| 摘要 |
<p>PURPOSE:To obtain the solid matter not bringing about the secondary environmental pollution with a low cost and low energy, by carrying out pressurized steam treatment after forming fine powdered burnt redidue containing Cr under the existence of Ca component and reducing agent. CONSTITUTION:Substance mainly composed of CaCO3, is added to waste matter containing Cr and is burnt or waste matter containing slaked lime or Ca, is added to burnt residue. Thus, Ca component in the residue is regulated at more than 10wt.% (calculated in terms of Ca). Next, compression forming is carried out after single or plural number of 1-30wt.%, preferably 5-15%, of reducing agent (Fe<++> salts, sulfurous acid or its salts, organic carbons, Mg, Ca, Zr or waste matter containing the above metal etc.), is added to the residue and is mixed, in order to prevent the elution of hexavalent Cr from the solid matter. Or, the surface is covered by the above mentioned reducing agent after formed body is made. Next, the formed body is silidified by carrying out steam autoclave treatment and on occasion demands, solidifying accelerator, such as silicic acid matter, clay etc., is added to the residue in order to carry out solidification fully.</p> |
