# US 12,180,118 B2 · Carbonation of reactive magnesia cement (RMC)-based systems

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 12,180,118 B2
- Document ID: US12180118B2
- Status: Granted
- Kind: B2
- Application number: 17/455,203
- Filed: 2021-11-16
- Published: 2022-05-19
- Granted: 2024-12-31
- Earliest claimed: 2020-11-16
- Assignees: Nanyang Technological University
- Applicants: Nanyang Technological University
- Inventors: En-Hua Yang; Xi Xiao; Cise Unluer; Tien Dung Nguyen
- Web page: https://patentgrep.com/patent/US12180118B2

## CPC

- C04B 28/105: {Magnesium oxide or magnesium carbonate cements}
- C04B 28/32: Magnesium oxychloride cements, e.g. Sorel cement
- C01F 5/02: Magnesia
- C04B 20/12: Multiple coating or impregnating
- C04B 40/0091: {Processes of mixing characterised by carbon dioxide treatment}
- C04B 40/0231: {Carbon dioxide hardening}
- C01P 2002/72: by d-values or two theta-values, e.g. as X-ray diagram
- C01P 2002/88: by thermal analysis data, e.g. TGA, DTA, DSC
- C01P 2004/03: obtained by SEM
- C04B 2111/00019: {Carbon dioxide sequestration}
- C04B 2111/00663: {as filling material for cavities or the like}
- C04B 2111/00724: {in mining operations, e.g. for backfilling; in making tunnels or galleries}
- C04B 2111/00732: {for soil stabilisation}
- Y02P 40/18: Carbon capture and storage [CCS]
- 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
- C01F: COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS (metal hydrides {monoborane, diborane or addition complexes thereof} C01B6/00; salts of oxyacids of halogens C01B11/00; peroxides, salts of peroxyacids C01B15/00; sulfides or polysulfides of magnesium, calcium, strontium, or barium C01B17/42; thiosulfates, dithionites, polythionates C01B17/64; compounds containing selenium or tellurium C01B19/00; binary compounds of nitrogen with metals C01B21/06; azides C01B21/08; {compounds other than ammonia or cyanogen containing nitrogen and non-metals and optionally metals C01B21/082; amides or imides of silicon C01B21/087}; metal {imides or} amides C01B21/092, {C01B21/0923}; nitrites C01B21/50; {compounds of noble gases C01B23/0005}; phosphides C01B25/08; salts of oxyacids of phosphorus C01B25/16; carbides C01B32/90; compounds containing silicon C01B33/00; compounds containing boron C01B35/00; compounds having molecular sieve properties but not having base-exchange properties C01B37/00; compounds having molecular sieve and base-exchange properties, e.g. crystalline zeolites, C01B39/00; cyanides C01C3/08; salts of cyanic acid C01C3/14; salts of cyanamide C01C3/16; thiocyanates C01C3/20; {double sulfates of magnesium with sodium or potassium C01D5/12; with other alkali metals C01D15/00, C01D17/00})
- C01P: INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS

## Abstract

Herein discloses a method of carbonating reactive magnesia cement, which includes: (i) providing an aqueous suspension including a carbon dioxide-producing bacteria; (ii) mixing the aqueous suspension with a precursor which the carbon dioxide-producing bacteria generates carbon dioxide from for a duration to form an aqueous mixture sufficient for substantially carbonating the reactive magnesia cement; (iii) mixing the aqueous mixture with the reactive magnesia cement to form a blend; wherein a nutrient is provided in the aqueous suspension of step (i) or in the reactive magnesia cement of step (iii) to sustain the carbon dioxide-producing bacteria in the reactive magnesia cement; and (iv) curing the blend to carbonate the reactive magnesia cement. A reactive magnesia cement composite formed by the method is also disclosed.

## Claims

### Claim 1

A method of carbonating reactive magnesia cement, the method comprising:
(i) providing an aqueous suspension comprising a carbon dioxide-producing bacteria;
(ii) mixing the aqueous suspension with a precursor which the carbon dioxide-producing bacteria generates carbon dioxide from for a duration to form an aqueous mixture sufficient for substantially carbonating the reactive magnesia cement;
(iii) mixing the aqueous mixture with the reactive magnesia cement to form a blend;
wherein a nutrient is provided in the aqueous suspension of step (i) or in the reactive magnesia cement of step (iii) to sustain the carbon dioxide-producing bacteria in the reactive magnesia cement; and
(iv) curing the blend to carbonate the reactive magnesia cement.

### Claim 2 (depends on 1)

The method of claim 1, wherein providing the aqueous suspension comprises dissolving the nutrient in water prior to dispersing the carbon dioxide-producing bacteria in the water.

### Claim 3 (depends on 1)

The method of claim 1, wherein the carbon dioxide-producing bacteria comprises an alkaliphilic bacteria or ureolytic bacteria.

### Claim 4 (depends on 1)

The method of claim 1, wherein the carbon dioxide-producing bacteria comprises Sporosarcina pasteurii, Bacillus sphaericus, Bacillus subtilis, and/or Bacillus cohnii.

### Claim 5 (depends on 1)

The method of claim 1, wherein the nutrient comprises yeast extract, soy broth, lysogeny broth, meat extract, and/or peptone.

### Claim 6 (depends on 1)

The method of claim 1, wherein mixing the aqueous suspension with the precursor comprises dissolving the precursor in water prior to mixing the aqueous suspension with the precursor.

### Claim 7 (depends on 1)

The method of claim 1, wherein the duration is 30 seconds or less.

### Claim 8 (depends on 1)

The method of claim 1, wherein the precursor comprises urea or magnesium lactate.

### Claim 9 (depends on 1)

The method of claim 1, wherein the aqueous mixture comprises water, and mixing the aqueous mixture with the reactive magnesia cement is carried out with the water of the aqueous mixture and the reactive magnesia cement present in a weight ratio of 0.43 to 0.7.

### Claim 10 (depends on 1)

The method of claim 1, further comprising mixing the reactive magnesia cement with a hydration agent prior to mixing the reactive magnesia cement with the aqueous mixture.

### Claim 11 (depends on 10)

The method of claim 10, wherein the hydration agent comprises hydrochloric acid, magnesium acetate, or magnesium chloride.

### Claim 12 (depends on 1)

The method of claim 1, further comprising mixing the aqueous suspension with seed particles, wherein the seed particles comprise hydromagnesite, carbon nanotubes, nano-sized silicon dioxide, nano-sized titanium dioxide, or carbon nanofibers.

### Claim 13 (depends on 12)

The method of claim 12, wherein mixing the aqueous suspension with the seed particles comprises dispersing the seed particles in water.

### Claim 14 (depends on 1)

The method of claim 1, further comprising mixing coarse aggregates with the blend prior to curing the blend.

### Claim 15 (depends on 14)

The method of claim 14, wherein the coarse aggregates have a size ranging from 4 mm to 10 mm.

### Claim 16 (depends on 1)

The method of claim 1, further comprising curing the blend at:
atmospheric pressure;
a temperature ranging from −10° C. to 50° C.; and
a humidity ranging from 75% to 100%.

### Claim 17 (depends on 1)

A reactive magnesia cement composite formed by the method of claim 1, the reactive magnesia cement composite comprising:
a carbon dioxide-producing bacteria; and
a X-ray diffraction pattern comprising:
one peak having a two theta value between 30° and 35° which corresponds to magnesite;
one peak having a two theta value between 35° and 40° which corresponds to brucite;
one peak having a two theta value between 40° and 45° which corresponds to periclase; and
wherein the intensity of the one peak which corresponds to brucite is lower in the presence of the carbon dioxide-producing bacteria as compared to another reactive magnesia cement composite absent of the carbon dioxide-producing bacteria.

### Claim 18 (depends on 17)

The reactive magnesia cement composite of claim 17, wherein the X-ray diffraction pattern further comprises:
one peak having a two theta value between 5° and 10° which corresponds to dypingite; and/or
one peak having a two theta value between 15° and 20° which corresponds to hydromagnesite.

### Claim 19 (depends on 17)

The reactive magnesia cement composite of claim 17, wherein the X-ray diffraction pattern further comprises one peak having a two theta value between 30° and 35° which corresponds to artinite.

### Claim 20 (depends on 17)

The reactive magnesia cement composite of claim 17, wherein the carbon dioxide-producing bacteria comprises Sporosarcina pasteurii, Bacillus sphaericus, Bacillus subtilis, and/or Bacillus cohnii.