Method for removing depleted uranium from contaminated soils

A method for removing uranium from particulate matter, comprising the steps of:

• a) forming a first slurry of the particulate matter in an aqueous medium containing water, acid, hydrogen peroxide and iron, thereby to leach uranium from the particulate matter,
• b) removing coarse particles in the first slurry,
• c) after said removing, treating the first slurry to produce a first uranium-containing supernatant and fine particles,
• d) forming a second slurry composed of the fine particles in an aqueous medium containing water, acid, hydrogen peroxide and iron, thereby to leach uranium from the fine particles,
• e) removing the fine particles in the second slurry to form a second supernatant,
• f) extracting uranium from the first and second supernatants by (i) raising the pH of the first and second supernatants to a level between about 4 and 4.5 by addition of anhydrous ammonia or MgO, to precipitate iron, but not uranium, (ii) removing the precipitated iron from the supernatants, (iii) raising the pH of the supernatants to a level between about 6.5 and 7 by addition of anhydrous ammonia or MgO, to effect precipitation of uranium, (iv) removing precipitated uranium from the supernatants, and,
• g) after said extracting, treating said first and second supernatants for reuse as reclaimed water in at least one of steps (a) and (d).

A method for removing uranium from particulate matter, comprising the steps of:

• a) forming a first slurry of the particulate matter in an aqueous medium containing water, acid, hydrogen peroxide and iron, thereby to leach uranium from the particulate matter,
• b) removing coarse particles in the first slurry,
• c) after said removing, treating the first slurry to produce a first uranium-containing supernatant and fine particles,
• d) forming a second slurry composed of the fine particles in an aqueous medium containing water, acid, hydrogen peroxide and iron, thereby to leach uranium from the fine particles,
• e) removing the fine particles in the second slurry to form a second supernatant,
• f) extracting uranium from the first and second supernatants by (i) passing the supernatants over an ion exchange material, (ii) washing said ion-exchange material with brine to form a uranium concentrate, (iii) raising the pH of the uranium concentrate to a level effective to precipitate uranium by addition of alkali selected from the group consisting of lime, ammonia, and magnesium oxide, (iv) removing precipitated uranium in the concentrate to form a supernatant, and,
• g) after said extracting, treating said first and second supernatants for reuse as reclaimed water in at least one of steps (a) and (d).

A method for removing uranium from particulate matter, comprising the steps of:

• a) forming a first slurry of the particulate matter in an aqueous medium containing water, sulfuric acid, hydrogen peroxide and iron, maintained at a pH of 1.5 or below, thereby to leach uranium from the particulate matter,
• b) removing coarse particles in the first slurry,
• c) after said removing, treating the first slurry to produce a first uranium-containing supernatant and fine particles,
• d) forming a second slurry composed of the fine particles in an aqueous medium containing water, sulfuric acid, hydrogen peroxide and iron, maintained at a pH of 1.0 or below, thereby to leach uranium from the fine particles,
• e) removing the fine particles in the second slurry to form a second supernatant,
• f) extracting uranium from the first and second supernatants, and,
• g) after said extracting, treating said first and second supernatants for reuse as reclaimed water in at least one of steps (a) and (d).