Manufaturing technique of refractory products is similar with that of common graphtie prodcut. The basic process are as follows:
Selecting Raw Material → Heating Raw Material → Smashing → Compounding → Molding Biscuit → Drying →Presintering Biscuit →Rough Machining →Sintering → Final Machining → Inspecting→ Finished Product.
1. Selecting Raw Material
When peolple are selecting raw material, they should take application into consideration. Most raw material is chemical material, only a few raw material is raw mineral materials. Usually, we can get raw material from market. And some special raw material should be compound by people themselves.
In general，the purity of raw material is very high. For example, when people produce magnesia carbon brick, content of magnesium oxide should exceed 95% and content of flake graphite should exceed 92%. From a material point then, the purity of raw material should be as high as possible. However, nothing is evidable. High purity means high cost.Like producing magnesia carbon brick, If people ensure the impurity of iron trioxide below 0.35%, the final product must will be qualified.
2. Heating Raw Material
The material which is applied to manufacturing graphite refractory products, especially oxidised raw material, need to be heated previously. Heating process can be divided into two aspects: the one aspect s calcine, which means burning raw material under a lower temperature that below final maching temperature, which aims at removing volatile impurities and inclusions, reducing contraction of briquettes, and promoting the transformation of allomorphic crystal form; the other aspect is electric smelting, the procedure of which is melting raw material with electric-arc furnace, smashing raw material after cooling, which can improve control on Dimension
Smashing is a really important procedure in the course of producing refractory products, whose objective is to change granularity of raw material. As for benefit of smashing procedure， it can sactter raw material so evenly that biscuit can be molded more easyly. What ‘s more, it can make solid-phase reaction ,which avail sintering under a high temperature circumstance and decreace firing temperature, become more throughly. Furthermore, it can expose more impurity, which increase the purity of raw material.
(To be continued)