Process for converting sodium nitrate-containing, caustic liquid radioactive wastes to solid insoluble products

Patent · Sat Jan 01 00:00:00 EST 1977

OSTI ID:862848

Barney, Gary S ^[1]; Brownell, Lloyd E ^[1]

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1. Richland, WA

A method for converting sodium nitrate-containing, caustic, radioactive wastes to a solid, relatively insoluble, thermally stable form is provided and comprises the steps of reacting powdered aluminum silicate clay, e.g., kaolin, bentonite, dickite, halloysite, pyrophyllite, etc., with the sodium nitrate-containing radioactive wastes which have a caustic concentration of about 3 to 7 M at a temperature of 30.degree. C to 100.degree. C to thereby entrap the dissolved radioactive salts in the aluminosilicate matrix. In one embodiment the sodium nitrate-containing, caustic, radioactive liquid waste, such as neutralized Purex-type waste, or salts or oxide produced by evaporation or calcination of these liquid wastes (e.g., anhydrous salt cake) is converted at a temperature within the range of 30.degree. C to 100.degree. C to the solid mineral form-cancrinite having an approximate chemical formula 2(NaAlSiO.sub.4) .sup.. xSalt.sup.. y H.sub.2 O with x = 0.52 and y = 0.68 when the entrapped salt is NaNO.sub.3. In another embodiment the sodium nitrate-containing, caustic, radioactive liquid is reacted with the powdered aluminum silicate clay at a temperature within the range of 30.degree. C to 100.degree. C, the resulting reaction product is air dried eitheras loose powder or molded shapes (e.g., bricks) and then fired at a temperature of at least 600.degree. C to form the solid mineral form-nepheline which has the approximate chemical formula of NaAlSiO.sub.4. The leach rate of the entrapped radioactive salts with distilled water is reduced essentially to that of the aluminosilicate lattice which is very low, e.g., in the range of 10.sup.-.sup.2 to 10.sup.-.sup.4 g/cm.sup.2 -- day for cancrinite and 10.sup.-.sup.3 to 10.sup.-.sup.5 g/cm.sup.2 -- day for nepheline.

• Research Organization: Atlantic Richfield Hanford Co., Richland, WA (United States)
• DOE Contract Number: AT(45-1)-2130
• Assignee: United States of America as represented by United States Energy (Washington, DC)
• Patent Number(s): US 4028265
• OSTI ID: 862848
• Country of Publication: United States
• Language: English

Related Subjects

process
converting
sodium
nitrate-containing
caustic
liquid
radioactive
wastes
solid
insoluble
products
method
relatively
thermally
stable
form
provided
comprises
steps
reacting
powdered
aluminum
silicate
clay
kaolin
bentonite
dickite
halloysite
pyrophyllite
etc
concentration
temperature
30
degree
100
entrap
dissolved
salts
aluminosilicate
matrix
embodiment
waste
neutralized
purex-type
oxide
produced
evaporation
calcination
anhydrous
salt
cake
converted
range
mineral
form-cancrinite
approximate
chemical
formula
naalsio
xsalt
52
68
entrapped
nano
reacted
resulting
reaction
product
air
dried
eitheras
loose
powder
molded
shapes
bricks
fired
600
form-nepheline
leach
rate
distilled
water
reduced
essentially
lattice
10
cm
cancrinite
nepheline
radioactive liquid
stable form
liquid wastes
liquid radioactive
sodium nitrate-containing
reaction product
radioactive waste
liquid waste
thermally stable
radioactive wastes
chemical formula
sodium nitrate
containing radioactive
resulting reaction
salt cake
solid mineral
powdered aluminum
air dried
silicate clay
distilled water
silicate matrix
active liquid
oxide produced
radioactive salt
soluble products
loose powder
converting sodium
/588/976/