In Aug, 25 tons refractory castables are packed for delivering to our customer in South Africa.
The molding methods of refractory dense castables are: vibration molding, ramming molding, plastic molding, grouting molding, hot pressing molding.
In general, the proportion of refractory dense castables formed by vibration is relatively large, and not many are used for grouting and hot pressing. Vibration molding is to use a vibrating rod to vibrate between the mold and the castable to make the castable particles have floating fluidity to fill all parts of the mold. At the same time, small particles can also be filled into the gaps of large particles to make refractory dense castables more dense.
The advantages of vibration molding are low labor intensity and low cost. It is suitable for large or plate-shaped bad bodies. The disadvantage is that due to the different stiffness of the steel plates and springs of the mold, especially the large-scale plate-shaped bad bodies have uneven density, and when the construction is resumed, there will be uneven density. In addition, in order to increase the molding density, pressure vibration can also be used to pressurize while vibrating.
Ramming molding is a molding method in which the ramming material is compacted with a rammer to obtain a certain degree of compactness. The ramming hammer is driven by pneumatic or electric drive, and it can also be rammed manually. The ramming material is added into the model layer by layer and then rammed in layers. Before each feeding, the surface of the last tamped material layer should be loosened to avoid separation or cracks between layers. But this method is too labor-intensive and too noisy.
Plastic molding is a molding method in which plastic materials are put into a mold and extruded. It is extruded into mud bars with a mud extruder, and then the mud bars are cut into blanks at the outlet of the required size. It is then dried and fired. In order to increase the density of the green body, vacuum equipment is used to facilitate the exhaust of the mud.
Grouting is to inject the powder suspension into the gypsum mold, and after the gypsum mold absorbs water, the slurry solidifies to obtain a green body. Then pour out the solidified mud that is not dehydrated in the central part. Grouting also includes pressure grouting, centrifugal grouting and vacuum grouting. Pressure grouting is to use gravity or compressed air to shorten the suction time and reduce the moisture in the blank slurry after demolding. Centrifugal grouting is to inject the slurry into the mold while rotating, and centrifugal grouting will make the material close to the mold wall. In this method, the thickness of the green body is uniform, it is not easy to deform, and there is less water. Vacuum grouting is to evacuate the model outside. This method has a fast water absorption effect and can improve the quality of the green body.
Hot pressing is rarely used in refractory dense castables, mainly in the ceramic industry.
In short, no matter what the molding method is, it depends on the different products of the refractory dense castables.
