Method for transporting a cementitious mixture to an underground space

• US 5,322,389 A
• Filed: 03/04/1993
• Issued: 06/21/1994
• Est. Priority Date: 03/04/1993
• Status: Expired due to Term

• Current Assignee: Conversion Systems, Inc., Envirosource Contract Services, Inc.
• Original Assignee: Conversion Systems, Inc.
• Inventors: Smith, Charles L.
• Primary Examiner(s): CORBIN, DAVID
• Application Number:
  US08/026,446
• Time in Patent Office: 474 Days
• Field of Search: 588/252, 588/256, 588/257, 405/128, 405/263, 405/266, 405/267
• US Class Current: 405/129.3
• CPC Class Codes: B09B 1/008 Subterranean disposal, e.g. in boreholes or subsurface fractures
• CPC Class Codes: C04B 18/062 Purification products of smoke, fume or exhaust-gases
• CPC Class Codes: C04B 18/08 Flue dust , i.e. fly ash
• CPC Class Codes: C04B 2111/00724 in mining operations, e.g. for backfilling; in making tunnels or galleries
• CPC Class Codes: C04B 2111/00784 for disposal only
• CPC Class Codes: C04B 28/18 containing mixtures of the silica-lime type
• CPC Class Codes: C04B 40/005 High shear mixing; Obtaining macro-defect free materials
• CPC Class Codes: E02D 15/02 Handling of bulk concrete specially for foundation or hydraulic engineering purposes lining canals E02B5/02; banks of the bodies of water E02B3/121
• CPC Class Codes: Y02W 30/91 Use of waste materials as fillers for mortars or concrete

Abstract

A method for transporting a cementitious mixture to an underground space includes subjecting the mixture to high-shear mixing to render it temporarily flowable and, while the mixture remains in its flowable state, transporting the mixture to the underground space. After a period of time following the high-shear mixing, the mixture reverts to its initial viscosity and subsequently reacts to form a cementitiously hardened product. The mixture used in the present invention includes flue gas desulfurization sludge, lime, fly ash and water.

Claims

1. A method for transporting a flow resistant mixture of flue-gas desulfurization sludge, fly ash, lime and water into an underground space by:

subjecting said mixture to high-shear mixing to temporarily render said mixture flowable;

transporting said mixture, while still in its flowable state, into the underground space; and

after said transporting step, permitting said mixture to react to form a cementitiously hardened product.

2. A method in accordance with claim 1 wherein said underground space is a room-and-pillar mine and the transporting step involves pouring said mixture, while still in its flowable state, down a bore hole and allowing horizontal spreading of said mixture in said room-and-pillar mine.

3. A method in accordance with claim 1 wherein said flue-gas desulfurization sludge predominantly includes calcium sulfate.

4. A method in accordance with claim 1 wherein said flue-gas desulfurization sludge predominantly includes calcium sulfite.

5. A method in accordance with claim 1 wherein the lime is intrinsic to at least one of the fly ash and the flue-gas desulfurization sludge.

6. A method in accordance with claim 1 wherein the lime is added in the form of calcium quicklime.

7. A method in accordance with claim 1 wherein said mixture includes:

a 0.5;

1 to 3;

1 ratio of fly ash to flue-gas desulfurization sludge on a dry weight basis;

2 to 7 weight percent lime on a dry weight basis; and

at least 45 percent solids.

9. A method in accordance with claim 1 wherein said mixture has an angle of repose, immediately after subjected to high-shear mixing, of less than 10°

.

10. A method in accordance with claim 9 wherein said mixture has an angle of repose, immediately after subjected to high-shear mixing, of about 2°

.

11. A method in accordance with claim 1 wherein said mixture has a viscosity, immediately after subjected to high-shear mixing, of below approximately 40,000 centipoise.

8. A method in accordance with claim 8 wherein said mixture has a viscosity, immediately after subjected to high-shear mixing, of about 25% to 40% of its viscosity immediately after subjected to low-shear mixing.