What material is used for the ramming material of the medium frequency furnace lining? The selection of ramming material for the medium frequency furnace lining depends on the atmosphere in the furnace. Because the atmosphere of the medium frequency furnace lining is divided into neutral, acidic, alkaline, and composite, and there are core induction and coreless induction furnaces.
Ramming Material Used for the Lining of the Intermediate Frequency Furnace
Ramming Material Used for Medium Frequency Furnace Lining
Generally, the acidic furnace lining material is a dry ramming material made of high-purity microcrystalline quartz sand and powder, mixed with high-temperature sintering agent and mineralizer. The particle size should be strictly controlled during the production process, and the amount of sintering agent added should be controlled during construction to ensure that the knotting can obtain a dense furnace lining. There are not too many furnaces with acidic furnace linings, and the ramming material for acidic furnace linings is not used frequently and is replaced frequently, so the amount is relatively large.
The neutral furnace lining material is a dry ramming material made of corundum sand and powder, alumina-magnesium spinel powder and sintering agent. This ramming material has strong density, good thermal shock stability, and the knotted furnace lining is uniform. If it is an alkaline furnace lining, a magnesium dry ramming material with good thermal shock stability, volume stability, and high temperature strength should be selected. Because when using it, the backing should be kept with a certain loose layer. In general, there are more coreless furnaces in alkaline atmosphere linings. Magnesium ramming materials have high stacking density and uniform heating speed of the lining. There are also cored induction furnaces, but they are few in number.
According to the usage, there have been more alkaline furnace linings in recent years, and most of them are coreless induction furnaces. The magnesium dry ramming materials used in the lining have also changed to varying degrees. In recent years, aluminum-magnesium ramming materials have been used more, because the price of magnesia sand has skyrocketed. But the most important thing is that aluminum-magnesium ramming materials have good thermal shock stability and are suitable for intermittent shutdowns and temperature fluctuations. And another feature is that because the alkaline furnace lining is a steel shell furnace, aluminum-magnesium ramming materials heat up quickly and save electricity.
However, the quality of aluminum-magnesium ramming materials is different according to the requirements of the number of furnaces used. The price is relatively high for furnaces with more than 100 furnaces, and the price is relatively cheap for furnaces with less than 70 furnaces. Of course, the quality of aluminum-magnesium ramming materials is determined according to the number of furnaces required by users.
The Difference between Acidic and Neutral Ramming Materials for Medium Frequency Furnaces
The difference between acidic and neutral ramming materials for medium frequency furnaces. Many customers think that acidic quartz sand ramming materials are easy to use, so they buy neutral ramming materials and use them according to the usage of quartz sand ramming materials, but the results are not satisfactory. Below, Rongsheng Refractory Material Manufacturer will tell you the difference between the two:
First, analyze the material. Quartz sand ramming materials are ramming materials mainly composed of quartz. And neutral ramming materials are ramming materials mainly composed of alumina and magnesium oxide.
Second, quartz sand ramming materials on the furnace can be easily operated. Because of the large expansion coefficient, the density will be relatively good after expansion in the later stage. The expansion coefficient of neutral ramming materials is low, and the furnace lining that was hit at the time will not change much in the later stage. Therefore, it is required that neutral ramming materials must be operated patiently when hitting the furnace, and the stronger the better.
Third, in terms of furnace baking time, acidic ramming materials can be baked in about an hour, while neutral ramming materials generally take more than 10 hours to complete sintering and need to be heated slowly.
Fourth, the density is different. The density of acidic ramming materials is 2.1, and the density of neutral ramming materials is above 2.8.
Fifth, the refractoriness is different. The acidic ramming materials are between 1780° and 1800°, and the neutral ramming materials are above 2180°.
Effect of CaO Addition on Sintering Properties of Aluminum-Magnesium Dry Ramming Mass for Medium Frequency Furnace
Aluminum-magnesium dry ramming mass was prepared by ramming molding with fused corundum and fused magnesia as the main raw materials and CaO as a sintering additive. The effect of CaO addition (mass fraction of 0, 0.5%, 1%, 1.5%, 2%) on the phase composition, sintering properties, and microstructure of aluminum-magnesium dry ramming mass after heat treatment at 1,600 ℃ for 3 h was studied. The results show that an appropriate amount of CaO can promote the sintering of aluminum-magnesium dry ramming mass, and the room temperature compressive strength is significantly improved. The reason is that CaO reacts with Al2O3 to form calcium hexaaluminate (CA6), which is interspersed between the corundum phase and the spinel phase, thereby improving the strength of the ramming mass. When the CaO addition is 1% (w), the ramming mass after heat treatment at 1,600 ℃ has good comprehensive properties and a linear expansion coefficient of 1.38%. The bulk density and apparent porosity are 2.86 g·cm-3 and 21.3%, respectively, and the compressive strength is 15.2 MPa.
(1) The introduction of an appropriate amount of CaO can improve the sintering of aluminum-magnesium dry ramming material and significantly increase the compressive strength. When the CaO addition amount is 1% (w), the sample has good comprehensive properties, and its linear expansion coefficient is 1.38%. The apparent porosity and bulk density are 21.3% and 2.86 g·cm-3, respectively, and the compressive strength is 15.2 MPa.
(2) The introduction of CaO generates a plate-like CA6 layer at the edge of the corundum aggregate particles. It is interspersed between corundum and MA to form a stable coating structure, thereby improving the mechanical properties of the material.
