Ordinary sintering magnesia brick production process

The firing process usually includes magnesia carbon brick crushing, grinding, grading, batching, mixing, molding, drying and sintering processes.

1) refractory raw material requirements. Chemical composition of sintered magnesia: MgO>87%, CaO = 2.5%, SiO2 = 5%, the appearance of brown or dark brown, dense crystal, good sintering, bulk the density is larger than 3.2g/cm3, igloss <0.3%, in order to ensure the product has good structure, control C/S<0.5.

2) particles should be considered with the most compact principle. The current domestic production of ordinary sintering magnesia brick has various forms according to the actual situation, some using mixed ingredients, the single sieve, the critical particle size 3mm or 2mm, some with three ingredients of 3 ~ 1mm, 1 ~ 0mm, <0.088mm also according to the actual size of refractory brick type and the critical particle size can be enlarged to 6mm, while using four or five ingredients. In order to improve the thermal shock resistance of products, may be appropriate to increase the critical particle size, or by increasing the large particle size. In order to improve the product load softening temperature and sintering, can be increased when the content of fine powder particles, reduce the upper limit.

3) Ingredients. In a factory three ingredients for example: 3 ~ 1mm, 40 ~ 50%; 1 ~ 0mm, 20 ~ 25%; less than or equal to 0.088mm, 30 ~ 35%. binder commonly used sulfite liquor or brine, adding amount of 4% ~ 6%, adding the waste brick, the general should be <20%.

4) Mixed. Usually, in the wet grinding machine in the order of operations: coarse grain - size - bond - fine powder, net mixing time of >15 minutes, mud water <3%, generally do not need trapped material.

5) The magnesia material for forming poor materials, easy molding, blank containing water less, at around 2.5%, low mud plasticity, should adopt high pressure molding, control body density >2.95g/cm3.

6) Dry. Make the body moisture <1%. if not high water content in the body, can take the natural drying, generally >24 hours. If using drying, it generally takes 8 to 12 hours should not be too high, the drying temperature, inlet and outlet temperature control, so as to avoid cracking.

7) Firing. In the heating process will change as follows: out of the water, the generation of liquid phase sintering, particle migration, solid phase reaction, recrystallization, and finally sintering. Strength is increased and the density increases. The firing temperature is generally 1500 to 1600 degrees centigrade.

Article Source: Ordinary sintering magnesia brick production process
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