone-shaped tip, and that has the dispersion gas path and the middle lance inside.

[0023] The reaction main blowing gas passage 31 supplies the reaction gas into the reaction shaft 1. The raw material passage 21 supplies the smelting raw material into the reaction shaft 1. The dispersion gas passage 16 supplies the dispersion gas into the reaction shaft 1. The reaction auxiliary gas passage 15 supplies the reaction auxiliary gas into the reaction shaft 1. The lump passage 14 supplies the granulated material into the reaction shaft 1.

[0024] The tip (lower end) of the dispersion cone 10 is frustum-shaped. A plurality of supply holes 18 are formed in the lower part of the side surface of the dispersion cone 10 to discharge the dispersion gas that has passed through the dispersion gas passage 16 into the reaction shaft 1. The supply holes 18 are arranged so that the gas is discharged in the normal direction to the bottom circle of the dispersion cone 17.

[0025] In this configuration, the sulfur-containing lumps pass through the inner cylinder 11 in the middle lance of the concentrate burner 4 and fall freely to just below the reaction shaft 1. In particular, since the lump passage 14 is provided in the center of the middle lance, the lump is less susceptible to the influence of the main reaction blast gas, the auxiliary reaction gas, and the dispersion gas, and is more likely to fall freely to just below the reaction shaft 1.

[0026] An inert atmosphere is preferably provided inside the lump passage 14. This is because oxidation of the sulfur source contained in the lump is suppressed and the influence on the amount of oxygen supply that controls the oxidation reaction of the copper concentrate in the reaction shaft 1 is suppressed. In addition, the injection of inert gas also contributes to preventing backflow of high-temperature gas when the pressure inside the flash smelting furnace 100 becomes higher than atmospheric pressure. For example, the inert atmosphere inside the lump passage 14 is preferably a nitrogen atmosphere. However, since the concentrate burner 4 originally has a structure that sucks in free air, the lump may be dropped while taking in free air from the outside. Oxygen-enriched air may be used instead of free air.

[0027] To improve wear resistance, the inner surface of the lump passage 14 is preferably lined. For example, it is possible to line the inner surface with a wear-resistant material such as ceramic or high-hardness wear-resistant steel, or to perform a surface treatment.

[0028] In cases where providing the lump passage 14 in the middle lance results in the middle lance becoming longer, flanges 19 may be provided on the top and bottom of the lump passage 14 in the upper part of the middle lance, as shown in Fig. 4, so that the lump passage 14 can be removed for inspection or replacement. In this case, inspection and replacement of the lump passage 14 becomes easier.

[0029] The sulfur-containing aggregates may be granulated materials obtained from a powdered sulfur-containing material and a recycled raw material. For example, the granulated materials can be obtained by mixing the powdered sulfur-containing material with the recycled raw material in a predetermined mixing ratio, and then pressing the mixture to form briquettes.

[0030] For example, a granulated material can be obtained using a briquetting machine. Fig. 5 is a diagram illustrating a briquetting machine 200. As illustrated in Fig. 5, the briquetting machine 200 includes a hopper 210, a screw 220, and a pair of rolls 230. The sulfur-containing material and recycled raw materials are fed into the hopper 210. The screw 220 is provided within the hopper 210, and by rotating, forcibly sends the raw materials between the pair of rolls 230.

[0031] Each of the pair of rolls 230 has a substantially cylindrical shape and is configured to be rotatable around a cylindrical axis as a rotation axis. The shapes of the pair of rolls 230 are substantially the same. The pair of rolls 230 are arranged so that their rotation axes are parallel and their circumferential surfaces face each other. The rotation axes of the pair of rolls 230 are substantially aligned in the horizontal direction. The pair of rolls 230 rotate in opposite directions to each other, thereby sandwiching the sulfur-containing material and recycled raw material sent from the screw 220 between their circumferential surfaces, forming lumps 240 and dropping them. The roll 230 may have a substantially cylindrical shape as a whole by combining multiple segments of the same shape, or may be a single, substantially cylindrical member.

[0032] Alternatively, the granulated material may be obtained by agglomerating the sulfur-containing material and the recycled raw material.

[0033] Examples of recyclable raw materials include copper scrap including chips, dust ash, and scrap electrical components. For example, the average composition of the recyclable raw materials is 10 to 95 mass% Cu, 0 to 50 mass% Fe, and 0 to 40 mass% Sn, Zn, Pb, and Al. The recyclable raw materials may be, for example, undersized sieves obtained by sieving with a maximum mesh size of 10 mm or less.

[0034] The recycled material has a true density (g / cm) greater than that of the sulfur-containing material. ３ ) is preferable. This is because the apparent density of the granulated material increases, making it easier to reach the metallic Cu contained in the mat 5. It is preferable to adjust the mixing ratio of the sulfur-containing material and the recycled raw material so that the apparent density of the granulated material is equal to or greater than the density of the slag 6. For example, when the density of the slag 6 is 3.5 (g / cm ３ ), so the apparent density of the granulated product is 3.5 (g / cm ３ ) or more. In addition, the granulated material preferably has a mechanical strength sufficient to prevent it from collapsing while falling inside the reaction shaft 1.

[0035] For example, the apparent density of a briquette made of copper concentrate alone is 3.5 (g / cm３ ), so the copper concentrate and the true density are 3.5 (g / cm ３ ) and a recycled raw material exceeding 3.5 (g / cm ３ For example, it is preferable to adjust the true density of copper concentrate to 6.3 (g / cm ３ ) recycled raw material in a weight ratio of 1:1.4 and granulated, the apparent density was 3.6 (g / cm ３ ) granules are obtained. Note that true density is the density obtained excluding the volume of pores present on the surface and inside of an object. Apparent density is the density obtained excluding only the volume of pores that connect to the surface of an object and including the volume of internal pores. Apparent density is measured based on the Japan Powder Process Industry and Engineering Association standard SAP02-82 "Method for measuring apparent density of granules."

[0036] Furthermore, when mixing the sulfur-containing material with the recycled raw material, it is preferable to adjust the water content of the mixture to a predetermined range to obtain granules, and then dry the granules. In this case, the mechanical strength of the granules is increased, and collapse of the granules can be suppressed even when an impact occurs when dropping into the molten metal. For example, when mixing the sulfur-containing material with the recycled raw material, it is preferable to adjust the water content to 2 mass% or more to obtain granules, and then dry the granules. For example, it is preferable to adjust the water content of the granules to a predetermined range by mixing copper concentrate containing moisture with dried recycled raw material.

[0037] On the other hand, when mixing the sulfur-containing material and the recycled raw material, if the water content of the mixture is high, the releasability from the roll 230 of the briquetting machine 200 may be deteriorated, and the product yield may decrease. Therefore, it is preferable to set an upper limit on the water content of the mixture. In this embodiment, it is preferable to adjust the water content of the mixture to 5 mass% or less.

[0038] It is also preferable to determine the mixing ratio of the sulfur-containing material and the recycled raw material in the granules so that the amount of sulfur contained in the granules exceeds the amount of sulfur required to matte the total amount of metallic Cu in the recycled raw material contained in the granules under the conditions in the reaction shaft 1. By doing so, the sulfur contained in the granules can be fully used to matte the metallic Cu contained in the matte 5.

[0039] If the diameter of the granules is small, the surface area of ​​the granules may not be sufficiently small. Therefore, it is preferable to set a lower limit for the average diameter of the granules. On the other hand, if the diameter of the granules is large, the mechanical strength may decrease due to an increase in the weight of the briquette. Therefore, it is preferable to set an upper limit for the average diameter of the granules. In this embodiment, the average diameter of the granules in the major axis direction is preferably 20 mm or more and 50 mm or less.

[0040] The weighed raw materials were mixed and fed into the hopper of a briquetting machine, where they were briquetted to obtain lumps. A melting test was conducted by dropping the resulting lumps into molten slag, and the changes in composition and weight of the lumps before and after melting were measured to understand the mass balance of the lumps before and after melting, and to evaluate the residual rate of sulfur components in the lumps. The melting behavior of the lumps was also observed when they were dropped.

[0041] In Example 1, powdered copper concentrate and metallic Cu powder were mixed and briquetted to produce a mass. The weight ratio of Cu powder to copper concentrate, i.e., the ratio of the weight of Cu powder to the weight of copper concentrate, was set to 0.67.

[0042] In Example 2, powdered copper concentrate and a simulated raw material (Cu: 80.1 mass%, Fe: 11.3 mass%, Zn: 4.5 mass%, Sn: 2.4 mass%, Pb: 1.6 mass%) that was not crushed by a parts scrap mill were mixed and briquetted to produce a mass. The weight ratio of the simulated raw material to the copper concentrate, i.e., the weight ratio of the simulated raw material to the copper concentrate, was set to 0.65.

[0043] In both Examples 1 and 2, cylindrical blocks of 20 mm diameter and approximately 10 g weight (sphere-equivalent diameter 9 mm) were prepared, and then their exact weights were measured. The apparent density of the blocks obtained in Example 1 was 3.9 g / cm. ３ The apparent density of the aggregate obtained in Example 2 was 4.1 g / cm ３ It was.

[0044] Next, as shown in FIG. 6 , the slag 52 placed in the alumina Tammann tube 51 was heated to 1250°C. Thereafter, the lumps 240 were dropped from the top of the alumina Tammann tube 51 and held there for 60 minutes. The dropping process was also visually observed on the spot. After holding for 60 minutes, the alumina Tammann tube 51 was cooled with argon and then water-cooled. The alumina Tammann tube 51 was dried and crushed, and the molten lumps 240 were taken out. The weight of the molten material was measured, and then its composition was analyzed by EPMA.

[0045] The results are shown in Table 1. As shown in Table 1, no desorption of sulfur components from the aggregates was confirmed in Example 1. This is thought to be because the aggregates had a diameter of 5 mm or more, which caused them to sink into the slag, and because the sulfur components were used to form a matte of the Cu powder.

[0046] In Example 2, almost no desorption of sulfur components from the aggregates was observed. This is also thought to be because the aggregates had a diameter of 5 mm or more, which allowed them to sink into the slag, and because the sulfur components were used to form a matte of Cu powder.

[0047] The above-described embodiment is a preferred example of the present invention. However, the present invention is not limited to this, and various modifications are possible within the scope of the gist of the present invention. In this specification, a case where Cu, which is insoluble in the matte, separates as a metal phase is described, but the present invention can also be applied to cases where other metals may separate as a metal phase in the matte. For example, when recycled raw materials containing a large amount of Fe as a metallic component are charged into a smelting furnace, if there is a possibility that the Fe metal phase in the matte may separate, the present invention can also be implemented.

[0048] REFERENCE SIGNS LIST 1 reaction shaft 2 settler 3 uptake 4 concentrate burner 5 matte 6 slag 10 dispersion cone 11 inner cylinder 12 middle cylinder 13 outer cylinder 14 lump passage 15 reaction auxiliary gas passage 16 dispersion gas passage 20 inner cylinder 21 raw material passage 30 outer cylinder 31 reaction main blast gas passage 100 flash smelting furnace 200 briquetting machine 210 hopper 220 screw 230 roll 240 lump

Claims

1. A method of operating a flash smelting furnace in which lumps containing sulfur and having an average particle size of 5 mm or more are fed into the flash smelting furnace.

2. A method for operating a flash smelting furnace as set forth in claim 1, wherein the lumps are introduced through a flow passage of a concentrate burner provided on the ceiling of the flash smelting furnace.

3. A method for operating a flash smelting furnace according to claim 1, wherein the lumps are granulated material obtained by mixing sulfur-containing material and recycled raw materials.

4. A method for operating a flash smelting furnace according to claim 2, wherein the concentrate burner is provided with a middle lance in a dispersion cone extending vertically at the center, the middle lance having at least two paths, a gas for oxidizing the smelting raw material flows through one of the two paths, and the lumps are introduced into the other of the two paths.

5. A method for operating a flash smelting furnace according to claim 4, wherein the middle lance is provided with a double pipe forming the two paths.

6. A method for operating a flash smelting furnace according to claim 5, wherein a gas for oxidizing the smelting raw material is flowed through the outer passage of the double pipe, and the lumps are introduced into the inner passage of the double pipe.

7. A method for operating a flash smelting furnace as set forth in claim 2, wherein gas is blown into the flash smelting furnace through a path for charging the lumps so that the gas in the flash smelting furnace does not flow back from the concentrate burner.

8. A method for operating a flash smelting furnace according to claim 7, wherein the gas flowing through the path for charging the lumps is an inert gas.

9. A method for operating a flash smelting furnace as claimed in claim 7, wherein the gas flowing through the path for charging the lumps is air.

10. A method for operating a flash smelting furnace as claimed in claim 7, wherein the gas flowing through the passage for charging the lumps is oxygen-enriched air.

11. A concentrate burner installed on the roof of a flash smelting furnace, the concentrate burner comprising a middle lance in a centrally extending vertical dispersion cone, the middle lance having a plurality of passages.

12. A concentrate burner according to claim 11, wherein the middle lance comprises a double pipe extending vertically.

13. A concentrate burner according to claim 11, wherein at least one of said plurality of passages is lined.

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