How to improve the service life of melting furnace lining through furnace construction technology

The induction melting furnace, water atomization system, gas Atomizer, vacuum gas atomization equipment and other industrial furnace are equipped with induction furnace lining. Here is some tips to the improvement the service life of melting furnace lining.
The high temperature performance of coreless induction furnace lining mainly depends on the physical and chemical properties and mineral composition of the refractory materials used. Under the premise of selecting raw and auxiliary materials, sintering process is the key process to obtain a good microstructure of the lining and fully exert its high temperature resistance. The densification degree of furnace lining sintering is related to factors such as the chemical composition, particle size ratio, sintering process, and sintering temperature of refractory materials. Through more than 20 years of continuous exploration and production testing, our factory has summarized a reasonable furnace tying and baking sintering process, which has significantly increased the furnace life.
1. Remove the mica paper when building the furnace.
2. The crystal quartz sand used for furnace construction shall be treated as follows:
2.1 Manual selection: mainly removes lumps and other impurities;
2.2 Magnetic Separation: Magnetic impurities must be completely removed;
2.3 Dry ramming material: Slow drying treatment must be carried out, with a drying temperature of 200 ℃ -300 ℃ and insulation for more than 4 hours.
3. Selection of Adhesive: Use boron anhydride (B2O3) instead of boric acid (H3BO3) as the adhesive, with an addition amount of 1.1% -1.5%.
4. Selection and proportioning of furnace building materials:
4.1 Selection of Furnace Materials: It should be noted that not all quartz sands with SiO2 ≥ 99% can be used as furnace lining materials for induction furnaces. The important thing is the size of quartz grains. The coarser the grains and the fewer lattice defects, the better (such as quartz sand with high SiO2 purity, white and transparent appearance). ）The larger the furnace capacity, the higher the requirements for grain size.
4.2 Proportion: The proportion of quartz sand used for furnace lining is 10% -15% for 6-8 mesh, 25% -30% for 10-20 mesh, 25% -30% for 20-40 mesh, and 25% -30% for 270 mesh.
5. Knotting of furnace lining: The quality of furnace lining knotting directly affects the sintering quality. When knotting, the sand particle size distribution is uniform and does not produce segregation. The sand layer after knotting has a high density, and the probability of cracking after sintering decreases, which is beneficial for improving the service life of the induction furnace lining.
5.1 Dry knotting furnace lining (taking a 2t coreless induction furnace as an example): Application of coil insulation adhesive: The induction coil of the 2t coreless induction furnace is coated with an insulation adhesive layer. Compared with the insulation materials such as mica and glass fiber cloth commonly used in induction circuits, using coil insulation adhesive has the following advantages: firstly, after drying, the coil insulation adhesive layer with a thickness of 8-15mm has good insulation performance and can completely replace mica and glass fiber cloth, serving as an insulation protection layer between the coil and the furnace lining; The thermal conductivity of the adhesive material is relatively high, so there is no need to worry about the relatively thick adhesive layer affecting the three-layer structure of the hot surface furnace lining. Secondly, the adhesive layer is located between the coil and the insulation layer. Under normal circumstances, the ambient temperature is very low (<300 ℃). Occasionally, when metal liquid approaches its surface, the adhesive layer will release a small amount of residual moisture, reducing the insulation resistance and providing early warning by the system.