| 摘要 |
PROBLEM TO BE SOLVED: To produce cement having little content of a repellent component by effectively causing reduction reaction with a reductive substance in a prescribed region of a cement kiln. SOLUTION: The surface of the reductive substance R such as coke powder is covered with a covering material C such as heat resistant glass powder having a softening point or melting point lower than about 1,450°C of the firing temperature in the cement kiln 2. When the covered reductive substance CR is supplied into the cement kiln, the reduction volatilization is effectively caused in a prescribed region in the kiln to accelerate the volatilization or insolubilization of the repellent component because the time, temperature condition, etc., for the exposure and reaction of the inside reductive substance differ according to the softening point or the melting point of the coating material, and as a result, the repellent component is removed from the cement production process to produce the cement having little content of the repellent component. The softening point and/or melting point of the coating material is controlled to ≥700°C and one or more of lead, zinc and 6-valent chromium are removed. The reductive substance can contain fine powder of less than 200 μm. COPYRIGHT: (C)2011,JPO&INPIT |
