Construction of Corundum-Mullite Castable for Rotary Kiln

Corundum mullite castable is a high-performance castable made of corundum aggregate and mullite aggregate as raw materials, plus micro powder and additives. Characteristics of corundum mullite castable:

(1) High refractory temperature and high load softening temperature.

(2) High high-temperature strength and good volume stability.

(3) Excellent slag resistance.

(4) Convenient construction. It can be cast as a whole or in severely worn areas.

(5) Excellent thermal shock resistance and good structural peeling resistance.

Corundum-Mullite Castable for Rotary Kiln

Application range of corundum mullite castable: Suitable for heating furnaces, soaking furnaces, heat treatment furnaces, and rotary kilns. Various high-temperature burner linings, heating furnace water pipe wrapping linings, steel molten furnace refining device components, and high-temperature wear-resistant linings for petrochemical catalytic cracking reactors. Blast furnace tapping troughs, cupola tapping troughs, integral powder spray guns for molten iron pretreatment, etc. Large and medium-sized cement kiln mouths, coal injection pipes, kiln head covers, cooler low walls, etc. Contact Rongsheng to get free solutions for furnace lining materials.

Construction of Corundum Mullite Castable for Rotary Kiln

Construction tool preparation:

Forced mixer, vibrating rod, iron wire, template, 2 electric welders, tile knife, mud bucket, shovel, level ruler, etc.

Welding of anchors

For the construction of rotary kiln lining, first clean the inner wall of the cylinder, including removing the old lining adhering to the inner wall of the cylinder. While ensuring that the inner wall of the cylinder is clean, weld anchors made of heat-resistant alloy steel (310 material). The shape of the anchor is Y-shaped, with a length of 150mm and a diameter of 10mm. The arrangement and spacing of the anchors are 250mm, the casting thickness of the lining is 180mm, and the use temperature and conditions are (1100℃). The anchors are generally arranged in two rows each, and the rows are staggered. The surface of the metal anchor is painted with asphalt, because the thermal expansion coefficient of the metal is larger than that of the refractory material. The welding of the anchors should be firm and regular, and the distribution and welding strength should be checked after welding.

Casting

The castable material is casted by a powerful mixer and then vibrated by a vibrating rod. The casting process is divided into four steps: dry mixing, wet mixing, transportation, and vibration molding of the castable material. In order to fully mix the materials of various particle sizes and various additives of the castable material, so as to obtain the maximum bulk density and the maximum application strength. The stirring time is required to be no less than 3 minutes, and the amount of water added is strictly controlled, and the amount of water should not be too large. Because as the amount of water used in the castable increases, its strength decreases and the apparent porosity increases.

After the castable is mixed evenly, it is transported to the construction site. When pouring, it is generally vibrated while adding materials until the surface of the castable is slurry without overflowing and no large amount of bubbles are discharged. The vibration time should not be too long to avoid segregation of materials of various particle sizes in the castable. It must be noted that the stirred materials should be used up within 30 minutes, and the materials that have begun to set are prohibited from use.

Requirements for Expansion Joints in Lining Construction

During construction, an expansion joint with a width of about 3-5mm should be opened every 2000mm in the annular length direction to accommodate the volume expansion of the surface of the lining during the heating process.

Baking of lining

After 24 hours of construction, the castable has formed a certain strength, and the formwork can be removed for natural curing. The curing time is 3 days or more, and insulation measures should be taken at low temperatures.

Baking time and insulation

• Normal temperature -150℃, 15℃ rise per hour, 10 hours, 150℃ constant temperature for 24 hours.

• 150℃-350℃, 15℃ rise per hour, 13 hours, 350℃ constant temperature for 30 hours.

• 350℃-600℃, 15℃ rise per hour, 17 hours, 600℃ constant temperature for 24 hours.

Lining material selection

Corundum mullite castable, the main raw material is corundum mullite, and the binder is aluminate cement and other materials. This product does not contain heavy metals and has good thermal shock stability.