Concentrate Burner

Abstract

To provide a concentrate burner capable of introducing smelting raw materials in an uniformly dispersed state in a peripheral direction from a lower end opening of a concentrate shute.SOLUTION: A concentrate burner 10 comprises: a generally cylindrical concentrate chute 11 for discharging smelting raw materials; a generally cylindrical oxyfuel burner 12 provided concentrically inside the concentrate chute 11; a plurality of concentrate supply pipes 13 connected diagonally from above at equal intervals in the circumferential direction at the same height position as a side wall of an upper end of the concentrate shute 11; and a burner cone sleeve 14 that serves as a flow path for reaction gas provided concentrically so as to house a portion other than the upper end of the concentrate shute 11, in which a center line O2 of the plurality of concentrate supply pipes 13 is aligned twisted with the center line O1 of the concentrate chute 11 and when viewed from directly above, the concentrate chute 11 as a whole is rotationally symmetrical with respect to the center line O1.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a concentrate burner for a flash smelting furnace used in the smelting of sulfide ores. [Background technology]

[0002] In the smelting of non-ferrous metals such as copper and nickel, raw ore, which is mainly composed of sulfide ore, is subjected to pretreatment such as crushing and sieving, and then concentrated by flotation to produce a concentrate for smelting. The produced concentrate is first oxidized and melted in a smelting process to separate part of the iron and gangue components as slag (oxides), and valuable metals contained in the concentrate are recovered as matte. After that, the matte is refined by dry or wet processes in a subsequent process to produce the final product.

[0003] Of the above series of processes, the smelting process uses a smelting furnace, typically a flash furnace. A flash furnace is primarily composed of a reactor tower where the concentrate charged from the top is oxidized and melted, a settler where the slag and matte produced by the oxidation and melting are separated by gravity, and an uptake where the exhaust gas generated in the flash furnace is directed to an outlet. A concentrate burner is installed at the center of the top of the reactor tower of a flash furnace with this configuration, and the concentrate (also called dry ore) dried in the preceding drying equipment is discharged into the reactor tower via this concentrate burner along with fluxes such as silica sand and auxiliary fuels (oxygen-enriched air for the reaction, heavy oil, etc.).

[0004] Various structures have been proposed for the above-mentioned concentrate burner. For example, Patent Document 1 discloses a concentrate burner consisting of a substantially cylindrical concentrate chute that guides the concentrate and discharges it into a reaction tower from its lower opening, an oxygen-fuel burner (also called an OF burner) concentrically installed inside the concentrate chute to introduce auxiliary fuel and oxygen into the reaction tower, and a burner cone sleeve (also called a burner cone liner) with a substantially cylindrical upper part and a substantially inverted conical lower part that houses the concentrate chute and serves as a flow path for the reaction gas, which is generally air. A plurality of concentrate supply pipes are connected to the upper end side wall of the concentrate chute at the same height and equidistantly spaced circumferentially. A dry ore storage is installed above the concentrate burner, and the concentrate temporarily stored in the dry ore storage is supplied to the concentrate burner via these concentrate supply pipes.

[0005] The concentrate burner in Patent Document 1 further includes a position adjustment unit that moves the oxygen-fuel burner horizontally. As a result, when any of the temperature measurements from a plurality of thermometers provided at equal intervals around the circumferential direction on the side wall of the reaction tower exceeds the control range, the position adjustment unit can adjust the position of the oxygen-fuel burner horizontally, so that the coating layer formed on the side wall of the reaction tower can be maintained in good condition without being reduced. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2014-084522 Summary of the Invention [Problem to be solved by the invention]

[0007] As described above, by connecting a plurality of concentrate supply pipes at equal intervals in the circumferential direction to the upper end side wall of a substantially cylindrical concentrate chute extending in the vertical direction, the concentrate can be efficiently made to fall freely into the annular flow path between the outer wall of a substantially circular tubular oxygen-fuel burner concentrically provided inside the concentrate chute and the inner wall of the substantially cylindrical concentrate chute, thereby enabling the concentrate to be dispersed and released into the inside of the reaction tower located below the concentrate chute. The concentrate released into the reaction tower in this way is immediately heated by radiant heat from the reaction tower and combustion heat of the auxiliary fuel, etc., and is burned and melted by an oxidation reaction with the reaction gas supplied from the concentrate burner.

[0008] However, with conventional concentrate burners, the concentrate was sometimes not uniformly dispersed in the circumferential direction when it was discharged from the lower opening of the concentrate chute. One of the reasons for this is thought to be that the concentrates introduced into the concentrate chute from the respective adjacent concentrate supply pipes collide with each other within the concentrate chute, causing local overcrowding within the concentrate chute, which is thought to deteriorate the uniform dispersion of the concentrate from the lower opening of the concentrate chute.

[0009] As described above, when the concentrate is discharged into the reaction tower, if it is not uniformly dispersed in the circumferential direction from the lower opening of the concentrate chute, combustion efficiency may be significantly reduced. Therefore, there has been a need for a concentrate burner that can discharge the smelting raw material, concentrate, in a state where it is uniformly dispersed in the circumferential direction from the lower opening of the concentrate chute. The present invention has been made in view of the above circumstances, and has an object to provide a concentrate burner that can discharge the smelting raw material, mainly consisting of concentrate, in a state where it is uniformly dispersed in the circumferential direction from the lower opening of the concentrate chute. [Means for solving the problem]

[0010] In order to achieve the above object, the concentrate burner of the present invention is a concentrate burner installed at the center of the top of a reaction tower of a flash smelting furnace used in the smelting of sulfide ore, and comprises: a substantially cylindrical concentrate chute that discharges smelting raw material mainly composed of concentrate into the reaction tower; a substantially circular tubular oxygen-fuel burner installed concentrically inside the concentrate chute; a plurality of concentrate supply pipes connected to the side wall of the upper end of the concentrate chute at the same height position, at equal intervals circumferentially, and diagonally from above; and a burner cone sleeve that is installed concentrically to accommodate the portion of the concentrate chute other than the upper end, has a substantially cylindrical upper part and a substantially inverted conical lower part, and serves as a flow path for reaction gas; the center lines of the plurality of concentrate supply pipes are all in a twisted positional relationship with respect to the center line of the concentrate chute, and are rotationally symmetrical as a whole about the center line of the concentrate chute when viewed from directly above. [Effects of the Invention]

[0011] According to the present invention, it is possible to discharge the smelting raw material, which is mainly composed of concentrate, from the lower end opening of the concentrate chute in a state in which it is uniformly dispersed in the circumferential direction. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a schematic vertical cross-sectional view of a flash smelting furnace provided with a concentrate burner according to an embodiment of the present invention. FIG. [Figure 2] FIG. 2 is a perspective view showing the reaction tower of the flash smelting furnace of FIG. 1 together with a concentrate burner according to an embodiment of the present invention provided at the center of the top of the reaction tower. [Figure 3] FIG. 1 is a longitudinal sectional view of a concentrate burner according to an embodiment of the present invention. [Figure 4] 4(a) and 4(b) are a perspective view and a plan view showing a state in which a plurality of concentrate supply pipes are connected to the upper end of a concentrate chute of the concentrate burner of FIG. 3. FIG. [Figure 5] FIG. 1 is a plan view showing a state in which a plurality of concentrate supply pipes are connected to the upper end of a concentrate chute of a conventional concentrate burner. [Figure 6]FIG. 1 is a cross-sectional view of a concentrate chute showing the results of a simulation of the distribution of the smelting raw material when the smelting raw material is introduced into the concentrate chute from four concentrate supply pipes in the concentrate burners of the examples and comparative examples of the present invention. [Figure 7] FIG. 10 is a partial vertical cross-sectional view showing a state in which a thermometer is inserted from the outside into an annular flow passage between a burner cone sleeve and an oxygen-fuel burner in concentrate burners according to an embodiment of the present invention and a comparative example. [Figure 8] 8 is a cross-sectional view of the annular flow path shown in FIG. 7, seen from directly above, with a thermometer inserted from the outside. FIG. [Figure 9] 1 is a graph showing the temperature distribution in a burner cone sleeve measured in a concentrate burner according to an embodiment of the present invention. [Figure 10] 1 is a graph showing the temperature distribution in a burner cone sleeve measured in a concentrate burner of a comparative example of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0013] A concentrate burner according to an embodiment of the present invention, which is installed in a flash smelting furnace used in the pyrometallurgical smelting of sulfide ore, will be described in detail below. The concentrate burner according to an embodiment of the present invention is installed in a flash smelting furnace 1 used in the smelting of sulfide ore, as shown in FIG. 1. Specifically, the flash smelting furnace 1 shown in FIG. 1 mainly comprises a substantially cylindrical reaction tower (also referred to as a reaction shaft) 1a, which oxidizes and melts the concentrate introduced from the top via a concentrate burner; a substantially rectangular parallelepiped settler 1b, which is located below the reaction tower 1a and separates the slag and matte produced by the oxidation and melting process based on their specific gravity; and a cylindrical uptake 1c, which guides sulfur-containing exhaust gas generated during the oxidation and melting process to an outlet. The slag and matte are separately extracted through a trough and transported to downstream equipment, while the exhaust gas is transported to a sulfuric acid production facility through a duct.

[0014] As shown in FIG. 2, a concentrate burner 10 according to an embodiment of the present invention is attached to the center of the top of the reaction tower of the flash smelting furnace 1 with its central axis extending vertically. As shown in FIG. 3, the concentrate burner 10 of the embodiment of the present invention is mainly composed of a substantially cylindrical concentrate chute 11 that discharges smelting raw materials into the reaction tower 1a, the raw materials being composed of concentrate as the main component and other raw materials (sometimes called miscellaneous raw materials) supplied from a dry ore storage facility (not shown), and flux such as silicon that is supplied separately; a substantially circular tubular oxygen-fuel burner (OF burner) 12 that is concentrically arranged inside the concentrate chute 11 and that injects auxiliary fuel such as heavy oil into the reaction tower 1a together with oxygen-containing gas containing oxygen; four concentrate supply pipes 13 that are connected circumferentially at equal intervals and obliquely from above at the same height position on the side wall of the upper end of the concentrate chute 11; and a burner cone sleeve 14 that is concentrically arranged to accommodate the portion of the concentrate chute 11 other than the upper end, and has a substantially cylindrical upper part and a substantially inverted conical lower part that serves as a flow path for reaction gas such as preheated air.

[0015] One or more reaction gas supply pipes 15 are connected to the upper part of the approximately cylindrical shape of the burner cone sleeve 14. The upper part of the approximately cylindrical shape of the burner cone sleeve 14 is sometimes called a wind box. A cylindrical wind speed regulator 16 is fitted around the outer periphery of the concentrate chute 11, excluding its upper and lower parts. The lower end of this wind speed regulator 16 has a partially enlarged diameter, and it can move up and down together with the concentrate chute 11. With this configuration, by moving the wind speed regulator 16 up and down together with the concentrate chute 11, the annular flow path between this wind speed regulator 16 and the burner cone sleeve 14 can be narrowed or widened, making it possible to adjust the speed and flow rate of the reaction gas blown into the reaction tower 1a.

[0016] In the concentrate burner 10 according to the embodiment of the present invention, as shown in Fig. 4, the center lines O2 of the four concentrate supply pipes 13 do not intersect with the center line O1 of the concentrate chute 11, and all of them are in a twisted positional relationship with respect to the center line O1 of the concentrate chute 11, and when viewed from directly above, the entire concentrate burner 10 is rotationally symmetrical about the center line O1 of the concentrate chute 11. More specifically, when there are n concentrate supply pipes 13 connected to the concentrate burner 10, there is n-fold symmetry or (360 / n)-degree symmetry. In the concentrate burner 10 according to the embodiment of the present invention, the number of concentrate supply pipes 13 is four, so there is four-fold symmetry or 90-degree symmetry.

[0017] With the above configuration, the smelting raw materials are extracted from the bottom of a dry ore storage or the like by a conveyor or other transport equipment, and then distributed and supplied to four concentrate supply pipes 13 via vertically extending cylindrical guides or the like. The smelting raw materials then slide down at an accelerated rate within these four concentrate supply pipes 13, which are arranged at an angle toward the concentrate chute 11, and are introduced into the concentrate chute 11. At this time, the smelting raw materials do not flow toward the center of the concentrate chute 11, but rather flow toward a position offset to the same side from the center. This allows the smelting raw materials to flow smoothly along the inner wall surface of the concentrate chute 11.

[0018] That is, as shown in Figure 4, if the smelting raw materials introduced into the concentrate chute 11 from the four concentrate supply pipes 13 all flow toward a position shifted to the left of the center line O1 of the concentrate chute 11, the smelting raw materials can be made to freely fall while rotating clockwise inside the concentrate chute 11 when viewed from directly above, and the smelting raw materials supplied from the four concentrate supply pipes 13 are less likely to collide with each other inside the concentrate chute 11. Therefore, when the smelting raw materials are released into the reaction tower 1a from the lower end opening of the concentrate chute 11, they can be uniformly dispersed in the circumferential direction.

[0019] On the other hand, in the conventional concentrate burner, the center line of the concentrate supply pipe 113 intersects with the center line of the concentrate chute 111 as shown in Figure 5. Therefore, the smooth flow of the raw material introduced from the concentrate supply pipe 113 into the concentrate chute 111 is sometimes hindered by the oxygen-fuel burner installed in the center of the concentrate chute 111, or the raw materials supplied from the multiple concentrate supply pipes 111 collide with each other inside the concentrate chute 111, causing localized overcrowding of the raw material inside the concentrate chute 111. In this case, it becomes difficult to uniformly disperse the raw material when it is released into the reaction tower 1a from the lower end opening of the concentrate chute 111, resulting in a significant decrease in combustion efficiency. In contrast, by adopting the concentrate burner 10 according to the embodiment of the present invention described above, it is possible to solve the problems of the conventional concentrate burner.

[0020] As shown in Figure 4(b), when the concentrate chute 11 is viewed from directly above, in each of the four concentrate supply pipes 13, it is preferable that the line segment C connecting the center point A of the center line O1 of the concentrate chute 11 viewed from directly above and the center point B of the upper end of the concentrate supply pipe 13 is deflected at a deflection angle α of 1 to 5 degrees with respect to the center line O2 of the concentrate supply pipe 13. If the deflection angle α is less than 1 degree, most of the concentrate introduced into the concentrate chute 11 from the concentrate supply pipe 13 flows toward the center point A of the concentrate chute 11, and the proportion of the smelting material introduced into the concentrate chute 11 that rotates along the inner wall surface of the concentrate chute 11 is extremely small. Conversely, if the deflection angle α exceeds 5 degrees, it becomes difficult to connect the concentrate supply pipe 13 to the concentrate chute 11, and the smelting material hits the inner wall surface of the concentrate chute 11 too hard, which makes the inner wall surface of the concentrate chute 11 more susceptible to wear.

[0021] In the concentrate burner 10 according to the embodiment of the present invention, as shown in FIG. 3, it is preferable that all four concentrate supply pipes 13 are connected to the concentrate chute 11 from above at an inclination angle β of 45 degrees or more and 75 degrees or less with respect to the horizontal plane. This allows the raw material to be more uniformly dispersed in the circumferential direction when released into the reaction tower 1a from the lower end opening of the concentrate chute 11. If the inclination angle β exceeds 75 degrees, it becomes difficult to connect the concentrate supply pipes 13 to the concentrate chute 11, and most of the raw material introduced into the concentrate chute 11 falls freely straight down without swirling along the inner wall surface of the concentrate chute 11, which is undesirable. Conversely, if the inclination angle β is less than 45 degrees, the initial velocity of the raw material when introduced into the concentrate chute 11 becomes slow, making it difficult for the raw material to swirl within the concentrate chute 11. In this case, most of the raw material also falls freely straight down, which is undesirable.

[0022] 3, in the concentrate burner 10 according to the embodiment of the present invention, it is preferable that the length L of each of the four concentrate supply pipes 13 is at least twice the inner diameter D. If the length L is less than twice the inner diameter D, the smelting raw material cannot flow smoothly in a straight line when it slides down inside the concentrate supply pipe 13, and therefore the proportion of the smelting raw material introduced from the concentrate supply pipe 13 into the concentrate chute 11 that flows in a direction different from the direction of the center line of the concentrate supply pipe 13 increases, which makes it difficult to rotate the smelting raw material inside the concentrate chute 11 or causes interference with the smelting raw material introduced from the other concentrate supply pipes 13, preventing it from flowing down smoothly, which is undesirable.

[0023] In the concentrate burner 10 according to the embodiment of the present invention described above, four concentrate supply pipes 13 are connected to the upper end side wall of the concentrate chute 11, but the number of concentrate supply pipes 13 is not limited to four. In general, the number of concentrate supply pipes is preferably between two and six, which allows the smelting raw material to be introduced into the concentrate chute 11 in a dispersed manner, and therefore allows the smelting raw material to be dispersed more uniformly in the circumferential direction when released from the lower end opening of the concentrate chute 11 into the reaction tower 1a.

[0024] On the other hand, if there is only one concentrate supply pipe 13, it becomes difficult to uniformly distribute the smelting raw materials from the lower end opening of the concentrate chute 11 into the reaction tower 1a. Conversely, if the number of concentrate supply pipes 13 exceeds six, the number of conveying equipment such as conveyors for supplying a fixed amount of concentrate and flux to be installed at the top of each of these concentrate supply pipes 13 also increases, which increases the equipment and maintenance costs and makes it difficult to install such equipment in the limited space at the top of the reaction tower 1a. [Example]

[0025] A concentrate burner according to an embodiment of the present invention, as shown in Fig. 3, was installed at the center of the top of a reaction tower 1a of a copper smelting flash furnace 1 as shown in Fig. 1, and its performance was evaluated. Specifically, the concentrate burner of this embodiment was composed of a vertically extending, generally cylindrical concentrate chute 11, a generally circular tubular oxygen-fuel burner 12 concentrically provided inside the concentrate chute 11, four concentrate supply pipes 13 connected obliquely from above at equal intervals in the circumferential direction at the same height position on the side wall of the upper end of the concentrate chute 11 and at an inclination angle β of 60 degrees relative to the horizontal plane, and a concentrically provided burner cone sleeve 14 with a generally cylindrical upper part and a generally inverted conical lower part, which was arranged to accommodate the entire portion of the concentrate chute 11 except for the upper end.

[0026] The four concentrate supply pipes 13 were connected to the concentrate chute 11 so that none of their center lines O2 intersected the center line O1 of the concentrate chute 11, but were twisted relative to the center line O1 of the concentrate chute 11, and were rotationally symmetrical about the center line O1 of the concentrate chute 11 as a whole when viewed from directly above. Specifically, when the concentrate chute 11 was viewed from directly above, in each of the four concentrate supply pipes 13, a line segment C connecting a center point A of the center line O1 of the concentrate chute 11 as viewed from directly above and a center point B of the upper end of the concentrate supply pipe 13 was connected so that it was deflected at an angle α of 3 degrees with respect to the center line O2 of the concentrate supply pipe 13. Each of the four concentrate supply pipes 13 was a circular pipe whose length L was 2.3 times the inner diameter D.

[0027] For comparison, a comparative concentrate burner was fabricated that was similar to the concentrate burner of the above-described example, except that four concentrate supply pipes 113 were connected to the concentrate chute 111 so that their center lines O2 all intersected the center line O1 of the concentrate chute 111, as shown in Figure 5. First, in the concentrate burners of the example and comparative example, the distribution of concentrate in the concentrate chute when smelting raw material was introduced into the concentrate chute from the four concentrate supply pipes was simulated. The results are shown in Figure 6. From Figure 6, it can be seen that the concentrate burner of the example distributes the smelting raw material more uniformly in the concentrate chute than the concentrate burner of the comparative example.

[0028] Next, for each of the concentrate burners of the above-mentioned examples and comparative examples, the flash smelting furnace was operated while supplying smelting raw materials at a rate of 50 to 70 t / h per concentrate supply pipe. As shown in Figures 7 and 8, six rod-shaped temperature measuring devices 21 to 26 were inserted through an inspection port provided in the burner cone sleeve 14. Each of these temperature measuring devices 21 to 26 had six temperature sensors spaced apart in the axial direction, so a total of 36 temperature sensors were used to measure the temperature distribution within the burner cone sleeve near the outlet of the concentrate burner. Based on the obtained temperature distribution, it was determined whether the concentrate was uniformly dispersed circumferentially from the concentrate chute 11.

[0029] As described above, by measuring the temperature distribution using a total of 36 temperature sensors, it is possible to determine whether the concentrate is uniformly dispersed circumferentially from the concentrate chute 11.The reason for this is that if the temperature distribution inside the burner cone sleeve is not uniform, and if there are locally high-temperature areas, for example, it can be assumed that the concentrate is locally coarse below that area and therefore the radiant heat from below the reaction tower 1a reaches the high-temperature area without being blocked by the concentrate; conversely, if there are locally low-temperature areas, it can be assumed that the concentrate is locally dense below that area and therefore the radiant heat from below the reaction tower 1a is excessively blocked by the concentrate.

[0030] The measurement results of the temperature distribution in the concentrate burner of the above-mentioned Example are shown in Figure 9, and the measurement results of the temperature distribution in the concentrate burner of the Comparative Example are shown in Figure 10. From the results shown in Figure 9, it can be seen that in the concentrate burner of the Example, the temperature generally rises from the center side to the outer periphery side of the burner cone sleeve, but the temperature rise tendency is about the same for all curves, and there is not much temperature variation on the same circumference shown by the dotted line in Figure 8. Therefore, it can be determined that the concentrate burner of the Example uniformly disperses the concentrate in the circumferential direction from the concentrate chute.

[0031] On the other hand, from the results shown in Figure 10, it can be seen that in the concentrate burner of the comparative example, the temperature varies greatly, especially on the outer periphery of the burner cone sleeve, even on the same circumference indicated by the dotted line in Figure 8. Therefore, it can be concluded that the concentrate burner of the comparative example does not uniformly disperse the concentrate in the circumferential direction from the concentrate chute. From the above results, it can be seen that by adopting the concentrate burner of the present invention, the concentrate, which is a smelting raw material, can be uniformly dispersed in the circumferential direction from the concentrate chute into the reactor. [Explanation of symbols]

[0032] 1 Flash-melting furnace 1a Reaction tower (reaction shaft) 1b Settler 1c Uptake 10 Concentrate Burner 11, 111 Concentrate chute 12 Oxy-fuel burner (OF burner) 13, 113 Concentrate supply pipe 14 Burner cone sleeve 15 Reaction gas supply pipe 16 Wind speed regulator 21~26 Temperature measuring device

Claims

1. 1. A concentrate burner installed at the center of the top of a reaction tower of a flash smelting furnace used in the smelting of sulfide ore, the concentrate burner comprising: a substantially cylindrical concentrate chute for discharging smelting raw material, mainly composed of concentrate, into the reaction tower; a substantially circular tubular oxygen-fuel burner installed concentrically inside the concentrate chute; a plurality of concentrate supply pipes connected to the side wall of the upper end of the concentrate chute at the same height position, at equal intervals circumferentially, and diagonally from above; and a burner cone sleeve installed concentrically to accommodate the portion of the concentrate chute other than the upper end, the burner cone sleeve having a substantially cylindrical upper portion and a substantially inverted conical lower portion, which serves as a flow path for reaction gas; wherein the center lines of the plurality of concentrate supply pipes are all in a twisted positional relationship with respect to the center line of the concentrate chute, and the concentrate burner as a whole is rotationally symmetrical about the center line of the concentrate chute when viewed from directly above.

2. 2. The concentrate burner according to claim 1, wherein, when the concentrate burner is viewed from directly above, in each of the plurality of concentrate supply pipes, a line connecting the center point of the concentrate chute and the center point of the upper end of the concentrate supply pipe is deflected at an angle of 1 degree or more and 5 degrees or less with respect to the center line of the concentrate supply pipe.

3. 3. The concentrate burner according to claim 1, wherein the length of the inclined portion of each of the plurality of concentrate supply pipes is at least twice the inner diameter of the inclined portion.

4. 3. The concentrate burner according to claim 1, wherein the number of said plurality of concentrate supply pipes is two or more and six or less.

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