Other Binders - Stabilization and Solidification of Hazardous, Radioactive, and Mixed Wastes - page 104

TABLE 6.1.2 (CONTINUED)
Selected Treatment Studies for Heavy Metals and Radionuclides Using
Phosphates; Includes Laboratory Studies, Field Trials, and Applications

Metal/
Metalloid
Studied

Media/
Conditions

Phosphate
Treatment

Mechanism/Solid Phases
Formed References

Cr, Cd,
Hg, Ni,
Pb, low-
level
mixed
waste

Aqueous solution,
solids

Phosphate
ceramic waste
form
(magnesium
potassium
phosphate)

Macroencapsulation 45

Cu, Zn Aqueous solution;

pH 5

Bone char Ion exchange and physical

adsorption

31

Cu, Pb, Zn Soil Phosphoric

acid,
dicalcium
phosphate,
phosphate
rock

Pyromorphite-like mineral,
no phosphate mineral of
Zn and Cu detected

28b

Eu, Ce Aqueous solution Synthetic

hydroxyapatite

Substitution of Eu for Ca 46

Ni U Aqueous solution Synthetic

hydroxyapatite

Not determined 47a

Ni Soil Synthetic

hydroxyapatite

U and Ni associated with Al
rich precipitates

48

Np Aqueous solution Synthetic

hydroxyapatite

Not determined 16b

Pb Aqueous solution Meat and bone

meal
combustion
residue

Surface complexation and
precipitation

50

Pb Aqueous solution Synthetic

hydroxyapatite

Initial formation of a solid
solution of Pb (10-x) Ca x
(PO 4 ) 6 (OH) 2 converting to
pure hydroxypyro-
morphite over time

51

Pb Mine tailings Phosphoric acid

and lime

Tertiary metal phosphates,
e.g., (Cu, Ca 2 )(PO 4 ) 2 ,
apatite, e.g., Pb 5 (PO 4 ) 3 Cl

52

Pb Soil Phosphoric acid Pb 5 (PO 4 ) 3 OH, Pb 5 (PO 4 ) 3 Cl 10, 16,

53-61

(continued)