With the development of high temperature industry and refractory materials, refractory raw materials need to meet the following requirements

With the development of high temperature industry and refractory materials, refractory raw materials need to meet the following requirements: fused aluminum chrome sand

The sustained and rapid development of the high temperature industry and the abundant resources of refractory raw materials have supported the golden development period of my country's refractory industry for many years, and also promoted the development of the refractory raw material industry itself, which is reflected in the continuous increase in output, the continuous enrichment of varieties, and the continuous improvement of performance. , quality improvement and so on. Refractory raw materials can be called the backbone of refractory products, and refractory products are interdependent and promote each other. The former ensures the realization of the characteristics of the latter, and the latter provides a broad application space for the former.

At present, the application of refractory materials presents the characteristics of specialization, functionalization, diversification, refinement, high efficiency and low consumption, and the development of refractory materials must be adapted to it. At this stage, affected by factors such as economic downturn, sluggish demand, and increasing constraints on resources and environmental protection, the high-temperature industry and refractory industry have entered a new stage of development to improve quality and efficiency. new requirements. At this stage, the new demands of the user industry, the strengthening of resources and environmental protection constraints, and the development direction of the application of refractory materials such as specialization, integration, greening, and low consumption are the main factors that lead to the diversification of the adaptability of refractory materials.

New requirements for user industries

New technology, new process and new process of high temperature industry have put forward new requirements for the performance and function of refractory materials. To this end, refractory products must have improvements or breakthroughs in performance and function. Correspondingly, refractory raw materials must also have new characteristics and new varieties to meet new demands.

Meet the needs of clean steel smelting

Meet the needs of clean steel smelting. With the adjustment of the variety structure and the development of special steel in the iron and steel industry, clean steel smelting technology has been widely adopted, which has put forward new requirements for the reduction of related auxiliary materials and refractory materials for iron and steel making, and the avoidance of pollution of molten iron and molten steel. It has been found in research and practice that aluminum-silicon-based refractories will pollute molten steel, magnesia materials will not pollute, and materials containing free calcium oxide will not only pollute, but also clean molten steel. The higher the calcium oxide content, the more obvious the effect. For this reason, sintered and electrofused magnesium-calcium raw materials containing free calcium oxide with good hydration resistance are favored.

In order to reduce the carbonation pollution of molten steel by carbon-containing refractories, it is necessary to reduce the carbon content of carbon composite refractories. In order to eliminate the side effects of carbon reduction on its thermal shock resistance and corrosion resistance, it is necessary to introduce a dispersed carbon source, which promotes the research and development and production of various nanocarbon sources suitable for refractory materials such as carbon black, carbon nanotubes, and graphene.

Meet the requirements of "green" production

In addition to the requirements of clean steel, some other high-temperature processes also require refractory materials not to contaminate the medium they carry. For example, in view of the carcinogenic effect of Cr6+ on humans and animals, chromium-containing refractories have been listed as restricted products by the Ministry of Environmental Protection, and it is imperative to replace chromium-containing materials with low-chromium and chromium-free new materials. In recent years, while developing and applying iron-aluminum spinel to replace magnesia-chrome bricks, new raw materials of magnesia-aluminum-iron composite spinel have also been synthesized and successfully applied in cement rotary kilns.

In order to reduce the harm of traditional aluminum silicate refractory fibers to the environment and human body in the process of production, processing, installation, after-use, etc., biodegradable and environmentally friendly calcium-magnesium-silicon-based refractory fibers have been developed and used, and have gradually become popular. .

Meet the requirements of high temperature industrial energy saving and emission reduction

With the increase of greenhouse effect and smog weather, the society's voice for realizing energy saving and emission reduction in high temperature industry is constantly rising. As the lining material of industrial furnace, it is imperative to use energy-saving refractory material with better energy-saving effect. New raw materials developed and applied in recent years that are beneficial to energy saving include: lightweight mullite raw materials with microporous structure, mullite hollow spheres, lightweight microporous sintered alumina, CA6-MA composite phase lightweight Aggregate, olivine light material, spinel light material, nanoporous silica powder and its polymer, etc. For example, the high-performance lightweight castable with a bulk density of about 1.8g/cm3 developed by microporous lightweight mullite aggregate and mullite hollow spherical aggregate can replace the same bulk density of about 2.5g/cm3. Uses Heavy castables are used for the working lining of magnesium reduction furnaces, the working linings of annular heating furnaces for steel rolling, and the water-beam column water-cooled pipe wrapping materials for steel rolling heating furnaces. Satisfactory use results have been achieved, the weight of the lining body is reduced, and the energy saving effect is obvious.

Requirements for developing economical refractory materials

At present, the refractory industry and high temperature industry related to the refractory raw material industry chain are in a downturn, and winning bids at low prices has become the direction indicator for some companies. At the same time, some high-grade natural mineral raw materials, such as high-bauxite, are gradually exhausted, the ore grade is declining, and the quality fluctuation is increasing. The status quo urges us to adjust the research and development direction, technical ideas and process routes, abandon the traditional design ideas, closely follow the pulse of the low-consumption, high-efficiency and green times, improve resource utilization and optimize the level of configuration, and improve product cost performance. Guided by this orientation, cheap and economical refractory raw materials and products will usher in more demand.

Low consumption is the main development direction of economical refractories. In the main direction of realizing low consumption of raw materials, the adoption and use of natural raw materials, light burning materials and recycled materials should be expanded. In order to ensure the high temperature volume stability of refractory materials, natural raw materials must be sintered or fused at higher temperatures to make them barren and tend to thermodynamic equilibrium as much as possible. This will lead to high energy consumption, and will also result in a certain degree of excess capacity, which will result in invisible resources and energy waste in a sense. Non-equilibrium raw materials with lower sintering temperature can be developed and applied, and even a certain amount of natural raw materials can be directly added to reduce the energy consumption of refractory materials to a certain extent.

The study found that the non-equilibrium raw materials continue to undergo beneficial in-situ reactions during use, which will bring some beneficial effects. The research results of the High-Temperature Materials Research Institute of Heke University and the Gengsheng Company show that adding a certain amount of natural raw meal to the castable has a good effect. Adding bituminous coal gangue or lightly burned coal gangue to the aluminum-silicon castable will generate in-situ mullite after heating, which can improve its thermal flexural strength, softening temperature under load, and improve thermal shock resistance. Lightweight material.

After a wealthy period of abundant resources, arbitrary mining, and abandoning the poor, practitioners increasingly feel the challenge of resource crisis and scarcity. When high-grade ores are gradually exhausted and low-grade ores are increasingly becoming the main source of raw materials, people must reconsider the scientificity, rationality and adaptability of raw materials and product indicators, and optimize the allocation of raw materials to make them more excellent and competitive. Powerful price/performance ratio. It should be considered to appropriately reduce the A12O3 content and bulk density of high-alumina refractories used in some non-melt scour and eroded parts, and relax the requirements for the impurity content of aluminum-silicon refractories used in some medium and low temperature parts.

In recent years, the recycling and utilization of refractory materials after use and the utilization rate of waste refractory materials have grown steadily, the level of recycling technology has gradually improved, and the recycling processing industry has gradually emerged. The material industry provides a certain amount of cheap, high-quality and cost-effective recycled materials, which improves the level and level of efficient utilization and recycling of refractory resources. This relieves the shortage of refractory raw material resources to a certain extent, and promotes the development of the refractory industry in the direction of low consumption, reduction and economy. In addition to the recycling of refractory materials after use, other industrial wastes should be expanded to become refractory materials for resource utilization, such as the use of ferrochromium, ferrotitanium, iron and steel waste slag, red mud, coal gangue and other wastes as raw materials for refractory materials.

diversification trend

Restricted by the development stage, the current refractory raw materials are mainly alumina-based, magnesium oxide-based, Al2O3-SiO2, Al2O3-MgO and graphite. (more heavy materials), high (high sintering or melting temperature)” phenomenon, lack of diversification, lack of serialization, lack of refinement, standard limitations and other problems are prominent. Therefore, the development direction of both diversification and integration should be implemented.

Diversification of raw material materials, forms and properties

In recent years, new progress has been made in developing new varieties and diversification of alkaline raw materials. For example, by adding other components to magnesia, the new magnesium-based raw materials developed include magnesia-iron spinel, magnesia-aluminum-iron composite spinel, magnesia-aluminum-titanium composite spinel, etc., to synthesize heavy and light forsterite raw materials In progress, rare earth-modified MgO-CaO sand and fused MgO-CaO sand have been put on the market, and periclase-spinel two-phase composite sintered materials and fused materials have been put on the market... The developed calcium oxide-containing The new raw materials include calcium hexaaluminate, anorthite, calcium titanate aluminate, CA6-MA composite raw materials and so on.

Fused aluminum chrome sand

Diversification of raw material status

The connotation and extension of refractory raw materials are expanding. In addition to the traditional oxide and non-oxide raw materials, the raw materials have been expanded from traditional non-metallic materials to metal materials, and the raw material state has expanded from solid to gaseous. For example, metal Al and Si are generally used as the main raw materials in the ingredients of sliding nozzles and ceramic cups, and they react with surrounding gaseous raw materials such as N2 and CO to form non-oxides during production and use, which enhances the high temperature performance of the material. With the development of technology, raw materials have developed from rigid to flexible, and expanded from tangible to intangible. It does not rule out the possibility that "invisible" substances such as magnetic fields will become a "special raw material" in the future.

Facilitation of the shape of raw materials

In addition to the "new" raw materials formed by changes in raw material components and properties, there are also "new" raw materials formed by changes in the shape of the raw materials. For example, the size of fine powder from ordinary fineness to micrometer and even submicrometer and nanometer can greatly increase the technical added value of raw materials. Spherical and nearly spherical particles help to improve the rheological properties of amorphous refractories. material is beneficial to improve thermal shock resistance, and so on. The inner and outer shape of raw materials together affect the manufacture, construction, performance and ultimate life of refractory products. Since the shape of the raw material is difficult to control when it is processed into particles in the later stage, the near-net-shape raw material has been proposed and put into effort in recent years.

Enrichment of raw material standards

Refinement of raw material grades and standards. In the period of abundant resources and rich ore scene, our raw material varieties are more extensive. For example, the classification of grades in "YB/T5179-2005 High Alumina Bauxite Clinker" is obviously coarser than that in "GB/T2273-2007 Sintered Magnesia"; the same grade of bauxite clinker can also be serialized according to bulk density. . Raw material standards are still missing. At present, there are no standards such as pyrophyllite, forsterite, recycled raw materials, and non-graphite carbonaceous raw materials for refractory materials. With the improvement of mine development and management level, and the complexity, variability and uniqueness of mineral deposits, it is necessary to refine the relevant raw material varieties, and make systematic, adaptive and personalized supplements, revisions and improvements to the grades of raw material standards.

special purpose requirements

In addition to the general high temperature industries and application fields, there are also some special industries and application fields, which require special requirements for one or some properties of refractory materials, or require them to have unique new properties according to the requirements of process technology or processing. , requires us to adopt new breakthrough raw materials, in order to make the refractory material have the characteristics to meet the special purpose. Sometimes this pushback mechanism from the market to the product and then to the raw material leads to the birth of new raw materials. For example, in order to enhance the erosion resistance of the material, dense fused corundum has been developed.

Studies have shown that anorthite and calcium hexaaluminate raw materials have better resistance to the erosion of CO gas and alkali vapor; the introduction of coke with a honeycomb structure on the surface can improve the permeability of the clay. In order to make the refractory material have good heat insulation at high temperature and reduce convective heat transfer, it has also prompted people to develop lightweight raw materials with microporous structure and so on.

Requirements for best use and sustainable development

Refractory materials are divided into acidic, basic and neutral. Due to the continuity of historical development and the limitation of resource distribution, the proportion of aluminum-silicon refractory production has always been high. The rapid development of the aluminum industry and the refractory industry has resulted in a huge consumption of refractory clay and bauxite, and the sharp decrease in resource reserves has caused the price of bauxite clinker to rise. In the long run, it will inevitably affect the production and application of aluminum-silicon refractories. From the perspective of improving resource utilization and sustainable development of the refractory industry, more attention should be paid to the variety and output of acidic, semi-acidic, alkaline and semi-basic refractory materials, and the advantages of research and development, technology, capital, policies and other elements should be gathered. On the use of relatively abundant and cheap silica and magnesite resources, deep processing is carried out, and more varieties are developed to make them play a greater role. At the same time, the proportion of acid, alkaline and neutral refractory production should be properly balanced, and the consumption rate of silica, magnesite and bauxite should be balanced; acid and alkaline refractories should be considered more in the design and selection of kilns to make them have Greater use; improving the adaptability of raw material supply to the development of refractory materials and the sustainability of the future development of the industry.

If we change our focus and lower the standards, and select refractory raw materials based on the criteria of no slag erosion and medium and low temperature use, more natural ores or tailings will meet the requirements, and more industrial products and their wastes will be available for selection. Construction wastes such as river sand, sea sand, desert sand, Portland cement, sanitary porcelain and architectural porcelain can all be recycled into refractory raw materials to a certain extent under certain conditions.

Conclusion

At present, my country's high-temperature industry and refractory industry are in the process of transforming from production expansion and incremental development to quality and efficiency improvement. New requirements are put forward for refractory raw materials, forcing refractory raw materials to improve their adaptability, focusing on high-temperature industry and refractory materials. To meet the new needs of the material industry, adhere to the sustainable development direction and develop a variety of high-quality raw materials. In addition to the innovation and improvement of traditional raw materials, the direction worthy of attention and efforts in the future also includes the serialization, diversification and integration of raw materials, new raw materials with unique properties, and green and environmentally friendly raw materials in a broad sense. To this end, we should strengthen the role of science and technology in predicting, guiding and supporting the development of raw materials, actively develop new high-quality raw materials with low consumption, high efficiency and green, to meet the new needs of the refractory industry, and promote the healthy and sustainable development of the refractory industry.