Claims
- 1. A method for in-situ immobilization of lead contaminated solid materials comprising:
- determining the amount of lead in the lead contaminated solid material that needs to be immobilized;
- mixing the lead contaminated solid material with an amount of solid insoluble calcium phosphate material sufficient to react with the lead in the lead contaminated solid material;
- allowing a sufficient time period for a chemical reaction to take place wherein the lead in the lead contaminated solid material becomes immobilized and biologically unavailable; and
- leaving the mixture of any remaining lead contaminated solid material, any remaining solid insoluble calcium phosphate material, and the immobilized lead in place.
- 2. The method of claim 1 wherein the lead contaminated solid material is soil, sand, sediment, solid waste, hazardous waste, or sludge.
- 3. The method of claim 2 wherein the lead contaminated solid material is soil.
- 4. The method of claim 2 wherein the lead contaminated material is sand.
- 5. The method of claim 4 wherein the sand is foundry sand.
- 6. The method of claim 4 wherein the sand is blow-down sand from sand-blasting of lead-based paint coatings.
- 7. The method of claim 2 wherein the lead contaminated solid material is sediment.
- 8. The method of claim 2 wherein the lead contaminated solid material is solid waste.
- 9. The method of claim 2 wherein the lead contaminated solid material is hazardous waste.
- 10. The method of claim 2 wherein the lead contaminated solid material is sludge.
- 11. The method of claim 1 wherein the amount of available phosphate in the solid insoluble calcium phosphate material is within the range of one to two times the stoichiometric amount necessary to immobilize the lead.
- 12. The method of claim 1 wherein the solid insoluble calcium phosphate material is naturally occurring apatite.
- 13. The method of claim 1 wherein the solid insoluble calcium phosphate material is synthetic hydroxyapatite.
- 14. The method of claim 1 wherein the solid insoluble calcium phosphate material is dibasic calcium phosphate.
- 15. The method of claim 1 wherein the solid insoluble calcium phosphate material is phosphate rock.
- 16. The method of claim 1 wherein the time period for the reaction of the lead contaminated solid material and the solid insoluble calcium phosphate material is 24-48 hours.
- 17. The method of claim 1 wherein the substantial portion of reacted lead is such that available lead is reduced to below 15 .mu.g/L.
Government Interests
This invention was made with Government support under Contract No. CR-816843-01-0 awarded by the United States Environmental Protection Agency. The Government has certain rights in the invention.
US Referenced Citations (3)
Number |
Name |
Date |
Kind |
4737356 |
O'Hara et al. |
Apr 1988 |
|
5193936 |
Pal et al. |
Mar 1993 |
|
5284636 |
Goff et al. |
Feb 1994 |
|