The refractory material for Rotary kiln

Dec 19,2017
Rotary kiln is the calcination of the most critical large-scale production equipment, the level of its operation rate directly affects the normal operation of calcination and subsequent processes. The operation rate of 45M kilns in China's major aluminum plant carbon mills is generally low, mainly due to the serious damage of kiln castable lining, frequent kiln shutdowns and the lack of coke yield after calcination, which affects the normal production of the anode. Therefore, to extend the longevity of rotary kiln lining and improve the operation rate is one of the important issues in the research of aluminum carbon plant.
1, Rotary kiln lining damage analysis
Rotary kiln lining, mainly refractory castable mixed with binder after casting in the kiln mold in kiln lining was observed in the production of the main reasons for the damage are as follows:
1.1 heavy (high aluminum and clay) castables
A, heavy material strength and thermal shock resistance is not enough, the line rate of change, construction joints and expansion joints larger shrinkage. Therefore, fine red carbon particles along the gap into the erosion lining, resulting in lining damage, combined with uneven kiln body slight vibration, but also speed up the damage rate.
B, heating kiln heating curve is unreasonable, the kiln early heating up too fast, the accumulation of water in the lining of the rapid evaporation of water evaporation, steam over the liner ultimate strength, resulting in parallel face cracking and surface spalling.
1.2 light castables
Light material is kiln lining thermal insulation layer, its strength and refractoriness is low, when the heavy material is damaged or shrinks serious, high temperature material into the lining, once in direct contact with it will melt loss damage, leakage from the construction joints Kiln skin caused by burning red.
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1.3 duct and tertiary duct castables
One, duct castable is in an externally ventilated and dynamic environment with an external high temperature (1250 ± 50 ° C). As the temperature difference between inside and outside the duct is too large, resulting in the outer surface of the thermal stress exceeds its structural strength, and cracks. Crack expansion extends the tube wall castable damage so as to fall off.
B, pouring duct casting material, in order to make castable fixed firmly in the duct wall, welded φ6mm grasping nail, when the duct castable off, some unsightly grab the nail will fall off, so that the duct wall Leave some small holes, these small holes in the high temperature oxidation, resulting in leakage of air duct burn.
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1.4 rotary kiln with the conservation of castables
Casting curing time is not enough, or construction in winter, pouring material frozen, baked out of castable strength of less than technical requirements.
1.5 Kiln lining damaged other reasons
In addition to the above reasons, the quality of construction, improper operation and maintenance, and the life of kiln lining also have a great impact.
2, selected kiln lined refractory castable
Lining material performance is good or bad, directly affect the kiln life. If the lining material is not suitable for the work environment in the kiln, then how to build a furnace, drying kiln, the effect is not satisfactory. Therefore, the choice of a good kiln lining material, but also the key to extending the kiln age Therefore, in order to improve kiln lining life, the selection of lining materials should pay attention to the following points:
A, refractoriness, at 1450 ~ 1500 ℃ temperature does not deform, not softened;
B, high temperature stability of the volume stability and reducing atmosphere is good, generally the line rate of change below 1% of the most ideal, as a rotary kiln lining, the line rate of change as small as possible.
C, good thermal shock resistance, anti-shock impact of rapid heat;
d, high temperature mechanical strength, wear resistance, erosion resistance.