Method of remediating heavy metal-containing soil

A method of remediating soil that contains heavy metals, comprising the steps of:

• removing and sieving a heavy metal-containing soil to remove stones and gravel;
• feeding a continuous stream of said soil into a turbo-reactor, which reactor comprises a cylindrical tubular body being laid with its axis horizontal, closed by end walls at its opposite ends, and provided with inlet openings for the soil to be treated and inlet openings for at least one reactant, as well as provided with at least one discharge opening, a bladed rotor rotatably mounted in the cylindrical tubular body and driven at a high rotational speed to produce a stream of finely divided soil particles, and a heating jacket for raising the temperature of the inner wall of the cylindrical tubular body to at least 110° C.;
• feeding a continuous stream of a reactant in the form of an aqueous solution of an alkali sulfide into the turbo-reactor in cocurrent with the soil stream;
• centrifuging the soil and the alkali sulfide solution against the inner wall of the cylindrical tubular body to form a highly turbulent, tubular dynamic fluid layer wherein the soil particles and the alkali sulfide solution are urged mechanically in intimate mutual contact by the rotor blades;
• and
• reacting the soil and the alkali sulfide in the thin layer while the latter is being urged, substantially in contact with the heated inner wall, toward said at least one discharge opening of the turbo-reactor, with simultaneous generation of steam,
• continuously discharging said soil stream through said at least one discharge opening (7).