Understanding sulphuric acid leaching of uranium from ore by means of 234U/238U activity ratio as an indicator
| Autor: | Mukhambetkali Burkitbayev, Bolat Uralbekov, Bagdat Satybaldiyev, Hanna Tuovinen, Juhani Suksi, Jukka Lehto |
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| Rok vydání: | 2015 |
| Předmět: |
Isotopes of uranium
Chemistry Radiochemistry 0211 other engineering and technologies Metals and Alloys chemistry.chemical_element 02 engineering and technology 010501 environmental sciences Uranium Natural uranium 01 natural sciences Industrial and Manufacturing Engineering Uranium ore Uraninite Third phase Materials Chemistry Leaching (metallurgy) Pregnant leach solution 021102 mining & metallurgy 0105 earth and related environmental sciences Nuclear chemistry |
| Zdroj: | Hydrometallurgy. 155:125-131 |
| ISSN: | 0304-386X |
| Popis: | Column leaching test was carried out for uranium ore samples obtained from a uranium in-situ leaching (ISL) mining site using 2.45 bed volumes (BVs) of 0.255 M sulphuric acid to study the evolution of uranium concentration and its isotopic 234 U/ 238 U activity ratio in the pregnant leach solution. The activity ratio of the two uranium isotopes in the pregnant leach solution was measured by alpha-spectrometry following radiochemical separation. Three phases of uranium leaching were identified based on the observed uranium concentration and the 234 U/ 238 U activity ratio. The first phase, up to 0.8 BVs, was characterised by low uranium extraction at approximately 3% and a 234 U/ 238 U activity ratio in the range of 1.21–1.25, which can be attributed to hexavalent uranium leaching from mineral grain surfaces. The second phase, up to 1.8 BVs, with somewhat over 80% uranium extraction is related to the oxidation and dissolution of tetravalent uranium from uranium-bearing minerals, mostly uraninite, with a 234 U/ 238 U activity ratio of 0.92–1.00. Uranium leaching was very slow in the third phase (between 1.8 and 2.45 BVs), with only 0.5% leached and the 234 U/ 238 U activity ratio raised to 1.05–1.16. The total recovery of uranium at 2.45 BVs was 85%. |
| Databáze: | OpenAIRE |
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