| 摘要 |
<p>PROBLEM TO BE SOLVED: To make usable wastes as a raw material of cement with reduced residual ratio of the lead contained therein by baking wastes, etc., to be treated at a temperature above the boiling point of lead chloride in the presence of chlorine of a quantity balanced with the total content of the lead compound and the alkaline metal compound. SOLUTION: Material to be treated containing lead compound such as residential and industrial wastes are baked at a temperature above the boiling point of lead chloride (about 950 deg.C) in the presence of chlorine, and the lead compound is vaporized and separated as lead chloride to reduce the lead content. The quantity of chlorine is balanced with the total content of the lead compound and the alkaline metal compound in the material to be treated. For example, the baking temperature of 950-1500 deg.C is preferable when the chlorine equivalent ratio A=(Cl-R)/Pb (Cl, R and Pb denote the chemical equivalent of chlorine, alkaline metal and lead, respectively) is >=-10, and further, the temperature is preferably 1,400-1,500 deg.C when A is between -10 and -5, and >=950 deg.C when A is >=-5. The residual ratio of lead contained in the wastes is <= about 20 wt.%, preferably <= about 3%.</p> |
