Treatment of soil and muds contaminated with heavy metals - by mixing with mineral clays and organic material, heating to form glass phase, and cooling ash residue obtd.

摘要

Method for the treatment of soil, mud and similar material contaminated with heavy metals is claimed, where the contaminated material is first mixed with a suitable quantity of mineral clays and organic material, such that the clay content becomes pref. at least 10% wt., and most pref. between 15 and 30%, and the quantity of organic material amounts to at least 2.5% wt. The material is then heated to between pref. 500 - 1100 (650 - 1000)[deg] C, for between 10 minutes to 2 hours, such that the clay is at least partially transformed to the glass phase, but is not noticeably sintered. The resultant ash residue obtained is cooled and conditioned for pref. at least 1 day, and most pref. 1 to 8 weeks, at a humidity level between 5 and 25% wt., and more pref. between 10 and 20% wt., at ambient temperature. During this conditioning phase, a reactive hydrated aluminosilicate phase is generated in which the heavy metals are immobilised and fixed in the matrix such that they can no longer leach out. The residue is also regularly turned over during conditioning to ensure good mixing. After conditioning, the material can be processed to building materials.