Methods of vitrifying waste with low melting high lithia glass compositions

• US 6,258,994 B1
• Filed: 09/28/2000
• Issued: 07/10/2001
• Est. Priority Date: 05/02/1998
• Status: Expired due to Fees

• Current Assignee: Savannah River Nuclear Solutions LLS
• Original Assignee: Westinghouse Savannah River Company
• Inventors: Jantzen, Carol M., Marra, James C., Cicero-Herman, Connie A., Pickett, John B.
• Primary Examiner(s): VINCENT, SEAN E
• Application Number:
  US09/675,800
• Time in Patent Office: 285 Days
• Field of Search: 588/11, 588/12, 588/252
• US Class Current: 588/12
• CPC Class Codes: C03C 1/002 Use of waste materials, e.g. slags
• CPC Class Codes: C03C 3/064 containing boron
• CPC Class Codes: C03C 3/087 containing calcium oxide, e.g. common sheet or container glass
• CPC Class Codes: C03C 3/091 containing aluminium
• CPC Class Codes: C03C 3/105 containing aluminium
• CPC Class Codes: Y10S 588/901 Compositions

Abstract

The invention relates to methods of vitrifying waste and for lowering the melting point of glass forming systems by including lithia formers in the glass forming composition in significant amounts, typically from about 0.16 wt % to about 11 wt %, based on the total glass forming oxides. The lithia is typically included as a replacement for alkali oxide glass formers that would normally be present in a particular glass forming system. Replacement can occur on a mole percent or weight percent basis, and typically results in a composition wherein lithia forms about 10 wt % to about 100 wt % of the alkali oxide glass formers present in the composition. The present invention also relates to the high lithia glass compositions formed by these methods. The invention is useful for stabilization of numerous types of waste materials, including aqueous waste streams, sludge solids, mixtures of aqueous supernate and sludge solids, combinations of spent filter aids from waste water treatment and waste sludges, supernate alone, incinerator ash, incinerator offgas blowdown, or combinations thereof, geological mine tailings and sludges, asbestos, inorganic filter media, cement waste forms in need of remediation, spent or partially spent ion exchange resins or zeolites, contaminated soils, lead paint, etc. The decrease in melting point achieved by the present invention desirably prevents volatilization of hazardous or radioactive species during vitrification.

Claims

1. A method of vitrifying radioactive, hazardous, or mixed waste comprising:

(1) mixing said waste with glass formers such that the resulting mixture comprises SiO₂ and alkali oxide glass formers, wherein said alkali oxide glass formers comprise lithia formers and other alkali oxide glass formers in amounts such that the lithia formers, calculated as Li₂O, are from 10.0 wt % to about 100 wt % of the total alkali oxide glass formers, calculated as M₂O, where M is an alkali metal;

(2) heating the mixture to a temperature below the melting point of a corresponding mixture without said lithia formers; and

(3) melting the resulting mixture at said temperature and cooling the melted mixture to form a glass composition.

2. The method according to claim 1, wherein said lithia formers are from about 11.0 wt % to about 76 wt % of the total alkali oxide glass formers.

3. The method according to claim 1, wherein

said mixture further comprise B₂O₃ formers in an amount sufficient to provide 5 wt % B₂O₃ or more in the glass composition;

said other alkali oxide glass formers comprise Na₂O;

said lithia formers are between about 30 wt % and about 50 wt % of said alkali oxide glass formers; and

said melting is at a temperature between about 1150°

C. and about 1200°

C.

4. The method according to claim 3, wherein said lithia formers are between about 35 wt % and about 50 wt % of said alkali oxide glass formers.

5. The method according to claim 4, wherein said lithia formers are between about 40 wt % and about 48 wt % of said alkali oxide glass formers.

6. The method according to claim 3, wherein said waste comprises a refractory mixture of waste water sludge and spent filter aids containing Al₂O₃ and SiO₂, and wherein said glass composition has a waste loading of about 90 wt %.

7. The method according to claim 1, wherein:

said mixture further comprises CaO formers in an amount sufficient to provide between about 0.25 wt % and about 0.5 wt % CaO in the glass composition;

said mixture either does not comprise B₂O₃ formers, or comprises B₂O₃ formers in amounts that provide less than 5 wt % B₂O₃ in the final glass composition;

said other alkali glass formers comprise Na₂O;

said lithia formers are between about 25 wt % and about 35 wt % of said alkali oxide glass formers; and

said melting is at a temperature between about 1150°

C. and about 1250°

C.

8. The method according to claim 7, wherein said lithia formers are about 30 wt % of said alkali oxide glass formers.

9. The method according to claim 7, wherein said waste comprises a refractory mixture of waste water sludge and spent filter aids containing Al₂O₃ and SiO₂, and wherein said glass composition has a waste loading of about 90 wt %.

10. The method according to claim 7, wherein said melting is at a temperature of about 1200°

C.

11. The method according to claim 1, wherein:

said mixture further comprises CaO formers in an amount sufficient to provide between about 12 wt % and about 30 wt % CaO in the glass composition;

said mixture either does not comprise B₂O₃ formers, or comprises B₂O₃ formers in amounts that provide less than 5 wt % B₂O₃ in the final glass composition;

said other alkali glass formers comprise Na₂O;

said lithia formers are between about 40 wt % and about 80 wt % of said alkali oxide glass formers; and

said melting is at a temperature between about 1175°

C. and about 1200°

C.

12. The method according to claim 11, wherein said lithia formers are between about 42 wt % and about 75 wt % of said alkali oxide glass formers.

13. The method according to claim 12, wherein said lithia formers are between about 42 wt % and about 47 wt % of said alkali oxide glass formers.

14. The method according to claim 11, wherein said waste comprises CaCO₃ containing sludge resulting from treatment of nitrate containing wastes by biodenitrification, followed by neutralization with lime.

15. The method according to claim 1, wherein:

said mixture further comprises CaO formers in an amount sufficient to provide between about 15 wt % and about 22 wt % CaO in the glass composition;

said mixture either does not comprise B₂O₃ formers, or comprises B₂O₃ formers in amounts that provide less than 5 wt % B₂O₃ in the final glass composition;

said other alkali glass formers comprise Na₂O;

said lithia formers are between about 37 wt % and about 46 wt % of said alkali oxide glass formers; and

said melting is at a temperature between about 1100°

C. and about 1200°

C.

16. The method according to claim 15, wherein said temperature is about 1150°

C.

17. The method according to claim 15, wherein said waste comprises Ca(OH)₂ and SiO₂, Ag, Ni, depleted uranium, or Tc⁹⁹.

18. The method according to claim 15, wherein said mixture further comprises iron compounds sufficient to provide about 9.0 wt % to about 13 wt % Fe₂O₃, based on the final glass composition.

19. The method according to claim 1, wherein:

said mixture further comprises CaO formers in an amount sufficient to provide between about 5 wt % and about 15 wt % CaO in the glass composition;

said mixture either does not comprise B₂O₃ formers, or comprises B₂O₃ formers in amounts that provide less than 5 wt % B₂O₃ in the final glass composition;

said other alkali glass formers comprise Na₂O;

said lithia formers are between about 11 wt % and about 50 wt % of said alkali oxide glass formers; and

said melting is at a temperature between about 1125°

C. and about 1275°

C.

20. The method according to claim 19, wherein the CaO content in the glass composition is from about 10 wt % to about 13 wt %.

21. The method according to claim 19, wherein said lithia formers are between about 28 wt % and about 50 wt % of said alkali oxide glass formers.

22. The method according to claim 19, wherein said melting temperature is about 1150°

C.

23. The method according to claim 19, wherein said waste comprises concentrated acidic or caustic wastes or oily mopwater waste containing beryllium, thorium, uranium, emulsified oils, soaps, cleansers, or HF scrubber solutions.

24. The method according to claim 19, wherein said mixture further comprises iron compounds sufficient to provide about 8 wt % to about 10 wt % Fe₂O₃, based on the final glass composition.

25. The method according to claim 19, wherein said mixture further comprises phosphorus compounds sufficient to provide about 3 wt % to about 5 wt % P₂O₅, based on the final glass composition.

26. The method according to claim 1, wherein:

said mixture further comprises BaO formers in an amount sufficient to provide between about 4 wt % and about 7 wt % BaO in the glass composition;

said mixture either does not comprise B₂O₃ formers, or comprises B₂O₃ formers in amounts that provide less than 5 wt % B₂O₃ in the final glass composition;

said other alkali glass formers comprise Na₂O;

said lithia formers are between about 40 wt % and about 45 wt % of said alkali oxide glass formers; and

said melting is at a temperature between about 1000°

C. and about 1200°

C.

27. The method according to claim 26, wherein said melting temperature is about 1050°

C.

28. The method according to claim 26, wherein said mixture further comprises lead compounds sufficient to provide about 8 wt % to about 12 wt % PbO, based on the final glass composition.

29. The method according to claim 26, wherein said mixture further comprises iron compounds sufficient to provide about 3 wt % to about 6 wt % Fe₂O₃, based on the final glass composition.

30. The method according to claim 26, wherein said waste comprises geologic mill tailings residues comprising radium, uranium, uranium daughter products, or heavy metals.

31. The method according to claim 1, wherein:

said mixture further comprises CaO formers in an amount sufficient to provide between about 8 wt % and about 10 wt % CaO in the glass composition;

said mixture either does not comprise B₂O₃ formers, or comprises B₂O₃ formers in amounts that provide less than 5 wt % B₂O₃ in the final glass composition;

said other alkali glass formers comprise Na₂O;

said lithia formers are between about 40 wt % and about 60 wt % of said alkali oxide glass formers; and

said melting is at a temperature between about 1000°

C. and about 1200°

C.

32. The method according to claim 31, wherein said lithia formers are 50 wt % of said alkali oxide glass formers.

33. The method according to claim 31, wherein said melting temperature is about 1150°

C.

34. The method according to claim 31, wherein said CaO formers are present in an amount sufficient to provide about 9 wt % CaO in the glass composition.

35. The method according to claim 31, wherein said waste comprises contaminated soils or clays.

36. The method according to claim 1, wherein:

said mixture further comprises MgO formers in an amount sufficient to provide between about 5 wt % and about 15 wt % MgO in the glass composition;

said mixture either does not comprise B₂O₃ formers, or comprises B₂O₃ formers in amounts that provide less than 5 wt % B₂O₃ in the final glass composition;

said other alkali glass formers comprise Na₂O;

said lithia formers are between about 18 wt % and about 45 wt % of said alkali oxide glass formers; and

said melting is at a temperature between about 1000°

C. and about 1200°

C.

37. The method according to claim 36, wherein said mixture further comprises iron compounds sufficient to provide about 8 wt % to about 25 wt % Fe₂O₃, based on the final glass composition.

38. The method according to claim 36, wherein said melting temperature is about 1150°

C.

39. The method according to claim 36, wherein said waste is asbestos containing material.