Glass furnace refractory applications trends

For many years, melt-cast AZS furnace roofs have successfully undergone the test of cooling and reheating to enable them to use multiple operating cycles. There is now a bit of experience in successfully implementing the top cooling and reheating of fused-alumina roofs, which represent an economically viable life when they use two or more cycles of operation. The results of the observation of the fused alumina roof in service (thermal observation and shutdown observation) show that these materials are both chemically and mechanically stable. This is the first observational study of such masonry because there was neither a reference to fused alumina at the time nor the empirical basis for its application to the roof.



High-chromium refractory products in the past mainly used to enhance the glass furnace, and a small amount used in insulation glass pool furnace. High chrome bricks are increasingly being used in some soda lime glass furnaces. Its main use has not only been limited to all or part of the flow hole, but also to the end wall and, to a limited extent, the corner brick for the feed opening The high-chilled brick masonry cavity provides the potential for increased kiln life Because this material is at least twice as corrosive to most glasses as molten AZS bricks.

It has been several years since low-glass phase fused AZS refractories have been successfully used in molten pool superstructures on a limited basis. Pure oxygen combustion technology has led to its wider use in the superstructure of molten pools for two reasons: first, the low glass phase content leads to a low bleed out of the glass phase, which is higher than that of the traditional molten AZS brick Structure is more "dry." Second, the low glass phase content makes it more creep-resistant so that the normal operating temperature can be raised from 1600 ° C to 1650 ° C. This is more useful for the superstructure of the feed zone of a pure oxygen fired furnace where the molten AZS brick not only has the resistance to dust particles from the combustion air flow but also can withstand higher temperatures 1650 ℃. Molten pool wall tiles have recently been developed to improve the top (liquid line) anti-erosion properties of new varieties and has been in the field test. This pool wall brick utilizes a unique approach that controls the crystal structure of the liquid line section so that the brick has a much stronger erosion resistance at the liquid line than the standard fused AZS brick.

High zirconium fused wares (HZFC or fused zirconia) have been widely accepted as refractories in contact with glass for use in specific locations in certain high quality glass furnaces. The reasons for using the refractory of this kind of component vary from one glass type to another. Color TV picture tube screen glass is a serious erosion of HZFC but it is also used as a base and pool wall tile at the end of a melt pool flow hole because it significantly reduces glass defects such as knuckles, bubbles and stones . The corrosion resistance of fused zirconia refractories is not superior to that of molten AZS, but usually it suffices to maintain an entire kiln cycle. In this way, the use of HZFC in color picture tube screen glass cell furnaces can greatly improve the quality of the glass without reducing the life of the kiln.

The adhesion of refractories materials

Thermal kilns and equipment require many specific shapes of refractory brick masonry. This requires a material that has some adhesion at both ambient and elevated temperatures. Usually we use refractory mud to achieve our goals. Silica, clay, high aluminum, magnesium refractory mud, at room temperature, through the intermolecular force, to achieve the bonding between refractory products. During high temperature use, ceramic bonding is generally achieved due to the sintering effect. In order to achieve ceramic bonding at lower temperatures, it is often necessary to add some sintering promoter in the slurry to sinter it in advance.



Recently, more and more composite adhesives are used. These include dextrin, silica sol, water glass, brine, refractory cement, leeches, resins, etc. at ambient room temperature, as well as chemical or other forms of bonding at moderate or elevated temperatures , To improve the strength of the material. In addition to most of the above-mentioned refractory materials have this feature, there are phosphoric acid, a variety of phosphate, polyphosphate, metaphosphate, sulfate, all kinds of ultrafine powder

In addition, organic binders are also one of the most popular refractory binders currently available and include tar, resins, modified bitumens, and the like. These binders have good bond strength at room temperature and form a carbon bond network after high temperature.

Because of its complementarity to various properties, organic binders are rapidly expanding and deepening their research because of their carbon residue is conducive to the high temperature performance of refractory materials.

What requirements should refractories meet?

Refractory materials used in a variety of high temperature equipment, which is subject to physical and chemical erosion and mechanical damage under high temperature conditions, the performance of refractory materials should meet the following requirements:

1, high refractoriness Modern metallurgy furnace and other industrial furnace heating temperature are generally between 1000 ~ 1800 ℃. Refractory materials should have a low melting temperature at high temperatures.



2, high temperature structural strength should be large. Refractory should not only have a higher melting temperature, but also should have under the load of the furnace masonry or other mechanical vibration, without softening deformation and collapse.

3, thermal stability is better. Metallurgical furnaces and other industrial kilns in the operation process due to sudden changes in temperature refractory parts of the uneven temperature, there will be stress inside the masonry and fission and spalling of the material. Therefore, refractory materials should have the ability to resist such damage.

4, strong slag resistance. Refractory materials in the use of the process, often by high temperature slag, metal and furnace dust chemical attack. Therefore, refractory materials must have the ability to resist erosion.

5, high temperature and volume stability. Refractory materials in the long-term high temperature use, the brick body will produce the volume contraction or expansion, resulting in the refractory brick damage. Therefore, refractory materials are required to be stable in volume at high temperature.

6, structured dimensions, tolerances should be small. Although the refractory brick masonry brick filled with refractory mud, but the density and intensity are worse than the refractory material in the drying process and easy to fall off, so the brick is the weak link masonry, easy to leak and erosion Therefore, the smaller the seam size, the smaller the better. Only the accurate dimensions can meet this requirement. Therefore, the refractory material can not have the defects of big distortion, lack of edge, notch, cave and crack, etc. Claim.

Focus on the refractory industry and optimize the structure

Since 2000, China's refractory industry has entered the fastest-growing stage and is now the world's largest producer and exporter of refractory materials. European Refractories Manufacturers Association survey of the global refractory production in 2011 showed that the global refractory output in 2011 was 42,750,000 tons, of which, China's refractory output was 29,500,000 tons, accounting for 69% of the global output.



With the relative trend of the company's shares Pu-resistant shares, Beijing Lill major innovation ability and technology and equipment levels have improved significantly, China's refractory industry in the international market, the advantages and status of refractory material has also been greatly improved. At present, the varieties and aggregates of refractory products in our country not only meet the needs of domestic high-temperature industrial production and development, but also increase their export volume year by year. The market covers more than 150 countries and regions in Asia, Europe and the Americas, and the export volume has been ranking the world for many years the first.

At present, China's refractory products industry will focus on the development of product structure optimization, focus on extending the industrial chain and enhance the overall competitiveness of industries; vigorously develop the deep processing of products, improve product added value and technical content, improve product quality; focus on the development of a safe, Environmental protection, energy saving, noise reduction, leakage prevention and other functions of new building materials and products to meet the needs of green building development.

Refractory products industry will speed up the development of inorganic non-metallic materials to support the development of strategic industries, promote joint reorganization, optimize the industrial layout, strengthen energy consumption, strict environmental management, development of high-end products, encourage technological innovation, eliminate backward production capacity and strengthen safety Production and other eight tasks, to refractory products listed companies and listed companies has brought new opportunities.

Refractory production process introduction, glass technology

According to the degree of compactness and shape of different products, there are sintering, casting and melt casting method.



Sintering method is to pre-burn the department of raw materials into clinker, crushing and screening, and then press a certain ratio and raw materials mixed by forming, drying and firing.

Casting method is the raw materials through mixing ingredients and fine grinding and other processes, melting at high temperatures, direct casting, cooling and crystallization, annealing products.

Their compact body, high mechanical strength, high temperature structural strength, slag resistance is good, the scope of use continues to expand. Melt blowing method is to melt the ingredients, the high pressure air or superheated steam injection, so that the dispersion into fibers or hollow ball method.

Products are mainly used as light refractory, heat insulation materials, but also made of powder or granular amorphous refractories, temporary use of tar, asphalt, cement, phosphate, sulfate or chloride binder bonding, without Forming and sintering directly.

Refractories enterprises facing difficulties and countermeasures

At present, the production environment of refractory materials is not optimistic. The main reason is that the products produced by high-temperature industries such as steel, nonferrous metals, glass and cement are in surplus. The market for refractory materials is reduced. The competition among similar enterprises in the industry is harsh. At the same time, Concerned that the financing difficulties, coupled with the difficulty of funds back to the production of enterprises has brought great difficulty, if we encounter several bad debts bad debts of users, enterprises will be difficult to survive. Thus, refractory companies how to survive and develop? Has become a topic of discussion in the industry.



In the current severe situation, refractories enterprises should also maintain a calm state of mind, to judge the situation with the new normal, pointed out that enterprises should face the problems and put forward countermeasures and suggestions:

First, the major enterprises, especially high-tech enterprises, should mainly focus on technological innovation, and give priority to considering the functionalization of refractory materials as a precondition, planning technical solutions for customers, and solving the energy-saving and environmental protection problems in their process or furnace equipment, and extending their use life.

The second is to recognize and see the adverse consequences brought by the severe competition of similar homogeneous enterprises to the enterprises and industries. With the leading products of coke oven silica brick, coal chemical industry with high-chrome brick, electrolytic silicon carbide with silicon carbide brick, cement kiln with the past of chromium-containing materials to the current spinel series of materials, ladle castable, heating Furnace castable series materials, the production of its own high-tech products to solve the user's key technical equipment problems, and equipment imported refractory configuration, instead of imported materials to promote technological progress, but the results of long-term competition everyone Not much money, low profit production. It is very necessary to conduct various exchanges and exchanges in various fields between refractory enterprises. Of course, such cooperation is voluntary. Competition is inevitable in the market and has made a contribution to society.

Third, in the current market situation, how to develop the business, is to enter or return temporarily suspended? All enterprises should be based on their own circumstances, depending on the degree of dependence on the market users of your products, according to the company's technology and equipment, management team, technical strength, capital strength and other aspects of a comprehensive choice.