Efficient defoaming agent for ultra-white glass melting furnace as well as preparation method and use method of efficient defoaming agent

Abstract

The invention discloses an efficient defoaming agent for an ultra-white glass melting furnace as well as a preparation method and a use method of the efficient defoaming agent. The efficient defoaming agent is prepared from 95 to 99.5 weight percent of carbon powder and 0.5 to 5 weight percent of a modified additive. The preparation method of the efficient defoaming agent comprises the following steps: grinding carbon powder, mixing the ground carbon powder with a dried modified additive in a nitrogen environment, heating to 200 DEG C, carrying out a heat preservation reaction for 1 hour, and coating the surface of the carbon powder with a modified layer; and naturally cooling to room temperature, and sieving to obtain the product. The efficient defoaming agent provided by the invention still keeps better stability in severe environments such as high temperature, high pressure, strong acid, strong alkali and the like, the conditions of layering, demulsification and the like of molten glass are not easy to occur, and the defoaming duration is long.

Description

Technical Field

[0001] This invention relates to the technical field of ultra-clear glass manufacturing, specifically to a high-efficiency defoamer for ultra-clear glass melting furnaces. The invention also relates to methods for preparing and using this defoamer. Background Technology

[0002] Ultra-clear glass, a special type of glass with high light transmittance (≥90%) and low iron content (Fe2O3≤0.015%), is widely used in photovoltaic modules, high-end building curtain walls, electronic displays and other fields. Its melting furnace production environment has the characteristics of high temperature (1200–1600℃) and strong oxidation, which puts strict requirements on the stability and cleanliness of defoamers.

[0003] Traditional glass defoamers often use antimony compounds (such as antimony oxide), fluorides (such as calcium fluoride), or mineral oil-based products to defoam by reducing the surface tension of molten glass. The common method of application is to directly sprinkle the defoamer into the melting furnace, relying on the volatiles of the defoamer components under high temperatures to destroy the foam structure, thereby eliminating the foam.

[0004] During use, traditional glass defoamers have revealed technical defects such as poor temperature resistance and weak stability, as well as the disadvantages of contaminating molten glass and reducing light transmittance. For example, antimony oxide easily decomposes into gaseous Sb₂O₃ in high-temperature environments above 1300℃, while fluorides volatilize to produce HF gas, resulting in a defoaming duration of less than 2 hours and requiring frequent replenishment of defoamer. At the same time, HF gas corrodes the refractory materials of the melting furnace (such as zircon bricks), causing bricks to peel off and mix into the molten glass, forming stone defects. Antimony residue also reduces the light transmittance of the glass by 0.5-1%. Thus, it not only corrodes the refractory materials of the furnace but also reduces the quality and light transmittance of the product. In addition, in the strong acid-base alternating environment of molten glass (pH fluctuation of 4-10), mineral oil-based products are prone to emulsification and stratification, resulting in defoaming efficiency fluctuations of up to 30% and weak stability. Furthermore, antimony is a heavy metal pollutant, and the EU RoHS directive limits its content to ≤0.1%, which traditional products find difficult to meet. Summary of the Invention

[0005] The purpose of this invention is to provide a high-efficiency defoamer for ultra-clear glass melting furnaces. This defoamer is high-temperature resistant, free of heavy metals, and compatible with the ultra-clear glass melting furnace environment. This invention uses carbon powder as the main defoamer, combined with modified additives, to obtain an environmentally friendly, safe, efficient, and economical defoamer for ultra-clear glass melting furnaces. Addressing the issue of excessive foam in melting furnaces during the production of ultra-clear glass from natural gas, this defoamer reduces the surface tension of the heterogeneous glass melt film through a chemical reaction with surface foam, destroys silanol groups, punctures bubbles, and eliminates foam on the surface of the glass melt. This solves the technical pain points of traditional defoamers, such as poor stability, furnace pollution, and reduced glass transmittance, achieving stable production and energy savings. Simultaneously, it better protects the furnace refractory materials from scratches by the glass melt surface.

[0006] The technical solution provided by this invention is as follows: a high-efficiency defoamer for ultra-white glass melting furnaces, comprising 95-99.5 wt% carbon powder and 0.5-5 wt% modified additives. The main component of the defoamer provided by this invention is carbon powder, which is used to adsorb gas and reduce surface tension; the modified additives are auxiliary components used to enhance the high-temperature stability of the defoamer and promote the dispersion of carbon powder.

[0007] The preferred composition of this invention is 98 wt% carbon powder and 2 wt% modified additives.

[0008] The modified additive is a compound of metal oxide and silicate, wherein the metal oxide is selected from at least one of cerium oxide, zirconium oxide, and aluminum oxide, and the silicate is selected from at least one of bentonite, sodium silicate, potassium silicate, and lithium silicate. The technical principle of the modified additive used in this invention is as follows: the modified additive reacts with SiO2 in the glass melt at high temperature to generate a stable silicon-oxygen bond hybrid structure (≡Si–O–M–O–Si≡, where M is Ce / Zr / Al). This structure anchors carbon powder particles, preventing them from agglomerating at high temperatures; at the same time, the carbon powder adsorbs CO2, O2, and other bubble nuclei in the glass melt through its porous structure, synergistically destroying the silicon-oxygen bond network of the foam, achieving a continuous "anchoring-adsorption-bubble breaking" effect.

[0009] The mass ratio of metal oxides to silicates in the modified additives is 3:1-2.

[0010] Another object of the present invention is to provide a method for preparing the above-mentioned defoamer.

[0011] The technical solution provided by this invention is as follows: a method for preparing an antifoaming agent, comprising the following steps:

[0012] (1) Raw material pretreatment: Grind the carbon powder and vacuum dry the modified additives;

[0013] (2) Mixed modification: The pretreated toner powder and the modified additives are mixed in a nitrogen atmosphere, then heated to 200°C and kept at that temperature for 1 hour to form a modified coating layer on the surface of the toner powder.

[0014] (3) Post-processing: Cool naturally to room temperature, then sieve to obtain the final product.

[0015] In step (1), the toner particle size D50 = 5 μm and D90 ≤ 10 μm; the modified additive is dehydrated at 80°C for 4 hours in a vacuum drying oven, and the moisture content is ≤ 0.1%.

[0016] In step (2), the nitrogen flow rate is 2 L / min, the pressure is 0.1–0.3 MPa, and the stirring speed is 1200 r / min for 30 minutes; the heating rate is 5 °C / min.

[0017] In step (3), a 200-mesh vibrating screen is used for sieving.

[0018] Another object of the present invention is to provide a method for using the above-mentioned high-efficiency defoamer, wherein 0.05–0.08 kg of defoamer is prepared per ton of molten glass, and the defoamer is sprayed into the melting furnace through the melting furnace blowing system.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] 1. High stability: It maintains good stability even under harsh environments such as high temperature, high pressure, strong acid, and strong alkali, and is not prone to delamination or demulsification. Static high-temperature furnace testing at 1600℃ shows that the defoaming time lasts for 4.5 hours, which is 2.3 times that of traditional antimony-based products.

[0021] 2. Environmental friendliness: According to SGS testing, the content of heavy metals (Sb, Pb, Cd) is all <0.001%, which meets the environmental protection requirements of GB / T30984-2014 "Photovoltaic Glass"; the light transmittance of the glass (380–780nm) reaches 91.8%, which is better than the national standard of 0.8%;

[0022] 3. Furnace protection: Trial data from a photovoltaic glass factory showed that after using this invention, the corrosion rate of the refractory material in the melting furnace decreased from 0.15 mm / month to 0.05 mm / month, and the furnace life was extended by 30%.

[0023] 4. Economic efficiency: The amount of glass melt used per unit is only 0.06 kg, which is 40% less than that of traditional products, saving about RMB120,000 per thousand tons of production capacity in annual additive costs. Detailed Implementation

[0024] The technical solution of the present invention will be further described in detail below with reference to specific embodiments, but this does not constitute any limitation on the present invention.

[0025] Example 1: Preparation of basic defoamer

[0026] Table 1

[0027]

[0028] Preparation method:

[0029] 1. Raw material pretreatment stage:

[0030] The toner was ground using an air jet mill to control the particle size D50 = 5μm and D90 ≤ 10μm; the modified additives were dehydrated in a vacuum drying oven at 80℃ for 4 hours, with a moisture content ≤ 0.1%.

[0031] 2. Hybrid modification

[0032] (1) Add the toner and modified additives to a twin-screw high-speed mixer (model SHJ-30) in proportion;

[0033] (2) Introduce nitrogen gas with a purity ≥99.99% (flow rate 2L / min, pressure 0.1–0.3MPa) to purge air, and stir at 1200r / min for 30 minutes;

[0034] (3) The temperature is increased to 200℃ at a heating rate of 5℃ / min and kept at the temperature for 1 hour to form a modified coating layer on the surface of carbon powder. Ce-O-Si bonds can be detected by X-ray photoelectron spectroscopy.

[0035] 3. Post-processing stage:

[0036] After naturally cooling to room temperature (approximately 25°C), the product is sieved through a 200-mesh vibrating screen (75μm mesh size). Qualified products are then packaged in waterproof packaging, while unqualified products are returned to the grinding process in the raw material pretreatment stage.

[0037] Instructions for use: Prepare 0.05–0.08 kg of defoamer per ton of molten glass, and spray the defoamer into the melting furnace through the furnace blowing system.

[0038] Performance: Tested in molten glass at 1500℃, foam elimination time was 3 minutes, continued defoaming for 4 hours, and glass transmittance was 91.8%.

[0039] Example 2: High acid resistance formula

[0040] Table 2

[0041]

[0042] The preparation and usage methods are the same as in Example 1.

[0043] Performance: In a simulated glass melt acid etching environment (pH=4), the defoaming efficiency is maintained at 90%, while traditional products only maintain 60%.

[0044] Example 3: Low-additive formulation (99.5% toner)

[0045] Table 3

[0046]

[0047]

[0048] The preparation and usage methods are the same as in Example 1.

[0049] Performance: Defoaming lasts for 3 hours at 1200℃, suitable for medium and low temperature melting furnaces, reducing costs by 15%.

[0050] Experimental example:

[0051] The defoamer prepared according to Example 1 was compared with a traditional antimony-based defoamer. The defoaming rate, glass transmittance, kiln corrosion rate, heavy metal Sb content, and defoaming duration of the two defoamers were tested. Finally, the comprehensive performance of the two defoamers was evaluated and recorded according to the national standard requirements and the performance indicators of the two defoamers. The specific performance of the two defoamers is shown in Table 4.

[0052] Table 4 Comparison of two defoamers

[0053]

Claims

1. A high-efficiency defoamer for use in ultra-clear glass melting furnaces, characterized in that, It includes 95-99.5 wt% toner and 0.5-5 wt% modified additives.

2. The high-efficiency defoamer for ultra-white glass melting furnaces according to claim 1, characterized in that, It includes 98 wt% toner and 2 wt% modified additives.

3. The high-efficiency defoamer for ultra-white glass melting furnaces according to claim 1, characterized in that, The modified additive is a compound of metal oxides and silicates.

4. The high-efficiency defoamer for ultra-white glass melting furnaces according to claim 3, characterized in that, The mass ratio of metal oxides to silicates in the modified additives is 3:1-2.

5. The high-efficiency defoamer for ultra-clear glass melting furnaces according to claim 3 or 4, characterized in that, The metal oxide is selected from at least one of cerium oxide, zirconium oxide and aluminum oxide, and the silicate is selected from at least one of bentonite, sodium silicate, potassium silicate and lithium silicate.

6. The method for preparing the high-efficiency defoamer for ultra-white glass melting furnace according to any one of claims 1-5, characterized in that, Includes the following steps: (1) Raw material pretreatment: The carbon powder is ground and the modified additives are vacuum dried; (2) Mixing modification: The pretreated toner powder and the modifying additive are mixed in a nitrogen atmosphere, then heated to 200°C and kept at that temperature for 1 hour to coat the surface of the toner powder with a modified layer. (3) Post-processing: Cool naturally to room temperature, then sieve to obtain the final product.

7. The method for preparing the high-efficiency defoamer for ultra-white glass melting furnace according to claim 6, characterized in that, In step (1), the particle size of the ground carbon powder is D50 = 5 μm and D90 ≤ 10 μm; the modified additive is dehydrated at 80°C for 4 hours in a vacuum drying oven, and the moisture content is ≤ 0.1%.

8. The method for preparing the high-efficiency defoamer for ultra-white glass melting furnace according to claim 6, characterized in that, In step (2), the flow rate of nitrogen is 2L / min, the pressure is 0.1–0.3MPa, and the stirring speed is 1200r / min for 30 minutes; Heating rate: 5℃ / min.

9. The method for preparing the high-efficiency defoamer for ultra-white glass melting furnace according to claim 6, characterized in that, In step (3), a 200-mesh vibrating screen is used for sieving.

10. The method of using the high-efficiency defoamer for ultra-clear glass melting furnace according to any one of claims 1-5, characterized in that, The defoamer is prepared at a ratio of 0.05–0.08 kg per ton of molten glass, and is injected into the melting furnace through the furnace blowing system.

Images