Method for remelting out-of-service photovoltaic glass after pyrolysis treatment to reconstruct ultra-white glass

Abstract

The invention discloses a method for remelting decommissioned photovoltaic glass after pyrolysis treatment to reconstruct ultra-white glass, which comprises the following steps: crushing waste photovoltaic glass after pyrolysis treatment to form waste photovoltaic glass particles; adding waste photovoltaic glass particles and a clarification and redox regulator into the ultra-white glass batch, and mixing to form a batch containing the waste photovoltaic glass particles; wherein the redox value of the batch containing the waste photovoltaic glass particles is 15.0-25.6, and the addition amount of the waste photovoltaic glass particles is not greater than 28 wt% of the mass of the ultra-white glass batch; heating and melting the batch containing the waste photovoltaic glass particles to form glass liquid; and preparing the glass liquid into the ultra-white glass. According to the method, the waste photovoltaic glass subjected to pyrolysis treatment is used as the raw material to remelt and reconstruct the ultra-white glass, the method belongs to a high-value utilization path, the economic additional value of the waste photovoltaic glass can be increased, and the photovoltaic industry can be promoted to stride towards the circular economy and sustainable development direction.

Description

Technical Field

[0001] The present invention relates to the field of glass technology, and in particular to a method for remelting retired photovoltaic glass after pyrolysis treatment to regenerate ultra-white glass. Background Art

[0002] Although photovoltaics are environmentally friendly and have zero pollution emissions during the power generation process, the conversion efficiency of its photovoltaic modules will gradually decline with environmental factors and the passage of time; the service life of photovoltaic modules is generally 20 to 30 years, and a large number of photovoltaic modules installed in the early days (after 2000) have entered the retirement period.

[0003] According to the forecast data of the International Renewable Energy Agency (IRENA) and the International Energy Agency (IEA), the global scrap volume of photovoltaic modules will reach 8 million tons in 2030 and will increase to 78 million tons in 2050. Although photovoltaic modules do not produce harmful waste and emissions during use, the problem of solid waste generated after their scrapping cannot be ignored. If a large number of waste photovoltaic modules are not properly handled, it will bring huge environmental risks. Therefore, how to reasonably recycle and reuse waste photovoltaic modules has become a major problem that countries around the world face and urgently need to solve. The components of photovoltaic modules are relatively complex. The traditional treatment method is to directly landfill them, which not only occupies a large amount of land resources, but also causes waste of resources. It will also cause the migration and diffusion of heavy metals and toxic substances in photovoltaic modules, causing serious environmental pollution and endangering human health. Therefore, the treatment, disposal and recycling of photovoltaic modules have become an important issue in the current field of environmental protection.

[0004] At present, the retired photovoltaic modules are mainly of crystalline silicon battery type. Especially in the late 20th century and the early 21st century, more than 95% were crystalline silicon photovoltaic cells. Therefore, the first batch of retired (scrapped) photovoltaic modules mainly focused on crystalline silicon photovoltaic modules. The crystalline silicon photovoltaic cell modules are mainly composed of aluminum frames, photovoltaic glass, ethylene-vinyl acetate copolymer (abbreviated as EVA), monocrystalline silicon cells, backsheets, junction boxes, etc. Among them, the early photovoltaic glass was 3.2 mm thick physically tempered ultra-white glass. The total iron oxide content in the ultra-white glass was less than 150 ppm, the photovoltaic transmittance was not less than 91.5%, the visible light transmittance was not less than 91.0%, and the bubble size was less than 1.2 mm. The photovoltaic glass is a flat glass with a single-sided embossed pattern produced by melting low-iron-content quartz sand and high-quality chemical raw materials by calendering. It has the characteristics of ultra-white, high-transmittance, and high-strength, and belongs to high-end flat glass products. Its quality accounts for about 70% of the photovoltaic module, but its scrap recycling value is the lowest, and most of them are disposed of by landfill. Through literature and report review, the photovoltaic glass of retired photovoltaic modules (abbreviated as waste photovoltaic glass) has been studied for use in building red bricks, ceramic materials, roadbed materials, etc. Kae-Long Lin studied the effect of the incorporation of waste photovoltaic glass on the properties of fired clay bricks and found that it can reduce the firing shrinkage rate and water absorption rate of clay bricks and improve the compressive strength. After sintering at 1000 °C, the water absorption rate and compressive strength of the clay bricks prepared by incorporating 30% by mass of waste photovoltaic glass reached the standards of first-class bricks for construction. This shows that waste photovoltaic glass can partially replace the amount of clay raw materials in the production of traditional clay bricks, which not only helps to optimize the mechanical properties of clay bricks but also improves their durability. Vasiliki Savvilotidou et al. successfully prepared high-performance glass-ceramic materials by mixing a large amount of waste photovoltaic glass with lignite fly ash and melting them. The results show that the addition of waste photovoltaic glass can significantly reduce the energy demand during the melting process and lower the sintering temperature from 1200 °C to 800 °C. And the prepared glass-ceramic materials meet the standards of bricks for heavy vehicle traffic in terms of porosity, bulk density, water absorption rate, compressive strength, and microhardness. HuiCong Hao et al. prepared geopolymers by incorporating different mass fractions of waste photovoltaic glass and found that after 28 days of curing, the microstructure of the sample incorporated with 10% by mass of waste photovoltaic glass was more uniform than that of the sample incorporated with 20% by mass, and the compressive strength increased by 7 MPa. The results show that waste photovoltaic glass has the potential to partially replace the relatively expensive metakaolin, making it have good properties without deteriorating the geopolymer. Juan Jimenez-Millan et al. combined sepiolite with high plasticity with other raw materials to prepare sepiolite-based clay bricks, using diatomite and waste photovoltaic glass as silicon-based defatting agents, and found that the addition of waste photovoltaic glass can reduce the plasticity of sepiolite and at the same time significantly improve the mechanical strength of the material, making the prepared clay bricks have excellent ceramic properties.M. Stehl et al. studied the potential application of waste photovoltaic glass in concrete masonry units. By comparing the mechanical properties and physical properties of concrete containing traditional aggregates and concrete in which all aggregates are replaced by waste photovoltaic glass, it was found that concrete using waste photovoltaic glass to completely replace aggregates has a lower density, and its compressive strength reaches the average requirements of load-bearing masonry units, and can meet the technical standards of building foundations and low-rise building load-bearing structures. However, the value of the above-mentioned comprehensive utilization products is low, and the production capacity consumption is low, and the enterprises are scattered. If resource recycling is implemented, it will be affected by the transportation distance and cannot generate positive economic benefits, making it difficult to promote and apply.

[0005] At present, the recycling and treatment methods for retired crystalline silicon photovoltaic modules at home and abroad mainly include chemical solvent method, heat treatment method, physical mechanical method and physical chemical method. Among them, the heat treatment method has relatively high efficiency and high material separation rate, and is a recycling and treatment method for retired crystalline silicon photovoltaic modules with good application prospects. During the heat treatment process of retired crystalline silicon photovoltaic modules, EVA decomposes and carbonizes, and 0.1wt% to 1wt% of decomposed small molecular organic substances and inorganic carbon remain on the surface of waste photovoltaic glass. When used in the production and manufacturing of glass products, dense bubbles and dark green or brown appearance will inevitably be produced during the melting process, resulting in visible light transmittance of less than 89%, which brings thorny problems to its recycling and resource utilization. In addition, the recycling value of traditional waste glass is mostly between 200 yuan / ton and 400 yuan / ton, which does not reflect the application value of waste photovoltaic glass. Photovoltaic glass production is mostly prepared with high-quality raw materials and clean energy natural gas, so the price of finished photovoltaic glass is as high as 2,800 yuan / ton to 3,500 yuan / ton. How to achieve a recycling value of waste photovoltaic glass greater than 1 / 3 of the original price of finished photovoltaic glass? Improving the recycling value of waste photovoltaic glass has become a critical concern at present. Figure 1(a) shows the waste photovoltaic glass particles before decarbonization, and Figure 1(b) shows the waste photovoltaic glass particles after decarbonization.

[0006] With the advent of the global photovoltaic module retirement wave, the recycling and processing technology of waste photovoltaic glass is limited to building material additives, resulting in low added value of converted products and insufficient resource utilization. The value of waste photovoltaic glass has not been effectively tapped. It is of great practical significance to explore the high-value utilization of waste photovoltaic glass. Summary of the invention

[0007] In view of the deficiencies in the prior art, the present invention provides a method for remelting retired photovoltaic glass after pyrolysis treatment to regenerate ultra-white glass, which can achieve efficient recovery and high value-added application of waste photovoltaic glass.

[0008] The present invention discloses a method for remelting retired photovoltaic glass after pyrolysis treatment to reconstruct ultra-white glass, comprising:

[0009] Step 1: Crush the pyrolysis-treated waste photovoltaic glass to form waste photovoltaic glass particles;

[0010] Step 2: Add waste photovoltaic glass particles, clarifying and redox regulators to the ultra-clear glass batch, and mix to form a batch containing waste photovoltaic glass particles; wherein, the redox value of the batch containing waste photovoltaic glass particles is 15.0 - 25.6, and the addition amount of waste photovoltaic glass particles is not more than 28 wt% of the mass of the ultra-clear glass batch;

[0011] Step 3: Heat the batch containing waste photovoltaic glass particles to a preset temperature and hold for a preset time to form glass liquid;

[0012] Step 4: Make ultra-clear glass from the glass liquid.

[0013] As a further improvement of the present invention, the quality requirements for the pyrolysis-treated waste photovoltaic glass are: carbon content ≤ 0.0242 wt%, total amount of impurity elements ≤ 245 ppm (mg / kg), wherein the impurity elements include Fe, Ti, Cu, Ni, and Cr, Fe ≤ 111 ppm, Ti ≤ 97 ppm, Cu ≤ 25 ppm, Ni ≤ 9 ppm, Cr ≤ 3 ppm.

[0014] As a further improvement of the present invention, the requirements for waste photovoltaic glass particles are: the proportion of 0.85 mm < D ≤ 25 mm is not less than 93.8 wt%, and the proportion of 0.15 mm ≤ D ≤ 0.85 mm is not more than 6.2 wt%; wherein, D is the maximum particle size.

[0015] As a further improvement of the present invention, the addition amount of waste photovoltaic glass particles is 8 wt% - 28 wt% of the mass of the ultra-clear glass batch.

[0016] As a further improvement of the present invention, based on 100 parts by weight of the ultra-clear glass batch, the chemical composition of the ultra-clear glass batch belongs to the low-aluminum sodium-calcium glass system.

[0017] As a further improvement of the present invention, the clarifying and redox regulators include glauber's salt, cerium oxide, and sodium nitrate. Based on 100 parts by weight of the ultra-clear glass batch, the addition amount of glauber's salt is 0.30 wt% - 0.82 wt%, the addition amount of cerium oxide is 0.15 wt% - 0.30 wt%, and the addition amount of sodium nitrate is 0.01 wt% - 2.15 wt%.

[0018] As a further improvement of the present invention, in Step 3, heat the batch containing waste photovoltaic glass particles to 1450 - 1550 °C and hold for 3.5 - 4.5 h; preferably, heat to 1500 °C and hold for 4 h.

[0019] As a further improvement of the present invention, the number of bubbles Q in the glass liquid formed in step 3 satisfies Q≤28, and the bubble diameter φ≤1.15 mm.

[0020] As a further improvement of the present invention, the visible light transmittance Tv (thickness 3.2 mm) of the ultra-white glass prepared in step 4 is ≥91.07%, and the chromaticity values (thickness 3.2 mm) are: L*≥96.21%, -0.23≤a*≤-0.03, 3.43≤b*≤4.30.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] The present invention can effectively cope with the environmental pressure brought by the retirement of large-scale photovoltaic modules and avoid secondary pollution;

[0023] The present invention can alleviate the shortage of high-quality quartz sand resources with low iron content and reduce the damage to the ecological environment caused by the mining and beneficiation of low-iron quartz sand;

[0024] The present invention can significantly reduce the resource consumption of the entire photovoltaic industrial chain;

[0025] The present invention has a significant energy-saving effect during the glass melting process, providing important technical support for realizing the green manufacturing of the entire life cycle of photovoltaic modules;

[0026] The present invention provides a feasible solution for the high-value utilization of pyrolyzed waste photovoltaic glass;

[0027] Compared with the conventional method of adding waste glass clinker, the present invention can greatly improve the number of bubbles, light transmittance, and colorless transparency;

[0028] The present invention uses the pyrolyzed waste photovoltaic glass as the raw material to remelt and reproduce ultra-white glass, which belongs to the high-value utilization path. It can not only increase the economic added value of waste photovoltaic glass but also promote the photovoltaic industry to move towards circular economy and sustainable development. Description of the Drawings

[0029] Figure 1(a) is a particle diagram of waste photovoltaic glass before decarbonization treatment;

[0030] Figure 1(b) is a particle diagram of waste photovoltaic glass after decarbonization treatment;

[0031] Figure 2(a) shows the number of bubbles and the maximum bubble diameter in the embodiment of the present invention;

[0032] Figure 2(b) shows the number of bubbles and the maximum bubble diameter in the comparative example of the present invention;

[0033] Figure 3 It is a physical diagram of the bubbles in the embodiment and the comparative example of the present invention;

[0034] Figure 4(a) shows the visible light transmittance of the embodiment of the present invention;

[0035] Figure 4(b) shows the visible light transmittance of the comparative example of the present invention;

[0036] Figure 5(a) shows the Munsell color system diagrams of the embodiment and the comparative example of the present invention;

[0037] Figure 5(b) shows the chromaticity coordinate diagrams of the embodiment and the comparative example of the present invention. Detailed Embodiments

[0038] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0039] The present invention will be further described in detail below with reference to the accompanying drawings:

[0040] The present invention provides a method for remelting and recycling pyrolysis-treated retired photovoltaic glass into ultra-clear glass, including:

[0041] Step 1: Crush the pyrolysis-treated waste photovoltaic glass to form waste photovoltaic glass particles; wherein, the quality requirements for the pyrolysis-treated waste photovoltaic glass are as follows: the carbon content rate ≤ 0.0242 wt%, the total amount of impurity elements ≤ 245 ppm (mg / kg), and the impurity elements include Fe, Ti, Cu, Ni, and Cr, with Fe ≤ 111 ppm, Ti ≤ 97 ppm, Cu ≤ 25 ppm, Ni ≤ 9 ppm, and Cr ≤ 3 ppm; the requirements for the waste photovoltaic glass particles are as follows: the proportion of 0.85 mm < D (maximum particle size) ≤ 25 mm is not less than 93.8 wt%, and the proportion of 0.15 mm ≤ D ≤ 0.85 mm is not more than 6.2 wt%.

[0042] Step 2: Add waste photovoltaic glass particles, clarifying and redox regulators to the ultra-clear glass batch, mix to form a batch containing waste photovoltaic glass particles, and control the redox value of the batch containing waste photovoltaic glass particles to be 15.0 - 25.6; wherein,

[0043] The ultra-clear glass batch refers to a composition composed of mineral raw materials with low iron oxide content (such as quartz sand, dolomite, calcite, etc.) and chemical raw materials (such as soda ash, potassium carbonate, aluminum hydroxide, etc.), with a chemical composition of a low-aluminum sodium-calcium glass system, which is similar to or consistent with the known ultra-clear glass composition;

[0044] Based on 100 parts by weight of the ultra-clear glass batch, the addition amount of waste photovoltaic glass particles is not more than 28 wt% of the mass of the ultra-clear glass batch. Preferably, the addition amount of waste photovoltaic glass particles is 5 wt% - 28 wt% of the mass of the ultra-clear glass batch, more preferably 8 wt% - 20 wt%, and even more preferably 8 wt% - 15 wt%.

[0045] The fining and redox regulator includes mirabilite, cerium oxide and sodium nitrate. Based on 100 parts by weight of the ultra-clear glass batch, the addition amount of mirabilite is 0.30 wt% - 0.82 wt%, the addition amount of cerium oxide is 0.15 wt% - 0.30 wt%, and the addition amount of sodium nitrate is 0.01 wt% - 2.15 wt%.

[0046] Step 3: Heat the batch containing waste photovoltaic glass particles to 1500 °C and hold for 4 h to form glass melt, and evaluate the melting and fining effect.

[0047] Step 4: Prepare the glass melt into a flat glass with a thickness of 3.2 mm, and evaluate the visible light transmittance and chromaticity value.

[0048] Among them, the test and evaluation characterization methods for the above performance indicators are as follows:

[0049] 1. The carbon content of waste photovoltaic glass is measured by a carbon-sulfur analyzer.

[0050] 2. Impurity elements are measured by an inductively coupled plasma atomic emission spectrometer (ICP-AES spectrometer).

[0051] 3. The particle size of waste photovoltaic glass is measured by a standard sieve and a balance.

[0052] 4. The evaluation of high-quality glass melt is carried out by using a high-temperature melting video system for glass batch. When the batch melts at 1500 °C for 4 h, take video pictures, and count the number of bubbles with a diameter greater than 0.05 mm and the maximum bubble diameter in a 30 mm × 25 mm video picture.

[0053] 5. The visible light transmittance and chromaticity value of the prepared ultra-clear glass are measured and calculated by a spectrophotometer, and the implementation standards are GB / T 2680-2021 Determination of Visible Light Transmittance, Solar Direct Transmittance, Total Solar Energy Transmittance, Ultraviolet Transmittance and Related Window Glass Parameters of Building Glass and GB / T 36142-2018 Measuring Methods for Color and Color Difference of Building Glass respectively.

[0054] In order to better present the invention concept and invention effect, the present invention selects 8 most representative examples, namely Examples 1 to 8 (see Tables 1 to 2). The examples only adopt typical numerical parameters and do not conduct infinite listing and expansion. The examples can already reflect and represent the innovation of the present invention.

[0055] In order to compare the advantages and inventive effects of the present invention, in accordance with the conventional process of flat glass, waste photovoltaic glass particles with the same addition amounts of 10wt%, 15wt%, 20wt%, and 28wt% were added, and 8 comparative examples were carried out, namely Comparative Example 1 to Comparative Example 8 (see Tables 3 to 4).

[0056] Table 1

[0057]

[0058] Table 2

[0059]

[0060] Table 3

[0061]

[0062]

[0063] Table 4

[0064]

[0065] From Tables 1 to 4 and the appendix Figures 2(a) to 5(b) it can be seen that

[0066] 1) The number of bubbles in the present invention is significantly reduced. That is, the number of bubbles in Examples 1 to 8 is 9 to 28, and the number of bubbles in Comparative Examples 1 to 8 is 44 to 97. The average value of the number of bubbles in Examples 1 to 8 is reduced by 73.9% compared with the average value of the number of bubbles in Comparative Examples 1 to 8. Among them, the number of bubbles and the maximum bubble diameter of Examples 1 to 8 and Comparative Examples 1 to 8 are statistically shown as Figures 2(a) to 2(b) shown, and the physical test diagrams of the melting and fining bubbles of Examples 1 to 8 and Comparative Examples 1 to 8 are shown as Figure 3 shown.

[0067] 2) The visible light transmittance index of the present invention is significantly improved. That is, the average value of the visible light transmittance of Examples 1 to 8 is 91.33%, and the average value of the visible light transmittance of Comparative Examples 1 to 8 is 89.73%, with a comprehensive increase of 1.60%. The indexes of Examples 1 to 8 all exceed 91% and meet the requirements of the ultra-clear glass standard, while the indexes of Comparative Examples 1 to 8 are all less than 91% and do not meet the ultra-clear glass standard. Among them, the visible light transmittance ratios of Examples 1 to 8 and Comparative Examples 1 to 8 are shown as Figures 4(a) to 4(b) shown.

[0068] 3) The chromaticity value of the present invention presents a bright colorless effect, that is, the average lightness value of Examples 1 to 8 is 96.52%, and the average lightness value of Comparative Examples 1 to 8 is 94.65%. The present invention improves by 1.87% in terms of the lightness value; in addition, the colorimetric indices a* and b* of Examples 1 to 8 are more inclined to 0, which is conducive to the glass presenting a more colorless effect. Among them, the Munsell color system diagrams and chromaticity coordinate diagrams of Examples 1 to 8 and Comparative Examples 1 to 8 are as Figures 5(a) to 5(b) shown.

[0069] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for remelting and recycling ultra-white glass from retired photovoltaic glass after pyrolysis treatment, characterized in that, Including: Step 1: Crush the pyrolysis-treated waste photovoltaic glass to form waste photovoltaic glass particles; Step 2: Add waste photovoltaic glass particles, clarifying and redox regulators to the ultra-clear glass batch, and mix to form a batch containing waste photovoltaic glass particles; wherein, the redox value of the batch containing waste photovoltaic glass particles is 15.0 - 25.6, and the addition amount of waste photovoltaic glass particles does not exceed 28wt% of the mass of the ultra-clear glass batch; Step 3: Heat the batch containing waste photovoltaic glass particles to a preset temperature and keep it warm for a preset time to form glass liquid; Step 4: Make the glass liquid into ultra-clear glass.

2. The method for remelting and reconstructing ultra-clear glass from pyrolysis-treated retired photovoltaic glass as claimed in claim 1, wherein The quality requirements of the pyrolysis-treated waste photovoltaic glass are: carbon content ≤ 0.0242wt%, total amount of impurity elements ≤ 245ppm, where the impurity elements include Fe, Ti, Cu, Ni, and Cr, Fe ≤ 111ppm, Ti ≤ 97ppm, Cu ≤ 25ppm, Ni ≤ 9ppm, Cr ≤ 3ppm.

3. The method for remelting and reconstructing ultra-white glass from pyrolyzed retired photovoltaic glass according to claim 1, characterized in that, The requirements for waste photovoltaic glass particles are: the proportion of 0.85mm < D ≤ 25mm is not less than 93.8wt%, and the proportion of 0.15mm ≤ D ≤ 0.85mm is not more than 6.2wt%; where D is the maximum particle size.

4. The method for remelting and reconstructing ultra-clear glass from pyrolysis-treated retired photovoltaic glass as claimed in claim 1, wherein, The addition amount of waste photovoltaic glass particles is 8wt% - 28wt% of the mass of the ultra-clear glass batch.

5. The method for remelting and reconstructing ultra-clear glass from pyrolysis-treated retired photovoltaic glass as claimed in claim 1, wherein, Based on 100 parts by weight of the ultra-clear glass batch, the chemical composition of the ultra-clear glass batch belongs to the low-aluminum sodium-calcium glass system.

6. The method for remelting and reconstructing ultra-white glass from pyrolyzed retired photovoltaic glass according to claim 1, wherein, The clarifying and redox regulators include glauber's salt, cerium oxide, and sodium nitrate. Based on 100 parts by weight of the ultra-clear glass batch, the addition amount of glauber's salt is 0.30wt% - 0.82wt%, the addition amount of cerium oxide is 0.15wt% - 0.30wt%, and the addition amount of sodium nitrate is 0.01wt% - 2.15wt%.

7. The method for remelting and reconstructing ultra-clear glass from pyrolysis-treated retired photovoltaic glass according to claim 1, characterized in that, In Step 3, heat the batch containing waste photovoltaic glass particles to 1450 - 1550°C and keep it warm for 3.5 - 4.5h.

8. The method for remelting and reconstructing ultra-clear glass from pyrolysis-treated retired photovoltaic glass according to claim 1, characterized in that, The number of bubbles Q of the glass liquid formed in Step 3 ≤ 28 and the bubble diameter φ ≤ 1.15mm.

9. The method for remelting and reconstructing ultra-white glass from pyrolysis-treated retired photovoltaic glass according to claim 1, characterized in that, The visible light transmittance Tv of the ultra-clear glass prepared in Step 4 ≥ 91.07%, chromaticity values: L* ≥ 96.21%, -0.23 ≤ a* ≤ -0.03, 3.43 ≤ b* ≤ 4.30.

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