The choice of ramming material for the lining of the intermediate frequency furnace depends on the atmosphere in the furnace. Because the working atmosphere of the intermediate frequency furnace lining is neutral, acidic, alkaline, and composite. And the intermediate frequency furnace is divided into core induction and coreless induction furnace. So, what kind of ramming material is used for the lining of the intermediate frequency furnace?
In general, the acid furnace lining material is made of high-purity microcrystalline quartz sand and powder, and a dry vibrating material mixed with a high-temperature sintering agent and a mineralizer. In the production process, the particle size should be strictly controlled, and the amount of sintering agent added during construction should be controlled to ensure that a dense furnace lining can be obtained by knotting. There are not too many furnaces with acid lining, the ramming material used for the acid lining is not used frequently, and the number of replacements is large, so the dosage is relatively large.
Ramming Material Used for the Lining of the Intermediate Frequency Furnace
The neutral furnace lining material is a dry kneaded material mixed with corundum sand, powder, aluminum-magnesium spinel powder, and sintering agent. This kind of ramming material has strong compactness, good thermal shock stability, and evenly knotted furnace lining.
If it is an alkaline furnace lining, a magnesia dry ramming material with good thermal shock stability, volume stability, and high-temperature strength should be selected. Because it is necessary to keep the inner lining with a certain loose layer when in use. The furnace lining of an alkaline atmosphere is generally used in coreless furnaces, and magnesium ramming material is used. The bulk density is high, and the furnace lining uniformly heats up quickly. There are also induction furnaces with cores, but they are few.
According to the situation of use, there are more alkaline furnace linings in recent years, and most of them are coreless induction furnaces. The magnesia dry ramming material used in the furnace lining has also changed to varying degrees. Therefore, in recent years, more aluminum-magnesium ramming materials are used. Because the soaring price of magnesia is a factor, but the most important thing is that the aluminum-magnesium ramming material has good thermal shock stability and is suitable for intermittent shutdown and temperature fluctuations. And another feature is that because the basic furnace lining is a steel shell furnace, the aluminum-magnesium ramming material heats up quickly and saves electricity.
However, the quality of the aluminum-magnesium ramming material is different in price according to the requirements of the heat used. If the number of heats exceeds 100, the price is relatively high, and if the number of heats is less than 70 times, the price will be relatively cheap. Of course, the quality of the aluminum-magnesium ramming material is determined according to the heat required by the user.
How to Choose Castable or Ramming Material for Intermediate Frequency Furnace Lining?
The choice of the lining refractory material for the intermediate frequency furnace depends on the size of the furnace to decide whether to use castable or ramming material. Under normal circumstances, a small furnace, that is, a 1-ton intermediate frequency furnace will use castables. If it is a vacuum furnace, it is first made into a crucible with castables, baked at 1200°C, and directly put into the furnace lining for use. For the lining of large intermediate frequency furnaces, such as intermediate frequency furnaces of more than 15 tons, refractory ramming materials are used as lining materials.
The material of the crucible castable is also the same as the material of the ramming material used for the large-tonnage furnace lining, which is made of aluminum-magnesium spinel castable. However, the particles have certain boundaries, and the particles of the castable are between 0-3. The particle size of the ramming material is 0-5mm, and the largest is 0-7mm. The refractory ramming material is rammed on site. Because the amount of water added to the ramming material is small, it is beneficial to the lining of the intermediate frequency furnace for baking.
Castable or Ramming Material for Intermediate Frequency Furnace Lining
If the castable for the lining of the vacuum furnace of small tonnage is used, it can also be constructed on-site. However, there are not many manufacturers with this kind of construction, because the furnace lining is small and it is not easy to pour. It is best to pour it directly into a crucible with the same shape as the furnace lining at the castable manufacturer, and then transport it to the manufacturer after roasting, and put it directly into the lining for use. This use effect will be better.
Whether it is castable or ramming material, depends on the working atmosphere of the intermediate frequency furnace selected the material. If it is the acid lining, use acid material as refractory ramming material, if it is neutral, use tabular corundum or white corundum to make corundum ramming material. And if it is an alkaline furnace lining, it is necessary to use an alkaline material as the ramming material.
Since the use of the intermediate frequency furnace is not continuous, the ramming material made of alkaline materials is not as good as neutral materials for thermal shock. With the continuous improvement of the actual use, the aluminum-magnesium spinel ramming material is used as the lining. In this way, the problem of thermal shock is solved, and the atmosphere of the material is basically the same as that of the lining. In this way, the castable with an alkaline lining atmosphere or the refractory ramming material lining will be used for a longer time.
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