Lead recovery method and apparatus

Abstract

To provide a lead recovery method in which lead can be recovered highly efficiently.SOLUTION: A mixed material S that is obtained by mixing lead oxide and / or lead sulfate separated from a lead battery and carbon is irradiated with a microwave under the air atmosphere for a predetermined time to heat the mixed material S. In this way, the present invention only requires mixing lead oxide and / or lead sulfate separated from the lead battery and carbon, and irradiating the mixed material S obtained through the mixing with a microwave for a predetermined time under the air atmosphere, and therefore, lead can be obviously recovered highly efficiently compared to before.SELECTED DRAWING: Figure 1

Description

Technical Field

[0005]

[0001] The present invention relates to a lead recovery method and apparatus capable of recovering lead from a lead battery.

Background Art

[0002] In recent years, despite the spread of lithium-ion batteries, which have attracted attention as batteries for electronic devices such as mobile computers and mobile phones that are becoming smaller or lighter, the market for lead batteries has continued to expand. Such lead batteries are known to be recycled after use, as described in Non-Patent Document 1. That is, after a used lead battery is crushed, it is separated into a case, waste acid, and electrode plates. The case is recycled as a plastic raw material, the waste acid is neutralized, and the electrode plates are recycled as lead ingots through a smelting process as lead raw materials.

Prior Art Documents

Non-Patent Documents

[0003]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, the above smelting process has problems such that the temperature during lead reduction is very high at 1400K to 1500K, the energy consumption is large, and it takes a great deal of labor and time to recover lead.

[0005] Therefore, in view of the above problems, an object of the present invention is to provide a lead recovery method and apparatus capable of recovering lead with high efficiency.

Means for Solving the Problems

[0006] The object of the present invention described above is achieved by the following means. The reference numerals in parentheses indicate the embodiments described later, but the present invention is not limited thereto.

[0007] The lead recovery method according to claim 1 involves a mixed material (S) obtained by mixing lead oxide and / or lead sulfate separated from a lead battery with carbon, under an air atmosphere where no additional equipment is required to prevent the air atmosphere. After doing that, Lead is reduced and recovered by irradiating the mixed material (S) with microwaves of 2.5kW to 5.0kW for a predetermined time and heating the material using only the microwaves. The aforementioned mixed material (S) is A material obtained by mixing the lead oxide and the carbon in a 1:1 molar ratio, A material obtained by mixing the lead sulfate and the carbon such that the lead sulfate and the carbon undergo a chemical reaction and the amount of carbon becomes 10 times or more the stoichiometric ratio, or The material is characterized by being one of the materials obtained by mixing the lead oxide and the lead sulfate with the carbon such that the lead oxide and the lead sulfate with the carbon undergo a chemical reaction and the amount of carbon is 10 times or more the stoichiometric ratio.

[0008] The lead recovery apparatus according to claim 2 includes a storage section (crucible 11) capable of containing a mixed material (S) obtained by mixing lead oxide and / or lead sulfate separated from a lead battery with carbon, The aforementioned storage section (crucible 11) inside Under an air atmosphere where no additional equipment is needed to prevent the air from becoming an air atmosphere. After doing that, It has a microwave irradiation means capable of irradiating with microwaves of 2.5kW to 5.0kW for a predetermined time, The aforementioned storage section (crucible 11) inside Under an air atmosphere where no additional equipment is needed to prevent the air from becoming an air atmosphere. After doing that, By irradiating the mixed material (S) with microwaves for a predetermined time using the microwave irradiation means, the mixed material (S) is heated using only microwaves, thereby reducing and recovering the lead. The aforementioned mixed material (S) is A material obtained by mixing the lead oxide and the carbon in a 1:1 molar ratio, A material obtained by mixing the lead sulfate and the carbon such that the lead sulfate and the carbon undergo a chemical reaction and the amount of carbon becomes 10 times or more the stoichiometric ratio, or The material is characterized by being one of the materials obtained by mixing the lead oxide and the lead sulfate with the carbon such that the lead oxide and the lead sulfate with the carbon undergo a chemical reaction and the amount of carbon is 10 times or more the stoichiometric ratio. [Effects of the Invention]

[0009] Next, the effects of the present invention will be described with reference to the reference numerals in the drawings. Note that the reference numerals in parentheses are those of embodiments described later, but the present invention is not limited thereto.

[0010] According to the inventions of claims 1 and 2, lead oxide and / or lead sulfate separated from a lead battery are mixed with carbon, and the mixed material (S) is subjected to an air atmosphere without the need for additional equipment to prevent it from being exposed to air. After doing that, By irradiating the mixed material (S) with microwaves of 2.5kW to 5.0kW for a predetermined time, the mixed material (S) is heated using only microwaves, thereby reducing and recovering lead. As a result, lead can be recovered with significantly higher efficiency compared to conventional methods. The mixed material (S) is one of the following materials: a material in which lead oxide and carbon are mixed in a 1:1 molar ratio; a material in which lead sulfate and carbon are mixed so that the amount of carbon is 10 times or more the stoichiometric ratio after a chemical reaction between the lead sulfate and carbon; or a material in which lead oxide and lead sulfate are mixed with carbon so that the amount of carbon is 10 times or more the stoichiometric ratio after a chemical reaction between the lead oxide and lead sulfate and carbon. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic diagram of a lead recovery device according to one embodiment of the present invention. [Figure 2] This is a schematic diagram of a conventionally known electric furnace. [Figure 3]The figure shows the XRD measurement results obtained by irradiating a mixed material of lead oxide and carbon, mixed at a molar ratio (stoichiometric ratio) of 1:1, with microwaves for a predetermined time in an air atmosphere to heat the mixed material. [Figure 4] The figure shows the XRD measurement results obtained by heating a mixed material of lead oxide and carbon, mixed at a molar ratio (stoichiometric ratio) of 1:1, in an electric furnace in an air atmosphere. [Figure 5] The figure shows the XRD measurement results obtained by irradiating a mixed material of lead oxide and carbon with microwaves for a predetermined time in an air atmosphere to heat the mixed material. [Figure 6] The figure shows the XRD measurement results obtained by irradiating a mixed material of lead sulfate and carbon with microwaves for a predetermined time in an air atmosphere to heat the mixed material. [Figure 7] The figure shows the XRD measurement results obtained by irradiating a mixed material of lead oxide and lead sulfate and carbon with microwaves for a predetermined time in an air atmosphere to heat the mixed material.

Embodiments for Carrying Out the Invention

[0012] Hereinafter, the lead recovery method according to the present invention will be specifically described with reference to the drawings. In the following description, when indicating the up-down, left-right directions, it refers to the up-down, left-right as seen from the front in the drawing.

[0013] The lead recovery method according to the present embodiment is to irradiate a mixed material of lead oxide and / or lead sulfate separated from a lead battery and carbon with microwaves for a predetermined time in an air atmosphere to heat the mixed material. Thus, a lead recovery method capable of recovering lead with high efficiency is provided.

[0014] More specifically, as described above, after use, the lead battery is crushed and separated into a case, waste acid, and electrode plates. It is known that these electrode plates contain lead oxide (PbO2) and lead sulfate (PbSO4). Therefore, conventionally, when recovering lead, it was recovered through a smelting process. However, this smelting process has problems such as the temperature during lead reduction being very high at 1400K - 1500K, a large energy consumption, and taking a great deal of labor and time to recover lead.

[0015] Therefore, in the present embodiment, for a mixed material obtained by mixing lead oxide and / or lead sulfate separated from a lead battery with carbon, microwave is irradiated for a predetermined time in an air atmosphere to heat the mixed material. By doing so, it is only necessary to mix lead oxide and / or lead sulfate separated from the lead battery with carbon and irradiate the mixed material with microwave for a predetermined time in an air atmosphere. Thus, compared with the prior art, lead can be recovered clearly with high efficiency. When separating the lead oxide and lead sulfate contained in the electrode plate, the electrode plate is calcined and the lead oxide is reduced, then the lead oxide and lead sulfate can be separated.

Example

[0016] Here, in order to prove that lead can be recovered by irradiating a mixed material obtained by mixing lead oxide and / or lead sulfate separated from a lead battery with carbon with microwave for a predetermined time in an air atmosphere to heat the mixed material, the present inventors conducted the following experiment.

[0017] <Experimental apparatus> As shown in FIG. 1, a lead recovery apparatus 1 which is an experimental apparatus has a mixed material S provided in a rectangular microwave oven 10. This mixed material S is a mixed material obtained by mixing lead oxide and / or lead sulfate separated from a lead battery with carbon.

[0018] However, as shown in Figure 1, the mixed material S is housed in a crucible 11, and the crucible 11 is supported by special refractory bricks 12. These special refractory bricks 12 are formed in a rectangular shape, as shown in Figure 1, and are placed inside the microwave furnace 10. A recessed hole 12b is provided approximately in the center of the upper surface 12a of the special refractory bricks 12, and the crucible 11 containing the mixed material S is inserted into this recessed hole 12b. In this way, the crucible 11 is supported by the special refractory bricks 12, and the mixed material S is provided inside the microwave furnace 10.

[0019] Thus, microwaves are irradiated into the microwave furnace 10, which is provided with the mixed material S, by a microwave oscillator (not shown).

[0020] On the other hand, in order to compare with the case using the lead recovery apparatus 1 described above, an electric furnace 100, which has a conventionally known structure, as shown in Figure 2, was used. This electric furnace 100 has a vertically elongated rectangular heating mechanism 101 in the center, and a crucible 11 containing the mixed material S is placed inside this heating mechanism 101. A pair of special refractory bricks 102 are provided on the left and right sides of this heating mechanism 101. A thermocouple 102 is provided inside the crucible 11.

[0021] Thus, the inventors conducted the following experiment using the lead recovery apparatus 1 configured in this manner and the electric furnace 100.

[0022] <Experiment to recover lead (Pb) from lead oxide (PbO2)> The inventors first conducted an experiment to recover lead (Pb) from lead oxide (PbO2). Specifically, they prepared a mixed material S consisting of 4g of lead oxide and 0.2g of carbon, with a molar ratio (stoichiometric ratio) of 1:1. Then, they heated the mixed material S in a microwave furnace 10 under an air atmosphere, irradiating it with 2.5kW microwaves for 15 seconds, 30 seconds, 45 seconds, 1 minute, 2 minutes, 5 minutes, and 10 minutes. Furthermore, they analyzed the heated mixed material S using an X-ray diffraction (XRD) system, Rigaku Ultimate-IV. The results of this analysis are shown in Figure 3.

[0023] According to Figure 3, it was confirmed that lead oxide (PbO2) and carbon (C) undergo a chemical reaction (PbO2 + C = Pb + CO2), and that lead (Pb) is reduced, meaning that lead (Pb) can be recovered, in just 15 seconds.

[0024] On the other hand, as a comparative experiment, the same mixed material S was placed in the electric furnace 100 shown in Figure 2 and heated at 400°C in an air atmosphere for 10 minutes, 15 minutes, and 20 minutes. The heated mixed material S was then analyzed using an X-ray diffraction (XRD) system, Rigaku Ultimate-IV. The results of this analysis are shown in Figure 4.

[0025] According to Figure 4, it was found that heating must be done for more than 15 minutes for the lead oxide (PbO2) and carbon (C) to chemically react and reduce the lead (Pb), that is, to recover the lead (Pb).

[0026] However, these experimental results demonstrated that by heating a mixed material of lead oxide separated from a lead battery and carbon with microwaves for a predetermined time in an air atmosphere, lead can be recovered in a shorter time compared to heating in an electric furnace.

[0027] Furthermore, the inventors conducted experiments using the lead recovery device 1 to determine whether lead could be recovered by changing the amount of carbon in the mixed material S. Specifically, the amount of lead oxide in the mixed material S remained at 4 g, and the amount of carbon was changed to 0.1 g, 0.2 g, and 0.4 g for the experiments. In these experiments, the microwave furnace 10 was placed in an air atmosphere and irradiated with 2.5 kW microwaves, heating the mixed material S for 10 minutes in each case. The results were then analyzed using an X-ray diffraction (XRD) system, Rigaku Ultimate-IV. The results of this analysis are shown in Figure 5.

[0028] According to Figure 5, at 0.1g of carbon, the amount of carbon was too small to reduce lead (Pb), but at 0.2g or more of carbon, it was confirmed that lead (Pb) could be reduced, i.e., recovered. However, at 0.4g of carbon, the amount of carbon was too large, and it was confirmed that lead (Pb) was re-oxidized (PbO, PbO2). Therefore, it was found that it is preferable to adjust the amount of carbon so that the molar ratio (stoichiometric ratio) of lead oxide to lead is 1:1.

[0029] <Experiment to recover lead (Pb) from lead sulfate (PbSO4)> Next, the inventors conducted an experiment to recover lead (Pb) from lead sulfate (PbSO4). Specifically, they prepared mixed materials S by mixing 5g of lead sulfate with 0.2g, 0.4g, 1.0g, 2.0g, and 3.0g of carbon, respectively. Then, they heated the mixed material S for 10 minutes by irradiating it with 5.0kW microwaves in an air atmosphere inside the microwave furnace 10. Furthermore, they analyzed the heated mixed material S using an X-ray diffraction (XRD) Rigaku Ultimate-IV. The results of this analysis are shown in Figure 6.

[0030] According to Figure 6, it was confirmed that when lead sulfate (PbSO4) and carbon (C) undergo a chemical reaction (PbSO4 + 2C → PbS + 2CO2, 3PbSO4 + PbS → 4PbO + 4SO2, 2PbO + PbS → 3Pb + SO2), and the amount of carbon becomes 10 times or more the stoichiometric ratio (amount of carbon: 0.2g), sulfur (S) is removed, reducing lead (Pb), and thus lead (Pb) can be recovered.

[0031] On the other hand, in a comparative experiment, the same mixed material S was placed in the electric furnace 100 shown in Figure 2 and heated at 1000°C in an air atmosphere, causing lead sulfate to volatilize. No lead residue remained at this time.

[0032] However, these experimental results demonstrate that by heating a mixed material of lead sulfate separated from a lead-acid battery and carbon with microwaves for a predetermined time in an air atmosphere, lead can be recovered in a shorter time compared to heating in an electric furnace. It should be noted that existing research has shown that too much carbon reduces the reduction rate of lead (reduction behavior of lead sulfate by solid carbon). Therefore, it is preferable to use a mixture S that contains only carbon, rather than mixing lead sulfate (PbSO4) and carbon (C).

[0033] <Experiment to recover lead (Pb) from lead oxide (PbO2) and lead sulfate (PbSO4)> Next, since electrode plates separated from lead-acid batteries contain lead oxide (PbO2) and lead sulfate (PbSO4), the inventors conducted an experiment to determine whether lead (Pb) could be recovered from lead oxide (PbO2) and lead sulfate (PbSO4). Specifically, a mixed material S was prepared by mixing 1.5g of lead oxide and 3.5g of lead sulfate with 0.22g and 2.2g of carbon, respectively. The microwave furnace 10 was then heated for 10 minutes by irradiating it with 5.0kW microwaves in an air atmosphere. Furthermore, the heated mixed material S was analyzed using an X-ray diffraction (XRD) Rigaku Ultimate-IV. The results of this analysis are shown in Figure 7.

[0034] According to Figure 7, it was confirmed that when lead oxide (PbO2) and lead sulfate (PbSO4) react chemically with carbon (C), and the amount of carbon becomes 10 times or more the stoichiometric ratio (amount of carbon: 0.22g), lead (Pb) is reduced, i.e., lead (Pb) can be recovered.

[0035] <Consideration> However, the experimental results above show that microwave heating allows for the recovery of lead from lead oxide and / or lead sulfate separated from lead batteries in a shorter time and under an air atmosphere (no additional equipment is needed to prevent an air atmosphere, such as an argon atmosphere). Therefore, according to this embodiment, lead can be recovered with significantly higher efficiency than conventional methods.

[0036] Furthermore, based on the experimental results above, the time required to reduce lead (Pb) from lead oxide (PbO2) is extremely short. Therefore, if lead sulfate (PbSO4) is reduced to lead oxide (PbO2) (for example, by heating lead sulfate in a quartz tube with an air stream at 1100K), and then lead (Pb) is reduced from the reduced lead oxide (PbO2), the lead recovery time can be shortened.

[0037] It should be noted that the shapes and other features shown in this embodiment are merely examples, and various modifications and changes are possible within the scope of the gist of the present invention as described in the claims. For example, in this embodiment, an example is shown in which the mixed material S is contained in a crucible 11, but it is not limited to this; any container or pipe that can contain the mixed material S is acceptable.

[0038] Furthermore, any method that can irradiate the mixed material S with microwaves is acceptable, such as a household microwave oven, as long as it can irradiate the mixed material S with microwaves. [Explanation of Symbols]

[0039] 1. Lead recovery device 10 Microwave Furnace 11 Crucible (containment section) S Mixed material

Claims

1. A mixed material of lead oxide and / or lead sulfate separated from a lead-acid battery and carbon is subjected to an air atmosphere that does not require additional equipment to prevent the presence of air. Then, microwaves of 2.5 kW to 5.0 kW are irradiated for a predetermined time, and the mixed material is heated using only the microwaves to reduce and recover the lead. The aforementioned mixed material is A material obtained by mixing the lead oxide and the carbon in a 1:1 molar ratio, A material obtained by mixing the lead sulfate and the carbon such that the lead sulfate and the carbon undergo a chemical reaction and the amount of carbon becomes 10 times or more the stoichiometric ratio, or A method for recovering lead, comprising a material obtained by mixing the aforementioned lead oxide and the aforementioned lead sulfate with carbon such that the amount of carbon is 10 times or more the stoichiometric ratio after a chemical reaction between the aforementioned lead oxide and the aforementioned lead sulfate with carbon.

2. A housing capable of containing a mixed material obtained by mixing lead oxide and / or lead sulfate separated from a lead battery with carbon, The device includes a microwave irradiation means capable of irradiating microwaves of 2.5 kW to 5.0 kW for a predetermined time, after creating an air atmosphere within the aforementioned housing, which does not require additional equipment to prevent the air atmosphere from being created. After creating an air atmosphere within the containment section, which does not require additional equipment to prevent an air atmosphere, the mixed material is heated using only microwaves by irradiating it with microwaves for a predetermined time using the microwave irradiation means, thereby reducing and recovering the lead. The aforementioned mixed material is A material obtained by mixing the lead oxide and the carbon in a 1:1 molar ratio, A material obtained by mixing the lead sulfate and the carbon such that the lead sulfate and the carbon undergo a chemical reaction and the amount of carbon becomes 10 times or more the stoichiometric ratio, or A lead recovery device comprising one of the materials obtained by mixing the lead oxide and the lead sulfate with the carbon such that the lead oxide and the lead sulfate with the carbon undergo a chemical reaction and the amount of carbon is 10 times or more the stoichiometric ratio.

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