Rare Earth Separation via Selective Acid Dissolution
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Solution Overview
Problem
Current solvent extraction methods for separating light rare earth elements and heavy rare earth elements from workpieces require large amounts of organic solvents, are environmentally hazardous, and necessitate complex apparatus and labor-intensive analysis of content ratios, making them inefficient and unsustainable.
Innovation Solution
A method involving the dissolution of composite oxides in hydrochloric or nitric acid, followed by precipitation, calcination, and selective dissolution in acid to separate light and heavy rare earth elements, reducing the need for organic solvents and simplifying the separation process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a solvent extraction method is used to separate light and heavy rare earth elements, then separation can be achieved, but large amounts of organic solvents are required and the apparatus becomes large-sized
Solution Approach 1:
The invention changes the chemical parameters of the separation process by using inorganic acids (hydrochloric acid or nitric acid) with specific concentrations (0.7 mol/L or more) instead of organic solvents. The calcine is added in controlled amounts (1.1 to 3.0 times the upper solubility limit) to achieve selective dissolution and separation of rare earth elements based on their different solubility characteristics in acidic environments.
2Quantity of substance
If a solvent extraction method is used to separate light and heavy rare earth elements, then separation can be achieved, but the apparatus becomes large-sized and environmentally hazardous
Solution Approach 1:
The invention replaces expensive and environmentally hazardous organic solvents with inexpensive, readily available inorganic acids (hydrochloric acid or nitric acid). These acids can be easily handled, are less environmentally problematic, and the process does not require complex recovery systems, making it more sustainable and safer for environmental protection.
3Ease of operation
If the solvent extraction method is used, then separation can be achieved, but work burden is imposed due to the need to analyze content ratio before setting treatment conditions
Solution Approach 1:
The process is designed to be self-adjusting based on the natural solubility differences of rare earth elements in acidic solutions. By adding the calcine in a specific amount range (1.1 to 3.0 times the upper solubility limit) to acid with concentration of 0.7 mol/L or more, the system automatically achieves selective dissolution and separation without requiring prior knowledge of the exact element ratios or complex condition optimization.
4Manufacturing precision
If the amount of calcine is not properly controlled in acid dissolution, then separation efficiency decreases, but excessive calcine increases waste
Solution Approach 1:
The invention establishes a precise parameter range for the amount of calcine to be added (1.1 to 3.0 times the upper solubility limit) and the acid concentration (0.7 mol/L or more). Within this optimized parameter range, the process achieves high separation efficiency while minimizing waste, as the selective dissolution occurs efficiently without requiring excessive reagents.
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 method allows for the efficient separation of light and heavy rare earth elements with reduced solvent usage, downsized apparatus, and decreased work burden, enabling effective recycling without extensive analysis of content ratios.
Implementation Method 1
adding the obtained calcine in an amount of 1.1 times to 3.0 times the upper solubility limit to hydrochloric acid and/or nitric acid having a concentration of 0.7 mol/L or more to give a solution and a residue
Implementation Method 2
a step of adding a precipitant to the obtained solution to give a precipitate
Implementation Method 3
a step of calcining the obtained precipitate
Data Source
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AI summary
An object of the present invention is to provide a method useful for separating a light rare earth element and a heavy rare earth element, which, for example, when a light rare earth element and a heavy rare earth element are separated from a workpiece containing a light rare earth element and a heavy rare earth element by a solvent extraction method, makes it possible to reduce the amount of extractant or organic solvent used or downsize the apparatus, or makes it possible to reduce the work burden on the process, such as the analysis of the content ratio between the light rare earth element and the heavy rare earth element contained in the workpiece. The method of the present invention as a means for resolution is characterized by including at least: (1) a step of obtaining, from a workpiece containing a light rare earth element and a heavy rare earth element, a composite oxide or mixture of oxides of the two; (2) a step of dissolving the obtained composite oxide or mixture of oxides of a light rare earth element and a heavy rare earth element in hydrochloric acid and/or nitric acid; (3) a step of adding a precipitant to the obtained solution to give a precipitate; (4) a step of calcining the obtained precipitate; (5) a step of adding the obtained calcine in an amount of 1.1 times to 3.0 times the upper solubility limit to hydrochloric acid and/or nitric acid having a concentration of 0.7 mol/L or more to give a solution and a residue; and (6) a step of separating the obtained solution and residue, thereby giving the solution as a light rare earth element-rich inclusion and the residue as a heavy rare earth element-rich inclusion (here, the term "rich" means that the content ratio of the concerned rare earth element to the other rare earth element is higher than the content ratio in the workpiece).