The general producers of gangue tunnel kilns use kiln types with large cross-sections. The kiln roof of large section tunnel kiln adopts light weight refractory concrete slab ceiling structure. Refractory concrete ceiling plate is made of aluminum silicate cement as a cementing agent, and porous high alumina refractory aggregates and fine powder according to a certain ratio, prefabricated by adding water, molding and maintenance. It is characterized by small bulk density and light weight; low thermal conductivity and good heat insulation; small line change after firing and good stability performance, and its use temperature is 1300℃～1350℃.
Lightweight refractory concrete ceiling slabs are highly susceptible to damage. Especially at the stage of kiln firing and baking, if the kiln temperature and heating speed are not properly controlled, the ceiling slab is prone to cracks, surface spalling and a sharp decrease in strength. Therefore, kiln drying is the key link in the use of lightweight refractory concrete ceiling slabs. The main role of kiln drying is to exclude free water and chemically bonded water from the kiln body and ceiling slab, and to obtain high temperature performance.
Lightweight refractory concrete ceiling panels in the use of special attention should be paid to the following issues.
First, the higher the content of aluminosilicate cement in the lightweight refractory concrete ceiling slab, the easier it is to bake the kiln with cracks, surface spalling and strength reduction. Therefore, the temperature and heating rate of the kiln should be based on the thermal performance of the lightweight refractory concrete ceiling slab.
Second, the lightweight refractory concrete ceiling plate in greater than 1300 ℃ to be sintered, while the highest firing temperature of gangue bricks for 1050 ℃, the ceiling plate can not reach the required sintering temperature, the strength is bound to be lower.
Therefore, in the operation of the kiln, the temperature in the kiln should be kept stable. Operators should pay attention to observation, and if they find that there are falling objects on top of the kiln carriage out of the kiln, they should find the reason and take corresponding measures.
Kiln body is easy to damage the parts of the kiln wall and curved seal brick, the main reason for damage is the collision and friction of the kiln car and other mechanical damage. Especially when the kiln car collapse, collapse of the products in the cooling belt cooling strength increased, it is very easy to the kiln wall and curved seal brick squeeze broken.
Therefore, we should pay attention to the operation in the yard, drying, roasting and other links, and strictly prevent the accident of collapsing stack. Once the accident of collapsing car in the tunnel roasting kiln, it is necessary to pull out the products collapsed in the cooling belt near the kiln wall at the mouth of the hot air extraction duct. For this reason, the cold air extraction pipe should be equipped with a blind tee, so that when you need to pull out the bricks, you can open the blind plate of the tee to facilitate the operation. It is better to add a 600mm high and 400mm wide accident processing hole between the cooling belt and the roasting belt, so that when needed, the blocked refractory bricks can be removed and used.