초록 ▼

Process for the irreversible treatment of toxic waste by means of a silicate, in the presence of water, in such a way as to form a solid aggregate includes treatment of the silicate in an acid medium, for the purpose of obtaining silicic acid of low molecular weight; mixing the silicic acid with the

Process for the irreversible treatment of toxic waste by means of a silicate, in the presence of water, in such a way as to form a solid aggregate includes treatment of the silicate in an acid medium, for the purpose of obtaining silicic acid of low molecular weight; mixing the silicic acid with the waste to be treated, in the presence of water and controlling the pH between 0 and 4 in a sufficiently acid medium to cause the waste to undergo at least partial solution; precipitation of a gel of high molecular weight from the resultant aqueous mixture; addition thereto of a mixture which reacts with the gel of high molecular weight to form a silicate, possibly in the presence of a cementation agent, in such a way as to produce a sludge, and the hardening of the sludge into a solid aggregate which can not be changed physically so as to release again the harmful or toxic waste into the environment.

대표청구항 ▼

A process for the formation of a chemically stable solid aggregate of wastes containing at least one heavy metal or heavy metal compound which is at least partially water soluble under acid conditions comprising the sequential steps of: (a) forming a low-polymerization-silicic-acid of molecular weig

A process for the formation of a chemically stable solid aggregate of wastes containing at least one heavy metal or heavy metal compound which is at least partially water soluble under acid conditions comprising the sequential steps of: (a) forming a low-polymerization-silicic-acid of molecular weight not exceeding 50,000 by reacting (i) a silicate selected from at least one of the group consisting of alkaline earth metal silicates, aluminum silicates, and aluminosilicates, (ii) water, and (iii) acid sufficient to provide the reaction mixture with a pH between about 0.5 and about 3; (b) mixing (i) the wastes containing heavy metals or heavy metal compounds, and (ii) the low-polymerization-silicic-acid, with (iii) sufficient water and acid, to adjust the mixture to one having at least 70% dissolved solids and a pH of less than 4; (c) synthesizing a higher-polymerization-silicic-acid/hydrated-heavy-metal coprecipitate gel, by reacting (i) the low-polymerization-silicic-acid, and (ii) the cations of the heavy metal in the wastes, (iii) in the presence of a base catalyst selected from at least one of the group consisting of sodium hydroxide, potassium hydroxide, calcium hydroxide, their carbonates or hydrocarbonates, in an amount sufficient to increase the pH of the mixture to progressively to at least 7; and (d) hardening the coprecipitate gel into a chemically stable solid aggregate; wherein the total amount of water in above steps (a) through (d) is at least 15 percent by weight based upon the total weight of solids.