Method for fixing waste material

DETAILED DESCRIPTION OF INVENTION EXAMPLE 1 A montmorillonite clay in the form of a bentonite clay was finely ground to a particle size of about 200 mesh.
This finely ground bentonite clay was then treated with a slurry of industrial waste which essentially contained inorganic constituents, in particular heavy metals such as arsenic, antimony, tin, copper, lead and mercury, and only a small fraction of organic substances, mainly phenol.
The amount of clay used was determined beforehand on a laboratory scale, such that essentially all contaminants could be absorbed or enclosed in the clay used.
If desired, the amount of water present in the slurry of industrial waste material was adjusted so as to be able to obtain an essentially granular product after the absorption step.
The absorbent containing contaminants which was obtained in this way was then mixed with approximately 2% of sodium silicate in the form of a solution.
An aqueous slurry was then formed by mixing 20 kg of particles, obtained as described above, with 40 kg of Portland cement and 40 l of water, after which 10 kg of fly ash were added.
The resulting mixture was allowed to harden for 28 days.
Neither the heavy metals nor the phenol could be detected by extraction from the hardened material obtained.
For comparison, the above experiment was repeated except for the addition of the sodium silicate solution.
The material thus obtained, after hardening for 28 days, had unacceptedly high leaching values in diverse leaching tests, both with respect to the heavy metals and to the organic material.
EXAMPLE 2 A clay modified with a quaternary ammonium compound is preferably used for the treatment of industrial waste material which has an organic substance content of more than 4%.
In the present example, the waste stream contained about 7% of organic substances, mainly phenol and chloronaphthalene.
After the treatment with sodium silicate, followed by mixing with Portland cement and fly ash in accordance with Example 1, a hardened material is obtained from which it was not possible to extract phenol and chloronaphthalene