Fluidized Bed Uranium Processing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing processes for producing uranium and rare earth elements from ores face challenges such as low turnover in rotary kilns, corrosion issues due to temperature gradients, and inefficiencies in heat and mass transfer, limiting scalability and requiring expensive materials.
Innovation Solution
A process involving mixing ore with 95%+ sulphuric acid, granulating into pellets, and treating in a fluidized bed at controlled temperatures, using off-gas as a heat transfer medium to maintain consistent temperatures and prevent corrosion, with an annular fluidized bed design for enhanced mass and heat transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If rotary kiln is used for acid treatment, then uranium and rare earth elements can be produced, but space-time-yield is low and scalability is limited
Solution Approach 1:
The patent replaces the mechanical rotary kiln system with a fluidized bed reactor system. The fluidized bed reactor uses gas fluidization to create a suspended particle bed, enabling better heat and mass transfer compared to the mechanical mixing in rotary kilns. This substitution allows for higher space-time-yield and improved scalability while maintaining the acid treatment function.
Solution Approach 2:
The patent changes the operational parameters by using fluidized bed technology instead of rotary kiln processing. The fluidized bed allows for controlled temperature profiles, better contact between acid and ore particles, and improved residence time distribution, thereby increasing productivity and enabling scalability.
2Productivity
If temperature is increased for sulphation, then reaction efficiency improves, but corrosion increases
Solution Approach 1:
The patent optimizes the temperature parameter in the fluidized bed reactor to maintain it above the dew point of SO3 (160-220°C) to ensure efficient sulphation reaction, while controlling it below the boiling point of sulphuric acid (330°C) to prevent excessive corrosion. This parameter optimization resolves the contradiction between reaction efficiency and corrosion resistance.
Solution Approach 2:
The fluidized bed reactor acts as an intermediary system that controls the temperature profile more precisely than conventional rotary kilns. The gas fluidization mechanism provides uniform heat distribution, allowing the process to operate at optimal temperatures that balance reaction efficiency with corrosion prevention.
3Loss of substance
If indirect heating is used to avoid acid loss, then acid evaporation is reduced, but temperature control becomes difficult and material costs increase
Solution Approach 1:
The patent replaces indirect heating mechanisms with direct gas-phase heating in the fluidized bed reactor. The gas stream directly contacts the ore particles, providing uniform and controllable heating without requiring complex indirect heat exchange systems. This approach maintains acid evaporation at minimal levels while simplifying temperature control and reducing material costs.
Solution Approach 2:
The fluidized bed reactor uses the process gas itself as the heating medium, creating a self-heating system where the gas stream carries heat directly to the particles. This self-service heating mechanism eliminates the need for separate heating systems and provides excellent temperature control while minimizing acid loss through evaporation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach increases space-time-yield, reduces corrosion, and optimizes energy balance, allowing for more efficient production of uranium and rare earth elements while minimizing material costs and maintaining consistent temperatures.
Implementation Method 1
The resulting mixture is granulated into pellets. The pellets are fed into at least one fluidized bed, which is fluidized by a fluidizing gas for a thermal treatment at temperatures between 200 and 1000° C.
Implementation Method 2
The pellets are fed into at least one fluidized bed, which is fluidized by a fluidizing gas for a thermal treatment at temperatures between 200 and 1000° C.
Implementation Method 3
The problem of this well-known process is a relatively low turnover in a rotary kiln. To avoid acid losses through evaporation the rotary kiln should be heated indirectly whereby this process cannot be upscaled unlimited.
Implementation Method 4
Afterwards, the resulting cake is leached with water to dissolve the rare earth elements as sulfates.
Implementation Method 5
using off-gas as a heat transfer medium to maintain consistent temperatures and prevent corrosion
Data Source
AI summary
In 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 a 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.