| 摘要 |
Clay-puzzuolana is produced by burning clay in an atmosphere substantially free from sulphur or sulphur compounds at a temperature of 550 to 800 DEG C. The firing may be direct, the fuel used being free from sulphur, or an electrically heated furnace may be used. With indirect firing, the clay is placed in substantially closed metal containers which are put into or passed through a kiln. Organic material is removed during the burning by supplying an excess of air in direct firing; for indirect firing, air may have access to the container, or there may be introduced into the container a substance which gives off oxygen during burning. The raw clay may be broken up to increase the surface, or it may be shaped into rod form. |
