Process for vitrifying asbestos containing waste, infectious waste, toxic materials and radioactive waste

• US 5,340,372 A
• Filed: 06/29/1992
• Issued: 08/23/1994
• Est. Priority Date: 08/07/1991
• Status: Expired due to Term

• Current Assignee: Pedro B. De Macedo, Theodore Aaron Litouitz
• Original Assignee: Pedro Buarque De Macedo, Theodore Aaron Litovitz
• Inventors: Macedo, Pedro B., Mohr, Robert K.
• Primary Examiner(s): Jones, W. Gary
• Application Number:
  US07/906,306
• Time in Patent Office: 785 Days
• Field of Search: 406/141, 406/145, 406/151, 65/21.1, 65/21.2, 65/21.3, 65/21.5, 65/19, 65/103, 65/122, 65/127, 65/133-136, 65/142, 65/27, 65/239, 65/DIG. 4, 264/122, 264/5, 264/8
• US Class Current: 65/21.1
• CPC Class Codes: B09B 3/0066 Disposal of asbestos
• CPC Class Codes: B09B 3/0075 Disposal of medical waste casings for used articles, e.g. sharps A61B50/362; sterilisation of refuse A61L11/00; disposal of used needles or syringes A61M5/3205; disintegrating medical waste B02C19/0075
• CPC Class Codes: B09B 3/29 involving a melting or softening step
• CPC Class Codes: C03B 19/1005 Forming solid beads chemical aspects C03C12/00
• CPC Class Codes: C03B 19/109 Glass-melting furnaces specially adapted for making beads
• CPC Class Codes: C03B 5/005 of glass-forming waste materials disposal or transformation of solid waste in general B09B; treatment of radioactive waste G21F9/00
• CPC Class Codes: C03B 5/0275 Shaft furnaces C03B5/0277 takes precedence
• CPC Class Codes: C03B 5/193 using gas, e.g. bubblers
• CPC Class Codes: C04B 18/026 Melted materials C04B14/22 takes precedence
• CPC Class Codes: C04B 18/04 Waste materials; Refuse
• CPC Class Codes: C04B 18/0475 Waste asbestos
• CPC Class Codes: G21F 9/305 Glass or glass like matrix C03B5/005 takes precedence; compositional aspects C03C
• CPC Class Codes: Y02P 40/50 Glass production, e.g. reusing waste heat during processing or shaping
• CPC Class Codes: Y02W 30/91 Use of waste materials as fillers for mortars or concrete
• CPC Class Codes: Y10S 65/04 Electric heat

Abstract

Material, such as, for example, sealed double bags of asbestos containing waste or ash from infectious waste or toxic material or radioactive waste, is transferred into a glass melt of a furnace. Gas bubbles released into the melt form a gas curtain which causes enhanced mixing of the material to accelerate the dissolution of the components of the added material. The presence of the gas bubbles reduces the cross-section of the molten glass through which current passes, which in turn increases the electrical resistance of the glass melt and therefore increases power generation of the melt or power density at constant current. A highly oxidizing hot region is produced under the location where the material is introduced into the furnace. Drawn off glass is shaped and quenched into at least two sizes of approximate spheres. The spheres are cooled sufficiently fast to be thermally tempered and have a surface compressive strength level above 5000 psi.

Claims

1. A process for converting waste materials into a silicate, said process comprising:

heating a silicate melt within an electrical glass melting furnace by passing an electric current through the melt between at least two electrodes so as to maintain the melt at a temperature above a decomposition temperature of waste materials;

generating a curtain of gas bubbles across a substantial portion of the current path between the at least two electrodes to increase the power density of the melt in the region of the curtain of gas bubbles;

supplying waste materials to the furnace above the melt so that the waste materials fall onto the melt and the waste materials are melted into silicates;

withdrawing molten silicate from the furnace in a molten glass stream at a temperature of at least 900°

C.;

cutting the molten glass stream into a set of gobs by interrupting the molten glass stream; and

contacting said gobs with a cold surface to form gems having at least one flattened surface.

2. The process of claim 1, wherein the gems are sufficiently annealed to avoid breakage during storage.

3. The process of claim 1, wherein the gems have a mass of at least about 2.0 grams.

4. The process of claim 1, wherein the gems have a mass between about 2.0 and 150 grams.

5. The process of claim 4, wherein the gems have a mass between about 2 and 50 grams.

6. The process of claim 1, wherein the gems have a packing efficiency greater than 70%.

7. The process of claim 1, wherein the waste materials include asbestos containing material.

8. The process of claim 1, wherein the waste materials include infectious waste.

9. The process of claim 1, wherein the waste materials include toxic materials.

10. The process of claim 1, wherein the waste materials include low level radioactive waste.

11. The process of claim 1, wherein the gems have two flattened surfaces.

12. A process for converting waste materials into a silicate, said process comprising:

heating a silicate melt within a glass melting furnace so as to maintain the melt at a temperature above a decomposition temperature of waste materials;

supplying waste materials to the furnace above the melt so that the waste materials fall onto the melt and the waste materials are melted into silicates;

withdrawing molten silicate from the furnace in a molten glass stream at a temperature of at least 900°

C., the molten silicate being withdrawn from the furnace through a melt outlet adjacent the bottom of the furnace, the melt outlet being connected to an airlift conduit in which gas bubbles are introduced to create an effective head pressure to force the melt up the airlift and out of the furnace,

cutting the molten glass stream into a set of gobs by interrupting the molten glass stream; and

contacting said gobs with a cold surface to form gems having at least one flattened surface.

13. The process of claim 12, wherein the gems are sufficiently annealed to avoid breakage during storage.

14. The process of claim 12, wherein the gems have a mass of at least about 2.0 grams.

15. The process of claim 12, wherein the gems have a mass between about 2.0 and 150 grams.

16. The process of claim 15, wherein the gems have a mass between about 2 and 50 grams.

17. The process of claim 12, wherein the gems have a packing efficiency greater than 70%.

18. The process of claim 12, wherein the waste materials include asbestos containing material.

19. The process of claim 12, wherein the waste materials include infectious waste.

20. The process of claim 12, wherein the waste materials include toxic materials.

21. The process of claim 12, wherein the waste materials include low level radioactive waste.

22. The process of claim 12, wherein the gems have two flattened surfaces.