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AU2007356815B2.Pdf (12) STANDARD PATENT (11) Application No. AU 2007356815 B2 (19) AUSTRALIAN PATENT OFFICE (54) Title Single stage purification for uranium refining (51) International Patent Classification(s) C22B 60/02 (2006.01) (21) Application No: 2007356815 (22) Date of Filing: 2007.07.24 (87) WIPO No: W009/013759 (43) Publication Date: 2009.01.29 (44) Accepted Journal Date: 2012.08.30 (71) Applicant(s) SECRETARY, DEPARTMENT OF ATOMIC ENERGY (72) Inventor(s) Shanmugavelu, P.;Dhavamani, D.;Agrawal, Ankur;Bhowmik, A. (74) Agent / Attorney Griffith Hack, GPO Box 1285, Melbourne, VIC, 3001 (56) Related Art US 4271127 A (12) INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT) (19) World Intellectual Property Organization International Bureau lllllllllllllllllllllllllllllllllllll^ (43) International Publication Date PCT (10) International Publication Number 29 January 2009 (29.01.2009) WO 2009/013759 Al (51) International Patent Classification: (74) Agents: MAJUMDAR, Subhatosh et al.; S. Majumdar & C22B 60/02 (2006.01) Co., 5, Harish Mukherjee Road, Kolkata 700 025 (IN). (21) International Application Number: (81) Designated States (unless otherwise indicated, for every PCT/IN2007/000305 kind of national protection available): AE, AG, AL, AM, AT, AU, AZ, BA, BB, BG, BH, BR, BW, BY, BZ, CA, CH, (22) International Filing Date: 24 July 2007 (24.07.2007) CN, CO, CR, CU, CZ, DE, DK, DM, DO, DZ, EC, EE, EG, ES, H, GB, GD, GE, GH, GM, GT, HN, HR, HU, ID, IL, (25) Filing Language: English IN, IS, JP, KE, KG, KM, KN, KP, KR, KZ, LA, LC, LK, LR, LS, LT, LU, LY, MA, MD, ME, MG, MK, MN, MW, (26) Publication Language: English MX, MY, MZ, NA, NG, NI, NO, NZ, OM, PG, PH, PL, PT, RO, RS, RU, SC, SD, SE, SG, SK, SL, SM, SV, SY, (71) Applicant (for all designated States except US): SEC­ TJ, TM, TN, TR, TT, TZ, UA, UG, US, UZ, VC, VN, ZA, RETARY, DEPARTMENT OF ATOMIC ENERGY ZM, ZW. [IN/IN]; Government of India, Anushakti Bhavan, Chha- trapati Shivaji Maharaj Marg, Mumbai 400 001 (IN). (84) Designated States (unless otherwise indicated, for every kind of regional protection available): ARIPO (BW, GH, (72) Inventors; and GM, KE, LS, MW, MZ, NA, SD, SL, SZ, TZ, UG, ZM, (75) Inventors/Applicants (for US only): BHOWMIK, A. ZW), Eurasian (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM), [IN/IN]; Chemical Technology Division, BARC, Trombay, European (AT, BE, BG, CH, CY, CZ, DE, DK, EE, ES, FI, Mumbai 400 085 (IN). SHANMUGAVELU, P. [IN/IN]; FR, GB, GR, HU, IE, IS, IT, LT, LU, LV, MC, MT, NL, PL, Chemical Technology Division, BARC, Trombay, Mum­ PT, RO, SE, SI, SK, TR), OAPI (BF, BJ, CF, CG, CI, CM, bai 400 085 (IN). DHAVAMANI, D. [IN/IN]; Chemical GA, GN, GQ, GW, ML, MR, NE, SN, TD, TG). Technology Division, BARC, Trombay, Mumbai 400 085 (IN). AGRAWAL, Ankur [IN/IN]; Chemical Technology Published: Division, BARC, Trombay, Mumbai 400 085 (IN). — with international search report IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIN Ai (54) Title: SINGLE STAGE PURIFICATION FOR URANIUM REFINING 2009/013759 (57) Abstract: A process for refining yellowcake to produce nuclear grade uranium using a single step precipitation route for the simultaneous removal of heavy metals, boron and other rare earth metals comprising dissolving the yellowcake in nitric acid under mild agitation and adding hydrogen peroxide at pre-defined pH and temperature to selectively precipitate uranium peroxide hydrate. Also described is a process for producing nuclear grade uranium starting from uranium ore utilizing the above process. w o WO 2009/013759 PCT/IN2007/000305 1 SINGLE STAGE PURIFICATION FOR URANIUM REFINING FIELD OF THE INVENTION The present invention relates to a process for the preparation of nuclear grade pure uranium dioxide, natural metallic uranium and uranium hexafluoride from yellow 5 cake containing boron, rare earth and other metallic impurities. More particularly, the present invention relates to a process for the preparation of pure uranium dioxide that meets the nuclear grade specifications of the equivalent boron content being less than 4pg/g on uranium basis as per ASTM C - 753-99. I 10 BACKGROUND AND PRIOR ART Yellowcakes are uranium concentrates, which represent an intermediate step in the processing of uranium ores. Yellowcakes are usually obtained through the milling and chemical processing of uranium ore forming a coarse powder, which is insoluble in water and contains about 60-80% of uranium oxide depending on type of 15 Yellowcakes such as Magnesium Di-uranate, Ammonium Di-uranate or Uranium peroxide. In the process conventionally used within the art, the ore is first crushed to a fine powder by passing the starting raw uranium ore through crushers and grinders to produce the pulped ore. The pulped ore is thereafter processed with concentrated acid or an alkaline solution to leach out the uranium and the eluate is subjected to 20 precipitation of Uranium concentrates that is then filtered and dried to produce yellowcake. This yellowcake usually contains boron, rare earths and other metallic impurities. The yellowcake thus produced is thereafter converted to nuclear grade pure uranium 25 dioxide, natural metallic uranium and uranium hexafluoride using various processes conventionally known in the art. In one of the known processes i,e Solvent Extraction, the yellowcake is first dissolved in nitric acid and thereafter feed preparation is done to adjust the nitric acid and uranium concentration. This feed is thereafter passed through a multi-stage counter current slurry extractor wherein WO 2009/013759 PCT/IN2007/000305 2 uranyl nitrate is extracted using a mixture of 33% tributyl phosphate and kerosene leaving behind impurities in the mother liquor known as raffinate. The organic phase containing pure uranyl nitrate is further subjected to another separation step using de-mineralized water to produce pure uranyl nitrate solution. This pure urnayl nitrate 5 solution is co-precipitated with ammonia to produce ammonium diuranate (ADU), which is thereafter converted to produce nuclear grade uranium dioxide or metallic uranium. The conventionally known solvent extraction process, which involves the use of 10 carcinogenic materials such as tributyl phosphate, highly inflammable kerosene and hazardous ammonia needs lots of monitoring and safety regulations for industrial . scale operations. This process also produces degraded tributyl phosphate due to reaction with nitric acid and radioactivity, which requires complicated disposal method involving further treatment and incineration facilities, generates lots of solid 15 and liquid wastes containing nitrates which are difficult to dispose off. The generated solid waste contains a preponderance of nitrates, which therefore cannot be recycled for the recovery of uranium without the removal of nitrates. The removal of nitrates from the solid wastes generated requires special treatment steps as nitrate contamination of the ground water may lead to methemoglobinemia and stomach 20 cancer. The conventionally used solvent extraction process is also disadvantageous in that it generates multiple streams of wastes. The liquid waste stream typically contains about 100 ppm of uranium along with the soluble nitrates Which are disposed off in large solar ponds. The disposal of the liquid wastes in the large solar ponds requires large space and a continuous monitoring of the ground water around 25 the solar pond. , In another “dry refining process”, the starting yellowcake is directly palletized and reduced with hydrogen to produce uranium dioxide at a temperature between 550 - 650 °C in a fluidized bed reactor. The uranium dioxide is thereafter converted to WO 2009/013759 PCT/IN2007/000305 3 uranium tetrafluoride and uranium hexafluoride in the fluidized bed/Flame reactor. - The thus produced uranium hexafluorides are thereafter “refined" using a two-stage pressure distillation process. Further, this process of refining uranium fluorides by pressure distillation is a technically difficult and potentially hazardous process. 5 ' Refining is a process aimed at reducing the harmful impurities to an acceptable level, particularly to meet the nuclear grade specification that the equivalent boron content (EBC) may not exceed 4pg/g on uranium basis as per ASTM C - 753-99. The process according to the present invention surprisingly brings down the initial 10 EBC of 180 μg/g in the starting yellowcake to about less than 1.0 qg/g of EBC in the final product. A further approach for the production of pure uranium grades has been to use purer forms of the starting yellowcakes using hydrogen peroxide for the reduction of Mo, 15 V, P, Zr, As, Ca, Mg, Na, Si and other sulfates to produce purer yellowcakes in the form of uranium peroxide from eluate solutions of sulfate nature compared with Ammonium diuranate and Magnesium diuranate are used as the starting materials. However, it has been found that the yellowcake produced in the form of uranium peroxide using the aforesaid approach also contains substantial levels of rare earth 20 impurities that remain in the yellow cake thus necessitating further refining steps. Without wishing to be bound by theory, the inventors believe that hitherto, it has been impossible to remove both heavy metals and rare earth impurities such as boron, gadolinium, cadmium, europium and samarium in a single refining step using 25 Hydrogen peroxide as precipitation route because the process involves stringent pH control by the addition of alkaline solutions, which interferes with the simultaneous removal of rare,earth impurities such as boron, gadolinium, cadmium, europium and samarium in single refining step. WO 2009/013759 PCT/IN2007/000305 4 US 4 024 215 describes a process for the preparation of yellowcake, with a reduced content of sodium and vanadium from the eluate. However, the disclosed is not suitable for the removal of the rare earth impurities. Further, the yellowcake produced is further refined using the wet solvent extraction process to produce , 5 nuclear grade uranium, which suffers from the above identified deficiencies.
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