US 4,409,137 A · Solidification of radioactive waste effluents

Abstract

A process and apparatus for solidifying radioactive waste liquid containing dissolved and/or suspended solids is disclosed. The process includes chemically treating for pH adjustement and precipitation of solids, concentrating solids with a thin-film evaporator to provide liquid concentrate containing about 50% solids, and drying the concentrate with heated mixing apparatus. The heated mixing apparatus includes a heated wall and working means for shearing dried concentrate from internal surfaces and subdividing dry concentrate into dry, powdery particles. The working means includes a rotor and helical means for positively advancing the concentrate and resulting dry particles from inlet to outlet of the mixing apparatus. The dry particles may also be encapsulated in a matrix material. Entrained particles in the vapor stream from the evaporator and mixer are removed in an integral particle separator and the vapor is subsequently condensed and may be recycled upstream of the thin-film evaporator. A section of the mixer may be used for mixing dry particles with the matrix material in a continuous drying and mixing sequence. A section of the mixer also may be used for mixing the treating chemical with the waste liquid.

Claims45

Dependent claims

A process for enveloping a radioactive waste liquid containing solids, said process comprising the steps of:

chemically treating said waste liquid by adding at least one chemical reagent to adjust the pH of said liquid to greater than 7.0;
concentrating said solids using a thin-film evaporator having a heated wall and means for distributing said waste liquid as a film on said wall to remove a portion of the moisture from said waste liquid and form a liquid concentrate containing a greater concentration of solids than in said waste liquid;
drying said concentrate in a mixing apparatus having a heated wall and rotor means for contacting said heated wall with said concentrate to remove the remaining liquid from said waste and form a solid waste residue, said rotor means including mixing means for shearing said solid waste residue so as to form dry particles and advancing means for engaging said dry particle to positively advance said dry particles toward an outlet of said mixing apparatus;
and,
enveloping said dry particles of waste material in a second material.

2 more elements

An apparatus for enveloping radioactive waste liquid containing solids comprising:

means for treating said waste with at least one chemical reagent to adjust the pH of said liquid to greater than 7.0;
thin-film evaporator means for concentrating said waste liquid, said thin-film evaporator means having a heated wall and rotor means for distributing said waste liquid as a thin-film on said wall so as to evaporate moisture from said waste and form a liquid concentrate containing a greater concentration of solids than in said waste liquid;
a heated mixing apparatus having a heated wall for drying said concentrate and rotor means for contacting said heated wall with said concentrate to remove the remaining liquid from said waste and form a solid waste residue, said rotor means including a plurality of mixing paddles for shearing said solid waste residue between said paddles and said heated wall and between different paddles so as to form dry particles, and advancing means for engaging said dry particles to positively advance said dry particles toward an outlet of said mixing apparatus;
means for discharging said concentrate from said thin-film evaporator to said mixing apparatus;
means for causing said waste liquid to pass through said thin-film evaporator and said concentrate to be discharged to said mixing apparatus so that the concentrate received by said mixing apparatus contains at least 30 weight percent moisture;
and,
means for enveloping said dry particles of waste solids in a second material.

4 more elements

Dependencies are inferred from the claim text.

Solidification of radioactive waste effluents

Life of this patent

Solidification of radioactive waste effluents

Life of this patent

Abstract

Claims45