JP6970044B2 - How to operate a copper smelting furnace - Google Patents

Description

The present invention relates to an operating method for a copper smelting furnace.

In recent years, the raw materials processed by copper smelting are shifting from raw materials mainly composed of copper concentrate to raw materials with an increased ratio of highly profitable raw materials (high margin raw materials). However, it was not able to cope with the deterioration of operations (deterioration of slag loss). The treatment of high-margin raw materials _{increases the amount of magnetite (Fe 3} O ₄ ) -based, sparingly meltable material produced in the furnace. However, the mechanism has not been specified, and only the ex post facto response after the deterioration of the furnace condition occurred. In addition, in the situation where the raw material composition cannot be changed, there is no other effective solution, so long-term operational deterioration is inevitable, and profits are greatly deteriorated.

As a prior art, a method for dealing with filling in a furnace, an increase in an intermediate layer, etc. caused by _{slag peroxide (Fe 3} O ₄ or the like) caused by deterioration of a solid air reaction on a reaction shaft is disclosed (for example, Patent Document 1). reference). However, in addition to being a post-mortem technology, the technology is less effective under operating conditions where high-margin raw materials have increased, and is not a sufficient countermeasure.

Therefore, by mixing an Fe metal source containing Fe metal such as pig iron with the starting material and charging it into the reaction shaft, the oxidation of FeO is suppressed by the reducing effect of Fe metal, and the allowable concentration _{of Al 2} O _{3 in the slag is reduced.} A technique for increasing the size and suppressing the formation of a composite oxide (FeAl ₂ O ₄ ) and Fe ₃ O ₄ is disclosed (see Patent Document 2).

Japanese Unexamined Patent Publication No. 2005-8965 Japanese Unexamined Patent Publication No. 2017-155260

However, the effect of reducing the oxygen partial pressure is limited in the Fe metal source. Due to the rising trend of S / Cu, which is a raw material for copper smelting, the amount of fuel used in the furnace such as carbon is also decreasing. Therefore, it is difficult to sufficiently reduce the oxygen partial pressure of the slag. _{In this case, it is easily affected by the Al 2} O ₃ grade in the raw material for copper smelting, and slag loss is likely to occur.

In view of the above problems, it is an object of the present invention to provide a method for operating a copper smelting furnace capable of suppressing slag loss.

The method for operating a copper smelting furnace according to the present invention is a method for operating a copper smelting furnace that produces mats and slag by injecting a reaction gas into a copper smelting furnace together with a starting material containing copper concentrate, at 1200 ° C. _{When the Al 2} O ₃ ratio in the slag at 1300 ° C. or lower is 4.5 mass% or more and 10 mass% or less , the carbonaceous material is put into the copper smelting furnace to reduce the oxygen partial pressure of the slag. It is characterized by controlling to ^{10-8.0 atm or less.}

In the operation method of the copper smelting furnace, 0.5 mass% or more of the charcoal material may be added to the starting raw material.

In the operation method of the copper smelting furnace, the S / Cu in the copper concentrate may be 0.8 to 1.5.

In the operation method of the copper smelting furnace, the oxygen partial pressure of the slag may be controlled to ^{10-9.5 atm or more.}

According to the operation method of the copper smelting furnace according to the present invention, slag loss can be suppressed.

It is a schematic diagram of the flash smelting furnace used in one Embodiment of a copper smelting method. (A) and (b) are copper smelting process diagrams using a flash smelting furnace. It is a figure which shows the relationship between the Al ₂ O ₃ grade in a slag and the Fe ₃ O _{4 grade in a slag.} It is a figure which shows the relationship between _{the Al 2} O ₃ grade in a slag and a slag loss. 1250 ° C., a diagram showing the relationship between _Al 2 _{O 3} grade and the partial pressure of oxygen in _{FeO-33mass% SiO 2 -Al 2} O 3 -2mass% CaO-1mass% MgO slag. FIG. 5 is a diagram showing the results of equilibrium calculation regarding the relationship between _{Al 2} O _{3 grade and temperature of the same slag as in FIG.} When slag oxygen partial pressure was added carbonaceous material such that ¹⁰ -8.0 atm or less, a diagram showing the relationship between _Al 2 _{O 3} grade and Suragurosu.

Hereinafter, the best mode for carrying out the present invention will be described.

(Embodiment)
FIG. 1 is a schematic view of a flash smelting furnace 100 used in one embodiment of a copper smelting method. As shown in FIG. 1, the flash smelting furnace 100 has a structure in which a reaction shaft 10, a settler 20, and an uptake 30 are arranged in order. A concentrate burner 40 is provided on the upper part of the reaction shaft 10.

2 (a) and 2 (b) are copper smelting process diagrams using the flash smelting furnace 100. First, as illustrated in FIG. 2A, the reaction shaft containing oxygen is mixed with copper concentrate, solvent, recycled raw material, etc. (hereinafter, these solid raw materials are referred to as starting raw materials) from the concentrate burner 40. It is thrown into 10. As a result, the copper concentrate undergoes an oxidation reaction according to the following reaction formula (1) or the like, and is separated into a mat 50 and a slag 60 at the bottom of the reaction shaft 10 as illustrated in FIG. 2 (b). In the following reaction formula _{(1), Cu 2 S ·} FeS corresponds to the main component of the mat, 2FeO · SiO ₂ corresponds to the main component of the slag. Silicic acid ore or the like is used as the solvent.
CuFeS ₂ + SiO ₂ + O ₂ → Cu ₂ S ・ FeS + 2FeO ・ SiO ₂ + SO ₂ + heat of reaction (1)

As the reaction gas, for example, oxygen-enriched air can be used. Oxygen-enriched air is air that has a higher oxygen concentration than the natural atmosphere. For example, oxygen-enriched air has an oxygen concentration of 60% to 90% by volume. Thereby, a sufficient oxidation reaction can be caused in the copper concentrate.

The components of the copper concentrate are, for example, Cu: 24 mass% to 30 mass%, Fe: 23 mass% to 28 mass%, S: 29 mass% to 35 mass%, SiO ₂ : 7 mass% to 12 mass%, Al ₂ O ₃ : 3 mass% to. It is 7 mass%. Further, S / Cu is in the range of 0.8 to 1.5, 1.0 to 1.4 and the like. In addition, S / Cu is in a high range of 1.25 due to recent trends.

With the recent decline in Cu grade in copper concentrate, the amount of gangue components such as _{Al 2} O _{3 is increasing.} Al ₂ O ₃ forms a FeO composite oxide (FeAl ₂ O _4), dissolved in a solid magnetite _(Fe 3 _{O 4).} In this case, _{the presence of Al 2} O ₃ produces solid magnetite spinel (hereinafter referred to as solid spinel) and stabilizes _{Fe 3} O _4. As a result, the amount _{of Fe 3} O _{4 increases in the molten metal.} FIG. 3 is a diagram showing the relationship between _{the Al 2} O ₃ grade in the slag 60 and the Fe ₃ O _{4 grade in the slag 60.} As shown in FIG. 3, it has been confirmed that as _{the Al 2} O ₃ grade in the slag 60 increases, the Fe ₃ O _{4 grade in the slag 60 also increases.} According to the result of the regression analysis based on the result of FIG. 3, when the Al ₂ O ₃ grade in the slag 60 _{is 4.5 mass% or more, the Fe 3} O ₄ grade in the slag 60 is 10 mass% or more. The temperature of the slag 60 is 1200 ° C. or higher and 1300 ° C. or lower.

The presence of solid spinel reduces the fluidity of the slag 60 and increases the amount of suspended mat in the slag 60, resulting in increased slag loss. FIG. 4 is a diagram showing the relationship between _{the Al 2} O ₃ grade in the slag 60 and the slag loss. The vertical axis of FIG. 4 represents a numerical value obtained by normalizing the slag loss from 0 to 100. As shown in FIG. 4, it has been confirmed that the _{slag loss increases as the Al 2} O _{3 grade in the slag 60 increases.} This is because the _{grade of Al 2} O ₃ in the slag 60 is increased, so that the grade of the solid spinel in the slag 60 is increased. According to the result of the regression analysis based on the result of FIG. 4, when the Al ₂ O ₃ grade in the slag 60 is 4.5 mass% or more, the slag loss is 1.0% or more. _{From the results of FIGS. 3 and 4, it can be derived that the Fe 3} O ₄ grade in the slag 60 needs to be 10 mass% or less in order to reduce the slag loss to 1.0% or less.

5, 1250 ° C., a diagram showing the relationship between _Al 2 _{O 3} grade and the partial pressure of oxygen in _{FeO-33mass% SiO 2 -Al 2} O 3 -2mass% CaO-1mass% MgO slag. Figure 6 is a diagram showing the equilibrium calculation results of the relationship between the Al ₂ O ₃ grade and temperature syngeneic slag.

When the oxygen partial pressure in the slag 60 was actually measured for the slag having the composition shown in Table 1, it was ^{10-7.7 atm at a value standardized at 1250 ° C.} Further, since the Al ₂ O ₃ grade in the slag 60 is 4.55 mass%, it is plotted at the position of “●” in FIG. Moreover, when the temperature of the slag 60 was measured, it was 1260 ° C. Therefore, it is plotted at the position of “●” in FIG. The slag of the composition in Table 1 is located in the region of molten slag, but near the boundary with the "molten slag + solid spinel" region. Solid spinel in the slag 60, FeO · (Fe, _Al) are mainly of 2 _{O 3,} made to be present in the slag 60 and cause the slag fluidity deteriorates. Therefore, it is preferably located farther from the boundary line with the "molten slag + solid spinel" region.

When the Al ₂ O ₃ grade is 10 mass% or less, a slight increase in oxygen partial pressure facilitates the formation of solid spinel. Even with the slag in Table 1, when the oxygen partial pressure rises, it enters the region of "molten slag + solid spinel". On the contrary, by lowering the oxygen partial pressure, as shown in FIG. 6, the melting point of the slag is lowered and the slag becomes highly fluid, and the reduction of the suspended Cu loss can be expected to reduce the slag loss.

From the results of FIG. 6, when _{the Al} 2 _{O 3} grade slag 60 is equal to or greater than 4.5Mass%, the oxygen partial pressure in the slag 60 With ¹⁰ -8.0 atm or less, sufficient slag 60 Can be retained in the molten slag area. For example, even if the temperature of the slag 60 is about 1250 ° C., the slag 60 can be kept in the molten slag region. Therefore, in the present embodiment, the oxygen partial pressure of the slag 60 ^{is controlled to 10-8.0} atm or less.

Therefore, as in Patent Document 2, it is conceivable to reduce the oxygen partial pressure by coexisting the molten metal and Fe metal. However, the reducing effect of Fe metal is limited, and it is difficult to reduce ^{the oxygen partial pressure of the slag 60 to 10-8.0 atm or less.} In particular, the S / Cu of copper concentrate tends to increase, and heat is obtained by the oxidation reaction of copper concentrate, so that the amount of fuel such as carbon used is also reduced. For example, S / Cu in copper concentrate has a high value such as 1.0 to 1.4. Therefore, it is difficult to reduce the oxygen partial pressure of the slag 60 to ^{10-8.0 atm or less.} Further, if a large amount of Fe metal is charged into the reaction shaft 10, the bottom coating layer may be reduced and the bottom temperature may rise.

Therefore, in the present embodiment, when the Al ₂ O ₃ grade in the slag 60 is 4.5 mass% or more, the oxygen partial pressure is ^{controlled to 10-8.0} atm or less by adding the carbonaceous material. _{Whether or not the Al 2} O ₃ grade in the slag 60 is 4.5 mass% or more can be grasped in advance from the composition of the starting raw material. Therefore, the charcoal material can be mixed with the starting material in advance. Alternatively, the charcoal material may be added after the starting material is added. For example, by a 0.5 mass% or more of carbonaceous material addition rate vs. starting material, the oxygen partial pressure can be below ¹⁰ -8.0 atm. On the other hand, if the oxygen partial pressure is too low, the distribution ratio of impurities to the mat 50 may increase. In this case, there is a concern that the increase in the impurity grade in the copper anode obtained by copper smelting may affect the electrolytic operation and the impurity standard of electrolytic copper may be exceeded. Therefore, the oxygen partial pressure of the slag 60 ^{is preferably 10-9.5} atm or more. The addition ratio of the charcoal material is (charcoal material addition amount) / (charcoal material addition amount + starting material input amount) × 100 mass%.

(Example)
The copper smelting furnace was operated according to the above embodiment. The amount of carbonaceous material added was such that the partial pressure of oxygen in the slag 60 was ^10-8.0 atm or less. As a result, by setting the carbonaceous material addition amount 0.5 mass% or more with respect to the raw material for copper smelting, the oxygen partial pressure in the slag 60 is ¹⁰ -8.0 atm or less were confirmed. The temperature of the slag 60 was controlled to 1240 ° C to 1300 ° C.

7, when the oxygen partial pressure in the slag 60 was added carbonaceous material such that ¹⁰ -8.0 atm or less, a diagram showing the relationship between _Al 2 _{O 3} grade and Suragurosu. The vertical axis of FIG. 7 represents a numerical value obtained by normalizing the slag loss from 0 to 100, as in FIG. 4. The regression line of FIG. 4 is drawn for comparison with FIG. As shown in FIG. 7, by comparing with this regression line, it can be seen that the slag loss is reduced when the carbonaceous material is added. This, _Al 2 _{O 3} grade slag 60 is even more 4.5Mass%, it was the oxygen partial pressure in the slag 60 and ¹⁰ -8.0 atm or less, formation of solid spinel is inhibited It is thought that this is because of the slag.

Although the examples of the present invention have been described in detail above, the present invention is not limited to the specific examples thereof, and various modifications and variations are made within the scope of the gist of the present invention described in the claims. It can be changed.

10 reaction shaft 20 setler 30 uptake 40 concentrate burner 50 mat 60 slag 100 flash smelting furnace

Claims (4)

In the operation method of a copper smelting furnace that produces mats and slag by putting a reaction gas into a copper smelting furnace together with a starting material containing copper concentrate.
_{When the Al 2} O ₃ ratio in the slag of 1200 ° C. or higher and 1300 ° C. or lower is 4.5 mass% or more and 10 mass% or less , the oxygen content of the slag is increased by putting the carbonaceous material into the copper smelting furnace. A method for operating a copper smelting furnace, characterized in that the pressure is ^{controlled to 10-8.0 atm or less.} The method for operating a copper smelting furnace according to claim 1, wherein the charcoal material is added in an amount of 0.5 mass% or more to the starting raw material. The method for operating a copper smelting furnace according to claim 1 or 2, wherein the S / Cu in the copper concentrate is 0.8 to 1.5. The method for operating a copper smelting furnace according to any one of claims 1 to 3, wherein the oxygen partial pressure of the slag ^{is controlled to 10-9.5 atm or more.}

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