Treatment of residues from incineration of wastes containing heavy metals and salts, comprises lixiviation, cementation with polysulfides and precipitation of salts with solid/liquid separation at each stage

摘要

The treatment of special industrial wastes containing salts and heavy metals such as incineration products and especially residues from the cleaning of fumes from the incineration of domestic waste comprises lixiviation by a washing solution followed by cementation with polysulfides and precipitation of salts in the liquid fraction The lixiviation stage, conducted at a slightly raised temperature (warm), places soluble species in solution and lowers the pH. After extraction of solid matter, the liquid fraction is subjected to cementation with polysulfides to precipitate heavy metals as sulfides. The solid fraction is preferably also so treated. After a further separation of solid matter, the liquid fraction is subjected to saline precipitation with hydraulic binders to precipitate the salts contained within it. The water from this stage is reused for a new treatment cycle. The solid fractions from the lixiviation and saline precipitation stages are united to obtain a clinker which can be value enhanced. An Independent claim is included for an apparatus for the above process comprising successively a lixiviation unit with an associated liquid/solid separator, a sulfuration cementation unit also with a liquid/solid separator and a saline precipitation unit with liquid/solid separator.