A fining agent for producing photovoltaic glass and a method for preparing the same

Abstract

The present application relates to the technical field of glass production aids, and discloses a fining agent for producing photovoltaic glass and a preparation method thereof, wherein the raw materials of the fining agent include 10-20 parts of sodium nitrate, 40-70 parts of sodium sulfate, 1-5 parts of antimony compounds and 5-15 parts of recycled powder according to weight fraction; the recycled powder includes optical glass polishing waste powder after recycling treatment. The present application uses optical glass polishing waste powder to prepare the fining agent for photovoltaic glass, effectively solves the problems of difficult economic recycling of the existing polishing waste powder, waste of rare earth resources and high cost of rare earth raw materials of the glass fining agent.

Description

Technical Field

[0001] This invention relates to the field of glass production additives, and in particular to a clarifying agent for the production of photovoltaic glass and its preparation method. Background Technology

[0002] As a key material for solar cell modules, the light transmittance of photovoltaic glass directly affects power generation efficiency. In the production of photovoltaic glass, a certain amount of clarifying agent is typically required to achieve ideal clarification and optical performance. Currently, commonly used glass clarifying agents mainly rely on rare and expensive rare earth raw materials such as antimony compounds or high-purity cerium oxide. For example, cerium oxide, as a primary clarifying agent, fully decomposes and releases oxygen when the glass is heated to 1400–1500℃. However, the procurement cost of these high-quality rare earth raw materials remains high, significantly increasing the production cost of photovoltaic glass and putting pressure on the economic efficiency of the entire photovoltaic industry.

[0003] To reduce costs, the industry has attempted to improve clarifying agent formulations, such as optimizing the ratio of antimony compounds to cerium oxide and using them in combination with other auxiliary clarifying agents. However, these improvements often only sacrifice clarification effects or slightly reduce costs. Because the cost of core active ingredients, such as high-purity cerium oxide, is difficult to significantly reduce, the overall cost reduction effect is not significant, failing to fundamentally solve the problem of high clarifying agent costs.

[0004] Meanwhile, in the manufacturing process of optical glass, polishing powder is typically used for fine polishing of its surface, with cerium oxide being the main raw material. Although the polishing waste powder generated during the polishing process is rich in rare earth elements such as cerium oxide and lanthanum oxide, its recycling faces significant challenges due to the presence of glass wear residues, such as silica and alumina, as well as iron impurities and organic additives from equipment wear. Current methods for recycling polishing waste powder typically involve reprocessing it into lower-quality polishing powder. However, impurities, especially silicon residues, significantly impact its usability as polishing powder, and separating these silicon residues requires substantial costs, rendering the recycling of polishing waste powder uneconomical. Therefore, polishing waste powder is currently considered a difficult-to-manage industrial waste, resulting in a waste of rare earth resources. Summary of the Invention

[0005] To address the aforementioned shortcomings, the present invention aims to provide a clarifying agent for the production of photovoltaic glass and its preparation method, thereby solving the problems of the difficulty in economically recycling polishing waste powder, the waste of rare earth resources, and the high cost of rare earth raw materials for glass clarifying agents.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] A clarifying agent for the production of photovoltaic glass, wherein the raw materials of the clarifying agent include, by weight, 10-20 parts sodium nitrate, 40-70 parts sodium sulfate, 1-5 parts antimony compound and 5-15 parts recycled powder;

[0008] The recycled powder includes recycled optical glass polishing waste powder. The dry basis content of the optical glass polishing waste powder, calculated by mass percentage and in terms of cationic oxides for metal elements, is as follows:

[0009] Cerium oxide 40~80%,

[0010] Lanthanum oxide 5~25%,

[0011] 5-40% silica

[0012] Alumina 0~15%,

[0013] Iron oxide 0.5~1.0%,

[0014] Other margins;

[0015] Loss on ignition at 1000℃ is 2-5%.

[0016] Preferably, the antimony compound is sodium pyroantimonate.

[0017] Preferably, the control parameters of the recovered powder, calculated as cationic oxides by mass percentage, are as follows:

[0018] Cerium oxide 55~65%,

[0019] Lanthanum oxide 10-15%,

[0020] Iron oxide 0.6~0.7%,

[0021] Loss on ignition at 1000℃ is less than 1%.

[0022] A method for preparing a clarifying agent, comprising the following steps:

[0023] 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.

[0024] S2. Preparation of recycled powder: Several batches of pretreated polishing waste powder are quantitatively mixed according to complementary components to obtain recycled powder;

[0025] S3. Preparation of clarifying agent: Sodium nitrate, sodium sulfate, antimony compound and recycled powder are mixed in proportion to prepare the clarifying agent.

[0026] 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.

[0027] Preferably, in step S1, the sieve used in the screening process is an ultrasonic vibrating sieve with an aperture of 5-20 micrometers.

[0028] Preferably, in step S1, the drying temperature is 105~120℃ and the time is 10~60 minutes.

[0029] Preferably, the recycled powder also includes industrial-grade cerium oxide, which, by weight, accounts for 10-30% of the total recycled powder.

[0030] 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.

[0031] Preferably, a three-dimensional motion mixer is used for mixing in steps S1, S2 and S3.

[0032] The technical solution provided by this invention may include the following beneficial effects:

[0033] 1. This invention provides an innovative solution for preparing photovoltaic glass clarifying agents using waste polishing powder from optical glass, effectively solving the problems of the difficulty in economically recycling existing polishing waste powder, the waste of rare earth resources, and the high cost of rare earth raw materials for glass clarifying agents. Optical glass typically requires polishing powder to polish its surface. The main raw material of polishing powder is cerium oxide. By using cerium oxide-containing waste polishing powder as a raw material for clarifying agents, the recycling of rare earth resources is achieved, significantly reducing production costs and providing significant environmental and economic benefits.

[0034] 2. By setting narrower control parameters for the key components of the recycled powder, the problem of unstable clarifier performance caused by fluctuations in the composition of the recycled powder 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.

[0035] 3. Prioritize production efficiency and glass product quality over raw material costs. By introducing industrial-grade cerium oxide as a regulating component into the recycled powder, when the tested indicators of the recycled powder slightly exceed the control range of the aforementioned indicators, such as cerium oxide being too low, or one or more of lanthanum oxide, iron oxide, and loss on ignition at 1000℃ being too high, there is no need for complex repeated mixing or scrapping. By adding industrial-grade cerium oxide, the indicators are brought within the control range, avoiding the problem of increased labor costs due to repeated mixing.

[0036] 4. 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.

[0037] 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.

[0038] 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.

[0039] 5. 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.

[0040] 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.

[0041] 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. Detailed Implementation

[0042] To facilitate understanding of the present invention, a more complete description is provided below. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the present invention.

[0043] Where specific techniques or conditions are not specified in the examples, they shall be performed in accordance with the techniques or conditions described in the literature in this field or in accordance with the product instructions. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0044] 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 invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0045] A clarifying agent for the production of photovoltaic glass, wherein the raw materials of the clarifying agent include, by weight, 10-20 parts sodium nitrate, 40-70 parts sodium sulfate, 1-5 parts antimony compound and 5-15 parts recycled powder;

[0046] The recycled powder includes recycled optical glass polishing waste powder. The dry basis content of the optical glass polishing waste powder, calculated by mass percentage and in terms of cationic oxides for metal elements, is as follows:

[0047] Cerium oxide 40~80%,

[0048] Lanthanum oxide 5~25%,

[0049] 5-40% silica

[0050] Alumina 0~15%,

[0051] Iron oxide 0.5~1.0%,

[0052] Other margins;

[0053] Loss on ignition at 1000℃ is 2-5%.

[0054] This invention provides an innovative solution for preparing photovoltaic glass clarifying agents using waste polishing powder from optical glass, effectively solving the problems of the difficulty in economically recycling existing polishing waste powder, the waste of rare earth resources, and the high cost of rare earth raw materials for glass clarifying agents. Optical glass typically requires polishing powder to polish its surface. The main raw material of polishing powder is cerium oxide. By using cerium oxide-containing waste polishing powder as a raw material for clarifying agents, the recycling of rare earth resources is achieved, significantly reducing production costs and providing significant environmental and economic benefits.

[0055] Due to the different polishing processes involved, the moisture content of waste powder from optical glass polishing varies greatly. The dry basis is a measurement method that calculates based on the solid dry matter in the material. In this scheme, the dry basis content is detected using dried material dried to constant weight at 105℃.

[0056] Optical glass comes in many varieties. In addition to silicon dioxide, its main components also require the addition of aluminum or lanthanum, which are relatively high in content, to meet performance requirements.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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℃.

[0064] 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.

[0065] Preferably, the antimony compound is sodium pyroantimonate.

[0066] 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.

[0067] 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.

[0068] Preferably, the control parameters of the recovered powder, calculated as cationic oxides by mass percentage, are as follows:

[0069] Cerium oxide 55~65%,

[0070] Lanthanum oxide 10-15%,

[0071] Iron oxide 0.6~0.7%,

[0072] Loss on ignition at 1000℃ is less than 1%.

[0073] 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.

[0074] 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.

[0075] A method for preparing a clarifying agent, comprising the following steps:

[0076] 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.

[0077] S2. Preparation of recycled powder: Several batches of pretreated polishing waste powder are quantitatively mixed according to complementary components to obtain recycled powder;

[0078] S3. Preparation of clarifying agent: Sodium nitrate, sodium sulfate, antimony compound and recycled powder are mixed in proportion to prepare the clarifying agent.

[0079] 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.

[0080] 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.

[0081] 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.

[0082] 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.

[0083] 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%.

[0084] Preferably, in step S1, the sieve used in the screening process is an ultrasonic vibrating sieve with an aperture of 5-20 micrometers.

[0085] 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.

[0086] Preferably, in step S1, the drying temperature is 105~120℃ and the time is 10~60 minutes.

[0087] Drying removes free moisture and prevents water vapor from carrying away cerium dioxide during rapid heating in the roasting process.

[0088] Preferably, the recycled powder also includes industrial-grade cerium oxide, which, by weight, accounts for 10-30% of the total recycled powder.

[0089] 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.

[0090] 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.

[0091] 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.

[0092] 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.

[0093] 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.

[0094] 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.

[0095] Preferably, a three-dimensional motion mixer is used for mixing in steps S1, S2 and S3.

[0096] 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.

[0097] Example 1

[0098] S1. Pretreatment of polishing waste powder:

[0099] 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%.

[0100] Drying: Place the polishing waste powder in an oven and dry it at 110℃ for 30 minutes to remove free moisture;

[0101] 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.

[0102] 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%.

[0103] 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.

[0104] Example 2

[0105] S1. Pretreatment of polishing waste powder:

[0106] 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%.

[0107] Drying: Place the polishing waste powder in an oven and dry it at 110℃ for 30 minutes to remove free moisture;

[0108] 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.

[0109] 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%.

[0110] 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.

[0111] Example 3

[0112] S1. Pretreatment of polishing waste powder:

[0113] 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%.

[0114] Drying: Place the polishing waste powder in an oven and dry it at 110℃ for 30 minutes to remove free moisture;

[0115] 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.

[0116] 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%.

[0117] 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.

[0118] S2. Preparation of recycled powder:

[0119] 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%.

[0120] 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%.

[0121] S3. Preparation of clarifying agent:

[0122] 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.

[0123] Glass melting test:

[0124] 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.

[0125] Comparative Example

[0126] 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.

[0127] Glass melting test:

[0128] 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.

[0129] 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.

[0130] 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.

[0131] 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 comprises 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%, loss on ignition at 1000℃ 2-5%; the rest; The optical glass polishing waste powder after recycling treatment is subjected to drying, screening, and calcination treatment. 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%, loss on ignition at 1000℃ less than 1%.

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 method for producing a clarifying agent, characterized by, The method for preparing the clarifying agent of any one of claims 1-2 comprises the following steps: S1, polishing waste powder pretreatment: sequentially subjected to drying, screening, calcination, and uniform mixing to obtain pretreated polishing waste powder, and component analysis and batch storage are performed; S2, preparation of recycled powder: a plurality of batches of pretreated polishing waste powder are mixed according to component complementation and quantification to obtain recycled powder; S3, preparation of clarifying agent: sodium nitrate, sodium sulfate, antimony compound, and recycled powder are mixed in proportion to obtain the clarifying agent.

4. The method of claim 3, wherein: In step S1, the calcination temperature is 600-700℃, the heating rate is 5-10℃ / min, and the holding time after heating to the highest temperature is 1-2h.

5. The method of claim 3, wherein: In step S1, the screening uses an ultrasonic vibrating screen with a pore size of 5-20 microns.

6. The method of claim 3, wherein: In step S1, the drying temperature is 105-120℃, and the time is 10-60 minutes.

7. A method for producing a clarifying agent, characterized by, The method for preparing the clarifying agent of any one of claims 1-2 comprises the following steps: S1, polishing waste powder pretreatment: sequentially subjected to drying, screening, calcination, and uniform mixing to obtain pretreated polishing waste powder, and component analysis is performed, and after component analysis, batches meeting the control index of the recycled powder are directly sent to step S3; batches not meeting the control index of the recycled powder are recorded for components and sent to step S2; S2, preparation of recycled powder: a plurality of batches of pretreated polishing waste powder are mixed according to component complementation and quantification, batches meeting the index complementation are mixed in a mass ratio of 1:1-3, and component analysis is performed again, and if the control index of the recycled powder is met, the recycled powder is obtained and sent to step S3; if the control index of the recycled powder is still not met, industrial-grade cerium oxide is added in an amount of 10-30% of the total amount of the recycled powder as the recycled powder, and the recycled powder is obtained and sent to step S3; S3, preparation of clarifying agent: sodium nitrate, sodium sulfate, antimony compound, and recycled powder are mixed in proportion to obtain the clarifying agent.

8. The method of claim 3 or 7, wherein: In steps S1, S2, and S3, a three-dimensional motion mixer is used for mixing.