Method for smelting copper concentrate

Abstract

To provide a method for smelting a copper concentrate in which a copper concentrate can be combusted at high strength in a self-melting furnace.SOLUTION: A method for smelting copper concentrate according to the present invention in which a smelting raw material including a copper concentrate and flux, which is supplied from an upper part of a reaction tower, falls toward a settler positioned below the reaction tower and is oxidized by gas for reaction supplied into the reaction tower to form matte and slag, where the average particle diameter of the flux is 40 μm or less.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] Copper sulfide concentrate (copper concentrate) is a powdery solid sulfide with a particle size of 1 μm to 300 μm, and is supplied as a smelting raw material to, for example, a flash smelting furnace (hereinafter referred to as a flash furnace), which is a type of smelting furnace, and is processed into matte with an increased copper content.

[0003] In a flash smelting furnace, copper concentrate, silica sand containing silicon dioxide, and auxiliary fuel such as heavy oil are blown into the reaction shaft along with oxygen-enriched air or other reactive gases delivered separately from a concentrate burner installed at the top of the reaction tower (reaction shaft). Within the reaction shaft, the copper concentrate is oxidized by the reactive gases to produce SO2 gas and two types of solution (matte and slag). The matte and slag fall in the form of droplets down the reaction shaft and are collected in the settler. Within the settler, the matte and slag separate into layers due to their difference in specific gravity, and a matte layer and a slag layer are formed in that order from the bottom of the settler.

[0004] In order to separate the matte and slag well in the settler, it is necessary to increase the fluidity of the slag and promote the settling of the matte, but it is difficult to obtain an optimal slag composition using copper concentrate alone.

[0005] Therefore, for example, a method has been proposed in which, when processing matte from copper concentrate in a flash smelting furnace, a flux such as silica stone, limestone, or iron ore is added as a melting material together with the copper concentrate, and a eutectic composition is used to obtain slag at a temperature lower than the melting point of the oxide (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 6387865 Summary of the Invention [Problem to be solved by the invention]

[0007] However, unless the flux added to the copper concentrate is supplied appropriately, it will not be possible to burn it at a high intensity, but the specific method for adding the flux has not been clarified until now.

[0008] An object of one aspect of the present invention is to provide a method for smelting copper concentrate, which is capable of burning copper concentrate at high intensity in a flash smelting furnace. In this specification, "burning at high intensity" means a reaction in which the maximum combustion temperature during combustion reaches 1,300°C. [Means for solving the problem]

[0009] One embodiment of the method for smelting copper concentrate according to the present invention comprises: A method for smelting copper concentrate, comprising: a smelting raw material, including copper concentrate and flux, supplied from the top of a reaction tower; the raw material being oxidized by a reaction gas supplied into the reaction tower while falling toward a settler located below the reaction tower, to produce matte and slag; In the method for smelting copper concentrate, the flux has an average particle size of 40 μm or less. [Effects of the Invention]

[0010] One aspect of the copper concentrate smelting method according to the present invention can efficiently realize a slag-forming reaction in a flash smelting furnace. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a diagram showing a schematic configuration of a flash smelting furnace to which a copper concentrate smelting method according to an embodiment of the present invention is applied. [Figure 2] FIG. 2 is a diagram showing an example of the results of a high-intensity combustion test in Example 1 of the present invention. [Figure 3] FIG. 10 is a diagram showing an example of the results of a high-intensity combustion test in Example 2 of the present invention. [Figure 4]FIG. 1 is a diagram showing an example of the results of a high-intensity combustion test in Comparative Example 1 of the present invention. [Figure 5] FIG. 10 is a diagram showing an example of the results of a high-intensity combustion test in Comparative Example 2 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present invention will be described in detail. To facilitate understanding of the description, the same components in each drawing will be assigned the same reference numerals, and duplicate explanations will be omitted. The scale of each member in the drawings may differ from the actual scale. In this specification, unless otherwise specified, "to" indicating a range of values ​​means that the values ​​before and after it are included as the lower and upper limits.

[0013] Before describing the copper concentrate smelting method according to the embodiment of the present invention, the configuration of a flash smelting furnace (flash furnace) to which the copper concentrate smelting method according to the embodiment of the present invention is applied will be described.

[0014] <Self-melting furnace> Fig. 1 is a diagram showing the schematic configuration of a flash smelting furnace to which the copper concentrate smelting method according to this embodiment is applied. As shown in Fig. 1, the flash smelting furnace 1 includes a reaction tower (reaction shaft) 10, a settler 20, and an exhaust flue 30. The flash smelting furnace 1 produces two types of solutions, slag and matte (copper grade 60% to 65%), from copper concentrate (copper grade 20% to 30%) and flux, which are smelting raw materials SP supplied into the reaction shaft 10. The slag and matte are separated into layers in the settler 20, and the matte with a high copper grade is recovered.

[0015] The smelting raw material refers to valuable minerals containing the target metal to be extracted, useless minerals (gangue), etc., and examples thereof include copper concentrate, flux, etc. In this embodiment, a case where the smelting raw material includes copper concentrate and flux will be described.

[0016] Copper concentrate is copper ore with a particle size of, for example, 1 μm to 300 μm, and is a powdery solid sulfide (Cu-Fe-S) containing copper, iron, and sulfur. The copper concentrate is oxidized by oxygen-enriched air in the flash smelting furnace 1 and contains iron oxide (FeOx), which is an Fe oxide. The Fe oxide contained in the copper concentrate may be in the form of FeO, Fe3O4, Fe2O3, etc.

[0017] Fluxes include silica (quartz sand), limestone, gypsum, iron ore, SiO2 reagent, CaO reagent, FeO reagent, etc., and are used as welding materials.

[0018] The average particle size of the flux is 40 μm or less, preferably 3 μm or less, and more preferably 0.1 μm to 3 μm. When the average particle size of the flux is 40 μm or less, the reaction interface area between the flux and the iron oxide contained in the copper concentrate increases, and the number of points where the eutectic composition is formed increases. This allows molten oxide slag to be formed in many places, facilitating the movement of substances such as oxygen diffusion, and resulting in high-intensity combustion of the copper concentrate. Furthermore, when the average particle size of the flux is 3 μm or less, higher-intensity combustion is possible, and the higher-intensity combustion can be achieved more quickly, thereby improving the smelting efficiency of the copper concentrate.

[0019] Silica sand is a mineral whose main component is SiO2. Silica sand contains SiO2 and other elements. The composition of silica sand can be determined by chemical analysis and X-ray fluorescence analysis.

[0020] Matte is a mixture containing copper sulfide (Cu2S) and iron sulfide (FeS) as its main components, and is a solution containing a large amount of Cu.

[0021] Slag is a solution containing iron oxide (FeOx) silicate (2FeOx-SiO2) as its main component and containing a large amount of Fe.

[0022] The flash smelting furnace 1 supplies the smelting raw material SP, including copper concentrate and flux, into the reaction shaft 10.

[0023] The reaction shaft 10 is a hollow structure having a cylindrical top with a bottom. The reaction shaft 10 is provided with a concentrate burner 11 at the top 10a. The number of concentrate burners 11 may be one or more.

[0024] The concentrate burner 11 injects the smelting raw material SP, auxiliary fuel such as heavy oil, and separately delivered reactive gas RA such as oxygen-enriched air into the reaction shaft 10 from the top 10a of the reaction shaft 10. The concentrate burner 11 can adjust the flow rate of the smelting raw material SP injected into the reaction shaft 10 by adjusting the flow rate of the reactive gas RA.

[0025] The concentrate burner 11 is provided with a concentrate chute 111 inside, through which the smelting raw material SP is supplied from the outside into the furnace, and an auxiliary fuel burner 112 inside the concentrate chute 111. A concentrate dispersion adjuster (not shown) may be provided inside the concentrate burner 11 so that it can move up and down. A suspension bolt (not shown) may be provided on the outer periphery of the concentrate chute 111, and the concentrate dispersion adjuster (not shown) may be configured to move up and down by moving the suspension bolt (not shown) up and down. By moving the concentrate dispersion adjuster (not shown) up and down relative to the fuel burner and changing its height position, the concentrate burner 11 may adjust the flow rate of the smelting raw material SP being sprayed, and adjust the degree of dispersion of the smelting raw material SP into the reaction shaft 10.

[0026] Furthermore, the concentrate burner 11 may be provided at its tip with a dispersion cone 113 formed in a downwardly diverging shape, and the angle of the dispersion cone 113 may be adjusted. By adjusting the angle of the dispersion cone 113, the concentrate burner 11 may adjust the degree of dispersion of the smelting raw material SP ejected from the concentrate burner 11 into the reaction shaft 10. The angle of the dispersion cone 113 is not particularly limited, and may be any angle as appropriate depending on the type, composition, flow rate, etc. of the smelting raw material SP.

[0027] Furthermore, the reaction shaft 10 may be provided with a gas supply nozzle 12 that supplies a gas such as an inert gas to the side wall 10b. The reaction shaft 10 may change the flow direction of the smelting raw material SP by blowing gas into the reaction shaft 10 using the gas supply nozzle 12 through a vent or the inspection port. The number of gas supply nozzles 12 may be one or more. When multiple gas supply nozzles 12 are provided, the multiple gas supply nozzles 12 may be arranged above and below the side wall 10b, or may be arranged around the axis. The gas supply nozzle 12 may be provided so as to penetrate into the reaction shaft 10 through a vent or inspection port provided in the side wall 10b. Examples of inert gases include N2 gas and Ar gas. The gas supply nozzle 12 may also be used as a blower nozzle for blowing reaction gas.

[0028] The average temperature inside the reaction shaft 10 is set to, for example, about 1300°C. In the reaction shaft 10, the copper concentrate burns while falling inside the reaction shaft 10, and melts and oxidizes, thereby producing two types of solutions (matte and slag) and sulfur dioxide gas.

[0029] The settler 20 is provided below the reaction shaft 10, and one end of the settler 20 (the left side in FIG. 1) is connected to the lower part of the reaction shaft 10. The settler 20 collects the matte and slag generated in the reaction shaft 10. In the settler 20, the matte and slag are separated into layers due to the difference in specific gravity between the matte and slag, and a matte layer and a slag layer are formed in this order from the bottom side of the settler 20. The settler 20 has, on its side, one or more slag holes 21 as slag outlets and one or more matte holes 22 as matte outlets.

[0030] The flue gas duct 30 is formed in a cylindrical shape, one end of which is connected to the top of the other end side (right side in Figure 1) of the settler 20, and the other end of which is connected to the boiler 31, and supplies the high-temperature sulfur dioxide gas generated in the reaction shaft 10 to the boiler 31.

[0031] The electric slag furnace 40 recovers the slag discharged from the settler 20 through the slag hole 21, and separates and recovers the trace amount of matte contained in the slag.

[0032] In the flash smelting furnace 1, copper concentrate, together with silica sand, auxiliary fuel such as heavy oil, and separately delivered reactive gas RA such as oxygen-enriched air, is injected into the reaction shaft 10 from the top 10a of the reaction shaft 10 by a concentrate burner 11. The copper concentrate injected into the reaction shaft 10 is heated by the combustion heat of the fuel, the sensible heat of the reactive gas, and radiant heat from the furnace wall of the reaction shaft 10, and the sulfur content in the raw material reacts with the reactive gas and burns instantaneously. The combustion heat generated by the combustion of the sulfur content in the raw material causes the dissolution and oxidation of copper concentrate particles (copper concentrate particles) in the raw material, and two types of solution (matte (CuS-FeS) and slag (FeOx-SiO2)) and sulfur dioxide gas are produced mainly by the reactions shown in the following formulas (1) and (2). CuFeS2+O2→Cu2S-FeS+FeOx+SO2···(1) FeOx+SiO2→FeOx-SiO2···(2)

[0033] The matte and slag generated in the reaction shaft 10 fall in the form of droplets into the settler 20 and are collected in the settler 20. At this time, droplets consisting of matte and slag (matte and slag droplets) repeatedly collide within the reaction shaft 10, increasing their particle size as they fall. In the settler 20, the matte and slag are separated into layers due to the difference in their specific gravities, and a matte layer and a slag layer are formed in this order at the bottom of the settler 20.

[0034] An appropriate amount of matte in the settler 20 is extracted through the matte hole 22 in response to requests from the converter (not shown), which is the destination of the transport, and the slag in the settler 20 is discharged appropriately through the slag hole 21. The slag discharged through the slag hole 21 is introduced into the electric slag furnace 40, where it is heated and maintained by heat transfer caused by the passage of current through the electrodes 41. Some of the matte in the flash slag layer does not settle to the bottom of the settler 20 but is discharged together with the slag, and during its residence time in the electric slag furnace 40, it further settles to the bottom, forming a matte layer and a slag layer within the electric slag furnace 40 as well. The matte in the electric slag furnace 40 is recovered, and only the slag containing a small amount of copper is discharged from the discharge port 42 to the outside of the furnace.

[0035] In this way, in the flash smelting furnace 1, the copper concentrate is separated into slag and matte, and the copper content in the recovered matte is set to, for example, 60% to 65%.

[0036] In addition, the high-temperature sulfur dioxide gas generated in the reaction shaft 10 is discharged through the settler 20 and the flue 30 and cooled in the boiler 31.

[0037] <Method of smelting copper concentrate> The copper concentrate smelting method according to this embodiment will be described below. The copper concentrate smelting method according to this embodiment will be described when applied to a flash smelting furnace 1 shown in FIG.

[0038] In the copper concentrate smelting method according to this embodiment, copper concentrate and flux are supplied from the top of the reaction shaft 10 .

[0039] Methods for supplying the copper concentrate and the flux include, for example, a method in which the copper concentrate and the flux are mixed and compacted to form tablets, and a method in which the copper concentrate and the flux are supplied separately and collided with each other during the course of movement within the furnace.

[0040] The supply amounts of copper concentrate and flux may be determined from a flow meter (not shown) or the like provided in a supply means (not shown) that supplies copper concentrate and flux to the reaction shaft 10 .

[0041] The copper concentrate and flux supplied from the top of the reaction shaft 10 fall toward the settler 20 located below the reaction shaft 10, reacting with the reaction gas supplied into the reaction shaft 10 to produce matte and slag.

[0042] The reaction gas for burning the copper concentrate is not particularly limited as long as it is a gas heated to a temperature at which the sulfur contained in the copper concentrate can ignite, and examples that can be used include gas heated by combustion of auxiliary fuels such as heavy oil, pulverized coal, liquefied natural gas (LNG), and liquefied petroleum gas (LPG), electrically preheated gas, etc. The temperature of the reaction gas is not particularly limited and can be selected appropriately depending on the purpose, but 570°C is preferred.

[0043] Although the embodiments have been described above, they are presented as examples and the present invention is not limited to the above embodiments. The above embodiments can be implemented in various other forms, and various combinations, omissions, substitutions, modifications, etc. can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the inventions and their equivalents as set forth in the claims. [Example]

[0044] The present embodiment will be described in more detail below with reference to examples, although the present embodiment is not limited to the following examples.

[0045] Example 1 [Slag production] 25 mg of copper concentrate and 4 mg of SiO2 reagent (average particle size of SiO2 less than 3 μm) as a flux were weighed and mixed with a spoon to obtain a mixture. 3 μL of water was added to the mixture and compacted to form tablets. The tablets were placed in a high-temperature air stream set at 570°C with an oxygen concentration of 80% and combusted. In Example 1, a total of six combustion tests were conducted, and high-intensity combustion occurred four times. The results are shown in Figure 2. In Figure 2, the solid line shows the change over time in the case of high-intensity combustion (a reaction in which the maximum combustion temperature during combustion reaches 1,300°C), and the dashed line shows the change over time in the case of non-high-intensity combustion.

[0046] <Example 2> [Slag production] Copper concentrate was combusted in the same manner as in Example 1, except that the average particle size of the SiO2 reagent was changed to less than 40 μm. In Example 2, a total of six combustion tests were conducted, and high-intensity combustion occurred three times. The results are shown in Figure 3. In Figure 3, the solid line shows the change over time in the case of high-intensity combustion, and the dashed line shows the change over time in the case of non-high-intensity combustion.

[0047] <Comparative Example 1> [Slag production] Copper concentrate was combusted in the same manner as in Example 1, except that no flux was added. In Comparative Example 1, a total of six combustion tests were conducted, with one high-intensity combustion occurring. The results are shown in Figure 4. In Figure 4, the solid line shows the change over time in the case of high-intensity combustion, and the dashed line shows the change over time in the case of non-high-intensity combustion.

[0048] <Comparative Example 2> [Slag production] Copper concentrate was combusted in the same manner as in Example 1, except that the average particle size of the SiO2 reagent was changed to 100 μm or more. In Comparative Example 2, a total of six combustion tests were conducted, but no high-intensity combustion occurred. The results are shown in Figure 5. In Figure 5, the dashed line indicates the change over time when high-intensity combustion was not performed.

[0049] From the results of Figures 2 to 5, in Example 2, by supplying an SiO2 reagent of less than 40 μm, the probability of high-intensity combustion occurring is increased compared to the single combustion of copper concentrate to which no SiO2 reagent was added (Comparative Example 1).

[0050] Furthermore, in Example 1, by supplying an SiO2 reagent of less than 3 μm, the probability of high-intensity combustion occurring was higher than in Example 1 and Comparative Example 1, and combustion could be achieved even more quickly and with higher intensity.

[0051] On the other hand, in Comparative Example 2, in which SiO2 reagent of 100 μm or more was supplied, the probability of high-intensity combustion was lower than in Comparative Example 1.

[0052] The embodiments of the present invention are as follows, for example. <1> A method for smelting copper concentrate, comprising: a smelting raw material, including copper concentrate and flux, supplied from the top of a reaction tower; the raw material being oxidized by a reaction gas supplied into the reaction tower while falling toward a settler located below the reaction tower, to produce matte and slag; A method for smelting copper concentrate, characterized in that the flux has an average particle size of 40 μm or less. <2> The flux is at least one of silica stone (quartz sand), limestone, gypsum, iron ore, SiO2 reagent, CaO reagent, and FeO reagent. <1> A method for smelting copper concentrate according to claim 1. <3> The average particle size of the flux is 3 μm or less. <1> or <2> A method for smelting copper concentrate according to claim 1. <4> The temperature of the reaction gas is 570°C or higher. <1> from <3> The method for smelting copper concentrate according to any one of the preceding claims. [Explanation of symbols]

[0053] 1 Flash-melting furnace 10 Reaction tower (reaction shaft) 11 Concentrate burner 20 Settler 30 Flue flue 40 Electric smelting furnace

Claims

1. A method for smelting copper concentrate, comprising: a smelting raw material, including copper concentrate and flux, supplied from the top of a reaction tower, falls toward a settler located below the reaction tower, and is oxidized by a reaction gas supplied into the reaction tower to produce matte and slag, A method for smelting copper concentrate, characterized in that the flux has an average particle size of 40 μm or less.

2. The flux is composed of silica (quartz sand), limestone, gypsum, iron ore, SiO ２ 2. The method for smelting copper concentrate according to claim 1, wherein the reagent is at least one of a CaO reagent and a FeO reagent.

3. 3. The method for smelting copper concentrate according to claim 1, wherein the flux has an average particle size of 3 μm or less.

4. 3. The method for smelting copper concentrate according to claim 1, wherein the temperature of the reaction gas is 570°C or higher.

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