There are many matters that need to be paid attention to during the use of continuous casting copper crucibles, covering preheating, temperature control, copper liquid management, equipment maintenance and other aspects, as follows:
Preheating
Slow heating preheating: New or long-unused continuous casting copper crucibles must be slowly preheated before use. Because the crucible is in direct contact with high-temperature copper liquid at room temperature, thermal stress will be generated due to rapid temperature changes, causing cracks or even ruptures in the crucible. Generally, a gradual heating method should be adopted. Within the first 1-2 hours, the temperature is raised to 100-200℃, and then gradually heated to the working temperature at an appropriate heating rate according to the material and specifications of the crucible.
Preheating uniformity: Ensure that the crucible is preheated evenly to avoid local overheating. Symmetrical heating can be used to allow the heating element to work evenly. At the same time, the crucible can be properly rotated or moved during the preheating process so that all parts can be fully heated. If conditions permit, temperature measuring equipment can be used to monitor the temperature of different parts of the crucible to ensure that the temperature difference is within a reasonable range.
Temperature control
Strictly control the working temperature: The working temperature of the continuous casting copper crucible is usually around 1100-1200℃, and the composition of different copper alloys may vary. The temperature must be strictly controlled according to the process requirements of the copper material being processed. Too high a temperature will accelerate the loss of the crucible material, reduce the service life of the crucible, and may also cause excessive oxidation of the copper liquid; too low a temperature will make the copper liquid have poor fluidity, affect the smooth progress of continuous casting, and may cause defects in the ingot.
Prevent temperature fluctuations: drastic temperature fluctuations will cause thermal fatigue damage to the crucible. A stable heating power supply and advanced temperature control system, such as a PID controller, should be used to ensure that the temperature fluctuation range is controlled within ±10℃. At the same time, avoid frequently turning on or off the heating equipment during the continuous casting process to reduce temperature changes caused by operation.
Copper liquid management
Control the composition of the copper liquid: Ensure that the composition of the copper liquid meets the process requirements and avoid excessive impurity content. Some impurities may react chemically with the crucible material and corrode the crucible. For example, when there is excessive oxygen in the copper liquid, it will react with the carbon in the graphite crucible to generate gases such as carbon monoxide, which will cause pores and looseness on the surface of the crucible, reducing the strength and service life of the crucible.
Avoid overflowing copper liquid: When injecting copper liquid into the crucible, strictly control the injection amount to prevent the copper liquid from overflowing. The overflowing copper liquid will adhere to the outer wall of the crucible, and after cooling, it may damage the insulation layer and heating element of the crucible, and also cause safety hazards. Generally, the liquid level of the copper liquid should be controlled at about 80% – 90% of the crucible height.
Equipment maintenance
Regularly check the crucible: During use, check the appearance and internal condition of the crucible regularly. Check whether there are defects such as cracks, peeling, deformation, etc. on the surface of the crucible, especially the bottom and sides of the crucible that are easily corroded. If slight cracks are found, timely measures should be taken, such as reducing the use temperature and reducing the residence time of the copper liquid; if the cracks are serious or large-scale peeling occurs, the crucible must be replaced immediately to avoid leakage accidents.
Cleaning and maintenance: Regularly clean the copper slag and impurities on the surface of the crucible to prevent excessive accumulation and affect the heat dissipation and heating effect of the crucible. When cleaning, special tools should be used to avoid scratching the surface of the crucible. At the same time, the heating system, insulation layer, spout and other components of the crucible should be inspected and maintained to ensure their normal operation.
Operation specifications
Standardized loading and unloading: When loading copper into the crucible, avoid direct impact of the copper material on the crucible wall to avoid damage to the crucible lining. When unloading, control the outflow rate of the copper liquid to avoid too fast or too slow. Too fast may cause the copper liquid to splash and cause safety accidents; too slow may cause the copper liquid to solidify at the spout and block the spout.
Follow the safe operating procedures: Operators must wear protective equipment, such as high-temperature resistant gloves, goggles, etc. When performing operations related to the crucible, strictly abide by the safe operating procedures to prevent accidents such as burns and electric shocks. At the same time, ensure that the working area is well ventilated and the harmful gases generated during the smelting process are discharged in time.
