Correct Selection of Refractory Materials for Lime Rotary Kiln

The design of a good and reasonable refractory lining is the premise of the service life of a kiln. The use of high-quality refractory materials and reasonable material matching of various parts are the key and prerequisite for the service life of the kiln. Selection of refractory materials for various parts of the lime rotary kiln. Since the refractory lining of the lime kiln is affected by high-temperature thermal shock, mechanical wear, structural stress and chemical erosion, the use conditions are very harsh. In view of the harsh use conditions, the refractory material must have good chemical erosion resistance, excellent high-temperature volume stability and masonry integrity, good thermal shock resistance, good mechanical erosion resistance and wear resistance.

Correct selection of refractory materials for lime rotary kiln

The lime rotary kiln is mainly composed of a preheater, a rotary kiln body (preheating zone, upper and lower transition zones, burning zone, cooling zone), and a cooler. The selection of refractory materials varies according to the working environment of different structures.

1 Preheater

The preheater is in front of the preheater. The limestone is first heated in the preheater. The heat source is the waste flue gas from the cooling section. The raw material particle size is 10-30mm, and the temperature entering the preheating section is 1000-1050℃. The requirements for the material are mainly high strength, good wear resistance, and certain thermal shock resistance. It mainly includes mullite castables, steel fiber reinforced castables, and secondary high-strength hanging bricks.

2 Upper and lower transition zones

The temperature of this section is 1200-1300℃, which is the transition stage of limestone to the burning zone. The temperature changes greatly at this stage, and some limestone has begun to react. Therefore, the thermal shock stability and strength of the refractory material should be good, and phosphate combined high alumina bricks are generally selected.

3 High-temperature firing zone

The high-temperature zone is adjacent to the firing zone, with a use temperature of 1300-1500℃ and frequent temperature changes. As the activity requirements of lime are higher, its firing temperature is higher. The following three types of refractory bricks are generally selected for this section: special phosphate-bonded high-alumina bricks, magnesia-alumina spinel bricks, and high-alumina silicon carbide bricks (silicon-molybdenum bricks). Among them, magnesia-alumina spinel bricks are more expensive, but have a longer service life. When laying bricks, it is necessary to use dry masonry without fire mud, and add steel plates between bricks.

4 Cooling zone

The cooling zone is very short, with only a few rings of bricks or castables, and the temperature is 1300-1400℃. Phosphate-bonded high-alumina bricks are generally used.

5 Cooler

This equipment is a cooling device for finished lime, which is cooled by a blower. This section requires the temperature of the cooled lime to be lower than 100℃. The cooled lime enters the silo through a belt. The temperature of the hot air after heat exchange is about 600℃, and it enters the rotary kiln as combustion-supporting air to mix with coal gas for combustion. Due to the complex structure, high-strength low-cement castables and steel fiber wear-resistant castables are generally used for casting construction. In addition, ceramic fiber blankets and calcium silicate insulation boards are also required to enhance the external insulation effect.

6 Refractory mud

Since most of the masonry of the lime rotary kiln at each stage needs to be matched with refractory mud, there are special requirements for refractory mud. Generally, suitable refractory mud should be selected according to the temperature and requirements of each part. Prevent the simple pursuit of high-quality refractory mud from matching the temperature and materials at this stage, which will affect the overall operation of the rotary kiln.

RS Kiln Refractory Factory is a comprehensive group enterprise integrating refractory research and development, production, sales, product technology overall solution, refractory construction general contracting and operation. The main products include more than 200 varieties of organic pressure-setting refractory materials, amorphous refractory materials, special bricks for carbon roasting furnaces, functional refractory materials, etc. The products are widely used in high-temperature kilns and equipment in metallurgy, chemical industry, building materials, electric power, military industry, non-ferrous metals, carbon industry, etc. To purchase high-quality refractory materials for high-temperature industrial furnaces, please contact RS for free samples and quotations.