PROCESS AND APPARATUS FOR PRODUCING URANIUM OR A RARE EARTH ELEMENT

Abstract

The above mentioned invention describes a process for producing uranium and/or at least one rare earth element selected from the group consisting of cerium, dysprosium, erbium, europium, gadolinium, holmium, lanthanum, lutetium, neodymium, praseodymium, promethium, samarium, scandium, terbium, thulium, ytterbium and yttrium out of an ore. The ore is mixed with sulphuric acid with an concentration of at least 95 wt.-% to a mixture, wherein the mixture is granulated to pellets. The pellets are fed into at least one fluidized bed fluidized by a fluidizing gas for a thermal treatment at temperatures between 200 and 1000 C. The at least one fluidized bed is developed such that it at least partly surrounds a gas supply tube for a gas or a gas mixture fed into the reactor and the gas or gas mixture is used as a heat transfer medium.

Claims

1. Process for producing uranium (U) and/or at least one rare earth element selected from the group consisting of cerium (Ce), dysprosium (Dy), erbium (Er), europium (Eu), gadolinium (Gd), holmium (Ho), lanthanum (La), lutetium (Lu), neodymium (Nd), praseodymium (Pr), promethium (Pm), samarium (Sm), scandium (Sc), terbium (Tb), thulium (Tm), ytterbium (Yb) and yttrium (Y) out of an ore, wherein the ore is mixed with sulphuric acid with an concentration of at least 95 wt.-% to a mixture, wherein the mixture is granulated to pellets, wherein the pellets are fed into at least one fluidized bed fluidized by a fluidizing gas for a thermal treatment at temperatures between 200 and 1000 C., wherein the at least one fluidized bed is developed such that it at least partly surrounds a gas supply tube for a gas or a gas mixture fed into the reactor, and wherein the gas or gas mixture is used as a heat transfer medium.

2. Process according to claim 1, wherein the gas or gas mixture is an off-gas of a downstream process stage.

3. Process according to claim 1, wherein the pellets have an average diameter between 100 and 500 m and/or 10 wt.-% of the pellets have a diameter more than 1 mm.

4. Process according to claim 1, wherein off-gas of a low temperature heating at temperatures between 200 and 350 C. is used as the gas or the gas mixture for a preheating at temperatures between 150 and 250 C. in the fluidized bed and/or off-gas of a high temperature heating at temperatures between 500 and 800 C. is used as the gas or the gas mixture for a low temperature heating.

5. Process according to claim 4, wherein at least two fluidized beds are connected in series.

6. Process according to claim 4, wherein the off-gas of the preheating is fed into a gas cleaning.

7. Process according to claim 1, wherein the residence time in the preheating stage is between 1 s and 5 minutes, and/or the residence time in the low temperature heating is between 5 and 20 minutes and/or the residence time in the high temperature heating is between 5 and 20 minutes.

8. Plant for producing uranium (U) and/or at least one rare earth element selected from the group consisting of cerium (Ce), dysprosium (Dy), erbium (Er), europium (Eu), gadolinium (Gd), holmium (Ho), lanthanum (La), lutetium (Lu), neodymium (Nd), praseodymium (Pr), promethium (Pm), samarium (Sm), scandium (Sc), terbium (Tb), thulium (Tm), ytterbium (Yb) and yttrium (Y) out of an ore comprising a granulation to mix the ore with sulphuric acid with an concentration of at least 95 wt.-% to a mixture and granulate the mixture to pellets, a fluidized bed reactor for a heat treatment at temperatures between 200 and 1000 C. with a feeding line to feed the pellets into the fluidized bed, whereby the fluidized bed reactor has a gas supply system which is at least partly surrounded by a stationary annular fluidized bed during operation, a downstream process stage, and an off-gas line from the downstream process stage to the gas supply system of the fluidized bed reactor.

9. Plant according to claim 8, wherein the fluidized bed reactor features a gas supply system extending upwards substantially vertically from the lower region of the fluidized bed reactor into a mixing chamber of the fluidized bed reactor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0032] FIG. 1 shows a schematically process in accordance with the present invention.

[0033] Ore containing uranium and/or at least one element of the group cerium, dysprosium, erbium, europium, gadolinium, holmium, lanthanum, lutetium, neodymium, praseodymium, promethium, samarium, scandium, terbium, thulium, ytterbium and yttrium is pulverized and fed into the granulation 11. Therein, it is mixed with sulphuric acid from acid line 12. The resulting mixture is pelletized to pellets, wherein at least 90% of the pellets have a diameter between 150 and 300 m. The temperature in the granulation is between 80 and 120 C.

[0034] Resulting pellets are fed via line 13 into a fluidized bed reactor 20. The fluidized bed reactor for preheating 20 is designed such that during operating it features a circulating annular fluidized bed for preheating 22. The fluidized bed for preheating 22 is fluidized via lines 25. A gas mixture system for preheating 21 is positioned such that an annular fluidized bed for preheating 22 surrounds the gas supply system for preheating 21. The end of the gas supply system for preheating 21 is above the annular fluidized bed for preheating 22 in a mixing chamber for preheating 23, Instead of a fluidized bed reactor the preheating equipment can be a venturi.

[0035] The gas mixture in the gas supply system 21 fed via line 53 is the off-gas of a second heating stage, the so called lower heating stage which is performed in the fluidized bed reactor for low temperature heating 30. The design of the fluidized bed reactor for low temperature heating 30 corresponds to the design of fluidized bed reactor for preheating 20. The annular fluidized bed for low temperature heating 32 is fluidized via lines 35. It includes also a gas supply system for low temperature heating 31, surrounded by an annular fluidized bed for low temperature heating 32 during operation. The gas supply system for low temperature heating 31 ends above the annular fluidized bed for low temperature heating 32 into the so called mixing chamber for low temperature heating 33. The gas fed to the gas supply system for low temperature heating 31 fed via line 52 is the off-gas of the fluidized bed reactor for high temperature heating 40.

[0036] Also fluidized bed reactor for high temperature heating 40 is designed with a circulating annular fluidized bed for high temperature heating 42 and with a gas supply system for high temperature heating 41 surrounded by a circulating annular fluidized bed for high temperature heating 42 being fluidized via lines 45. During operation, the gas supply system ends upon the annular fluidized bed for high temperature heating 42 in the mixing chamber for high temperature heating 43.

[0037] The gas mixture for fluidized bed for high temperature heating 40 is supplied via line 51. The gas mixture of line 51 can be air, which is used as combustion air for combustion of fuel introduced into fluidized bed reactor 40. Fuel can be coal, natural gas, diesel oil, heavy fuel oil, etc. and is introduced via line 59.

[0038] The resulting sulfates from this process are withdrawn from the annular fluidized bed 42 via line 44 and led to further process stages like leaching. Also, remaining solids are filtered. In the not shown leaching, the uranium and/or at least one rare earth element is a soluble sulfate form that dissolves in water at elevated temperature while the bulk of impurities like iron are insoluble oxides. After leaching these impurities are removed via a solid/liquid separation step. The remaining filtrate contains dissolved uranium and/or at least one rare earth element. Possibly contained dissolved impurities are removed in further purification stages. The final solution contains only the valuable elements (uranium and/or at least one rare earth element). This solution passes through further treatment stages for recovery of the valuable elements in the desired compound.

[0039] To optimize the energy balance of the shown process, off-gas of the high temperature reactor 40 is used as a heat transfer medium supplied via the gas supply system in low temperature fluidized bed reactor 30, while the off-gas of the fluidized bed reactor for low temperature heating 30 is transported via line 53 into the fluidized bed reactor for preheating 20 as a heat transfer medium.

[0040] The resulting off-gas is passed to a separator 54, wherein the solids are separated from the gas. The solids are passed back into the preheating fluidized bed reactor 20 via line 52, while the gas is passed through a gas cleaning stage 57 via line 56. In the gas cleaning stage 57, SO.sub.3 is decomposed to SO.sub.2.Those gases are passed via line 58 into a not shown sulphuric acid plant.

REFERENCE LIST

[0041] 10 acid mixing and granulation

[0042] 11-13 line

[0043] 20 fluidized bed reactor or venturi for preheating

[0044] 21 gas supply system for preheating

[0045] 22 annular fluidized bed for preheating

[0046] 23 mixing chamber for preheating

[0047] 24 line

[0048] 25 fluidizing gas system for preheating

[0049] 30 fluidized bed reactor for low temperature heating

[0050] 31 gas supply system for low temperature heating

[0051] 32 annular fluidized bed for low temperature heating

[0052] 33 mixing chamber for low temperature heating

[0053] 34 line

[0054] 35 fluidizing gas system for low temperature heating

[0055] 40 fluidized bed reactor for high temperature heating

[0056] 41 gas supply system for high temperature heating

[0057] 42 annular fluidized bed for high temperature heating

[0058] 43 mixing chamber for high temperature heating

[0059] 44 line

[0060] 45 fluidized gas system

[0061] 51-53 line

[0062] 54 separator

[0063] 55, 56 line

[0064] 57 gas cleaning

[0065] 58, 59 line