The variety quality of refractory materials is very related to the production process, the same raw materials using different processes can be manufactured without varieties and quality products.
General block fired refractory brick production process:
Raw material → Raw material processing → batching and mixing → molding → drying → firing → Finished product inspection → finished product storage
l, raw materials
The manufacture of different refractory products requires the use of raw materials composed of different chemical minerals.
The requirements of refractory products for raw materials are: suitable chemical mineral composition, impurity content in raw materials: less and evenly distributed; It is easy to mine, process and manufacture, and the cost is low.
2, raw material processing
Raw material processing includes dressing, drying, burning, crushing and screening.
(1) Beneficiation
In order to obtain refractory products with high temperature resistance, high pressure and good slag resistance, raw materials need to be selected before crushing and calcination. Its methods include mechanical washing, manual selection and electromagnetic magnet.
(2) Drying and calcination of raw materials
Due to the different conditions of mining season, mining method and transportation, the water content of raw materials is also different. Raw materials with high water content should be dried before crushing; In addition, in order to obtain refractory materials with high temperature volume stability and good thermal stability, raw materials are calcined in shaft kiln or rotary kiln before dosing.
(3) Crushing and screening of raw materials
In order to obtain a certain density of refractory products, the raw materials must be broken into a certain particle size, and then through powder punching and screening, the raw materials are divided into large, medium and small three levels, according to the process requirements, the manufacture of refractory products, respectively, with various particles, the amount of addition is determined according to the accumulation test.
3. Batching and mixing (mixing)
The ingredients are raw materials (large, medium and small particles, raw material and clinker), additives (binder, mineralizer) and water in a certain proportion.
In the process of making refractory bricks, if only a certain particle composition can not obtain high density refractory products, and dense particles filled with each other to obtain high density products; If only use clinker as aggregate to make refractory bricks, one is low strength, the second is difficult to burn, therefore, in addition to the general refractory products with clinker, but also need to add a certain amount of raw materials and also need to add water (such as clay bricks).
In order to obtain a relatively stable mineral composition, some refractories need to add a small amount of mineralizing agent to promote the formation of a stable mineral in the brick (such as silicon brick).
The purpose of mixing is to mix raw materials and additives of different sizes of particles and water evenly to avoid segregation. Elephant. The mud after mixing is placed for a certain time before forming, the purpose is to further homogenize the mud; Increase the plasticity of mud and the strength of refractory products. This process is called trapping.
4. Forming and drying
The purpose of molding is to make the refractory products have the specified density, shape size and strength. The forming method can be divided into two kinds: adjustable and semi-dry forming. Most refractory products used in the metallurgical industry are semi-dry forming methods. Semi-dry forming can be divided into mechanical forming and manual forming, the former is suitable for refractory bricks with simple shape and large production volume, and the latter is used for special-shaped refractory bricks with small production volume and not easy to mechanize operation.
The brick after forming has a high water content and is dried before firing. Its purpose is to improve the mechanical strength, easy transportation, kiln loading and to avoid cracks caused by rapid temperature rise and severe water discharge during firing. The water content of the brick is related to the molding method, and the general water content of the plasticized brick is 10~20%. The water content of semi-dry molding is 3~10%. Both mouldable and semi-dry moulded bad materials should be dried before burning.
After drying, the fired brick can be fired into the kiln when the moisture is reduced to less than 2%. A series of physical and chemical reactions are carried out in the sintering process, which makes the brick body become dense, the strength increases, the volume is stable, and it becomes a refractory product with a certain shape size.
During the sintering process, the brick includes the process of crystal growth, formation of new crystals and growth, formation of liquid phase and filling pore bonded crystals, which is the result of the formation and recrystallization of liquid phase, solid phase reaction, recrystallization and aggregation and recrystallization. The specific process of different refractories is different, and specific analysis should be carried out. The sintering process should control the firing temperature, firing time and atmosphere properties. At present, the main firing equipment is tunnel kiln and inverted flame kiln.
