Clarifying agent for producing photovoltaic glass and preparation method thereof

Abstract

The invention relates to the technical field of glass production auxiliaries, and discloses a clarifying agent for producing photovoltaic glass and a preparation method thereof.The clarifying agent is prepared from, by weight, 10-20 parts of sodium nitrate, 40-70 parts of sodium sulfate, 1-5 parts of antimony compound and 5-15 parts of recycled powder; the recycled powder comprises the optical glass polishing waste powder subjected to recycling treatment. The optical glass polishing waste powder is used for preparing the photovoltaic glass clarifying agent, and the problems that existing polishing waste powder is difficult to economically recycle, rare earth resources are wasted, and the rare earth raw material cost of the glass clarifying agent is high are effectively solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of glass production aids, in particular to a fining agent for producing photovoltaic glass and a preparation method thereof. BACKGROUND

[0002] As a key material of solar cell modules, the light transmittance of photovoltaic glass directly affects the power generation efficiency. In the production of photovoltaic glass, a certain amount of fining agent is usually required to achieve ideal fining effect and optical performance. The commonly used glass fining agent mainly relies on antimony compounds or high-purity cerium oxide and other rare and expensive rare earth raw materials. For example, cerium oxide, as the main fining agent, will fully decompose and release oxygen when the glass is heated to 1400-1500℃. However, the procurement cost of these high-quality rare earth raw materials is high, which significantly increases the production cost of photovoltaic glass and puts pressure on the economic benefits of the entire photovoltaic industry.

[0003] In order to reduce the cost, the industry has also tried to make some improvements to the fining agent formula, such as optimizing the ratio of antimony compounds and cerium oxide, and mixing with other auxiliary fining agents. However, these improvement techniques can only sacrifice the fining effect or slightly reduce the cost, but due to the difficulty in significantly reducing the cost of core active ingredients such as high-purity cerium oxide, the overall cost reduction effect is not significant, and the problem of high cost of fining agent has not been fundamentally solved.

[0004] At the same time, in the manufacturing process of optical glass, polishing powder is usually used for fine polishing of its surface, and cerium oxide is the main raw material of polishing powder. The polishing waste powder generated in the polishing process is rich in rare earth elements such as cerium oxide and lanthanum oxide, but due to the mixing of glass wear residues such as silicon dioxide and aluminum oxide, as well as iron impurities and organic aids caused by equipment wear, its recycling faces great challenges. The recycling of existing polishing waste powder is usually to use it to make lower quality polishing powder again, but the impurities, especially silicon residues, have a great impact on its use as polishing powder, and separating the silicon residues requires a lot of cost, making the recycling of polishing waste powder lose economic value. Therefore, polishing waste powder is currently considered as a kind of difficult-to-handle industrial waste, causing waste of rare earth resources. SUMMARY

[0005] In view of the above defects, the purpose of the present application is to provide a fining agent for producing photovoltaic glass and a preparation method thereof, which solves the problems of difficult economic recycling of polishing waste powder, waste of rare earth resources, and high cost of rare earth raw materials of glass fining agent.

[0006] To achieve this purpose, the technical scheme adopted by the present application is as follows: A kind of clarifier for producing photovoltaic glass, according to weight fraction, the raw materials of clarifier include: sodium nitrate 10~20 parts, sodium sulfate 40~70 parts, antimony compound 1~5 parts and recovery powder 5~15 parts; The recovery powder includes optical glass polishing waste powder after recovery treatment, according to mass percentage, the dry base content of the optical glass polishing waste powder is calculated by metal element cation oxide: CeO 40~80%, La 2 O 3 5~25%, SiO 2 5~40%, Al 2 O 3 0~15%, Fe 2 O 3 0.5~1.0%, Other balance; Loss on ignition 2~5% at 1000℃.

[0007] Preferably, the antimony compound is sodium pyroantimonate.

[0008] Preferably, according to mass percentage, the control index of the recovery powder calculated by metal element cation oxide is: CeO 55~65%, La 2 O 3 10~15%, Fe 2 O 3 0.6~0.7%, Loss on ignition less than 1% at 1000℃.

[0009] A preparation method of clarifier, for preparing the above-mentioned clarifier, comprising the following steps: S1, polishing waste powder pretreatment: sequentially through drying, screening, calcination and mixing uniformly, to prepare pretreated polishing waste powder, and to carry out component analysis and batch storage; S2, preparation of recovery powder: a plurality of batches of pretreated polishing waste powder are mixed according to component complementation, to prepare recovery powder; S3, preparation of clarifier: sodium nitrate, sodium sulfate, antimony compound and recovery powder are mixed in proportion, to prepare clarifier.

[0010] Preferably, in step S1, the calcination temperature is 600~700℃, the heating rate is 5~10℃ / min, and the holding time is 1~2h after heating to the highest temperature.

[0011] Preferably, in step S1, the screen mesh in screening adopts ultrasonic vibration screen, and the aperture is 5~20 microns.

[0012] Preferably, in step S1, the drying temperature is 105~120℃, and the time is 10~60 minutes.

[0013] Preferably, the recovery powder further includes industrial grade cerium oxide, and the amount is 10~30% of the total amount of recovery powder by weight ratio. In step S1, after component analysis, batches meeting the recycled powder control indicators are directly stored as recycled powder or enter step S3; batches not meeting the recycled powder control indicators are recorded after component analysis, enter step S2, and batches meeting the indicators are mixed at a ratio of 1:1~3, and component analysis is performed again, if meeting the recycled powder control indicators, they are stored as recycled powder or enter step S3, if still not meeting the recycled powder control indicators, 10~30% of industrial-grade cerium oxide is added and stored as recycled powder.

[0014] Preferably, a three-dimensional motion mixer is used for mixing in steps S1, S2 and S3.

[0015] The technical solution provided by the present application can include the following beneficial effects: 1. The present application provides an innovative scheme for preparing photovoltaic glass clarifying agent using optical glass polishing waste powder, effectively solving the problems of difficult economic recycling of polishing waste powder, waste of rare earth resources, and high cost of glass clarifying agent raw materials. Optical glass usually needs to be polished on the surface using polishing powder, and the main raw material of polishing powder is cerium oxide. By using polishing waste powder containing cerium oxide as the raw material of clarifying agent, the recycling of rare earth resources is realized, the production cost is significantly reduced, and significant environmental and economic benefits are achieved.

[0016] 2. By setting narrower control indicators for the key components of the recycled powder, the problem of unstable clarifying agent performance caused by fluctuations in the composition of the recycled powder is effectively solved. The content of cerium oxide and lanthanum oxide is controlled in a more precise range to ensure the stable supply of active rare earth components in the clarifying agent, thereby ensuring the consistency of glass clarifying efficiency and decolorization effect.

[0017] 3. Relative to the cost of raw materials, priority is given to ensuring production efficiency and the quality of glass products. By introducing industrial-grade cerium oxide as an adjusting component in the recycled powder, when the detection indicators of the recycled powder slightly exceed the control range of the above indicators, such as lower cerium oxide, or higher lanthanum oxide, iron oxide, and 1000℃ loss on ignition, complex repeated adjustment or scrap processing is not required. By adding industrial-grade cerium oxide, the indicators fall within the control indicator range, avoiding the problem of increased labor costs due to repeated adjustment.

[0018] 4. The present application provides a systematic and efficient clarifying agent preparation method, effectively solving the problems of complex sources of polishing waste powder, different compositions, and the presence of various impurities.

[0019] Through the pretreatment of drying, screening and calcination in step S1, free water, large particle inclusions and organic matter in the polishing waste powder can be completely removed, the inclusions brought into the glass solution can be reduced, and the purity and activity of the waste powder can be significantly improved. After that, each batch of polishing waste powder is mixed uniformly to avoid sampling deviation affecting the results of component analysis, laying a foundation for subsequent utilization.

[0020] Step S2 aims to solve the problem that the components of the polishing waste powder generated due to the difference in the processing technology of different optical glass types are different. Different batches of polishing waste powder are stored in batches, and the components are complementarily adjusted, so that the scheme can be applied to more types of polishing waste powder, and the components of the recovered powder and the prepared fining agent are still stable. The "complementary quantitative mixing of components" ingeniously utilizes the difference in the components of different batches of polishing waste powder. By quantitative proportioning, the batches with components higher than the control index and the batches with components lower than the control index are complementarily mixed, so that the components of the recovered powder prepared finally are stable and meet the requirements of the fining agent, thereby more types of polishing waste powder from different sources can be efficiently utilized, and the problem that the components of the fining agent prepared from the polishing waste powder fluctuate and the use effect is unstable due to the unstable components of the polishing waste powder is solved.

[0021] 5. By adopting one-time mixing, the components in different batches of polishing waste powder are balanced, so that the components of the recovered powder tend to be stable, the control index is prevented from fluctuating, and the mixing ratio is controlled to avoid the problem of uneven mixing.

[0022] After one-time mixing, the components of the recovered powder have already approached or completely fallen within the control index. If the components still slightly exceed the control index after re-detection, an appropriate amount of industrial-grade cerium oxide is added for dilution adjustment to ensure that the components fall within the control index range. This avoids the problems of increasing labor costs, easily introducing secondary pollution and re-adding impurities caused by multiple mixing operations.

[0023] This "single mixing adjustment" plus the final adjustment mechanism can not only stabilize the overall components of the recovered powder to the greatest extent, but also significantly reduce the production complexity and labor costs. The use of a small amount of industrial-grade cerium dioxide balances the cost and quality of the fining agent, greatly improves the actual utilization rate and recycling economic value of the polishing waste powder, and ensures the stability of the final fining agent and the quality of the photovoltaic glass. DETAILED DESCRIPTION

[0024] In order to facilitate the understanding of the present application, the present application will be described more fully below. The present application can be implemented in many different forms, and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0025] Unless otherwise indicated, the techniques and conditions employed in the examples follow those described in the literature or those specified by the manufacturer of the products used.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description herein is for describing particular embodiments only and is not intended to be limiting of the application. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0027] A clarifying agent for producing photovoltaic glass, according to weight parts, the raw materials of the clarifying agent include: sodium nitrate 10~20 parts, sodium sulfate 40~70 parts, antimony compound 1~5 parts and recycled powder 5~15 parts; The recycled powder includes optical glass polishing waste powder after recycling treatment, according to mass percentage, the dry basis content of the optical glass polishing waste powder is calculated by metal element cation oxide: cerium oxide 40~80%, lanthanum oxide 5~25%, silicon dioxide 5~40%, aluminum oxide 0~15%, iron oxide 0.5~1.0%, the rest; 1000℃ loss on ignition 2~5%.

[0028] The application provides an innovative scheme for preparing a photovoltaic glass clarifying agent by using optical glass polishing waste powder, effectively solving the problems of difficult economic recycling of existing polishing waste powder, waste of rare earth resources and high cost of rare earth raw materials of glass clarifying agent. Optical glass usually needs to be polished on the surface by using polishing powder, and the main raw material of the polishing powder is cerium oxide. By using the polishing waste powder containing cerium oxide as the raw material of the clarifying agent, the recycling of rare earth resources is realized, the production cost is significantly reduced, and significant environmental and economic benefits are obtained.

[0029] The optical glass polishing waste powder is derived from different polishing processes, and the moisture content fluctuates greatly. The dry basis is a measurement method for calculating the dry basis content of the dry material by drying the material to constant weight at 105 DEG C.

[0030] Optical glasses are various, and in addition to silicon dioxide, aluminum or lanthanum needs to be added to meet the performance requirements.

[0031] Cerium oxide is the most valuable component in polishing powder waste as a glass clarifying agent. In conventional clarifying agents that use cerium oxide as the main raw material, cerium oxide will fully decompose and release oxygen when the glass is heated to 1400–1500°C. The cerium oxide in polishing powder is in the micron range, which can further reduce its decomposition temperature range in actual use to 1400~1450°C.

[0032] Lanthanum can reduce iron impurities in glass from yellow / brown ferric ions to pale green / colorless ferrous ions, thereby reducing the blue-green color of the glass and making it closer to colorless and transparent.

[0033] Silicon is the main component of glass and originates from the wear residue during the glass polishing process. Existing polishing waste powder recycling processes usually involve reprocessing it into lower-quality polishing powder. The silicon residue has a significant impact on the use of polishing powder, and separating the silicon residue requires a large investment of resources, making the recycling of polishing waste powder uneconomical and hindering its further development.

[0034] However, when polishing waste powder is used as a raw material for glass clarifiers, the overall amount of glass clarifier used is small. The silicon and aluminum residues will dissolve back into the glass product during use, having virtually no impact on the product's performance. As for other impurities, their relatively low content in the polishing waste powder also means they will not have a practical effect. Therefore, using polishing waste powder as a raw material for glass clarifiers solves both the problems of difficult recycling of polishing waste powder and waste of rare earth resources, as well as the high cost of using rare earth raw materials for glass clarifiers, thus possessing significant environmental and economic value.

[0035] Iron is an unavoidable impurity in raw materials, and it is also difficult to completely avoid using iron-containing parts in polishing equipment. After long-term use, the surface oxidation of iron-containing parts will cause iron particles to fall off and become mixed in with polishing waste powder.

[0036] The loss on ignition at 1000℃ is mainly caused by organic matter in the polishing waste, which mainly comes from organic additives in the polishing powder and wear of the inner lining of the grinding equipment.

[0037] The lower the iron content, the closer the glass color is to transparency and the higher the photovoltaic transmittance. Organic matter will cause a large number of bubbles to be generated uncontrollably in the low-temperature region where the viscosity of the glass solution is low. Both iron and organic matter will have an adverse effect on the quality of glass products. Therefore, it is necessary to monitor and adjust the iron oxide in polishing waste powder and the loss on ignition at 1000℃.

[0038] Sodium nitrate, sodium sulfate, antimony compounds, and cerium oxide from recycled powder are combined to generate gas over a wide temperature range to remove inclusions and bubbles from the glass solution, thus enabling the effective reuse of polishing waste powder in the clarifying agent.

[0039] Preferably, the antimony compound is sodium pyroantimonate.

[0040] Sodium pyroantimonate, as a clarifying agent, can work synergistically with cerium oxide, sodium nitrate, and sodium sulfate during the glass melting process to release oxygen within a specific temperature range, effectively capturing and removing bubbles and inclusions in the molten glass, thus ensuring the clarity of the glass products.

[0041] As a simple replacement, antimony compounds can also be mixed with or used alone with sodium antimonosulfate, requiring corresponding adjustments to the glass heating and holding time.

[0042] Preferably, the control parameters of the recovered powder, calculated as cationic oxides by mass percentage, are as follows: Cerium oxide 55~65%, Lanthanum oxide 10-15%, Iron oxide 0.6~0.7%, Loss on ignition at 1000℃ is less than 1%.

[0043] By setting narrower control parameters for the key components of the recycled powder, the problem of unstable clarifier performance caused by fluctuations in the recycled powder composition is effectively solved. Controlling the content of cerium oxide and lanthanum oxide within a more precise range ensures a stable supply of active rare earth components in the clarifier, thereby guaranteeing consistent glass clarification efficiency and decolorization effect.

[0044] Furthermore, strictly controlling the iron oxide content between 0.6% and 0.7% significantly reduces the coloring of the glass, making the photovoltaic glass closer to transparency and greatly improving its transmittance, which is crucial for improving the power generation efficiency of photovoltaic modules. Simultaneously, controlling the loss on ignition at 1000℃ to less than 1% effectively reduces the organic matter that may be introduced into the recycled powder, preventing the generation of a large number of uncontrollable bubbles due to the decomposition of organic matter during glass melting, thereby improving the overall quality and production stability of glass products.

[0045] A method for preparing a clarifying agent, comprising the following steps: S1. Pretreatment of polishing waste powder: The polishing waste powder is obtained by drying, sieving, calcining and mixing in sequence, and then the composition is analyzed and stored in batches. S2. Preparation of recycled powder: Several batches of pretreated polishing waste powder are quantitatively mixed according to complementary components to obtain recycled powder; S3. Preparation of clarifying agent: Sodium nitrate, sodium sulfate, antimony compound and recycled powder are mixed in proportion to prepare the clarifying agent.

[0046] This invention provides a systematic and efficient method for preparing clarifying agents, effectively solving the problems of complex sources, inconsistent compositions, and multiple impurities in polishing waste powder.

[0047] The drying, sieving, and calcination pretreatment in step S1 can thoroughly remove free moisture, large particle inclusions, and organic matter from the polishing waste powder, reduce inclusions introduced into the glass solution, and significantly improve the purity and activity of the waste powder. Subsequently, each batch of polishing waste powder is mixed evenly to avoid sampling deviations affecting the results of component analysis, laying the foundation for subsequent utilization.

[0048] Step S2 addresses the issue of inconsistent polishing waste powder composition due to differences in processing techniques for different types of optical glass. By storing different batches of polishing waste powder in separate batches and adjusting their composition accordingly, this solution can be applied to a wider range of polishing waste powders while maintaining the stability of the recovered powder and the clarifying agent it produces. The "complementary quantitative mixing" method cleverly utilizes the differences in composition between different batches of polishing waste powder. Through quantitative mixing, batches with corresponding indicators higher than or lower than the control indicators are complementaryly mixed, resulting in a stable composition of the final recovered powder that meets the requirements of the clarifying agent. This allows for the efficient utilization of a wider variety of polishing waste powders from different sources, solving the problem of fluctuating clarifying agent composition and inconsistent performance caused by the instability of polishing waste powder composition.

[0049] Preferably, in step S1, the calcination temperature is 600~700℃, the heating rate is 5~10℃ / min, and the holding time after reaching the maximum temperature is 1~2h.

[0050] Controlling the heating rate effectively prevents the rapid decomposition of organic matter from causing the generated gases to carry away the cerium oxide powder. Simultaneously, removing the organic matter coating the surface of the cerium oxide powder significantly increases the actual contact area between the powder and the molten glass during use, thus activating the cerium oxide and further reducing its decomposition temperature. This solves the problem of low decomposition efficiency caused by the obstruction of organic matter coating, which results in a lower actual temperature for the cerium oxide powder. A calcination process controlled at 600℃ for 1 hour typically meets the requirement of 1% loss on ignition at 1000℃. For higher requirements, the calcination temperature can be increased to 700℃ and the time extended to 2 hours, further reducing the loss on ignition to below 0.5%.

[0051] Preferably, in step S1, the sieve used in the screening process is an ultrasonic vibrating sieve with an aperture of 5-20 micrometers.

[0052] Ultrasonic vibrating screens, combined with micron-sized mesh, effectively remove particulate impurities from polishing waste powder. Utilizing the high-frequency vibration of ultrasound, screening efficiency is significantly improved, preventing fine powder from clogging the screen holes and thus thoroughly removing particulate impurities from polishing waste powder that could cause defects in glass products. Simultaneously, due to the removal of iron filings, the iron content after screening will also be slightly reduced.

[0053] Preferably, in step S1, the drying temperature is 105~120℃ and the time is 10~60 minutes.

[0054] Drying removes free moisture and prevents water vapor from carrying away cerium dioxide during rapid heating in the roasting process.

[0055] Preferably, the recycled powder also includes industrial-grade cerium oxide, which, by weight, accounts for 10-30% of the total recycled powder. In step S1, after component analysis, batches that meet the control indicators for recycled powder are directly stored as recycled powder or proceed to step S3; batches that do not meet the control indicators for recycled powder are recorded and then proceed to step S2, where batches with complementary indicators are mixed at a ratio of 1:1 to 3, and component analysis is performed again. If they meet the control indicators for recycled powder, they are stored as recycled powder or proceed to step S3; if they still do not meet the control indicators for recycled powder, 10 to 30% industrial-grade cerium oxide is added before they are stored as recycled powder.

[0056] By using a single mixing method, the composition of different batches of polishing waste powder is balanced, making the composition of the recycled powder more stable, avoiding fluctuations in control indicators, and controlling the mixing ratio to avoid uneven mixing.

[0057] If the composition of the recovered powder is close to or completely within the control limits after one mixing, and the composition still slightly exceeds the control limits after another test, add an appropriate amount of industrial-grade cerium oxide for dilution and adjustment to ensure that it falls within the control limits. This avoids multiple mixing operations that increase labor costs and are prone to secondary pollution and the introduction of impurities.

[0058] This "single-mixing adjustment" plus final adjustment mechanism can stabilize the overall composition of the recycled powder to the greatest extent, significantly reduce production complexity and labor costs, and achieve a balance between the cost and quality of the clarifying agent by using a small amount of industrial-grade cerium dioxide. This greatly improves the actual utilization rate and recycling economic value of polishing waste powder, while ensuring the stability of the final clarifying agent and the quality of photovoltaic glass.

[0059] Prioritizing production efficiency and glass product quality over raw material costs, industrial-grade cerium oxide is introduced into the recycled powder as a regulating component. When the recycled powder's test indicators slightly exceed the control range of the aforementioned indicators—such as low cerium oxide levels, or high levels of one or more of the following: lanthanum oxide, iron oxide, or loss on ignition at 1000℃—complex re-blending or scrapping is unnecessary. Adding industrial-grade cerium oxide brings the indicators back within the control range, avoiding the increased labor costs associated with repeated blending.

[0060] By adding an appropriate amount of industrial-grade cerium oxide, the overall composition of the recycled powder can be effectively diluted and adjusted, quickly bringing it back to the specified control range, thereby ensuring the quality and performance stability of the final clarifying agent. This method not only avoids the increased labor costs and time consumption caused by repeated mixing and reduces production complexity, but also prioritizes production efficiency and the quality of photovoltaic glass products, maximizing the utilization of recycled powder and optimizing economic benefits.

[0061] Preferably, a three-dimensional motion mixer is used for mixing in steps S1, S2 and S3.

[0062] The three-dimensional motion mixer, through its unique multi-dimensional flipping, translation, and oscillating motion, enables materials to undergo complex shearing, diffusion, and convection within the mixing container. This achieves uniform mixing of micron-sized powders in a short time, effectively solving the problem of uneven mixing of micron-sized powders. It ensures that all components in the clarifying agent are evenly distributed, allowing them to exert their optimal clarifying effect during glass melting, thus guaranteeing the consistency and stability of photovoltaic glass product quality.

[0063] Example 1 S1. Pretreatment of polishing waste powder: A batch of waste powder from optical glass polishing was sampled and analyzed. Based on mass percentage and calculated as cationic oxides, the dry basis content of the metal elements was: cerium oxide 55.11%, lanthanum oxide 11.03%, silicon dioxide 35.25%, aluminum oxide 5.31%, iron oxide 0.81%, and loss on ignition at 1000℃ 3.10%. Drying: Place the polishing waste powder in an oven and dry it at 110℃ for 30 minutes to remove free moisture; Screening: The dried polishing waste powder is screened through an ultrasonic vibrating screen with a screen aperture of 10 micrometers to remove large particles of impurities and some iron particles. Calcination: The sieved polishing waste powder was placed in a calcination furnace and heated to 650°C at a heating rate of 7°C / min, and held at that temperature for 1.5 hours. After calcination, the loss on ignition at 1000°C of the polishing waste powder decreased to 0.61%. After thorough mixing, the composition of the pretreated polishing waste powder is as follows: cerium oxide 56.45%, lanthanum oxide 11.27%, silicon dioxide 35.34%, aluminum oxide 5.23%, iron oxide 0.61%, and loss on ignition at 1000℃ 0.61%. This batch meets the control indicators for recycled powder and can be directly stored as recycled powder for later use.

[0064] Example 2 S1. Pretreatment of polishing waste powder: A batch of waste powder from optical glass polishing was sampled and analyzed. Based on mass percentage and calculated as cationic oxides, the dry basis content of the metal elements was: cerium oxide 69.56%, lanthanum oxide 6.15%, silicon dioxide 20.10%, aluminum oxide 3.36%, iron oxide 0.95%, and loss on ignition at 1000℃ 2.81%. Drying: Place the polishing waste powder in an oven and dry it at 110℃ for 30 minutes to remove free moisture; Screening: The dried polishing waste powder is screened through an ultrasonic vibrating screen with a screen aperture of 5 micrometers to remove large particles of impurities and some iron particles. Calcination: The sieved polishing waste powder was placed in a calcination furnace and heated to 650°C at a heating rate of 7°C / min, and held at that temperature for 1.5 hours. After calcination, the loss on ignition at 1000°C of the polishing waste powder decreased to 0.55%. After thorough mixing, the composition of the pretreated polishing waste powder is as follows: cerium oxide 70.20%, lanthanum oxide 6.11%, silicon dioxide 20.25%, aluminum oxide 3.47%, iron oxide 0.69%, and loss on ignition at 1000℃ 0.55%. The cerium oxide content of this batch is higher than the control index of the recycled powder, while the lanthanum oxide content is lower than the control index of the recycled powder. It is designated as batch A and stored for further mixing.

[0065] Example 3 S1. Pretreatment of polishing waste powder: A batch of waste powder from optical glass polishing was sampled and analyzed. Based on mass percentage and calculated as cationic oxides, the dry basis content of the metal elements was: cerium oxide 48.12%, lanthanum oxide 20.19%, silicon dioxide 37.91%, aluminum oxide 5.58%, iron oxide 1.00%, and loss on ignition at 1000℃ 3.5%. Drying: Place the polishing waste powder in an oven and dry it at 110℃ for 30 minutes to remove free moisture; Screening: The dried polishing waste powder is screened through an ultrasonic vibrating screen with a screen aperture of 5 micrometers to remove large particles of impurities and some iron particles. Calcination: The sieved polishing waste powder is placed in a calcination furnace and heated to 650℃ at a heating rate of 5℃ / min, and held at that temperature for 1.5 hours. After calcination, the loss on ignition at 1000℃ of the polishing waste powder is reduced to 0.5%. After thorough mixing, the composition of the pretreated polishing waste powder is as follows: cerium oxide 48.55%, lanthanum oxide 20.73%, silicon dioxide 38.03%, aluminum oxide 5.51%, iron oxide 0.81%, and loss on ignition at 1000℃ 0.56%. The cerium oxide content of this batch is lower than the control index of the recycled powder, while the iron oxide content is higher than the control index of the recycled powder. It is designated as batch B and stored for further mixing. S2. Preparation of recycled powder: The cerium oxide and lanthanum oxide contents of batch A prepared in Example 2 and batch B of this Example are complementary. Batch A and batch B were mixed at a mass ratio of 1:1 to obtain a mixed powder. The composition of the mixed powder was analyzed, and the results are as follows: cerium oxide 59.35%, lanthanum oxide 13.47%, silicon dioxide 29.50%, aluminum oxide 4.50%, iron oxide 0.75%, and loss on ignition at 1000℃ 0.55%.

[0066] Since the iron oxide content of 0.75% is slightly higher than the control target of 0.6-0.7%, in order to further optimize the composition, 15% of the total mass of industrial-grade cerium oxide with a purity of 99.9% was added to the mixed powder. The final recycled powder obtained after mixing has the following composition analysis results: cerium oxide 64.65%, lanthanum oxide 11.66%, silicon dioxide 25.34%, aluminum oxide 3.90%, iron oxide 0.65%, and loss on ignition at 1000℃ 0.48%. S3. Preparation of clarifying agent: According to the weight ratio, 10 parts sodium nitrate, 40 parts sodium sulfate, 3 parts sodium pyroantimonate, and 10 parts recycled powder are added together with the other components into a three-dimensional motion mixer for thorough mixing to obtain a clarifying agent.

[0067] Glass melting test: The prepared clarifying agent was added to the glass molten pool and heated to 1450℃ for melting. During the melting process, it was observed that the glass molten liquid had a good clarification effect and the bubbles escaped steadily. After melting, a photovoltaic glass with a thickness of 3.2mm was obtained. The color was close to colorless and transparent, and the visible light transmittance reached 91.8%. There were no residual bubbles or inclusions inside the glass.

[0068] Comparative Example This comparative example aims to verify the effectiveness of untreated polishing waste powder as a clarifying agent raw material. The initial untreated optical glass polishing waste powder from Example 1 was directly taken, dried at 110°C to remove free moisture, and then used to replace the recovered powder component in the clarifying agent. The components were put into a mixer and mixed in the same weight ratio as in Example 3 to obtain the clarifying agent of the comparative example.

[0069] Glass melting test: A comparative amount of clarifying agent was added to the glass molten pool, and the temperature was raised to 1450℃ for melting. During the melting process, a large number of uncontrollable bubbles were observed in the molten glass, accompanied by a pungent odor from the decomposition of organic matter. After melting, a 3.2mm thick photovoltaic glass was obtained, with a pale yellow-green color and a visible light transmittance of only 88.5%. Numerous residual bubbles were present inside the glass.

[0070] As can be seen from the glass melting tests of Comparative Example 3 and Comparative Example 1, the present invention effectively pre-treats and controls the composition of polishing waste powder, thereby solving the adverse effects of impurities such as organic matter and iron oxide in polishing waste powder on the quality of glass products. It also fully utilizes the clarifying effect of cerium oxide and the decolorizing effect of lanthanum oxide in the waste powder, resulting in significant technological progress and economic and environmental benefits.

[0071] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0072] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A fining agent for the production of photovoltaic glass, characterized in that, The raw materials of the clarifying agent include, in parts by weight, sodium nitrate 10-20 parts, sodium sulfate 40-70 parts, antimony compound 1-5 parts, and recycled powder 5-15 parts; The recycled powder includes optical glass polishing waste powder after recycling treatment, and the dry basis content of the optical glass polishing waste powder, calculated in terms of cation oxides of metal elements, is: cerium oxide 40-80%, lanthanum oxide 5-25%, silicon dioxide 5-40%, aluminum oxide 0-15%, iron oxide 0.5-1.0%, the balance; 1000℃ loss on ignition 2-5%.

2. A fining agent for the production of photovoltaic glass according to claim 1, characterized in that: The antimony compound is sodium pyroantimonate.

3. A fining agent for the production of photovoltaic glass according to claim 1, characterized in that: The control index of the recycled powder, calculated in terms of cation oxides of metal elements, is: cerium oxide 55-65%, lanthanum oxide 10-15%, iron oxide 0.6-0.7%, 1000℃ loss on ignition less than 1%.

4. A method for producing a clarifying agent, characterized by, The method for preparing the clarifying agent of any one of claims 1-3 comprises the following steps: S1, polishing waste powder pretreatment: sequentially dried, sieved, calcined and uniformly mixed to obtain pretreated polishing waste powder, and then analyzed for composition and stored in batches; S2, preparing recycled powder: a plurality of batches of pretreated polishing waste powder are mixed in a quantitative manner according to complementary composition to obtain recycled powder; S3, preparing clarifying agent: sodium nitrate, sodium sulfate, antimony compound and recycled powder are mixed in a proportion to obtain the clarifying agent.

5. The method of claim 4, wherein: In step S1, the calcination temperature is 600-700℃, the heating rate is 5-10℃ / min, and the holding time at the highest temperature is 1-2h.

6. The method of claim 4, wherein: In step S1, the screen mesh in the sieving process is an ultrasonic vibrating screen with a pore size of 5-20 microns.

7. The method of claim 4, wherein: In step S1, the drying temperature is 105-120℃, and the time is 10-60 minutes.

8. The method of claim 4, wherein: The recycled powder also includes industrial-grade cerium oxide, and the amount is 10-30% of the total amount of the recycled powder; In step S1, after the composition analysis, the batches that meet the control index of the recycled powder are directly stored as recycled powder or enter step S3; the batches that do not meet the control index of the recycled powder are recorded for composition, enter step S2, mixed with batches with complementary indexes in a ratio of 1:1-3, and then analyzed for composition again; if the control index of the recycled powder is met, the batches are stored as recycled powder or enter step S3; if the control index of the recycled powder is still not met, the batches are stored as recycled powder after adding 10-30% of industrial-grade cerium oxide.

9. The method of claim 4, wherein: In steps S1, S2 and S3, a three-dimensional motion mixer is used for mixing.