Refractory castables are widely used in high-temperature equipment in metallurgy, chemical industry, cement, glass and other industries. As furnace lining materials, they have good high temperature resistance, corrosion resistance and compressive strength. However, under long-term high temperature environment and mechanical load, refractory castables may suffer varying degrees of damage, requiring timely repair and maintenance to ensure the normal operation of the equipment and extend its service life. This article will discuss the repair and maintenance methods of refractory castables.

1. Damage types of refractory castables
Refractory castables may encounter the following types of damage during use:

Thermal cracks: Due to sudden temperature changes or uneven temperature distribution, refractory castables may crack, resulting in reduced thermal insulation and strength of the furnace lining.

Thermal expansion damage: When refractory castables are affected by high temperatures, thermal expansion or thermal contraction may be uneven, resulting in cracks or peeling.
Erosion damage: In a high-temperature atmosphere, corrosive gases, slag, and charge in the furnace body will corrode the refractory castable, causing surface wear or material shedding.
Mechanical damage: During operation, the surface of the refractory castable may be worn and cracked due to material impact, friction, or vibration of the equipment.
Chemical damage: Chemical reactions in a high-temperature environment may cause the chemical structure of the refractory castable to change, reducing its performance.
2. Repair methods for refractory castables
The repair methods are different for different types of damage. The following are several common repair methods:

Crack repair:

Heat treatment repair method: For cracks caused by uneven thermal expansion or thermal stress, they can be repaired by heating and cooling. Through reasonable heat treatment control, the overall structure of the refractory castable can be restored.
Injection repair method: For finer cracks, a special refractory castable repair agent can be used for injection filling. This method can quickly repair cracks and restore their thermal stability.
Erosion damage repair:

Coating repair method: Local erosion damage on the surface of refractory castables can be repaired by applying high-performance high-temperature resistant coatings. The coating can not only effectively prevent erosion by gas and slag, but also enhance the high temperature resistance of refractory castables.
Local pouring repair method: For erosion damage over a larger area, the same refractory castable can be used for local pouring repair. This method can restore the refractory properties of the damaged part and reduce maintenance costs.
Abrasion repair:

Mortar repair method: For surface wear caused by improper operation or material impact, refractory mortar with appropriate proportion can be used for repair. The compactness of the refractory mortar needs to be maintained during repair to prevent new cracks or falling off during subsequent use.
Re-pouring repair method: For large-area damage caused by impact and other reasons, re-pouring repair can be considered. This method can effectively restore its original performance by re-pouring refractory castables with the same proportion as the raw materials.
Thermal expansion damage repair:

Expansion repair method: For cracks caused by uneven thermal expansion, they can be repaired by using repair materials with good thermal expansion properties. This can effectively supplement the strength of the refractory castable and avoid further crack expansion.
Chemical damage repair:

Chemical plating repair method: If the performance of the refractory castable is reduced due to chemical corrosion, it can be repaired by chemical plating. Through plating repair, the chemical stability of the refractory castable can be restored and the corrosion can be prevented from further aggravation.
3. Maintenance methods of refractory castables
Regular maintenance is an important means to extend the service life of refractory castables. The following are several effective maintenance methods:

Regular inspection and evaluation:

During use, the damage of the refractory castable should be checked regularly, especially the high-temperature parts such as the furnace lining and furnace mouth. Through visual inspection, flaw detection and other means, cracks, shedding or wear and other problems can be discovered in time.
Cleaning and maintenance:

During the use of the furnace body, the ash and slag on the surface of the refractory castable should be cleaned regularly to avoid secondary damage to the refractory castable. At the same time, using a high-temperature resistant detergent for surface cleaning can improve the thermal stability of refractory castables.
Avoid drastic temperature changes:
During use, avoid drastic temperature fluctuations. For example, when starting the furnace body, gradually increase the temperature to avoid excessive heating that causes uneven thermal expansion, which can cause cracks.
Prevent erosion:
When using highly corrosive materials, strengthen the protection of refractory castables. For example, a layer of anti-corrosion paint can be applied to the surface of the equipment to prevent slag, gas and other corrosive substances from corroding the refractory castables.
Reasonable workload control:
Control the workload of the furnace body to avoid overload operation. Overload will not only cause excessive wear of the refractory castable, but may also cause damage to other parts of the equipment.
Regular maintenance and repair:
At regular intervals, the refractory castable should be fully maintained, including replenishing the worn parts, filling the cracks and performing surface coating treatment. Timely repair can effectively prevent further damage.
IV. Summary
The repair and maintenance of refractory castables are important measures to ensure their long-term use and normal operation of equipment. Through reasonable repair methods and regular maintenance, the service life of refractory castables can be effectively extended, production downtime can be reduced, and the economic benefits of equipment can be improved. During the repair process, the appropriate repair plan should be selected according to the type of damage, and in daily maintenance, attention should be paid to the temperature changes, workload and external environmental factors of the equipment to minimize damage.