REMOVAL OF RADIONUCLIDES FROM MIXTURES

Abstract

The present invention relates to a method of separating radioactive elements from a mixture, wherein the mixture is treated with at least one alkanesulfonic acid and at least one further acid, selected from the group consisting of hydrochloric acid, nitric acid, amidosulfonic acid and mixtures thereof and also the use of at least one alkanesulfonic acid and at least one further acid for separating radioactive elements from mixtures comprising these.

Claims

1. A method of separating a radioactive element from a mixture, the method comprising: treating the mixture with at least one alkanesulfonic acid and at least one further acid selected from the group consisting of hydrochloric acid, nitric acid, amidosulfonic acid and a mixture thereof.

2. The method according to claim 1, wherein the at least one alkanesulfonic acid and the at least one further acid are aqueous compositions.

3. The method according to claim 1, wherein the mixture is treated firstly with the at least one alkanesulfonic acid and subsequently with the at least one further acid.

4. The method according to claim 1, wherein the mixture is treated firstly with the at least one further acid and subsequently with the at least one alkanesulfonic acid.

5. The method according to claim 1, wherein methanesulfonic acid is used as the at least one alkanesulfonic acid.

6. The method according to claim 1, wherein the mixture is treated with an aqueous composition comprising the at least one alkanesulfonic acid and the at least one further acid.

7. The method according to claim 1, wherein the mixture is treated with an aqueous composition consisting of the at least one alkanesulfonic acid, the at least one further acid, and water.

8. The method according to claim 1, wherein the mixture is an ore or an ore concentrate.

9. The method according to claim 1, wherein the radioactive element is selected from the group consisting of uranium-238, thorium-230, radium-226, lead-210, polonium-210, uranium-235, palladium-231, thorium-227, radium-228, thorium-228 and a mixture thereof.

10. The method according to claim 1, wherein the mixture is an aqueous slurry.

11. The method according to claim 1, wherein the mixture is treated with an aqueous composition comprising from 0.5 to 2 moles of hydrochloric acid and from 1 to 20% by weight of methanesulfonic acid.

12-13. (canceled)

Description

EXAMPLES

[0062] An ore concentrate from the Australian Olympic Dam is used as test substance. This typically has the following composition:

TABLE-US-00001 TABLE 1 Component Amount Cu 37.8% by weight Fe 27.1% by weight S 24.4% by weight Copper sulfides 1.55% by weight Al.sub.2O.sub.3 1.77% by weight SiO.sub.2 5.29% by weight CaO 0.61% by weight K.sub.2O 0.45% by weight MgO 0.14% by weight BaO 0.15% by weight U.sub.3O.sub.8 1390 ppm by weight Ag 64 ppm by weight As 392 ppm by weight Cd 15 ppm by weight Pb 260 ppm by weight Zn 200 ppm by weight

[0063] The metals listed in table 1 are present as uraninite, coffinite, brannerite, uranothorite, thorianite, hematite, pyrite, chalcopyrite, bornite, chalcocite, bastnasite, florencite, monazite, xenotime, zircon, quartz, sericite, chlorite, fluorite, barite, siderite, feldspars, galena, altaite or clausthalite.

TABLE-US-00002 TABLE 2 Analysis of the composition obtained after the individual experiments DNA U-238 Gamma Gamma ppm Th- Ra- Pb- Po- Pa- Th- weight 230 226 210 210 U-235 231 227 Ra-228 Th-228 No. Aqueous composition by Bq/g Bq/g Bq/g Bq/g Bq/g Bq/g Bq/g Bq/g Bq/g Bq/g 1179 14.6 14.8 14.1 17.9 18.6 0.76 0.72 0.75 0.16 0.16 C1 (base case - 80 g/l of H.sub.2SO.sub.4 77 0.95 1.9 14.6 16.0 15.1 <0.08 0.57 0.58 0.17 0.04 H.sub.2SO.sub.4) 2 (BASF-1A) 5% by weight of MSA in H.sub.2SO.sub.4 50 0.61 2.4 15.3 13.6 17.6 <0.06 <0.17 0.45 0.18 0.04 3 (BASF-1B) 10% by weight of MSA in 48 0.59 1.8 15.5 12.9 12.3 0.03 <0.15 0.50 0.17 0.04 H.sub.2SO.sub.4 4 (BASF-2A) 20% by weight of MSA in 46 0.57 2.5 15.4 15.6 16.8 0.03 <0.14 0.56 0.19 0.04 H.sub.2SO.sub.4 C5 (BASF-3A) 100% by weight of MSA (2 h) 202 2.5 3.8 4.1 6.0 16.7 0.13 0.14 0.18 0.06 0.05 C6 (BASF-4A) 100% by weight of MSA (24 h) 53 0.66 1.3 1.3 2.1 13.1 0.030 0.29 0.60 <0.010 0.012 7 (BASF-4B) 10% by weight of MSA in 1M 33 0.41 0.95 0.72 1.6 14.2 0.019 0.17 0.048 <0.011 <0.010 HCl C8 (base case - 1M HCl 79 0.98 2.2 6.4 2.6 10.3 0.045 — 0.11 — — HCl)

[0064] C1 is carried out using a solution of 80 g of H.sub.2SO.sub.4 in 1 l of water at a temperature of 70° C. for 24 hours at a solids content of the ore dispersion of 55% by weight.

[0065] C8 is carried out using a 1 molar hydrochloric acid in water at a temperature of 60° C. for 6 hours at a solids content of the ore dispersion of 20% by weight.

[0066] Experiments 2, 3 and 4 are carried out using a solution of 80 g of H.sub.2SO.sub.4 in 1 l of water and the corresponding amount of methanesulfonic acid (MSA) at a solids content of the ore dispersion of 55% by weight.

[0067] Experiment 7 is carried out in a 1 molar solution of HCl and the corresponding amount of methanesulfonic acid (MSA) at a solids content of the ore dispersion of 20% by weight. Since a large part of the acid was consumed during the experiment, concentrated hydrochloric acid was added after 2 hours.

[0068] Experiments C5 and C6 are carried out in pure methanesulfonic acid (MSA); the c(MSA) is 157 g/I.

[0069] Table 3 shows the amount of radionuclides extracted and of the metals present relative to the respective initial amounts.

TABLE-US-00003 TABLE 3 Extraction [%] Pb- No. U-238 Th-230 Ra-226 210 Po-210 Cu Pb U C1 93.7 83.7 1.6 16.6 21.8 0.1 7.4 93.7 2 96.4 86.1 7.0 34.9 18.9 4.2 17.6 96.4 3 96.4 89.1 1.9 35.7 41.0 6.2 17.6 96.2 4 96.4 84.6 0.7 20.8 17.9 3.9 12.6 96.4 C5 81.3 74.3 71.6 67.3 12.4 0.2 36.2 78.1 C6 96.1 92.4 92.0 89.8 39.0 2.8 >99 96.1 7 97.8 93.6 94.9 91.1 23.6 13.6 >99 97.8