[China Glass Net] It can be known from the types and formation causes of various glass defects that to prevent various defects, it must be prepared in glass composition and batch materials. The melting system, the selection of refractory materials, the design and construction of the furnace, and other aspects have taken effective measures.
(1) Optimize the glass frit formula
In order to prevent the formation of stones, the glass composition should be rationally designed. The glass composition points should fall on the eutectic or phase boundary of the ternary phase diagram. And add a small amount of other oxides that can reduce the tendency of the product. Try to reduce the tendency of crystallization, reduce the cooling rate during forming, or need to repeatedly heat or cool the glass, should pay attention to reduce the tendency of the product; in order to reduce the bubble of the mixture, should choose the appropriate clarifying agent according to the characteristics of glass melting And flux, to ensure the amount of clarifying agent, should also control the amount of oxidant or reducing agent used with the clarifying agent. In order to slow the erosion of the refractory material, the composition or raw materials, such as fluorite and thenardite, which are seriously eroded by the refractory material, should be used as little or as little as possible in the glass composition. Soda ash should use alkali as much as possible, without using light alkali, to prevent the light alkali from flying under the flame, causing cockroaches and chest wall erosion to produce dripping and melting materials to contaminate the glass.
(2) Improve the quality of the batch materials and the quality of the materials
First of all, it should be ensured that the particle size of various powders meets the process requirements. In particular, the history of refractory aluminum and silicon raw materials should be controlled to control the upper and lower limits of the material. Secondly, it is necessary to prevent the incorporation of oxidation during the transportation of raw materials and storage materials. Iron, chrome oxide and other harmful tops and other miscellaneous tops. It should also ensure the correctness of the weighing, improve the uniformity of the batch, and distribute the various fluxing components and auxiliary materials evenly, and fully exert its effects. In addition, in the process of storage and transportation of the batch materials, it is necessary to reduce vibration, strengthen the seal, and prevent the fly material and the material. The thin layer feeder should be used to increase the width of the feed port and increase the melting speed of the pile. The feeder should also be linked with the glass liquid blood automatic control system to ensure the stability of the glass surface, prevent liquid level fluctuations, and accelerate the erosion of the pool wall.
(3) Improve the operating system
The improvement of the operating system should firstly determine the glass melting system so that the output and quality of the melting furnace are balanced with the kiln age. It is not necessary to increase the melting temperature and forming speed for the one-sided pursuit of production. Otherwise, a large number of glass defects will be generated, which will greatly reduce Glass quality, and caused refractory materials to be severely eroded, shortening the life of the furnace. When formulating the glass melting system, the melting, clarification and cooling capacity of the melting furnace should be balanced to maximize the production capacity of the melting furnace and increase the glass yield and quality. Sufficient clarification temperature and clarification time should be ensured to facilitate the elimination of the material bubbles. The hot spot should be moderate, and there should be a proper temperature difference between the hot spot and the feed port to form a certain heat convection to help stabilize the bubble boundary. It is also important to maintain an appropriate atmosphere system and pressure system to promote the better functioning of clarifiers. During the glass cooling phase, care should be taken to avoid fluctuations in temperature, atmosphere, and pressure. Otherwise, secondary bubbles are easily generated. Attention should also be paid to the uniformity of cooling to avoid excessive temperature differences.
In order to prevent the occurrence of crystallization stones, it is possible to increase the forming operation temperature in the process so that the forming temperature is higher than the liquidus temperature (the crystallization upper limit temperature), and care is taken to prevent the glass liquid which is easily devitrified at the dead corner from participating in the forming flow.
(4) Use high quality refractory materials
To avoid or reduce various glass defects caused by poor quality of overfire materials. The refractory material must have sufficient refractoriness, excellent slag resistance, good high temperature mechanical strength, thermal shock resistance, low reburning line shrinkage, and no contamination of the molten glass. Refractory materials should also be reasonably selected according to different parts and different conditions, not the lower the price, the better. The molten refractory material with excellent slag resistance must be used for the molten steel portion of the glass melting furnace and the portion where the cooling portion is in direct contact with the molten glass, such as the pool wall and the bottom of the tank. Since the presence of C and CO in the reduction method of zirconium corundum AZS bricks reduces the softening temperature and viscosity of the glass phase, the slag resistance is poor. And it is easy to generate bubbles in the glass, so the pool wall should use oxidation AZS bricks whenever possible. For the particularly serious feeding corners, fluids, kiln, bubbling bricks, electrode bricks, etc., high-grade high-quality fused zirconia corundum such as 41#, 43# oxidation AZS bricks, melting kiln and chest wall should also be used. High quality silica bricks or fused AZS bricks should be used.
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