Bastnaesite Rare Earth Separation with Staged Acid Roasting
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Solution Overview
Problem
Existing bastnaesite treatment processes face issues such as low cerium oxide purity in recycling cerium-rich residues, high emissions of fluorine and sulfur-containing gases, and high treatment and recovery costs, along with low concentration of leaching liquors, posing environmental and economic challenges.
Innovation Solution
A combination method involving roasting under controlled atmospheres, followed by hydrochloric acid leaching and sulfuric acid roasting, with controlled acid addition and high-temperature aging to enhance rare earth recovery and minimize fluorine and sulfur emissions, utilizing adsorption for fluorine recovery and closed-loop recycling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If concentrated sulfuric acid roasting is used to treat mixed rare earth concentrate, then rare earth recovery rate is improved, but fluorine and sulfur emissions increase and treatment cost increases
Solution Approach 1:
The treatment process is divided into two separate segments: first treating bastnaesite with hydrochloric acid to extract rare earth, then treating monazite with concentrated sulfuric acid. This segmentation allows each acid to be used optimally for its target mineral, reducing unnecessary chemical reactions and emissions while maintaining high recovery rates.
Solution Approach 2:
The patent changes the chemical environment parameters by using different acids (hydrochloric acid for bastnaesite, sulfuric acid for monazite) and controlling pH levels, temperatures, and concentrations to optimize extraction while minimizing harmful emissions through controlled reaction conditions.
2Ease of manufacture
If hydrochloric acid leaching is used to treat bastnaesite, then investment cost is reduced, but cerium oxide purity decreases and fluorine recycling becomes difficult
Solution Approach 1:
The patent introduces an intermediary step of oxidizing roasting before hydrochloric acid leaching. This intermediary treatment converts cerium(III) to cerium(IV), which improves the efficiency of subsequent leaching and enhances cerium recovery in the form of cerium oxide, thereby improving purity while maintaining cost-effectiveness.
Solution Approach 2:
The process uses a composite approach combining oxidizing roasting with hydrochloric acid leaching, creating a synergistic effect where the roasting step prepares the material for more efficient leaching, achieving both cost-effectiveness and high purity cerium oxide recovery.
3Productivity
If continuous large-scale production is implemented, then productivity is improved, but tail gas treatment complexity increases
Solution Approach 1:
The patent converts the harmful fluorine and sulfur emissions into recoverable resources by implementing gas washing systems that capture fluorine as calcium fluoride and sulfur as sulfuric acid. This transforms waste treatment into a resource recovery process, maintaining continuous production while simplifying environmental compliance.
Solution Approach 2:
The process implements recovery systems for fluorine and sulfur that were previously discarded as waste. By capturing and recovering these elements in usable forms, the system maintains high productivity while reducing the complexity of waste disposal and environmental treatment.
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
The process achieves high rare earth leaching rates of 70-95% with low fluorine and sulfur emissions, reducing treatment costs and environmental impact, enabling efficient and clean production of rare earth concentrates.
Implementation Method 1
adding the roasted concentrate with a hydrochloric acid to leach rare earth
Implementation Method 2
adding the dehydrated leach residue with a concentrated sulfuric acid, roasting
Implementation Method 3
leaching the roasted product with water, and neutralizing to remove impurities so as to obtain a rare earth sulfate solution
Data Source
AI summary
The present invention provides a process for metallurgy and separating a rare earth concentrate using a combination method, the process including: treating the rare earth concentrate containing bastnaesite by using a method including roasting under an atmosphere, leaching with hydrochloric acids, and roasting with a sulfuric acid, wherein stepping acid leaching with low-concentration hydrochloric acids is controlled during the leaching with the hydrochloric acids so as to obtain a rare earth solution with a high concentration (150-250 g/L REO), such that a leaching rate of Ce reaches 60% or more, and the content of F in a leaching liquor is reduced by aging; and rare earth is further recovered from a leach residue by roasting with the sulfuric acid and leaching with water, and the total yield of the rare earth reaches 95% or more.