Method for recovering valuable metals from waste containing Mo, Ni, and V

Abstract

To provide a recovery method of valuable metals from Mo, Ni, and V-containing waste capable of preventing deterioration of solubility of a heating furnace, even if a content of Al2O3 in the Mo, Ni and V-containing waste becomes large.SOLUTION: A recovery method of valuable metals from a Mo, Ni, and V-containing waste comprises: a first step (S1) of roasting waste containing Mo, Ni, and V; a second step (S3) of charging at least roasted ore, a reducing agent, and lime into an electric furnace and melting them to produce metal and a V-containing slag; and a third step (S4) of reducing the V-containing slag separated from the metal with a reducing agent to produce an Fe-V alloy and V-free slag, wherein in the second step (S3), roasted ore, reducing agent, and lime are charged into an electric furnace in multiple batches, and a blending ratio of lime (weight of lime / weight of roasted ore) is increased, and thereafter the blending ratio of the lime is reduced to perform a gradient blending of lime.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for recovering valuable metals from Mo, Ni, V-containing waste.

Background Art

[0002] In fields such as oil refining and gas treatment industries, a desulfurization catalyst is provided in the refining process. In the desulfurization catalyst, Mo, Ni, V, etc. are condensed in the form of oxides. Therefore, Mo, Ni, V, etc. are recovered from the used desulfurization catalyst.

[0003] Also, for example, in a power plant, a boiler for burning petroleum-based fuels such as heavy oil is provided. Ni, V, etc. are also condensed in the form of oxides in the boiler sludge deposited at the bottom of the boiler and the boiler ash captured by the dust collector. Therefore, Ni, V, etc. are recovered from the boiler sludge and boiler ash.

[0004] As a method for recovering valuable metals from Mo, Ni, V-containing waste such as these used desulfurization catalysts, boiler sludge, and boiler ash, the recovery method described in Patent Document 1 is known. This recovery method includes a first step of roasting the Mo, Ni, V-containing waste, a second step of charging the roasted ore, a reducing agent, and lime into a heating furnace and melting them to produce a metal (for example, an Fe-Mo-Ni-based alloy) and a V-containing slag, and a third step of reducing the V-containing slag separated from the metal with a reducing agent to produce an Fe-V-based alloy and a V-removed slag. According to this method, oxides of V, Ni, Mo in the Mo, Ni, V-containing waste can be recovered as an Fe-Mo-Ni-based alloy, an Fe-V-based alloy, etc.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

[0006] However, the Al2O3 content in Mo, Ni, V-containing waste can sometimes increase. For example, if the amount of spent desulfurization catalyst in the Mo, Ni, V-containing waste increases and the amount of boiler sludge and boiler ash decreases, the Al2O3 content will increase. When Mo, Ni, V-containing waste with a high Al2O3 content is charged into a heating furnace after roasting, the viscosity of the V-containing slag increases, causing a foaming phenomenon in the V-containing slag (a phenomenon in which the V-containing slag foams up due to poor gas release), making it impossible to continuously charge the raw materials. This presents a problem of reduced solubility in the heating furnace.

[0007] To ensure smooth operation of the heating furnace, Patent Document 1 discloses increasing the amount of lime charged into the heating furnace, that is, charging lime so that the CaO / Al2O3 ratio of the V-containing slag is 0.6 to 1.5, thereby lowering the melting point of the V-containing slag to 1350°C to 1550°C (see Patent Document 1,

[0015] ).

[0008] However, since lime is difficult to dissolve, increasing the amount of lime charged into the heating furnace creates new problems, such as lime remaining undissolved after the reduction process is complete, or lime segregating (lime accumulating near the furnace opening).

[0009] The present invention aims to solve the above problems and to provide a method for recovering valuable metals from Mo, Ni, V-containing waste that can prevent a decrease in the solubility of the heating furnace even when the Al2O3 content in the Mo, Ni, V-containing waste is high. [Means for solving the problem]

[0010] To solve the above problems, one aspect of the present invention is a method for recovering valuable metals from Mo, Ni, V-containing waste, comprising: a first step of roasting Mo, Ni, V-containing waste; a second step of charging at least roasted ore, a reducing agent, and lime into a heating furnace and melting them to produce metal and V-containing slag; and a third step of reducing the V-containing slag separated from the metal with a reducing agent to produce an Fe-V alloy and V-free slag, wherein in the second step, the roasted ore, the reducing agent, and the lime are charged into the heating furnace in multiple stages, increasing the lime mixing ratio (weight of lime / weight of roasted ore), and then decreasing the lime mixing ratio, thereby performing a gradient mixing of lime. [Effects of the Invention]

[0011] According to the present invention, since the difficult-to-dissolve lime is charged into the heating furnace early, even if the Al2O3 content in the Mo, Ni, and V-containing waste increases, the foaming phenomenon of V-containing slag, undissolved lime, and segregation of lime can be suppressed. Therefore, a decrease in the solubility of the heating furnace can be prevented. [Brief explanation of the drawing]

[0012] [Figure 1] This is a process diagram of a method for recovering valuable metals from Mo, Ni, V-containing waste according to one embodiment of the present invention. [Figure 2] This is an illustrative diagram of the inside of an electric furnace, from the time raw materials are charged into the furnace until the V-containing slag is dispensed. [Figure 3] This figure shows an example of the raw material formulation for the example. [Modes for carrying out the invention]

[0013] Hereinafter, an embodiment of the present invention for recovering valuable metals from Mo, Ni, V-containing waste will be described with reference to the attached drawings. However, the present invention for recovering valuable metals from Mo, Ni, V-containing waste can be implemented in various forms and is not limited to the embodiments described herein. This embodiment is provided with the intention that those skilled in the art will be able to fully understand the invention by making full disclosures in the specification.

[0014] Figure 1 shows a process diagram of a method for recovering valuable metals from Mo, Ni, and V-containing waste according to one embodiment of the present invention. In this embodiment, the method for recovering valuable metals uses Mo, Ni, and V-containing waste as raw materials, and recovers the oxides of V, Ni, and Mo in the Mo, Ni, and V-containing waste as Fe-Mo-Ni alloys and Fe-V alloys.

[0015] The method for recovering valuable metals according to this embodiment comprises a first step (S1) of roasting Mo, Ni, and V-containing waste, a second step (S3) of charging at least roasted ore, a reducing agent, and lime into a heating furnace such as an electric furnace and melting them to produce metal (Fe-Mo-Ni alloy) and V-containing slag, and a third step (S4) of reducing the V-containing slag separated from the metal with a reducing agent to produce Fe-V alloy and V-free slag.

[0016] Mo, Ni, V-containing waste includes spent catalysts, boiler sludge, boiler ash, and ammonium metavanadate obtained by wet alkaline treatment of boiler ash. These Mo, Ni, V-containing wastes contain valuable metals such as Mo, Ni, and V in the form of oxides. When the amount of spent desulfurization catalyst in the Mo, Ni, V-containing waste increases and the amount of boiler sludge and boiler ash decreases, the Al2O3 content in the waste increases. According to the method for recovering valuable metals in this embodiment, even if the Al2O3 content in the waste increases, it is possible to prevent a decrease in the solubility of the heating furnace.

[0017] The following describes each step of the method for recovering valuable metals according to this embodiment in detail. First, the Mo, Ni, V-containing waste is roasted (S1). For roasting, for example, a rotary kiln is used. The Mo, Ni, V-containing waste contains moisture, C content, and S content. By roasting the Mo, Ni, V-containing waste in a rotary kiln, the moisture in the Mo, Ni, V-containing waste evaporates, and the C content and S content are thermally decomposed and removed as CO2 and SO2. Next, the roasted ore is crushed by a crusher or the like and granulated by a pelletizer or the like (S2).

[0018] Next, the granulated roasted ore, reducing agent, and lime are charged into an electric furnace as raw materials and melted (S3). As the reducing agent, at least one of carbon materials such as coke, Al, and Si can be used. In this embodiment, a carbon material is used. Lime is CaO. Dust pellets, splash metal, etc. (not shown) may be added to the raw materials.

[0019] When the raw materials are melted in the electric furnace, the Mo oxide and Ni oxide in the roasted ore are reduced, and a metal (Fe-Mo-Ni-based alloy) and V-containing slag are generated. The V oxide in the roasted ore is not reduced and migrates to the V-containing slag.

[0020] Figure 2 shows an image inside the electric furnace 1 from when the raw materials are charged into the electric furnace 1 until the V-containing slag is tapped (one tap of the V-containing slag). The second step will be described in detail while referring to this Figure 2.

[0021] The raw materials are charged into the electric furnace 1 in a time series in multiple batches, for example, 4 to 22 batches. That is, into the electric furnace 1, for example, using a trolley, the raw materials of the first trolley, the second trolley, the third trolley..., the thirteenth trolley are charged. In this embodiment, an example of charging the raw materials in 13 batches will be described. The raw materials for each trolley include roasted ore, carbon material, and lime (see Figure 1). The roasted ore is evenly blended. That is, the blending amount (weight) of the roasted ore is the same for each trolley. The carbon material is also evenly blended. That is, the blending ratio (weight of the carbon material / weight of the roasted ore) is the same for each trolley.

[0022] Lime is proportioned in a sloping manner. That is, the proportion of lime (weight of lime / weight of roasted ore) is increased first and then decreased. For example, the proportion of lime in the first half of the first to the sixth trucks is increased, and the proportion of lime in the second half of the seventh to the thirteenth trucks is decreased. Also, for example, the initial proportion of lime in the first truck is the highest, the proportion of lime in the first half of the second to the sixth trucks is the second highest, and the proportion of lime in the second half of the seventh to the thirteenth trucks is the lowest.

[0023] Figure 2(a) shows the state where the raw materials 5 from the first to the third trucks are charged. 2 is the remaining molten slag (V-containing slag) from the previous tap, 3 is the metal, and 4 is the soil from the previous tap. The raw materials from the first to the third trucks are charged in one batch to cover the molten surface. Since V-containing slag is being discharged from the previous tap, the molten heat is decreasing. Therefore, when charging the raw materials from the first to the third trucks, a submerged operation is performed to bury the electrode 6 in the raw materials 5 to heat the raw materials 5 with the molten heat. When the molten heat is insufficient, Al may be added to generate heat.

[0024] Figure 2(b) shows the state where the raw materials 5 from the fourth to the sixth trucks are charged. Even in this state, a submerged operation is performed to bury the electrode 6 in the raw materials 5 to heat the raw materials 5 with the molten heat. When the raw materials 5 are melted by the submerged operation, the Mo oxide and Ni oxide in the roasted ore are reduced, increasing the metal 3 and the V-containing slag 2.

[0025] Figure 2(c) shows the state where the raw materials 5 from the seventh to the thirteenth trucks are charged. Figure 2(d) shows the state where the raw materials are melted. As shown in Figure 2(c), when the raw materials 5 are melted by the submerged operation, more metal 3 and V-containing slag 2 are generated, so the metal 3 and V-containing slag 2 further increase. After the raw materials 5 are melted, the operation is switched from the submerged operation to an arc operation where the electrode 6 is exposed from the molten surface as shown in Figure 2(d). This is to prevent the reaction between the carbon of the electrode 6 and the oxide of the V-containing slag 2 from generating CO gas and causing a foaming phenomenon.

[0026] The lime in raw material 5 is poorly soluble, but becomes more soluble when it combines with Al2O3. If the lime is mixed evenly, problems arise such as undissolved lime or segregation of lime after the 13th raw material is charged.

[0027] To solve this problem, a gradient mixing method is used, where the proportion of lime is increased initially and then decreased later. In other words, by charging the less soluble lime early, undissolved lime and lime segregation are suppressed. Since the residual slag has a high Al2O3 content, even if the proportion of lime is high in the initial stage, it can combine with the Al2O3 and dissolve. In addition, by charging a large amount of lime when the water level is low, the segregated lime is incorporated into the V-containing slag and dissolves as the water level rises. Therefore, lime segregation can be mitigated.

[0028] The lime is blended so that the CaO / Al2O3 ratio of the V-containing slag is 0.37 to 0.8, preferably 0.4 to 0.6, at the end of the reduction process (when the raw material for the 13th batch is dissolved (see Figure 2(d))). Setting the CaO / Al2O3 ratio of the V-containing slag high to 0.37 to 0.8 lowers the melting point and viscosity of the V-containing slag, thereby mitigating the foaming phenomenon of the V-containing slag.

[0029] Furthermore, by setting the CaO / Al2O3 ratio of the V-containing slag to a high 0.37-0.8 at the end of the reduction process, the sulfur retention capacity of the V-containing slag is improved. As a result, it becomes unnecessary to transfer sulfur into the metal using carbon material, and the proportion of carbon material can be reduced in the later stages of the reduction reaction (gradual carbon material blending).

[0030] Conversely, if the CaO / Al2O3 ratio of the V-containing slag is less than 0.37, the melting point and viscosity of the V-containing slag are high, and foaming occurs in the V-containing slag. If the CaO / Al2O3 ratio of the V-containing slag is greater than 0.8, the melting point of the V-containing slag becomes higher, and the V-containing slag becomes thicker due to the lime. When the V-containing slag is thick, it mixes and rises between the raw materials, causing the V-containing slag to boil around the electrode, and reducing the thermal efficiency of the electrode. The optimal range for the CaO / Al2O3 ratio of the V-containing slag is 0.37 to 0.8.

[0031] After melting the 13th raw material, aluminum may be added to the molten metal. In reduction with carbon material, phosphorus (P) remains in the vitamin V-containing slag and migrates to the Fe-V alloy. P that migrates to the Fe-V alloy cannot be removed, but P that migrates to the Fe-Mo-Ni alloy can be removed. For this reason, aluminum may be added to the molten metal to migrate P to the Fe-Mo-Ni alloy.

[0032] Adding aluminum (Al) to the molten metal increases the amount of Al2O3 in the V-containing slag, decreasing the CaO / Al2O3 ratio. As a result, the CaO / Al2O3 ratio of the V-containing slag after Al addition drops to 0.3-0.55. Lowering the CaO / Al2O3 ratio of the V-containing slag after Al addition to 0.3-0.55 makes it easier to dissolve the first layer of lime.

[0033] As shown in Figure 2(e), after adding Al to the molten metal, V-containing slag is dispensed. After dispensing, residual slag 2 remains in the electric furnace 1. The amount of metal 3 generated in the electric furnace 1 during one dispensing of V-containing slag is small. Therefore, after tapping the V-containing slag 12 times, that is, after repeating the process shown in Figures 2(a) to 2(e) for 12 times, metal 3 is dispensed.

[0034] In the initial stages of operation, it is desirable to charge iron into the electric furnace 1 and melt it to create an iron bath in the electric furnace 1 beforehand. In this case, the iron bath is used to reduce the Mo and Ni in the roasted ore. The carbon material charged into the electric furnace 1 as a raw material in the process shown in Figures 2(a) to 2(c) is used to reduce the iron oxide produced by the reduction by the iron bath. Of course, the Mo and Ni in the roasted ore may also be reduced by reducing agents such as carbon material, Si, and Al charged in the process shown in Figures 2(a) to 2(c) without forming an iron bath in the electric furnace 1 beforehand. In this case, a metal (Fe-Mo-Ni alloy) iron source is added to the raw material.

[0035] As shown again in Figure 1, the V-containing slag is separated from the metal (Fe-Mo-Ni alloy) and poured into a ladle with a stirring function (S4). A reducing agent such as Al and V2O5 for adjusting the composition are added to this ladle. In the ladle with a stirring function, the V-containing slag is reduced. When the V-containing slag is reduced, Fe-V alloy and de-V slag are produced. The Fe-V alloy is then cast into a mold to become the product.

[0036] After the V-containing slag is separated, the metal (Fe-Mo-Ni alloy) is poured into a ladle with a stirring function (S5). In the ladle, the metal undergoes dephosphorization (P, S, and C) treatment. The metal is then cast into a mold to become the product. The ladle from which the V-containing slag is poured and the ladle from which the Fe-Mo-Ni alloy is poured may be the same or different. [Examples]

[0037] According to the process diagram in Figure 1, Mo, Ni, and V-containing waste was roasted, crushed, and granulated to produce roasted ore. As shown in Figure 3, roasted ore, coke (charcoal material), lime, and dust pellets were charged into the electric furnace as raw materials in 13 separate batches per tap of V-containing slag. Table 1 shows the components of the roasted ore, lime, and dust pellets. The Mo, Ni, and V-containing waste mainly consisted of spent desulfurization catalyst, and the Al2O3 content of the roasted ore was high at 60%.

[0038] [Table 1]

[0039] Roasted ore, coke, and dust pellets were mixed in equal proportions. Specifically, 1000 kg of roasted ore, 35 kg of coke, and 30 kg of dust pellets were charged each time.

[0040] On the other hand, the lime was mixed in a tiered manner. Specifically, the initial lime ratio for the first cart was set to 450 / 1000 = 45%, the lime ratio for the first half of the second to sixth cars was set to 30%, and the lime ratio for the second half of the seventh to thirteenth cars was set to 24%.

[0041] From the first to the thirteenth carton, raw materials were charged and melted to produce metal and V-containing slag. The predicted CaO / Al2O3 values ​​for the V-containing slag from the first to the thirteenth carton were 0.87, 0.75, ..., 0.60, respectively. When the raw material from the thirteenth carton was melted, the measured CaO / Al2O3 of the V-containing slag was approximately the same as the predicted value, at 0.6. The melting point of the V-containing slag was 1580°C to 1610°C.

[0042] During the loading and melting of raw materials from the first to the thirteenth carton, no significant foaming occurred in the electric furnace. Furthermore, after melting the raw material from the thirteenth carton, no undissolved lime or segregation occurred.

[0043] After melting the 13th raw material, 900 kg of Al was added to the electric furnace. The addition of Al increased the Al2O3 in the V-containing slag, and the CaO / Al2O3 ratio decreased from 0.6 to 0.5. [Examples]

[0044] Roasted ore, lime, coke, and recycled materials (dust pellets) were charged into the electric furnace in 12 separate batches. The roasted ore, lime, and recycled materials used were those with the components listed in Table 1.

[0045] Roasted ore, coke, and recycled materials were mixed in equal proportions. Lime, on the other hand, was mixed in a tiered manner. Specifically, 500 kg of lime was charged per cart in the first half (from the 1st to the 4th cart), and 200 kg per cart in the second half (from the 5th to the 12th cart). The proportions of roasted ore, lime, and recycled materials relative to the total weight were 60%, 18%, and 22%, respectively.

[0046] During the loading and melting of raw materials from the first to the twelfth carton, no significant foaming occurred in the electric furnace. Furthermore, after melting the raw material from the twelfth carton, no undissolved lime or segregation occurred.

[0047] After melting the 12th raw material, Al was added to the electric furnace. The CaO / Al2O3 ratio of the V-containing slag after Al addition was 0.45-0.55. The operating time for one tap of V-containing slag was fast at 390 minutes (minutes / tap), and the power consumption per unit was low at 1659 (kWh / t-raw material). Comparative Example 1

[0048] Roasted ore, lime, coke, and recycled materials (dust pellets) were charged into the electric furnace in 12 separate batches. All of the roasted ore, lime, coke, and recycled materials were mixed equally. The roasted ore, coke, and recycled materials used were those with the components shown in Table 1. The mixing ratios of roasted ore, lime, and recycled materials relative to the total weight were 69%, 22%, and 9%, respectively.

[0049] During the process of loading and melting raw materials from the first to the twelfth carton, foaming occurred in the electric furnace, preventing the continuous loading of raw materials. Furthermore, after melting the raw materials from the twelfth carton, undissolved lime and segregation occurred.

[0050] After melting the 12th batch of raw materials, Al was added to the electric furnace. The CaO / Al2O3 ratio of the V-containing slag after Al addition was low, at 0.30-0.40. The operating time for one tap of V-containing slag was slow at 490 minutes (minutes / tap), and the power consumption was high at 2038 (kWh / t-raw material). [Explanation of symbols]

[0051] 1...Electric furnace (heating furnace) S1…Project 1 S3…Project 2 S4…Project 3

Claims

1. The first step involves roasting the waste containing Mo, Ni, and V, A second step involves charging at least roasted ore, a reducing agent, and lime into a heating furnace and melting them to produce Fe-Mo-Ni alloy metal and V-containing slag, A method for recovering valuable metals from Mo, Ni, V-containing waste, comprising: a third step of recovering the metal of the Fe-Mo-Ni alloy from which the V-containing slag has been separated; and reducing the V-containing slag separated from the metal with a reducing agent to produce an Fe-V alloy and V-free slag, In the second step described above, The roasted ore, the reducing agent, and the lime are charged into the heating furnace in multiple batches. A method for recovering valuable metals from Mo, Ni, and V-containing waste, characterized by performing a gradient mixing of lime, in which the mixing ratio of lime (weight of lime / weight of roasted ore) is increased, and then the mixing ratio of lime is decreased.

2. In the second step, the CaO / Al ratio of the V-containing slag at the end of the reduction process ２ O ３ A method for recovering valuable metals from Mo, Ni, V-containing waste according to claim 1, characterized in that lime is added so that the ratio is 0.37 to 0.

8.

3. In the second step, a carbon material is used as the reducing agent, and after the reduction by the carbon material is completed, the CaO / Al of the V-containing slag ２ O ３ The method for recovering valuable metals from Mo, Ni, V-containing waste according to claim 2, characterized by adding Al so that the ratio becomes 0.3 to 0.55.

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