Refractory of Refractory Materials for Forging Kiln

For the stability and high strength of raw materials, many natural raw materials and synthetic raw materials need to be calcined at high temperature to make clinker. There are two main types of fire-resistant raw material calcination equipment: shaft kiln and rotary kiln.

1. shaft kiln

Vertical kiln is one of the raw material calcining equipment, often used to calcinate dolomite, magnesite, clay, high bauxite and other raw materials.

The shaft kiln is a cylindrical kiln body, the material is added from the top of the kiln, and then the kiln bottom is discharged. The air needed for fuel combustion is fed from the bottom of the kiln and the combustion product is discharged from the top of the kiln, so the shaft kiln belongs to countercurrent thermal equipment.

The material needs to pass through three zones in the shaft kiln, that is, preheating zone, calcination zone and cooling zone. The calcining zone lining is easy to damage, which is the key to the selection of shaft lining. In the same shaft kiln, the temperature, chemical erosion, mechanical wear, temperature change and material impact of each section of the working layer are very different, so the lining material should be selected according to the specific situation.

In the preheating zone, the material is preheated by the heat of the flue gas, and the raw material is decomposed at the higher temperature. In this area, the lining is mainly affected by the impact and friction of the material cloth is distributed, the scour and heat shock when the dust rises, or the carbon deposition is damaged by the chemical erosion of the gas.

The calcined zone material is calcined with the heat released by fuel combustion. The lining in this area is mainly subjected to high temperature and strong chemical erosion and thermal impact of furnace dust at high temperature. The lining of this part is generally selected according to the calcined raw material.

The calcined material in the cooling zone is heat exchanged with the bulging cold air, the material is cooled, and the air is heated into the calcined zone as combustion-supporting air. Its working environment is similar to that of preheating belt.

 Generally clay shaft kiln, because its calcination temperature is relatively low, generally at 1400℃, so its lining can use clay brick; high bauxite shaft kiln calcination belt and cooling belt should be built with high aluminum brick, other parts can use clay brick; For alkaline refractory calcining shaft kiln, high quality magnesia brick and magnesia-aluminum brick are generally used, vaporization cooling wall can be used, other parts can be built with clay brick and high aluminum brick with high strength.

2. rotary kiln

Rotary kiln is a kind of advanced equipment with large production capacity and high mechanization degree. Because of its strong adaptability to raw materials, calcined synthetic products and products with special requirements, its application is increasing day by day. There are the following characteristics compared with the shaft kiln: can calcinate debris, can make full use of mine resources, the kiln block size of the shaft kiln calcined ore is at least 25~30 mm, and the rotary kiln block size is at least 25~30 mm, and the rotary kiln block size can be reduced to 5 mm. The rotary kiln can calcine the raw materials which are difficult to sintered and easy to knot, such as the super grade and the first grade high bauxite with high alumina content. When the shaft kiln is calcined, the high temperature is easy to bond the kiln, and the temperature is too much. But the rotary kiln capital construction investment is many, the equipment weight is big, the exhaust gas contains the dust quantity, the product raw material and the fuel unit consumption is big.

The lining of clay and high aluminum rotary kiln is generally built with clay brick and high aluminum brick; the lining of magnesia and dolomite rotary kiln is made of magnesia-aluminum brick or magnesia-chromium brick in firing zone, and clay brick or clay castable in other parts.