Process for the purification of waste materials or industrial by-products comprising chlorine

A process for the purification of waste materials or industrial by-products comprising chlorine (B), the process comprising the steps of:

• a) preparing a composition (C) by blending or mixing waste materials or industrial by-products comprising chlorine (B) with one or more materials comprising heavy metals (HM);
• b) reacting (B) and (HM) by thermal treatment of (C);
• c) separating evaporated heavy metal chloride compounds (HMCC);
• and
• d) obtaining a solid material after the thermal treatment step, wherein:
• the heavy metals (HM) are one or more from the following set of elements:
• Zn, Pb, Hg, Cu, Cd, Tl, In, Sn, Ni, Co;
• the thermal treatment is carried out at a temperature of 500-1200° C. and under a non-oxidizing atmosphere;
• the materials comprising heavy metals (HM) and the waste materials or industrial by-products comprising chlorine (B) are mixed or blended in the presence of water, with 2-50% by mass of water being present in the composition (C);
• and:
• a) a ratio of the materials comprising heavy metals (HM) to the waste materials or industrial by-products comprising chlorine (B) is chosen so that a chlorine content of the composition (C) is between 100 and 150% of an amount necessary for a stoichiometric conversion of the heavy metals (HM) in the materials comprising heavy metals (HM) into chlorides;
• or
• b) the ratio of the materials comprising heavy metals (HM) to the waste materials or industrial by-products comprising chlorine (B) is chosen so that the chlorine content of the composition (C) is between 80 and 100% of the amount necessary for a stoichiometric conversion of the zinc in the materials comprising heavy metals (HM) into chlorides.