Many methods of hydration resistance of high magnesia-calcium refractory are mostly proposed for raw materials, namely magnesia-calcium sand or dolomite sand, such as: adding additives, two-step forging and so on. These methods can only delay the hydration of magnesia-calcium refractory materials, but can not fundamentally solve the hydration problem, which is also a problem that has troubled scholars at home and abroad for many years.
For the brick itself, in order to improve the hydration resistance, high temperature performance and slag erosion and penetration resistance and stripping resistance of magnesia dolomite brick must start from the brick making process, among many factors affecting the brick making process, it is necessary to optimize the preparation process such as particle grading, mixing, molding and firing. In order to improve the performance of magnesia-calcium brick, more detailed research can be carried out from the aspects of additives and matrix composition after these technological parameters are defined.
1. The production process of magnesia dolomite brick
The entire production process of refractory materials includes formula design, mud preparation, molding, drying and heat treatment, firing and post-processing, but not all of the production process of refractory materials includes all of the above processes. In addition to the formulation design, mud preparation, drying and heat treatment processes are necessary, other processes are not necessary for every product.
At present, the production process of magnesia dolomite brick in China is as follows: magnesia calcium sand or dolomite sand, fused magnesia, sintered magnesia as raw materials, and anhydrous resin or paraffin as bonding agent. After the particle grading is determined, magnesia calcium sand is used as aggregate, fused magnesia is used as fine powder, hot mixing is used, hot molding is used, and fired in the tunnel kiln. The fired brick is mainly treated with impregnated asphalt and impregnated wax under the condition of vacuum, in order to seal the brick sample and improve its hydration resistance.
2. Control factors of waterproofing in the production process of magnesia dolomite brick
All aspects of the production process of magnesium-calcium brick should prevent hydration, starting from the preservation of raw materials, raw materials must be effectively waterproof preservation, such as the use of sealed buckets, multi-layer plastic bags and other measures. Special attention should be paid to the preservation of fine powder, such as dolomite fine powder, magnesium calcium sand fine powder and even magnesia fine powder have to be carefully preserved waterproof measures, because the activity of fine powder is higher, it is easier to react with water vapor to make hydration serious, especially in rainy days and humidity seasons. Because once the raw material is hydrated, the performance of the prepared magnesia-calcium brick is relatively large, the performance of the basic brick will drop to half of the original or even worse. In the mixing and molding process is suitable for a dry environment, the mixed raw materials can not be placed for too long must be formed in a very short time. For the molding good brick sample also need to be calcined as soon as possible, calcined good magnesia dolomite brick more need waterproof measures, the use of more methods are impregnated paraffin wax method, sealed packaging method and so on.
