JP7368407B2 - How to dispose of waste solar panels - Google Patents

Description

The present invention relates to a method for treating waste photovoltaic panels.

Methods to effectively utilize waste photovoltaic panels include separating the glass used in the photovoltaic panels and recycling it as glass cullet, and separating the cell parts and recycling the silver and other materials used in the cell electrodes. Methods for recovering valuable materials such as copper are known, but there are problems in that it is not easy to separate and recover glass and cells so that they do not mix, and it is difficult to process in large quantities. Furthermore, due to the difficulty of processing, the silver and copper contained in cells are sometimes disposed of in landfills because the processing costs cannot be recovered.

Furthermore, in recent years, with the spread of solar power generation, a large number of solar power generation panels have been manufactured and used. For this reason, the amount of waste photovoltaic panels disposed of is low these days, but it is predicted that the amount of waste photovoltaic panels generated will increase rapidly in a few decades as a large number of photovoltaic panels reach the end of their useful life. . Coupled with the difficulty of processing the waste photovoltaic panels mentioned above, there is concern that this will lead to a serious industrial waste problem. Therefore, an efficient method for processing waste photovoltaic panels is desired.

A solar power generation panel generally includes a frame (usually made of aluminum), a cover glass, a back sheet (usually made of a resin such as polyvinylidene fluoride), a solar cell, and the front and back surfaces of the solar cell are sealed. It has a sealant (usually made of EVA resin), and also has a cable for supplying power from the solar cell to the outside. Among these members, there are techniques to separate and collect the cover glass (Patent Document 1: Japanese Patent Application Laid-open No. 2018-176002), techniques to take out solar cells (Patent Document 2: Japanese Patent Application Laid-Open No. 2015-071162), etc. exists.

Japanese Patent Application Publication No. 2018-176002 Japanese Patent Application Publication No. 2015-071162

The method described in Patent Document 1 allows the cover glass to be taken out as a plate, and the method described in Patent Document 2 allows the solar cell to be obtained without destroying it. Since the target member is not destroyed, processing is time-consuming and processing costs are high. Furthermore, no means has been proposed for efficiently processing and recovering the cover glass and the solar cell at the same time, and for effectively utilizing the cover glass and the solar cell.

The present invention has been made in view of the above-mentioned problems, and in one embodiment, an object of the present invention is to propose a flow for effectively collecting the cover glass and photovoltaic cells of a waste photovoltaic panel at the same time.

As a result of intensive studies, the present inventor has found that the above problem can be solved by collecting the cover glass and solar cells of waste photovoltaic panels without separating them and using them as a solvent for non-ferrous smelting furnaces. I found it. The present invention was completed based on the above findings, and is exemplified below.

[1]
A method for processing a waste photovoltaic panel having at least a cover glass, a frame, a solar cell, an encapsulant, and a cable, the method comprising:
a separation step of separating the frame;
an incineration step of incinerating members other than the frame;
A method for processing waste solar power generation panels, including a reuse step of adding the incinerated product obtained in the incineration step to a non-ferrous smelting furnace.
[2]
The method for processing a waste solar power generation panel according to [1], further comprising a crushing step of crushing members other than the frame before the incineration step.
[3]
The method for processing a waste solar power generation panel according to [1] or [2], wherein the incineration step reduces the resin mass of the waste solar power generation panel to 10% or less of the total mass of the incineration product.
[4]
The method for processing a waste solar power generation panel according to any one of [1] to [3], wherein the cable is separated from the incineration product by sieving before the reuse step.
[5]
The treatment of waste solar power generation panels according to any one of [1] to [3], wherein the cable is separated before the incineration step, and the incineration step incinerates members other than the frame and the cable. Method.
[6]
The incineration step is carried out using a heating furnace that is divided into two stages, an upper stage and a lower stage, in the height direction by a grid-like partition, the upper stage stores the items to be incinerated, and the lower stage stores the items to be incinerated. The method for treating a waste solar power generation panel according to any one of [1] to [4], wherein the waste solar power generation panel is recovered.
[7]
The incineration process is carried out using a heating furnace that is divided into two stages, an upper stage and a lower stage, in the height direction by a grid-like partition. The method for processing waste solar power generation panels according to [5], wherein the lower stage collects the incineration product, and the cable is collected from the heat-resistant container.
[8]
The method for processing a waste solar power generation panel according to any one of [1] to [7], wherein in the separation step, the frame is separated from other members by breaking the cover glass.
[9]
The method for processing a waste solar power generation panel according to any one of [1] to [8], wherein in the reuse step, the incineration product is mixed with silicate ore and then introduced into the non-ferrous smelting furnace.
[10]
The non-ferrous smelting furnace is a flash smelting furnace, and before the reuse step, the incineration product is further sieved to remove foreign substances and then introduced into the flash smelting furnace, [1] [9] The method for processing a waste solar power generation panel according to any one of items.

According to the present invention, the cover glass and frame of a waste solar power generation panel can be effectively collected at the same time.

Next, embodiments of the present invention will be described in detail. It is understood that the present invention is not limited to the following embodiments, and that design changes, improvements, etc. may be made as appropriate based on the common knowledge of those skilled in the art without departing from the spirit of the present invention. Should.

(1. Waste solar power generation panels)
The specific structure and material of the waste solar power generation panel are not limited as long as it has at least a cover glass, a frame, a solar cell, a sealant, and a cable. The frame is usually made of aluminum, the encapsulant is usually made of plastic such as EVA resin, and the cable is usually copper wire covered with an insulating material. As an example, in a waste photovoltaic power generation panel, a cover glass, an EVA encapsulant, a solar cell, an EVA encapsulant, and a back sheet are laminated in this order, with the front side made up of the cover glass and the back side made up of the back sheet. has been done. The solar battery cell is provided with a cable for outputting power to the outside. Additionally, more cables may be included to form an electrical circuit.

(2. Separation process)
In one embodiment of the invention, a separation step is performed to separate the frame from the waste photovoltaic panel. The reason for implementing this process is as follows.

As an example of a product similar to a solar power generation panel, Japanese Patent Laid-Open No. 2001-296509 discloses a technique in which glass pieces obtained by crushing a liquid crystal panel are fed into a non-ferrous smelting furnace. In this treatment method, the organic matter contained in the liquid crystal panel is carbonized or burned, then crushed by a crusher, adjusted to a predetermined particle size (for example, maximum 5 to 10 mm), and then processed in a smelting furnace.

As mentioned above, plastic encapsulants such as EVA are also used in waste photovoltaic panels to sandwich the solar cells. Organic materials such as plastics must be incinerated because they serve as coloring materials for sulfuric acid, a byproduct of nonferrous smelting. However, if waste solar power generation panels are incinerated as is, they must be put into an incinerator including the frame, and especially in the case of large-capacity panels, a large heating furnace that can carry waste solar power generation panels is required. This is not preferable in terms of workability, processing cost, etc.

Therefore, before performing the incineration process, a separation process is performed to separate the frame from other members. The specific method of separation is not particularly limited, but it is possible to remove the frame by the method described in Patent Document 1, for example, or by breaking the cover glass and breaking the joints between the frame and other members. It is possible to separate. Although the specific means for breaking the cover glass is not particularly limited, a typical method is to press the glass surface with a machine to break it. This is because, as will be described later, since the cover glass is reused by being put into a non-ferrous smelting furnace, there is no need to avoid damage to the cover glass or the solar battery cells.

(3. Incineration process)
In the incineration process, other components of the waste photovoltaic panel after the frame has been separated are incinerated. The purpose of incineration is to prevent the contamination of sulfuric acid from the waste gas when the crushed materials crushed in the previous process are processed in a non-ferrous smelting furnace. This method involves removing resin components such as inhibitors, and preferably reduces the resin mass of the waste solar power generation panel to 10% or less of the total mass by an incineration process. From the viewpoint of suppressing adverse effects in the non-ferrous smelting furnace as much as possible, the resin mass after the incineration step is more preferably 8% or less of the total mass of the incinerated product, even more preferably 5% or less, and 2% or less of the total mass of the incinerated product. It is even more preferable that it is the following.

Since metals such as copper wire used in cables are valuable metals, it is preferable to collect them before or after the incineration process. In one embodiment of the present invention, after the incineration step and before the reuse step described below, the cable is recovered by separating it from the incineration product by sieving. Also, in another embodiment of the invention, the cable is pre-separated before the incineration process, and the cable is not incinerated together with other components.

The specific configuration of the incinerator used in the incineration process is not limited, and examples include a stationary furnace, a rotary kiln, and a stoker furnace. In one embodiment, the incineration process is carried out using a heating furnace that is divided into two stages, an upper stage and a lower stage, in the height direction by a grid-like partition, and the upper stage above the grid-like partition is used to store the material to be incinerated. The lower level under the lattice-like partition can be used to collect incinerated items. In the upper stage, items to be incinerated may be stored in combustible bags. By using such a two-tiered incinerator, it becomes easier to distinguish between the items that should be incinerated and the items to be incinerated, and it is possible to prevent items containing unburned resin from being mixed in with the items to be incinerated. be able to. In addition, when using a batch type furnace such as a stationary furnace, it is possible to prevent contamination with incinerated materials other than those derived from waste solar power generation panels, even if the furnace is not dedicated to incinerating waste solar power generation panels. As a result, it becomes easier to understand the amount of incinerated items collected.

When the cables are separated in advance before the incineration process, the specific configuration of the incinerator used in the incineration process is not limited, and examples include a stationary furnace, a rotary kiln, and a stoker furnace. In one embodiment, the heating furnace is divided into two stages, an upper stage and a lower stage, in the height direction by a lattice-like partition, and the upper stage above the lattice-like partition stores the materials to be incinerated. , a heat-resistant container containing cables is stored, and the lower tier under the lattice-like partition can be used to collect incinerated items. In this case, the cable can be recovered from the heat-resistant container with the insulation material removed.

The conditions of the incineration step are not particularly limited, but the temperature is typically maintained within the range of 100 to 650°C.

(4. Grinding process)
In order to perform incineration efficiently or to improve operational convenience, it is preferable to perform a pulverization step of pulverizing members other than the frame before the incineration step. The crushing process may be performed after the separation process of separating the frames, or the frames may be separated from the disassembled waste photovoltaic panels during the crushing process. That is, the separation step may be performed during the pulverization step.

The size control of the pulverized product after pulverization may be adjusted as appropriate depending on the method used and the specifications of the equipment.

(5. Reuse process)
The incinerated product obtained after the incineration process contains many glass components derived from the cover glass. The glass typically contains 50 to 65% SiO ₂ , 2 to 4% magnesium oxide, 10 to 16% sodium oxide, and also contains calcium oxide, aluminum oxide, and the like. In another embodiment of the present invention, a recycling step is performed in which the incinerated product obtained from the incineration step is added to a non-ferrous smelting furnace. Hereinafter, copper will be explained as an example of a non-ferrous metal.

In the copper smelting furnace, copper concentrate is subjected to an oxidation reaction to produce copper matte with a copper grade of about 65%, and in the flash smelting furnace, copper matte is oxidized to produce copper matte with a copper grade of about 99. There are converters that produce blister copper of approximately 30%. In a flash furnace or converter, the raw material is kept in a molten state by the heat of oxidation reaction, and separated into two layers: copper matte and slag, or blister copper and slag, and recovered. Solvents are added to lower the melting point.

Although there are various types of solvents, silicate ore containing SiO ₂ as a main component is generally used. When silicate ore is used as a solvent, the following reactions occur in a flash furnace or converter.
Flash furnace: CuFeS ₂ +SiO ₂ +O ₂ →Cu ₂ S・FeS+2FeO・SiO ₂ +SO ₂
Converter: Cu ₂ S・FeS+SiO ₂ +O ₂ →Cu+2FeO・SiO ₂ +SO ₂

As mentioned above, since the waste photovoltaic panel cover glass contains a large amount of SiO ₂ , it is possible to use the incinerated product obtained by the incineration process as a substitute for silicate ore. Furthermore, when solar cells are also treated at the same time, valuable metals such as silver contained in the solar cells are dissolved into the matte or blister copper. Then, when the blister copper is electrolytically refined to produce electrolytic copper, it migrates into electrolytic precipitates. By treating the obtained electrolytic precipitate using a known precipitate treatment technique, it is possible to finally refine and recover product silver.

When the non-ferrous smelting furnace is a flash furnace, the solvent is usually introduced in the form of powder and granules, so foreign substances (for example, unburned residues of waste solar cell backsheets, sealants, etc. that are several centimeters or larger) If there is, the raw material charging section of the flash furnace may become clogged. Therefore, it is preferable to sieve the incinerated product to remove foreign matter before introducing it into the flash furnace.

As mentioned above, the cover glass of waste photovoltaic power generation panels can be reused by adding it to a non-ferrous smelting furnace as a solvent, and valuable materials such as silver contained in the photovoltaic cells can also be recovered. cover glass and solar cells can be effectively collected at the same time. Further, according to some embodiments of the present invention, valuable metals and aluminum frames contained in cables and the like can be efficiently recovered, thereby making it possible to reduce waste to zero.

EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples, but the present invention is not limited to these Examples.

(Crucible test)
The waste photovoltaic panels were disassembled by hand and the cover glass was separated. The composition of this cover glass is shown in Table 1. Table 1 also shows the composition of silicate ore used as a common solvent. This cover glass and silicate ore were crushed using a disk mill.

In addition, copper concentrate having the composition shown in Table 2 was prepared.

First, the temperature of the heating furnace was raised to 1300°C. Next, the ratio of copper concentrate and solvent was adjusted and mixed so that Fe/SiO ₂ was 1.05, and the mixture was filled into a crucible, and the crucible was placed in a heating furnace. In the reference example, only silicate ore was used, whereas in the test example, silicate ore was partially replaced with a cover glass.

Next, air was blown into the crucible at a rate of 1 L/min and held for 30 minutes. Thereafter, the crucible was taken out of the heating furnace and allowed to cool naturally in the atmosphere. As a result, metallic copper could be obtained in both the reference example and the test example. In addition, in the test example in which part of the solvent was replaced with a cover glass, slag was generated without any remaining cover glass, confirming that it functioned as a solvent.

(actual machine test)
A cover glass separated from a waste photovoltaic panel was used for testing. The composition of this cover glass is shown in Table 4.

This cover glass was supplied together with silicate ore to a flash furnace in which copper concentrate was subjected to an oxidation reaction in the proportions shown in Table 5. Note that the supply amount (t) indicates the amount per day.

A sample of the slag obtained by the treatment in the flash furnace of each example was taken, and the copper quality in the slag was measured using a fluorescent X-ray device.The value of Conventional Example 1 was set as 1, and the relative value of each example was evaluated. The results are shown in Table 6.

If the cover glass derived from waste photovoltaic panels functions as a solvent, the reaction that produces 2FeO SiO ₂ will be hindered, and FeO will be oxidized with oxygen, resulting in a relative increase in the amount of magnetite produced. The viscosity of the solution increases. If the viscosity of the solution increases, the settling of matte particles in the slag will slow down, and the quality of Cu in the slag will increase. However, in the example, since no increase in the quality of Cu in the slag was observed, it was confirmed that the cover glass derived from the waste solar power generation panel was functioning as a solvent.

From this, it was found that as a treatment method for waste photovoltaic power generation panels, if a cover glass can be obtained through pretreatment such as separation, crushing, and incineration, it is possible to introduce it into a nonferrous smelting furnace as a solvent.

Claims (9)

A method for processing a waste photovoltaic panel having at least a cover glass, a frame, a solar cell, an encapsulant, and a cable, the method comprising:
a separation step of separating the frame;
an incineration step of incinerating members other than the frame;
A reuse step of adding the incinerated product obtained from the incineration step to a non-ferrous smelting furnace ,
A method for processing waste photovoltaic panels , wherein the cable is separated from the incineration product by sieving before the reuse step . A method for processing a waste photovoltaic panel having at least a cover glass, a frame, a solar cell, an encapsulant, and a cable, the method comprising:
a separation step of separating the frame;
an incineration step of incinerating members other than the frame;
A reuse process of adding the incinerated product obtained in the above incineration process to a non-ferrous smelting furnace.
including;
A method for processing a waste solar power generation panel, wherein the cable is separated before the incineration step, and in the incineration step, members other than the frame and the cable are incinerated. The method for processing a waste solar power generation panel according to claim 1 or 2 , further comprising a crushing step of crushing the members excluding the frame before the incineration step. The method for processing a waste solar power generation panel according to any one of claims 1 to 3 , wherein the incineration step reduces the resin mass of the waste solar power generation panel to 10% or less of the total mass of the incineration product. The incineration step is carried out using a heating furnace that is divided into two stages, an upper stage and a lower stage, in the height direction by a grid-like partition, the upper stage stores the items to be incinerated, and the lower stage stores the items to be incinerated. The method for processing waste solar power generation panels according to claim 1 or claim 3 or 4 dependent on claim 1, wherein the waste solar power generation panels are collected. The incineration process is carried out using a heating furnace that is divided into two stages, an upper stage and a lower stage, in the height direction by a grid-like partition. 3. The method for processing waste photovoltaic power generation panels according to claim 2 , wherein the lower stage collects the incineration product, and the cable is collected from the heat-resistant container. The method for treating a waste solar power generation panel according to any one of claims 1 to 6 , wherein in the separation step, the frame is separated from other members by breaking the cover glass. 8. The method for treating waste photovoltaic panels according to claim 1, wherein in the recycling step, the incinerated product is mixed with silicate ore and then introduced into the non-ferrous smelting furnace. The non-ferrous smelting furnace is a flash smelting furnace, and before the reuse step, the incineration product is further sieved to remove foreign matter before being charged into the flash smelting furnace. 8. The method for processing waste solar power generation panels according to any one of 8 .