1.Characteristics of Refractory Materials for Chlorination Roasting Rotary Kilns

The main factors causing damage to the kiln lining during the chlorination roasting process are mechanical stress, thermal stress, and chemical corrosion. The stresses experienced by the lining vary depending on the kiln type, operation, the lining's position within the kiln, and the deformation of the flame, kiln feed, and kiln shell during operation. To mitigate corrosion of the kiln lining and shell and improve operational efficiency, the refractory material for rotary kiln linings should possess the following characteristics:

(1) High temperature resistance. It can operate for a long time in a high-temperature environment of around 800℃.

(2) High strength and excellent wear resistance. Refractory materials need to have a certain mechanical strength to withstand the expansion stress at high temperatures and the stress generated by the deformation of the rotary kiln shell.

(3) Excellent chemical and thermal stability. It can prevent corrosion from chemicals in flue gas and withstand alternating thermal stress.

(4)Good thermal expansion stability. Although the thermal expansion coefficient of the rotary kiln shell is greater than that of the rotary kiln refractory material, the shell temperature is generally 150~300℃, while the temperature that the refractory material withstands is generally around 800℃. This may cause the refractory material to have a greater thermal expansion than the rotary kiln shell, thus making it easier to fall off.

(5) Low porosity. High porosity allows flue gas to easily penetrate refractory materials, thereby eroding them.

2.Physical and chemical properties of high-strength refractory castables:

To meet the requirements of the chlorination roasting process in a certain project, the rotary kiln for chlorination roasting uses acid-resistant high-strength castable as the basic material for the kiln lining. It has the following characteristics:

(1) The main chemical component is Al2O3, accounting for ≥78%, with high strength, high temperature resistance, and resistance to acidic substances.

(2) According to the relationship between bulk density and apparent porosity, if the bulk density is ≥2.85g/cm3, then the apparent porosity is <20% and the refractory temperature is >1550℃; this can prevent low melting point substances from adhering to the kiln lining.

(3) Good high-temperature stability against heat load and hot wear

In conclusion, high-strength refractory castables meet the requirements for kiln linings, and their physical properties directly affect the service life of the kiln lining.