Unshaped Refractory Archives - Rongsheng Refractory Castable Cement for Sale Manufacturer and Supplier

Rongsheng Unshaped Refractory Materials Manufacturer is a powerful manufacturer and seller of refractory materials. Rongsheng Environmental Protection’s fully automatic unshaped refractory material production line provides a reliable guarantee for the efficient and long-life operation of high-temperature industrial furnace linings. Among them, the application of alumina-magnesium spinel castables is becoming increasingly widespread. Contact us to get free samples and quotes. This article will introduce the practical application of unshaped refractory materials, alumina-magnesium spinel castables.

Application and Construction of Aluminum Magnesium Spinel Castables

Tundish aluminum-magnesium castables and ladle aluminum-magnesium castables are both based on aluminum-magnesium spinel materials. There are also steel fiber aluminum-magnesium castables, which are the main working layer refractory castables often used in steel plants. Because they are more convenient during construction, they are welcomed by steel mills and enterprises. However, sometimes due to changes in the construction conditions of alumina-magnesia spinel castables, some problems may occur, affecting the use effect and life of the furnace lining.

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Problems and Solutions in the Construction of Aluminum-Magnesium Spinel Castables

Solidification time is an important factor affecting the construction of aluminum-magnesium castables. The ambient temperature has a great influence on the solidification time of aluminum-magnesium castables, especially in summer. When the ambient temperature exceeds 35°C, aluminum-magnesium castables tend to solidify quickly, which brings a series of problems to the casting construction:

①Increased the labor intensity of construction workers. When the ambient temperature is high and the solidification time of the castable is shortened, the rheology of the castable itself becomes worse. Especially when the castable is rapidly solidified, the castable released from the mixer has no time to enter the bag, and has solidified on the upper surface of the bag and the launder. This makes feeding castables into the wall more labor-intensive.

②Influence the service life. In hot summer, workers often add more water to increase the fluidity of castables. Due to the increase in water consumption, the porosity of the castables increases and the strength decreases after drying. In addition, when the ambient temperature exceeds 40°C, even if more water is added, the castable will still tend to set quickly, affecting the service life.

③ Difficulty in rebirth. Under normal circumstances, after the ladle is poured, it needs to be left for 24 hours before it comes out. However, in the hot summer, due to the shortened solidification time of the castable, the castable and the tire package are tightly stuck together, making it difficult to remove the tire.

Therefore, whether it is from the perspective of reducing the labor intensity of workers, or creating a good condition for pouring construction, extending the service life of castables, and reducing usage accidents. It is necessary to fundamentally adjust the solidification time of aluminum-magnesium castables to meet the on-site usage requirements. After a period of research, it was found that lignosulfonate can change the setting time of castables, so that the initial setting time of aluminum-magnesium castables can be extended to more than 30 minutes even when the ambient temperature exceeds 35°C. This completely solves the problem of short solidification time of aluminum-magnesium castables in summer. It should be noted that the solidification time of aluminum-magnesium castable is related to the amount of lignosulfonate added. On the premise of meeting construction requirements, the smaller the amount added, the better. In addition, as the seasons change, the amount added must also be adjusted accordingly. Generally, a large amount is added in summer, and less or even no amount is added in winter. If more lignosulfonate is added in winter, the final setting time of the aluminum-magnesium castable will be extended, which will cause material collapse during normal operation, which is harmful.

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Problems and Solutions when Using Aluminum-Magnesium Spinel Castables

(1) Cracks.

Aluminum-magnesium castables crack during use, reducing their service life. When the ladle was used for 5 heats, cracks began to appear on the inner wall of the ladle, covering the entire ladle wall. As the number of uses increased, the cracks became deeper and wider. When more than 20 furnaces were used, they had to be discontinued. To solve the problem of castable cracks, some methods have been tried:

① Replace the bauxite clinker calcined in the vertical kiln with bauxite calcined in the down-flame kiln. In this way, the sinterability and bulk density of alumina are increased. It was thought that the volume shrinkage caused by incomplete calcination of the alumina and re-sintering during use could be reduced, but this was not successful.

② It is believed that the cracks are related to the total amount of fine powder in the castable. Trying to reduce the fine powder in the castable to less than 30% (mass fraction), or as low as 25%, did not solve the problem.

③ Solve the cracks starting from a chemical reaction. Because Al2O3 and MgO can generate alumina-magnesia spinel under the action of high temperature, it is accompanied by large volume expansion. After a series of tests and adjusting the ratio of Al2O3/MgO, satisfactory results were not achieved. Even when the MgO content is too high, peeling occurs instead.

Finally, the following method is basically used to solve this problem:

① Increase the upper limit of aggregate particle size from the original 15mm to 25mm. Among them, the 20-25mm part accounts for 7.2% (mass fraction) of the total. This is due to the presence of oversized particles, which not only act as a skeleton but also change the direction of long cracks, helping to prevent the expansion of internal cracks.
② Add zircon powder to the matrix. This zircon powder is produced in Australia, and its ZrO2 content is about 66%. Since ZrO2 itself has a high melting point, it can absorb CaO in the slag during use, react to generate CaZrO3 with high melting point and high corrosion resistance, and seal pores and cracks. At the same time, due to the presence of zircon, micro-crack structures can also be formed in the castable to improve the high-temperature performance of the castable.
③ Reduce the dosage of activated silicon carbon powder as much as possible. Since the quality of silica fume powder is unstable and a large amount is added, a lot of impurities will be brought in, which is detrimental to use. Controlling the amount of silica fume in the castable below 1.5% (mass fraction) will achieve better results.
④When pouring, it is also critical to strictly control the amount of water added and ensure uniform vibration.

(2) Peeling

Spalling is also one of the common problems in the use of aluminum-magnesium castables. It is the result of uneven stress within the castables. If A12O3 and MgO in the matrix are affected by high-temperature molten steel during use, they will easily react to form MA spinel, accompanied by a large volume expansion. If this reaction is very intense, structural peeling will easily occur under the impact of molten steel. Therefore, to control this spinel reaction in the matrix, it is necessary to control the content of each component, especially the content of MgO, which is critical. If the MgO content is too high, in addition to the spinel reaction, it also has a large linear change rate, resulting in volume expansion, which will also promote spalling. Generally, the content of magnesia is controlled at about 10% (mass fraction), and the effect is better.

Pouring construction also has an impact on the occurrence of spalling. In this regard, the amount of water added must be strictly controlled and uniform vibration must be achieved. If the amount of water added is too large and the green body vibrates unevenly, the porosity will increase, and steel drilling will easily occur during use, causing the wall of the bag to peel off.

(3) The slag line erodes quickly

Due to the complex composition of steel slag, it is easy to react chemically with the castables, causing the castables in the slag line to be prematurely corroded, resulting in the slag line and the wall being unable to be used simultaneously. This is also a problem encountered in actual use. On the premise of significantly increasing costs, some methods are adopted:

① Specially configured slag line material is used for pouring the slag line parts. The raw materials of slag strand materials are improved to a higher level. For example, the bauxite powder uses high-quality high-alumina bauxite clinker with ω (A1203) = 86% and a bulk density of >3.2g/cm3.
② Add some pre-synthesized aluminum-magnesium spinel to the slag strand material and use a high MgO ratio, which can improve the ability to resist alkaline slag.
③ Reduce the dosage of active silica fume and control it to around 1.0% (mass fraction).
④Strictly control the amount of water added and vibrate evenly during pouring. Through these measures, the lifespan of the slag line and the package wall is basically synchronized.

Measures and Methods for Efficient Use of Aluminum-Magnesium Spinel Castables

①Retarding technology is one of the key technologies in the construction of magnesium-aluminum castables. According to changes in seasons and ambient temperature, retarders such as lignosulfonate should be added in a timely manner to make the setting time meet the needs of pouring construction.
② Adding some oversized aggregate and zircon powder to the castable is very beneficial to inhibit the occurrence of cracks.
③ The slag line uses a high MgO ratio and adds some pre-synthesized aluminum-magnesium spinel powder to improve the slag erosion resistance of the slag line.
④ During pouring construction, strictly control the amount of water added and vibrate evenly, which is of great significance to increase the service life of the castables.

To ensure the efficient and long-life operation of the ladle lining, it is not only necessary to purchase high-quality aluminum-magnesium spinel castable products, but also strictly follow the construction instructions and adjust the formula of the aluminum-magnesium spinel castable according to the actual construction conditions. Rongsheng unshaped refractory material manufacturers can customize the formula of refractory castables according to the actual working conditions of customers. To improve the service life of high-temperature furnace linings and save production costs for enterprises.

Micro-Expansion Refractory Plastic for Power Plant Boilers

With the continuous development of modern industry, the power industry plays an increasingly important role in people’s lives. As an important part of power plant boilers, the performance of the lining material has a great impact on the operating efficiency and life of the boiler. Therefore, the emergence of micro-expansion wear-resistant and refractory plastic has become an important lining material and is favored by power plant boiler manufacturers and maintenance engineers.

Micro-expansion wear-resistant refractory plastic has the characteristics of low thermal conductivity, high-temperature resistance, good thermal shock stability, wear resistance, corrosion resistance, and not susceptible to mechanical vibration. Its obvious feature is that under high-temperature conditions, the formation of an oxide layer can effectively protect the lining material, thereby extending the service life of the boiler. In addition, the micro-expansion properties allow the material to have better crack resistance and wear resistance at high temperatures, further improving the boiler’s operating efficiency and performance.

In the application of power plant boilers, micro-expansion wear-resistant, and refractory plastics are widely used in lining materials, patch materials and supplementary materials. As a lining material, it replaces traditional hard materials and can reduce the noise and vibration of the boiler and extend the life of the boiler. Patch materials are often used for boiler lining repairs and will not peel off the base material or affect thermal conductivity during the repair process. Supplementary materials refer to adding micro-expansion wear-resistant refractory plastic to the lining of the boiler to improve overall performance and life.

In short, the application of micro-expansion wear-resistant and refractory plastics in power plant boilers has become a trend. It is known for its high performance and excellent fire resistance. The range of applications is getting wider and wider. In the future, we believe that this material will play a more important role in the power industry and continue to provide a strong guarantee for the operating efficiency and performance of boilers.

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Rongsheng Micro-Expansion Plastic Refractory Manufacturer

How to Identify Refractory Plastic and Refractory Clay

Refractory plastics are made of refractory aggregates and powders, raw clay, chemical composite binders, and admixtures, which are mixed and extruded into brick shapes. Refractory materials that still have good plasticity after being packaged and stored for a certain period of time can be constructed using the tamping method. Commonly used bonding methods include chemical bonding, ceramic bonding, polycondensation bonding, etc.

Refractory mud, also known as refractory mud or joint material, is a joint material used for the masonry of refractory products. According to the material, it can be divided into clay, high alumina, silica and magnesia refractory clay. It is composed of refractory powder, binder, and admixture. Almost all refractory raw materials can be made into powders used to prepare refractory mud. Ordinary refractory clay, which is made from refractory clinker powder and an appropriate amount of plastic clay as a binder and plasticizer, has low strength at room temperature. Only when it forms a ceramic bond at high temperatures does it have higher strength. Chemically bonded refractory mud, which uses hydraulic, gas-hardening or thermo-hardening bonding materials as binding agents, hardens through a certain chemical reaction before the temperature drops below the temperature at which ceramic bonding occurs. The particle size of refractory mud varies according to the use requirements. Its limit particle size is generally less than 1mm, and some are less than 0.5mm or finer. When selecting the material of refractory mud, it should be consistent with the material of the refractory products of the masonry. In addition to being used as a joint material, refractory mud can also be used as a protective coating for the lining by applying or spraying.

Refractory mud properties and applications. 1. Good plasticity and convenient construction. 2. High bonding strength and strong corrosion resistance. 3. The refractoriness is relatively high, reaching up to (around 1650℃). 4. Good resistance to slag erosion. 5. Good thermal peelability. Refractory mud is mainly used in coke ovens, glass kilns, blast furnaces, and other industrial kilns.

Rongsheng Unshaped Refractory Material Manufacturer

Rongsheng Refractory Castable Manufacturer is a powerful manufacturer and seller of unshaped refractory materials. Rongsheng’s environmentally friendly, fully automatic unshaped refractory castable production line reliably guarantees the production and supply of refractory castables for high-temperature industrial furnaces. Rongsheng Refractory Castable Manufacturer already has customers in more than 120 countries, such as South Africa, Chile, Egypt, Colombia, Uzbekistan, Italy, Indonesia, Ukraine, Hungary, Spain, Kenya, Syria, Zambia, Oman, Venezuela, India, Peru, the United States, Ethiopia, etc. If you have the need to purchase unshaped refractory castables, or micro-expansion refractory plastics for power plant boiler maintenance, please contact us. Get free samples and quotes.