Method for smelting copper concentrate

Abstract

To provide a method for smelting a copper concentrate in which a copper concentrate can be efficiently combusted at high strength while flux is added to promote formation of slag in combustion of a copper concentrate.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. The method has: a step of adding the flux to the copper concentrate and combusting the copper concentrate to obtain a melt; and a step of adding the flux to the melt to obtain slag of an objective composition. A mixture ratio (Fe / SiO2) between the amount of iron (Fe) included in the copper concentrate and the amount of silicon dioxide (SiO2) included in the flux added in the step of obtaining the melt is 2 to 5.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). The reaction shaft is heated by the combustion heat of the auxiliary fuel and radiant heat from the furnace walls. In the reaction shaft, the copper concentrate is oxidized by the reactive gases to produce SO2 gas and two solutions (matte and slag). The matte and slag fall in the form of droplets down the reaction shaft and are collected in a settler. In the settler, the matte and slag separate into layers due to their difference in specific gravity, forming a matte layer and a slag layer, 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, by adding flux, part of the combustion heat of the copper concentrate is used to heat the flux, which lowers the temperature of the copper concentrate and reduces the combustion intensity.If an excessive amount of flux is supplied, the copper concentrate will fall into the settler without completing the reaction and will be sent to the next process.

[0008] Therefore, in the combustion process of copper concentrate smelting, it is necessary to add an appropriate amount of flux that does not inhibit the combustion of copper concentrate.

[0009] An object of one aspect of the present invention is to provide a method for smelting copper concentrate, which can efficiently combust copper concentrate at high intensity while promoting the formation of slag during combustion of the copper concentrate by adding a flux. In this specification, "combustion at high intensity" means a reaction in which the maximum combustion temperature during combustion reaches 1,300°C. [Means for solving the problem]

[0010] 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, 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, adding the flux to the copper concentrate and burning the copper concentrate to obtain a melt; and adding the flux to the molten material to obtain a slag having a desired composition. This is a method for smelting copper concentrate, wherein the mixing ratio (Fe / SiO2) of the amount of iron (Fe) contained in the copper concentrate to the amount of silicon dioxide (SiO2) contained in the flux added in the step of obtaining the melt is 2 to 5. [Effects of the Invention]

[0011] One embodiment of the copper concentrate smelting method according to the present invention can efficiently combust copper concentrate at high intensity while promoting the formation of slag during the combustion of the copper concentrate by adding flux. [Brief explanation of the drawings]

[0012] [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. [Figure 6] FIG. 10 is a diagram showing an example of the results of a high-intensity combustion test in Comparative Example 3 of the present invention. [Figure 7] FIG. 1 is a diagram showing an example of the results of a high-intensity combustion test when a CuFeS2 reagent is combusted in an example of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments of the present invention will be described in detail. To facilitate understanding of the description, the same components in each drawing are denoted by the same reference numerals, and duplicate explanations will be omitted. The scale of each component 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.

[0014] 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.

[0015] <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.

[0016] 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.

[0017] 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.

[0018] Fluxes include silica (quartz sand), limestone, gypsum, iron ore, SiO2 reagent, CaO reagent, FeO reagent, etc., and are used as welding materials.

[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, with a high iron content.

[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 method for smelting copper concentrate according to this embodiment, copper concentrate and flux are supplied from the top of the reaction shaft 10. Specifically, the method includes a step of adding the flux to the copper concentrate and combusting the copper concentrate to obtain a melt, and a step of adding the flux to the melt to obtain slag with a target composition.

[0039] Furthermore, in the copper concentrate smelting method according to this embodiment, the mixing ratio (Fe / SiO2) of the amount of iron (Fe) contained in the copper concentrate to the amount of silicon dioxide (SiO2) contained in the flux added in the step of obtaining the melt is 2 to 5. By setting the mixing ratio (Fe / SiO2) of the amount of iron (Fe) contained in the copper concentrate to the amount of silicon dioxide (SiO2) contained in the flux to 2 to 5, it is possible to minimize the decrease in reaction temperature due to the addition of flux, generate a melt, and promote the reaction of the copper concentrate. Furthermore, by supplying the remaining required amount of flux to the high-temperature melt after the reaction and causing it to react, it is possible to efficiently generate slag of the desired composition.

[0040] 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.

[0041] 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 .

[0042] 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 a melt.

[0043] Thereafter, flux that is insufficient relative to the control value of the mixture ratio (Fe / SiO2) of the melt in the settler 20 is supplied from the concentrate burner 11 or the reaction shaft 10, and after reaction, it is caused to collide with and react with the melt to produce matte and slag.

[0044] 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.

[0045] 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]

[0046] 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.

[0047] Example 1 [Slag production] 25 mg of copper concentrate and 4 mg of SiO2 reagent as flux were weighed and mixed with a spoon to obtain a mixture. 3 μL of water was added to the mixture, which was then compacted to form a tablet. The tablet was placed in a high-temperature air stream set at 570°C with an oxygen concentration of 80%, and burned to obtain a melt. The mixture ratio of iron (Fe) to flux (SiO2) (Fe / SiO2) was 4.4, and the maximum temperature during combustion was 1,475°C. The results are shown in Figure 2.

[0048] <Example 2> [Slag production] Copper concentrate was combusted in the same manner as in Example 1, except that the mixing ratio (Fe / SiO2) of iron (Fe) and flux (SiO2) was changed to 2.1. The maximum temperature during combustion was 1,768°C or higher, exceeding the maximum temperature measurable with an R-type thermocouple. The results are shown in Figure 3.

[0049] <Comparative Example 1> [Slag production] Copper concentrate was combusted in the same manner as in Example 1, except that the mixing ratio (Fe / SiO) of iron (Fe) and flux (SiO) was changed to 1.9. The maximum temperature during combustion was 1,093°C. The results are shown in Figure 4.

[0050] <Comparative Example 2> [Slag production] Copper concentrate was combusted in the same manner as in Example 1, except that the mixing ratio (Fe / SiO) of iron (Fe) and flux (SiO) was changed to 1.7. The maximum temperature during combustion was 1,085°C. The results are shown in Figure 5.

[0051] <Comparative Example 3> [Slag production] Copper concentrate was combusted in the same manner as in Example 1, except that the mixing ratio (Fe / SiO) of iron (Fe) and flux (SiO) was changed to 1.4. The maximum temperature during combustion was 988°C. The results are shown in Figure 6.

[0052] 2 to 6, it can be seen that the combustion strength was high when the mixing ratio (Fe / SiO2) was 2 to 5. On the other hand, when the mixing ratio (Fe / SiO2) was 2 or less (i.e., when excessive SiO2 was added), the combustion strength decreased.

[0053] Furthermore, in Example 1, the copper concentrate was changed to CuFeS2 reagent, and the combustion test was conducted with the mixing ratio (Fe / SiO2) changed in the range of 1 to 10. The results of the maximum temperature when this was done are shown in Figure 7. Note that Figure 7 shows the results when the ratio of copper (Cu) contained in the CuFeS2 reagent and the ratio of oxygen as a reactive gas were changed. The results in Figure 7 also show that when the mixing ratio (Fe / SiO2) was 2 to 5, the combustion intensity was high.

[0054] 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, 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, adding the flux to the copper concentrate and burning the copper concentrate to obtain a melt; and adding the flux to the molten material to obtain a slag having a desired composition. A method for smelting copper concentrate, characterized in that the mixing ratio (Fe / SiO2) of the amount of iron (Fe) contained in the copper concentrate to the amount of silicon dioxide (SiO2) contained in the flux added in the step of obtaining the melt is 2 to 5. <2> The flux is at least one of silica stone, limestone, gypsum, iron ore, SiO2 reagent, CaO reagent, and FeO reagent. <1> A method for smelting copper concentrate according to claim 1. <3> The temperature of the reaction gas is 570°C or higher. <1> or <2> A method for smelting copper concentrate according to claim 1. [Explanation of symbols]

[0055] 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, adding the flux to the copper concentrate and burning the copper concentrate to obtain a melt; and adding the flux to the molten material to obtain a slag having a desired composition. The amount of iron (Fe) contained in the copper concentrate and the amount of silicon dioxide (SiO ) contained in the flux added in the step of obtaining the melt ２ ) and the mixing ratio (Fe / SiO ２ ) is 2 to 5.

2. The flux is made of silica stone, 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 temperature of the reaction gas is 570°C or higher.

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