WO2025187348A1 - Flash furnace operation method, and concentrate burner - Google Patents

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

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

In a copper smelting furnace, reactive gases are fed into the furnace from the concentrate burner along with smelting raw materials such as copper concentrate and solvents. The reactive gases cause an oxidation reaction of the smelting raw materials, producing matte and slag.

Japanese Patent Application Laid-Open No. 2007-092133 Special Publication No. 51-047410

In recent years, the proportion of recycled raw materials used in smelting 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 this invention, these 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 added to a flash smelting furnace, measures are required to allow the sulfur source to react with the metallic components in the matte phase.

The present invention was made in consideration of the above-mentioned problems, and aims 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.

The method for operating a flash smelting furnace according to the present invention involves feeding lumps containing sulfur and having an average particle size of 5 mm or more into the flash smelting furnace. The lumps may be fed through a flow path of a concentrate burner installed on the ceiling of the flash smelting furnace. The lumps may be granulated material obtained by mixing a sulfur-containing material with recycled raw materials. The concentrate burner may have a vertically extending middle lance in its center, and the middle lance may have at least two paths, with gas for oxidizing the smelting raw materials flowing through one of the two paths and the lumps being fed through the other of the two paths. The middle lance may have a double pipe forming the two paths. Gas for oxidizing the smelting raw materials may be flowed through the outer path of the double pipe, and the lumps may be fed through the inner path of the double pipe. Gas may be blown into the flash smelting furnace from the path for feeding 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. The gas flowing through the path for introducing the lumps may be air. The gas flowing through the path for introducing the lumps may be oxygen-enriched air.

The concentrate burner according to the present invention is a concentrate burner installed on the ceiling of a flash smelting furnace, and is equipped with a middle lance extending vertically in the center, with the middle lance having multiple passages. The middle lance may be equipped with a double pipe extending vertically. At least one of the multiple passages may be provided with a ceramic lining.

The present invention provides 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.

1 is a diagram illustrating a schematic configuration of a flash furnace for copper smelting according to an embodiment. FIG. 1 is a phase diagram showing the solubility of Cu in a matte. FIG. 2 is a diagram illustrating details of a concentrate burner. FIG. 2 is a diagram illustrating details of a concentrate burner. FIG. 1 illustrates a briquetting machine. FIG. 1 is a diagram for explaining an embodiment.

(Embodiment)
FIG. 1 is a diagram illustrating a schematic configuration of a flash smelting furnace 100. As illustrated in FIG. 1, the flash smelting furnace 100 includes a reaction shaft 1, a settler 2, and an uptake 3, in which copper concentrate and a reaction gas are mixed and reacted. A concentrate burner 4 is provided on the ceiling of the reaction shaft 1. The concentrate burner 4 supplies a main reaction blast gas, an auxiliary reaction 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 main reaction blast gas and the auxiliary reaction gas are oxygen-enriched air, and the dispersion gas is air or oxygen-enriched air.

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 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.
CuFeS ₂ + SiO ₂ + O ₂ → Cu ₂ S·FeS + FeO·SiO ₂ + SO ₂ + Reaction heat (1)

Recycled raw materials may contain metallic components. If the amount of metallic components is small, they will sulfide and become matte 5 as they fall from the concentrate burner 4. Therefore, no metal phase is produced.

However, as the amount of recycled raw materials processed increases, the proportion of metallic components (metallic Cu as an example) 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 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. The following explanation focuses on metallic Cu contained in recycled raw materials, but can also be applied to other metallic components.

As the proportion of metallic Cu in the smelting raw material increases, the metallic Cu is not completely sulfidized as it falls 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 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 taken from "Takazaietsu and Yazawa Akira, 1983, Journal of Selected Research and Development."

As a result, one approach is to introduce powdered sulfur-containing material into the reaction shaft 1, thereby sulfiding the metallic Cu contained in the matte 5 and forming matte. However, there is a risk that the powdered sulfur-containing material will oxidize when introduced into the reaction shaft 1. There is also a risk that the powdered sulfur-containing material will be captured by slag 6 floating on the matte 5 and not reach the matte 5. As a result, one approach is to supply the sulfur-containing material by injection using an inert gas as a carrier. However, this method is difficult to operate and presents many challenges.

Therefore, in this embodiment, sulfur-containing agglomerates containing sulfur and having an average particle size (average spherical equivalent diameter) of 5 mm or more are supplied from the concentrate burner 4 into the reaction shaft 1. The spherical equivalent diameter refers to the diameter when the volume of each agglomerate is measured and that volume is assumed to be a sphere. The volume of the agglomerates is measured by submerging the agglomerates in pure water or ethanol in a measuring cylinder and observing the change in the liquid level. The use of sulfur-containing agglomerates reduces the specific surface area of the sulfur in contact with the atmosphere in the reaction shaft 1, thereby suppressing sulfur oxidation. Furthermore, the use of agglomerates makes them more likely to sink in the slag 6 and reach the metallic Cu in the matte 5 than when powdered sulfur-containing agglomerates are used. This makes it easier to sulfurize the metallic Cu contained in the matte 5 and convert it into matte.

Furthermore, directly below the reaction shaft 1, molten droplets produced in the reaction shaft 1 rain down, forming a mixed layer where matte 5 and slag 6 mix. 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 this reaction shaft 1, the granulated material can easily penetrate the slag 6 and reach the matte 5. As a result, when increasing the amount of recycled raw material processed in a copper smelting furnace, the sulfur source can react with metallic Cu in the matte 5.

Since larger sulfur-containing lumps are more likely to reach the mat 5, the average particle size of the sulfur-containing lumps is preferably 10 mm or more, and more preferably 20 mm or more.

Examples of sulfur-containing materials that can be included in the sulfur-containing aggregates include FeS minerals (pyrrhotite), _FeS2 minerals (pyrite), _CuFeS2 minerals (chalcopyrite), minerals containing FeS and _FeS2 , and sulfur-containing copper concentrates. When comparing FeS minerals and _FeS2 minerals, it is preferable to use _FeS2 minerals, which are believed to contain a higher amount of sulfur necessary for matte formation. Alternatively, sulfur-containing tailings generated in the ore-dressing process of non-ferrous metal raw materials can be used as the sulfur-containing material. For example, tailings generated in the flotation process are an example of sulfur-containing tailings. For example, the sulfur content of powdered sulfur-containing materials is approximately 20 mass% to 55 mass%.

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

Figure 3 is a diagram illustrating the details of the concentrate burner 4. As illustrated in Figure 3, the concentrate burner 4 has a dispersion cone 10 in the center that extends vertically from the outside to the inside of the reaction shaft 1 in Figure 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, inner cylinder 20, and outer cylinder 30 are arranged approximately concentrically. The space between the dispersion cone 10 and 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 outer cylinder 30 functions as a reaction main blast gas passage 31 through which the reaction main blast gas passes.

The dispersion cone 10 comprises an inner tube 11, a middle tube 12 that covers the inner tube 11 while being spaced apart from the inner tube 11, and an outer tube 13 that covers the middle tube 12 while being spaced apart from the middle tube 12. The inner tube 11, middle tube 12, and outer tube 13 are arranged approximately concentrically. Therefore, the inner tube 11 and middle tube 12 form a double pipe. This double pipe is the middle lance. The middle lance (inner tube 11 and middle tube 12) and the outer tube 13 form a triple pipe. The space inside the inner tube 11 functions as a lump passage 14 through which the sulfur-containing lump passes. The space between the inner tube 11 and the middle tube 12 functions as a reaction auxiliary gas passage 15 through which the reaction auxiliary gas passes. The space between the middle tube 12 and the outer tube 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 section located inside the dispersion cone, which comprises two or more paths other than the dispersion gas path, one for the sulfur-containing lumps and one for the reaction assisting gas. Also, in the present invention, the dispersion cone is defined as a cylinder located in the center of the concentrate burner, with a truncated conical tip, and having a dispersion gas path and a middle lance inside.

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

The tip (lower end) of the dispersion cone 10 is frustum-shaped. The lower part of the side of the dispersion cone 10 has multiple supply holes 18 formed therein, which 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.

In this configuration, the sulfur-containing lumps pass through the inner tube 11 in the middle lance of the concentrate burner 4 and fall freely to just below the reaction shaft. In particular, because the lump passage 14 is located in the center of the middle lance, the lump is less susceptible to the influence of the main reaction blast gas, auxiliary reaction gas, and dispersion gas, making it easier for the lumps to fall freely to just below the reaction shaft 1.

It is preferable that the lump passage 14 be an inert atmosphere. This is because it inhibits oxidation of the sulfur source contained in the lump and reduces the effect on the amount of oxygen supplied, which controls the oxidation reaction of the copper concentrate in the reaction shaft 1. In addition, blowing in an inert gas also helps prevent backflow of high-temperature gas when the pressure inside the flash smelting furnace 100 becomes higher than atmospheric pressure. For example, it is preferable that the inert atmosphere inside the lump passage 14 be a nitrogen atmosphere. However, because the concentrate burner 4 is originally designed to suck 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.

The inner surface of the lump passage 14 is preferably lined to improve wear resistance. For example, it may be possible to line it with a wear-resistant material such as ceramic or high-hardness wear-resistant steel, or to apply a surface treatment.

If providing the lump passage 14 to the middle lance results in a longer middle lance, flanges 19 may be provided on the top and bottom of the lump passage 14 at the top of the middle lance, as shown in Figure 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.

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

For example, granulated material can be obtained using a briquetting machine. Figure 5 is a diagram illustrating a briquetting machine 200. As illustrated in Figure 5, the briquetting machine 200 includes a hopper 210, a screw 220, and a pair of rolls 230. 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, it forcibly sends the raw materials between the pair of rolls 230.

Each of the pair of rolls 230 has a roughly cylindrical shape and is configured to be rotatable around its cylindrical axis. The shapes of the pair of rolls 230 are roughly 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 roughly aligned horizontally. By rotating in opposite directions, the pair of rolls 230 sandwich the sulfur-containing material and recycled raw materials sent from the screw 220 between their circumferential surfaces, forming lumps 240 that are then dropped. The roll 230 may have a roughly cylindrical shape as a whole by combining multiple segments of the same shape, or it may be a single, roughly cylindrical component.

Alternatively, granulated material can be obtained by agglomerating sulfur-containing material and recycled raw materials.

Recycled raw materials can include copper scrap including chips, dust ash, and scrap electrical components. For example, the average composition of recycled raw materials is 10 to 95 mass% Cu, 0 to 50 mass% Fe, and a total of 0 to 40 mass% Sn, Zn, Pb, Al, etc. Furthermore, recycled raw materials can be, for example, the undersized material obtained by passing it through a sieve with a maximum mesh size of 10 mm or less.

The recycled raw material preferably has a greater true density (g/cm ³ ) than the sulfur-containing material. 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, since the density of the slag 6 is often about 3.5 (g/cm ³ ), it is preferable that the apparent density of the granulated material be 3.5 (g/cm ³ ) or more. In addition, it is preferable that the granulated material has a mechanical strength sufficient to prevent it from collapsing while falling through the reaction shaft 1.

For example, since the apparent density of a briquette made of copper concentrate alone is less than 3.5 (g/cm ³ ), it is preferable to mix copper concentrate with recycled raw material having a true density of more than 3.5 (g/cm ³ ) to adjust the apparent density of the granulated product to 3.5 (g/cm ³ ) or more. For example, by mixing copper concentrate with recycled raw material having a true density of 6.3 (g/cm ³ ) in a weight ratio of 1:1.4 and granulating the mixture, a granulated product having an apparent density of approximately 3.6 (g/cm ³ ) can be 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 by excluding only the volume of pores connected to the surface of an object and including the volume of internal pores. The apparent density is measured based on the Japan Powder Process Industry and Engineering Association standard SAP02-82, "Method for measuring the apparent density of granulated products."

Furthermore, when mixing the sulfur-containing material with the recycled raw material, it is preferable to adjust the moisture content of the mixture to a predetermined range, 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 if an impact occurs when the granules are dropped into the molten metal. For example, when mixing the sulfur-containing material with the recycled raw material, it is preferable to adjust the moisture content to 2 mass% or more, obtain granules, and then dry the granules. For example, it is preferable to adjust the moisture content of the granules to a predetermined range by mixing copper concentrate containing moisture with dried recycled raw material.

On the other hand, when mixing sulfur-containing material with recycled raw materials, if the mixture has a high moisture content, it may be difficult to release from the roll 230 of the briquetting machine 200, which could result in a lower product yield. Therefore, it is preferable to set an upper limit on the moisture content of the mixture. In this embodiment, it is preferable to adjust the moisture content of the mixture to 5 mass% or less.

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

If the diameter of the granulated material is small, the surface area of the granulated material may not be sufficiently small. Therefore, it is preferable to set a lower limit on the average diameter of the granulated material. On the other hand, if the diameter of the granulated material 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 on the average diameter of the granulated material. In this embodiment, it is preferable that the average diameter of the granulated material in the major axis direction is 20 mm or more and 50 mm or less.

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 determine 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.

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 0.67.

In Example 2, powdered copper concentrate was mixed with a simulated raw material (Cu: 80.1 mass%, Fe: 11.3 mass%, Zn: 4.5 mass%, Sn: 2.4 mass%, Pb: 1.6 mass%) made from unground scrap mill material, and then briquetted to produce a mass. The simulated raw material/copper concentrate weight ratio, which is the ratio of the weight of the simulated raw material to the weight of the copper concentrate, was set to 0.65.

In both Examples 1 and 2, cylindrical blocks of approximately 10 g and 20 mm in diameter (sphere-equivalent diameter: 9 mm) were prepared and then accurately weighed. The apparent density of the blocks obtained in Example 1 was 3.9 g/ ^cm3 . The apparent density of the blocks obtained in Example 2 was 4.1 g/ ^cm3 .

Next, as shown in Figure 6, the slag 52 placed in the alumina Tammann tube 51 was heated to 1250°C. After that, the lump 240 was dropped from the top of the alumina Tammann tube 51 and held there for 60 minutes. The dropping process was also visually observed on-site. 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 lump 240 was removed. The weight of the molten material was measured, and then its composition was analyzed using an EPMA.

The results are shown in Table 1. As shown in Table 1, in Example 1, no desorption of sulfur components from the lumps was confirmed. This is thought to be because the lumps sank into the slag due to the diameter of the lumps being 5 mm or more, and because the sulfur components were used to matte the Cu powder.

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.

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

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 (13)

A method of operating a flash smelting furnace in which lumps containing sulfur and with an average particle size of 5 mm or more are fed into the flash smelting furnace. The method for operating a flash smelting furnace described in claim 1, wherein the lumps are introduced through a flow path of a concentrate burner installed in the ceiling of the flash smelting furnace. The 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. The concentrate burner has a middle lance in a vertically extending dispersion cone at its center,
the middle lance has at least two paths;
A gas for oxidizing the smelting raw material is flowed through one of the two pipes,
3. The method for operating a flash smelting furnace according to claim 2, wherein the lumps are charged into the other of the two furnaces. The method for operating a flash smelting furnace according to claim 4, wherein the middle lance is provided with a double pipe that constitutes the two paths. A gas for oxidizing the smelting raw material is flowed through a path outside the double pipe,
6. The method for operating a flash smelting furnace according to claim 5, wherein the lumps are charged into a passage inside the double pipe. A method for operating a flash smelting furnace as described 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. The 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. The method for operating a flash smelting furnace according to claim 7, wherein the gas flowing through the path for feeding the lumps is air. The method for operating a flash smelting furnace according to claim 7, wherein the gas flowing through the path for charging the lumps is oxygen-enriched air. A concentrate burner installed on the ceiling of a flash smelting furnace,
A middle lance is provided within a dispersion cone extending vertically at the center,
The middle lance has a plurality of passages. The concentrate burner described in claim 11, wherein the middle lance comprises a double pipe extending vertically. 12. The concentrate burner of claim 11, wherein at least one of said plurality of passages is lined.