# US 5,349,118 A · Method for obtaining a geopolymeric binder allowing to stabilize, solidify and consolidate toxic or waste materials

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- Number: US 5,349,118 A
- Document ID: US5349118A
- Status: Granted
- Kind: A
- Application number: 08/090,950
- Filed: 1993-07-13
- Granted: 1994-09-20
- Earliest claimed: 1990-09-04
- Inventors: Joseph Davidovits
- Web page: https://patentgrep.com/patent/US5349118A

## CPC

- C04B 28/006: {containing mineral polymers, e.g. geopolymers of the Davidovits type}
- C04B 12/005: {Geopolymer cements, e.g. reaction products of aluminosilicates with alkali metal hydroxides or silicates}
- C04B 2111/00784: {for disposal only}
- Y02P 40/10: Production of cement, e.g. improving or optimising the production methods; Cement grinding
- Y02W 30/91: Use of waste materials as fillers for mortars or concrete
- Y10S 106/90: Soil stabilization
- C04B: LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE {(roofing granules E04D7/005)}; CERAMICS (devitrified glass-ceramics C03C10/00); REFRACTORIES; TREATMENT OF NATURAL STONE
- Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02W: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS

## Abstract

The method of the invention provides a geopolymeric binder in powder, used for the ultra rapid treatment of materials, soils or mining tailings, containing toxic wastes. The geopolymeric binder has a setting time equal to or greater than 30 minutes at a temperature of 20.degree. C. and a hardening rate such as to provide compression strengths (Sc) equal to or greater than 15 MPa, after only 4 hours at 20.degree. C., when tested in accordance with the standards applied to hydraulic binder mortars having a binder/sand ratio equal to 0.38 and a water/binder ratio between 0.22 and 0.27. The preparation method includes the following three reactive constituents: a) an alumino-silicate oxide (Si.sub.2 O.sub.5,Al.sub.2 O.sub.2) in which the Al cation is in (IV-V) coordination as determined by MAS-NMR analytical spectroscopy for .sup.27 Al; b) a disilicate of sodium and/or potassium (Na.sub.2,K.sub.2)(H.sub.3 SiO.sub.4).sub.2 ; c) a silicate of calcium where the molar ratios between the three reactive constituents being equal to or between ##EQU1## where Ca.sup.++ designates the calcium ion belonging to a weakly basic silicate of calcium whose atomic ratio Ca/Si is lower than 1.

## Claims

### Claim 1

In a method of consolidating toxic wastes for long-term disposal thereof, comprising reacting said wastes with a binder, the improvement wherein
said binder is a geopolymeric compound in powder form comprising
(a) 100 parts by weight of alumino-silicate oxide (Si.sub.2 O.sub.5,Al.sub.2 O.sub.2) having the Al cation in (IV-V) coordination as determined by MAS-NMR analytical spectroscopy for .sup.27 Al,
(b) 42-64 parts of sodium disilicate Na.sub.2 (H.sub.3 SiO.sub.4).sub.2 and
(c) 50-70 parts of vitreous basic silicate, composed partly of at least one of gehlinite, akermanite and wollastonite,
said geopolymeric compound providing a compressive strength greater than 15 MPa after only four hours at 20.degree. C. when tested in a standard mortar with a binder/sand ratio of 0.38, in the substantial absence of Portland cement, and
mixing of said toxic waste with said geopolymeric compound is carried out in the absence of water, followed by adding water so as to provide a water/binder ratio lower than 0.27, thereby obtaining hardening and capture of said toxic waste within a resultant geopolymeric matrix in the substantial absence of Portland cement.

### Claim 2

In a method of consolidating toxic wastes for long-term disposal thereof, comprising reacting said wastes with a binder, the improvement wherein
said binder is a geopolymeric compound in powder form comprising
(a) 100 parts by weight of alumino-silicate oxide (Si.sub.2 O.sub.5,Al.sub.2 O.sub.2) having the Al cation in (IV-V) coordination as determined by MAS-NMR analytical spectroscopy for .sup.27 Al,
(b) 48-72 parts by weight of potassium disilicate K.sub.2 (H.sub.3 SiO.sub.4).sub.2 or a mixture of (i) 35-40 parts of potassium silicate K.sub.2 O, 3SiO.sub.2, 3H.sub.2 O, (ii) 7-15 parts of potassium hydroxide KOH which is at least 90% anhydrous, and (iii) an amount of amorphous silica up to 65 parts, and
(c) 50-70 parts of vitreous basic silicate, composed partly of at least one of gehlinite, akermanite and wollastonite,
said geopolymeric compound providing a compressive strength greater than 15 MPa after only four hours at 20.degree. C. when tested in a standard mortar with a binder/sand ratio of 0.38, in the substantial absence of Portland cement, and
mixing of said toxic waste with said geopolymeric compound is carried out in the absence of water, followed by adding water so as to provide a water/binder ratio lower than 0.27, thereby obtaining hardening and capture of said toxic waste within a resultant geopolymeric matrix in the substantial absence of Portland cement.

### Claim 3

In a method of consolidating toxic wastes for long-term disposal thereof, comprising reacting said wastes with a binder, the improvement wherein
said binder is a geopolymeric compound in powder form comprising the following reactive constituents:
(a) an alumino-silicate oxide (Si.sub.2 O.sub.5,Al.sub.2 O.sub.2) in which the Al cation is in (IV-V) coordination as determined by MAS-NMR analytical spectroscopy for .sup.27 Al,
(b) a disilicate of sodium and/or potassium (Na.sub.2,K.sub.2)(H.sub.3 SiO.sub.4).sub.2 ;
(c) a silicate of calcium
the molar ratios between the three reactive constituents being equal to or between ##EQU4## where Ca.sup.++ designates the calcium ion belonging to a weakly basic silicate of calcium whose atomic ratio Ca/Si is lower than 1,
said geopolymeric compound providing a compressive strength greater than 15 MPa after only four hours at 20.degree. C. when tested in a standard mortar with a binder/sand ratio of 0.38, in the substantial absence of Portland cement, and
mixing of said toxic waste with said geopolymeric compound is carried out in the absence of water, followed by adding water so as to provide a water/binder ratio lower than 0.27, thereby obtaining hardening and capture of said toxic waste within a resultant geopolymeric matrix in the substantial absence of Portland cement.

### Claim 4 (depends on 3)

A method of consolidating toxic waste according to claim 3 wherein said geopolymeric binder corresponds to the formation of a geopolymer of the type (Ca,K)-poly(sialate-siloxo) of formula varying between (0.6K+0.2Ca)(--Si--O--Al--O--Si--O--), H.sub.2 O and (0.4K+0.3Ca) (--Si--O--Al--O--Si--O--), H.sub.2 O.

### Claim 5 (depends on 3)

A method of consolidated toxic waste according to claim 3 wherein said silicate of calcium is selected from the group consisting of gehlinite, akermanite, wollastonite and mixtures thereof.