Roasting method for valuable metal-containing waste

Abstract

To provide a method of roasting valuable metal-containing waste, which can stabilize the S concentration of roasted ore.SOLUTION: Provided is a method of roasting valuable metal-containing waste in which multiple kinds of valuable metal-containing waste are blended, oxidized, and roasted in a kiln, the method including: measuring at least the S concentration of each of the multiple kinds of valuable metal-containing waste (S1); blending the multiple kinds of valuable metal-containing waste so that the S concentration of the blended raw material is equal to or lower than M / V (S2, S3); and oxidizing and roasting the blended raw material in a kiln (S4). Here, M (kg / h) is the amount of S per unit time of the blended raw materials fed into the kiln, and V (kg / h) is the ore feeding rate of the kiln.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a method for roasting waste containing valuable metals, which comprises blending a plurality of types of waste containing valuable metals and subjecting the blend to oxidative roasting in a kiln.

Background Art

[0002] In fields such as petroleum refining and gas treatment industries, a desulfurization catalyst is provided in the refining process. Valuable metals such as Mo, Ni, and V are condensed in the form of oxides in the desulfurization catalyst. Therefore, recovery of valuable metals from used desulfurization catalysts has been carried out.

[0003] Also, for example, in a power plant, a boiler for burning petroleum-based fuels such as heavy oil is provided. Valuable metals such as Ni and V are 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, recovery of valuable metals from boiler sludge and boiler ash has been carried out.

[0004] As a method for recovering valuable metals from waste containing valuable metals such as 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 subjecting waste containing valuable metals to oxidative roasting in a kiln, a second step of charging roasted ore, a reducing agent, and lime into an electric furnace and melting them to produce metal (Fe-Mo-Ni-based alloy) 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-based alloy and V-removed slag. According to this recovery method, V, Ni, and Mo can be recovered as an Fe-Mo-Ni-based alloy and an Fe-V-based alloy.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

[0006] In the first step of conventional recovery methods (roasting method for valuable metal-containing waste), the valuable metal-containing waste is oxidatively roasted to burn the carbon (C) and sulfur (S) components in the waste, removing them as COx and SOx.

[0007] However, conventional roasting methods for valuable metal-containing waste have a problem: the sulfur concentration in the roasted ore discharged from the kiln varies greatly. Large variations in sulfur concentration lead to the generation of harmful SOx in the electric furnace. Therefore, it is necessary to reduce the amount of roasted ore fed into the electric furnace, which prevents improvements in productivity.

[0008] The present invention aims to solve the above problems and to provide a method for roasting valuable metal-containing waste that can stabilize the sulfur concentration of the roasted ore. [Means for solving the problem]

[0009] To solve the above problems, one aspect of the present invention is a method for roasting valuable metal-containing waste in which multiple types of valuable metal-containing waste are blended and oxidized in a kiln, wherein the concentration of at least S in each of the multiple types of valuable metal-containing waste is measured, and the multiple types of valuable metal-containing waste are blended so that the S concentration of the blended raw materials is M / V or less, and the blended raw materials are oxidized in a kiln. Here, M (kg / h) is the amount of S per unit time of the blended raw materials fed into the kiln, and V (kg / h) is the ore feeding rate of the kiln.

[0010] Another aspect of the present invention is a method for roasting valuable metal-containing waste in which multiple types of valuable metal-containing waste are blended and oxidatively roasted in a kiln, wherein the oil content and moisture content of each of the multiple types of valuable metal-containing waste are measured, and the multiple types of valuable metal-containing waste are blended based on an index using the initial heat acquisition amount of the blended raw materials obtained by subtracting the heat of vaporization of moisture from the calorific value of oil, and the blended raw materials are oxidatively roasted in a kiln. [Effects of the Invention]

[0011] According to one aspect of the present invention, the amount of sulfur (S) per unit time of the blended raw materials fed into the kiln can be kept below a certain M or M. This allows for the stabilization of the sulfur concentration in the roasted ore.

[0012] Inside the kiln, the blended raw materials first heat up and their temperature rises. After the temperature rises, the carbon (C) component of the blended raw materials burns, followed by the sulfur (S) component. According to another aspect of the present invention, by controlling the initial heat absorption rate of the blended raw materials, time can be secured for the combustion of the carbon (C) and sulfur (S) components of the blended raw materials, thereby stabilizing the temperature distribution inside the kiln. As a result, the sulfur concentration of the roasted ore can be stabilized, and the sulfur concentration of the roasted ore can be reduced. [Brief explanation of the drawing]

[0013] [Figure 1] This is a diagram showing the configuration of a roasting apparatus for carrying out a roasting method for valuable metal-containing waste according to one embodiment of the present invention. [Figure 2] This is a process diagram of a waste roasting method according to one embodiment of the present invention. [Figure 3] This is a process diagram for a recovery method that extracts valuable metals from roasted ore. [Figure 4] This graph compares examples that satisfy equation (4) (plotted with ●) with examples that do not satisfy equation (4) (plotted with ○). [Figure 5] This graph compares examples that satisfy equation (5) (plotted with ●) with examples that do not satisfy equation (5) (plotted with ○). [Modes for carrying out the invention]

[0014] Hereinafter, an embodiment of the roasting method for valuable metal-containing waste according to the present invention will be described with reference to the attached drawings. However, the roasting method for valuable metal-containing waste according to the present invention can be embodied 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. (Configuration of the roasting apparatus)

[0015] Figure 1 shows the configuration of a roasting apparatus for carrying out a roasting method for valuable metal-containing waste according to one embodiment of the present invention. 1a, 1b, and 1c are hoppers for storing multiple types of valuable metal-containing waste (hereinafter simply referred to as waste A, B, and C), 2a, 2b, and 2c are weighing devices, 3 is a conveyor, 4 is a hopper for storing blending raw material D, 6 is a conveyor, 7 is a metal feeder, and 8 is a kiln.

[0016] Waste materials A, B, and C include, for example, used catalysts, boiler sludge, boiler ash, and ammonium metavanadate obtained by wet alkaline treatment of boiler ash.

[0017] Waste materials A, B, and C are stored in hoppers 1a, 1b, and 1c, respectively, according to their type. Weighing devices 2a, 2b, and 2c weigh the respective amounts of waste materials A, B, and C, and mix them in the predetermined mixing ratio.

[0018] The blending raw material D is transported by conveyor 3 and fed into hopper 4. The blending raw material D fed into hopper 4 is fed into the ore feeder 7 via weighing device 5 and conveyor 6. The ore feeder 7 supplies the blending raw material D to the inlet of kiln 8 at a predetermined feeding rate. For kiln 8, for example, a horizontal rotary kiln or a vertical kiln can be used. Kiln 8 oxidizes and roasts the blending raw material D by stirring it and allowing it to remain for a predetermined residence time. When the blending raw material D is oxidized and roasted in kiln 8, the C and S components in the waste are burned, generating roasted ore 9 and gases such as COx and SOx. The roasted ore 9 is discharged from the bottom of the secondary combustion chamber 10 located at the outlet of kiln 8. The gases 11 such as COx and SOx are discharged from the top of the secondary combustion chamber 10. (Roasting method of this embodiment)

[0019] FIG. 2 shows a process diagram of a waste roasting method according to an embodiment of the present invention. In the waste roasting method of this embodiment, first, the S concentration, C concentration, oil content, and moisture content of each of the plurality of types of wastes A, B, and C are measured (S1). For example, in the case of used desulfurization catalysts, boiler sludge, boiler ash, etc., these numerical values are different. Also, even for used catalysts, these numerical values differ depending on the supplier. Therefore, these numerical values are measured for each type of waste. The oil content is, for example, a normal hexane extractable substance.

[0020] The S concentration and C concentration are measured using, for example, a carbon-sulfur analyzer. The measurement methods for the S concentration and C concentration are specified in JIS M 8819:1997 (Elemental analysis method by equipment for coal and coke). The normal hexane extractable substance is measured as the oil content. The measurement method for the normal hexane extractable substance is specified in JIS K 0101:2017 (Hexane extractable substance). The moisture is measured using, for example, the distillation method. The measurement method for the moisture is specified in JIS K 2275:2015 (Crude oil and petroleum products - Method for determining moisture).

[0021] In addition, when blending a plurality of types of wastes based only on the S concentration of the blending raw materials, the measurement of the C concentration, oil content, and moisture can be omitted. Also, when blending a plurality of types of wastes based only on the initial heat absorption amount of the blending raw materials, the measurement of the S concentration and C concentration can be omitted.

[0022] Next, the blending ratio of the plurality of types of wastes is determined so as to satisfy Condition 1 and Condition 2 (S2). Condition 1 is that the S concentration of the blending raw materials becomes M / V or less. Here, M (kg / h) is the amount of S per unit time of the blending raw materials input into the kiln, and V (kg / h) is the feeding rate. M is preset from the operation results based on the amount of SOx generated from the electric furnace, the amount of S that can be processed in the electric furnace, etc. V is preset from the operation results based on the S concentration of the roasted ore, etc.

[0023] As shown in Table 1, if the sulfur concentrations (by weight) of wastes A, B, and C are Sa, Sb, and Sc, respectively, and their mixing ratios are a, b, and c, respectively, then the sulfur concentration (by weight) of the blended raw materials is expressed as Sa × a + Sb × b + Sc × c.

[0024] [Table 1] Under condition 1, the blending ratios a, b, and c are determined such that the S concentration of the blended raw materials satisfies either equation (1) or (2) below.

[0025] (Math 1) S concentration of blended ingredients = Sa × a + Sb × b + Sc × c = M / V ... (1) S concentration of blended ingredients = Sa × a + Sb × b + Sc × c ≤ M / V ... (2)

[0026] (1) By determining the mixing ratio to satisfy equation (1), the amount of sulfur (S) per unit time of the raw materials fed into the kiln can be kept constant at M. Furthermore, by determining the mixing ratio to satisfy equation (2), the amount of sulfur (S) per unit time of the raw materials fed into the kiln can be kept below M. Therefore, the sulfur concentration of the roasted ore can be stabilized.

[0027] Condition 2 is that the initial heat absorption of the blended raw materials is equal to or greater than a predetermined value. In Condition 2, first, the calorific value of oil (kcal / kg) is calculated from the oil content (weight %) of waste A, B, and C, and the heat of vaporization of water (kcal / kg) is calculated from the water content (weight %) of waste A, B, and C, and then the initial heat absorption amounts of Ca, Cb, and Cc (kcal / kg) of waste A, B, and C are calculated by subtracting the heat of vaporization of water (kcal / kg) from the calorific value of oil (kcal / kg).

[0028] As shown in Table 2, when the oil content of waste A is Na (weight %) and the water content is La (weight %), the initial heat absorption of waste A is expressed as Ca = Na × 10.1 (kcal / kg) - La × 0.6 (kcal / kg). The initial heat absorption amounts Cb and Cc of wastes B and C are similar.

[0029] [Table 2]

[0030] Then, the initial heat absorption amount F of the blended raw material is calculated from the initial heat absorption amounts Ca, Cb, and Cc of waste materials A, B, and C, respectively. As shown in Table 3, when the initial heat absorption amounts of waste materials A, B, and C are Ca, Cb, and Cc, respectively, the initial heat absorption amount F of the blended raw material is expressed as F = (Ca × a + Cb × b + Cc × c) × V.

[0031] [Table 3] Under condition 2, the blending ratios a, b, and c are determined such that the initial heat absorption amount F of the blended raw materials satisfies equation (3).

[0032] (Math 2) F=(Ca×a+Cb×b+Cc×c)×V≧G…(3) Here, G is predetermined based on operational results, taking into account factors such as the S concentration of the roasted ore.

[0033] Once blending ratios a, b, and c that satisfy conditions 1 and 2 are obtained, these blending ratios a, b, and c will be considered the final blending ratios.

[0034] Next, waste materials A, B, and C are mixed according to the final determined ratios a, b, and c (S3). Finally, the mixed raw materials are placed in the kiln and subjected to oxidative roasting (S4).

[0035] Inside the kiln, the blended raw materials first heat up and their temperature rises. After the temperature rises, the carbon (C) component of the blended raw materials burns, followed by the sulfur (S) component. By controlling the initial heat absorption rate of the blended raw materials to satisfy equation (3), time can be secured for the carbon and sulfur components of the blended raw materials to burn, and the temperature distribution inside the kiln can be stabilized. As a result, the sulfur concentration of the roasted ore can be stabilized, and the sulfur concentration of the roasted ore can be reduced. (Variation 1)

[0036] In addition to the initial heat gain F itself, as shown in equation (3), an index using the initial heat gain F can also be used, which is the ratio of the input (C+S) to the amount of heat brought in as raw materials, i.e., input (C+S) / amount of heat brought in as raw materials.

[0037] Here, the input amount of C (kg / h) is expressed as C concentration of the blended raw materials (weight %) × supply rate V (kg / h). The input amount of S (kg / h) is expressed as S concentration of the blended raw materials (weight %) × supply rate V (kg / h). The input amount (C+S) (kg / h) is expressed as input amount of C (kg / h) + input amount of S (kg / h).

[0038] The raw material input heat G (kcal / h) = initial heat absorption F of the blended raw materials (calorific value of oil in the blended raw materials - heat absorption from evaporation of water in the blended raw materials) + heat of combustion C + heat of combustion S. The initial heat absorption F (kcal / h) is as described above. The heat of combustion C (kcal / h) is expressed as input amount of C (kg / h) × 8.1 (kcal / kg). The heat of combustion S (kcal / h) is expressed as input amount of S (kg / h) × 2.3 (kcal / kg). In the first modified example, the mixing ratios a, b, and c are determined so as to satisfy equation (4) instead of equation (3).

[0039] (Math 3) Input amount (C+S) / Calorific value of raw materials brought in ≤ H (kg / kcal) ... (4) Here, H is predetermined based on operational records, taking into account factors such as the sulfur concentration of the roasted ore. (Modification 2)

[0040] As an index using the initial heat transfer rate F, the ratio of the initial heat transfer rate F to the heat transfer rate G of the raw materials, i.e., F / G, can also be used. The initial heat transfer rate F (kcal / h) and the heat transfer rate G (kcal / h) of the raw materials are as described above. In the second modified example, the mixing ratios a, b, and c are determined so as to satisfy equation (5) instead of equation (3).

[0041] (Math 4) F / G>J…(5) Here, J is predetermined based on operational results, taking into account factors such as the S concentration of the roasted ore.

[0042] The method for roasting waste according to this embodiment has been described above. The present invention is not limited to the embodiments, modification 1, and modification 2 described above, and can be modified to other embodiments without changing the gist of the invention.

[0043] For example, in the above embodiment, the sulfur (S) concentration, carbon (C) concentration, oil content, and moisture content of each waste material are measured, and the blending ratio is determined based on the S concentration and initial heat absorption rate of the blending raw materials. However, the blending ratio may be determined based only on the S concentration of each waste material and the S concentration of the blending raw materials. Alternatively, the oil content and moisture content of each waste material may be measured, and the blending ratio may be determined based only on the initial heat absorption rate of the blending raw materials. (Methods for recovering valuable metals)

[0044] Figure 3 shows a process diagram of an example of a recovery method for recovering valuable metals from roasted ore. In this recovery method, the roasted ore discharged from the kiln is first crushed and granulated (S1).

[0045] Next, the granulated roasted ore, reducing agent, and lime are charged into an electric furnace as raw materials and melted (S2). When the raw materials are melted in the electric furnace, the Mo oxides and Ni oxides in the roasted ore are reduced, producing metal (Fe-Mo-Ni alloy) and V-containing slag. The V oxides in the roasted ore are not reduced and are transferred to the V-containing slag.

[0046] The V-containing slag is separated from the metal (Fe-Mo-Ni alloy) and poured into a ladle with a stirring function (S3). This ladle reduces the V-containing slag. 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 form the product.

[0047] After the V-containing slag is separated, the metal (Fe-Mo-Ni alloy) is poured into a ladle with a stirring function (S4). This ladle then performs dephosphorization (P, S, C) on the metal. The metal is then cast into a mold to form the final product. [Examples]

[0048] According to the process diagram in Figure 2, the S concentration, oil content, and moisture content of waste materials A, B, and C were measured. Table 4 shows the measurement results for the S concentration, oil content, and moisture content of waste materials A, B, and C.

[0049] [Table 4]

[0050] Next, the mixing ratio was determined so that the S concentration of the blended raw materials satisfies equations (1) and (3). That is, the mixing ratio of wastes A, B, and C was determined so that M / V = 6.4% in equation (1). Here, based on past operating results, M in equation (1) was set to 235 kg / h and V was set to 3690 kg / h. In addition, the mixing ratio of wastes A, B, and C was determined so that the initial heat transfer amount F in equation (3) was greater than or equal to G. Here, based on past operating results, G in equation (3) was set to 72 Gcal / D. Note that G in Gcal / D is giga and D is 24h.

[0051] The final determined mixing ratio was 73:10:17. Since the S concentration of the blended raw materials was 6.4%, this mixing ratio satisfied equation (1). Also, since the initial heat transfer F of the blended raw materials was 86 Gcal / D, this mixing ratio satisfied equation (3).

[0052] Waste materials A, B, and C were mixed according to the final determined ratio, and the mixed raw materials were oxidized and roasted in a kiln. The sulfur concentration of the roasted ore discharged from the kiln each day of operation was measured, and the average value was a low 0.15% by weight. [Examples]

[0053] As an index using the initial heat transfer amount F, the input amount (C+S) / raw material heat amount was used. Based on past operating results, H in equation (4) was set to 0.102 t / kcal, where t is 1000 kg.

[0054] The blending ratio was determined to satisfy equation (1) and equation (4) (amount of input (C+S) / amount of raw material heat ≤ 0.102). Table 5 shows the amount of input C, amount of input S, amount of input (C+S), amount of input (C+S) / amount of raw material heat, and S concentration of roasted ore for each day of operation.

[0055] [Table 5] By satisfying equations (1) and (4), the sulfur concentration in the roasted ore could be reduced to 0.14% by weight or less.

[0056] Table 6 shows examples that satisfy equation (1) but do not satisfy equation (4) (amount of input (C+S) / calories of raw materials brought in > 0.102).

[0057] [Table 6]

[0058] Even in the examples that did not satisfy equation (4), the sulfur concentration of the roasted ore remained stable as long as equation (1) was satisfied. However, in the examples that did not satisfy equation (4), the sulfur concentration of the roasted ore was high, at 0.25% by weight or more.

[0059] Figure 4 is a graph comparing an example that satisfies equation (4) with an example that does not. ● represents an example that satisfies equation (4), and ○ represents an example that does not satisfy equation (4). By satisfying equation (4), the sulfur concentration of the roasted ore could be reduced to 0.20% by weight or less. [Examples]

[0060] As an index using the initial heat transfer amount F, the ratio of initial heat transfer amount F / raw material heat transfer amount G was used. Based on past operational results, J in equation (5) was set to 0.3%.

[0061] The blending ratio was determined to satisfy equation (1) and equation (5) (F / G > 0.3%).

[0062] Table 7 shows the amount of heat added to raw materials, the initial heat absorption, the ratio of initial heat absorption to the amount of heat added to raw materials, and the sulfur concentration of the roasted ore for each day of operation.

[0063] [Table 7] By satisfying equations (1) and (5), the sulfur concentration in the roasted ore could be reduced to 0.20% by weight or less.

[0064] Table 8 shows examples that satisfy equation (1) but not equation (5) (initial heat transfer amount / raw material heat transfer amount ≤ 30%).

[0065] [Table 8]

[0066] In the examples that satisfied equation (1) but not equation (5), the sulfur concentration of the roasted ore remained stable. However, in the examples that did not satisfy equation (5), the sulfur concentration of the roasted ore was high, at 0.25% by weight or more.

[0067] Figure 5 is a graph comparing an example that satisfies equation (5) with an example that does not. ● represents an example that satisfies equation (5), and ○ represents an example that does not satisfy equation (5). By satisfying equation (5), the sulfur concentration of the roasted ore could be reduced to 0.25% by weight or less.

Claims

1. In a method for roasting valuable metal-containing waste, in which multiple types of valuable metal-containing waste are mixed and oxidized in a kiln, We measured the S concentration (by weight) of each of several types of valuable metal-containing waste products. Multiple types of valuable metal-containing waste are blended so that the sulfur concentration (weight %) of the blended raw materials is M / V or less. A method for roasting vanadium-containing waste by oxidizing and roasting the raw materials in a kiln. Here, M (kg / h) is the amount S of the blended raw materials fed into the kiln per unit time, and V (kg / h) is the ore feeding rate of the kiln.

2. We measured the oil content and moisture content of each of the multiple types of valuable metal-containing waste materials. A method for roasting vanadium-containing waste according to claim 1, characterized in that multiple types of valuable metal-containing waste are blended such that, based on the initial heat absorption amount F of the blended raw materials obtained by subtracting the heat of vaporization of water from the calorific value of oil, the input amount (C+S) / heat amount of raw materials brought in G, or the initial heat absorption amount F / heat amount of raw materials brought in G, the initial heat absorption amount F is greater than or equal to a value predetermined from operational results, the input amount (C+S) / heat amount of raw materials brought in G is less than or equal to a value predetermined from operational results, or the initial heat absorption amount F / heat amount of raw materials brought in G is greater than a value predetermined from operational results. Here, the input amount (C + S) (kg / h) is expressed as input amount C (kg / h) + input amount S (kg / h), and the raw material heat input amount G (kcal / h) is expressed as initial heat acquisition amount F of the blended raw materials + heat of combustion amount C + heat of combustion amount S.

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