The production of refractory cement is a complex process that mainly includes steps such as raw material preparation, crushing, grinding, mixing,batching, forming, drying, and high-temperature calcination.
Step Description
Raw material preparation: Select and inspect raw refractory ores (bauxite, magnesite, silica, clay etc.), remove impurities.
Crushing: Break large ore blocks into small coarse particles using jaw/hammer crushers.
Grinding: Further mill coarse particles into fine powder by ball mills or Raymond mills to meet particle size requirements.
Batching: Weigh different powders, additives and binders according to the formula, mix uniformly.
Forming: Press the mixed material into target shapes (bricks, blocks) via hydraulic pressing or casting.
Drying: Remove free water from green bodies at low/medium temperature to avoid cracking during firing.
High-temperature calcination: Heat dried green bodies at high temperature (1200–1800°C) in kilns, sinter to get dense refractory finished products.
The high-quality step is raw material preparation. The extracted raw materials such as bauxite usually contain moisture and impurities, and need to be crushed and screened first to meet certain particle size requirements.
The second step is ingredient preparation and mixing. According to the chemical composition requirements of the product, different grades of raw materials are accurately proportioned, and then an appropriate amount of binder and water are added. The mixture is thoroughly stirred in the refractory mixer to form a malleable mud material.
The third step is molding. The mixed by castable refractory mixer clay can be molded into the desired shape, such as bricks, irregular parts, or bulk materials, by pressing, extruding, or pouring.like Refamix refractory mixer is good choice of mixing for refractory raw materials.
The fourth step is drying. The formed body contains a certain amount of moisture, which is removed through a drying process to prevent cracking caused by rapid evaporation of moisture during subsequent high-temperature calcination.
The fifth step is high-temperature calcination. This is the most crucial step. The dried billet is sent into a kiln and subjected to long-term calcination in an environment much higher than its operating temperature. This process is called "sintering", which causes chemical reactions between raw material particles to form a strong, high-density ceramic bond, thereby obtaining the final refractory performance. The calcination temperature and time directly affect the density, strength, and refractoriness of the product.
There are several key factors to consider for the quality of refractory cement:
Fire resistance: This is the most basic indicator, referring to the outstanding temperature at which a material does not soften or melt at high temperatures. It directly determines the upper limit of the material's operating temperature.
High temperature flexural strength: The ability of a material to resist external damage at high temperatures. Under high temperature conditions, the strength of materials will decrease, and good flexural strength can ensure structural stability.
Thermal shock stability: refers to the ability of a material to resist rapid temperature changes without cracking. Many industrial equipment require frequent heating and cooling, and if the thermal shock stability is poor, the material is prone to cracking and damage.
Volume stability: When materials are used for a long time at high temperatures, their volume changes should be minimized as much as possible. Excessive expansion or contraction can lead to stress concentration in the structure, causing damage.
Chemical stability: The ability of a material to resist corrosion from chemical substances such as slag and smoke at high temperatures. Different industrial environments have different chemical corrosivity, and it is necessary to choose refractory cement with corresponding corrosion resistance.
