| 摘要 |
PROBLEM TO BE SOLVED: To surely and easily fire without damaging the shape and further to decrease the discharge of a harmful gas generated in firing by arranging a shielding material containing a carbonaceous material to shield the contact with oxygen and firing at a specific temp. SOLUTION: The firing is carried out at 400-1000 deg.C. The carbonaceous material is a granular or the like activated carbon, coke, charcoal, anthracite, raw coal, carbon black or the like and the activated carbon or a fired coke is particularly preferable. In the case of incorporating an alkali (earth) metallic compound in the shielding material, the acidic harmful gas generated by firing is allowed to react with the metals to be made hamless. As the alkali (earth) metal, potassium, sodium, calcium and magnesium are mentioned and a compound of the metal can be selected from a carbonate, a bicarbonate, an oxide or a hydroxide. |
