CO2 Crystallization of Metal Salts for Low-Effluent Purification
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Solution Overview
Problem
Existing methods for separating and purifying metals like cobalt or rare earth metals from batteries are inefficient and generate substantial effluents, and there is a need for processes that require minimal chemical additives and produce little effluents.
Innovation Solution
A process using carbon dioxide to purify and crystallize metal salts, particularly from mixtures containing different metals, involving suspension, and the use of carbon dioxide, which involves no or little effluents, and the process involves no or little chemical additives, and generate no or little effluents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If acidic leaching and separation steps are used to separate metals from battery mixtures, then metal separation is achieved, but substantial amounts of effluents are produced and numerous chemical additives are required
Solution Approach 1:
The invention changes the pH parameter of the solution by adding base to adjust pH higher than 10, transforming the chemical environment to enable selective precipitation of metal hydroxides without requiring numerous chemical additives or producing substantial effluents
Solution Approach 2:
The invention utilizes phase transition by precipitating metal hydroxides from solution through pH adjustment, then redissolving them in acidic medium, and finally precipitating them again as carbonates or hydroxycarbonates through CO2 treatment, achieving separation through repeated phase changes rather than through chemical reaction with multiple additives
2Productivity
If numerous chemical additives are used for metal separation, then separation efficiency is improved, but the complexity of the process increases and more effluents are generated
Solution Approach 1:
The invention employs the metal salts themselves to perform the separation function through selective solubility and precipitation behavior at different pH levels, eliminating the need for numerous external chemical additives and reducing process complexity while maintaining separation efficiency
Solution Approach 2:
The invention achieves separation by changing physical-chemical parameters (pH, temperature, CO2 pressure) rather than by adding numerous chemical substances, simplifying the process while maintaining high separation efficiency
3Manufacturing precision
If traditional purification methods are used, then metal salts can be purified, but the crystallinity and purity of the final product are limited
Solution Approach 1:
The invention achieves high crystallinity by utilizing controlled phase transitions: precipitation of metal hydroxides at high pH, redissolution in acid, and final precipitation as crystalline carbonates or hydroxycarbonates through CO2 treatment, where the slow crystallization process under controlled conditions produces highly crystalline products
Solution Approach 2:
The invention changes the chemical composition parameter by introducing carbonate ions through CO2, which leads to formation of highly crystalline carbonate or hydroxycarbonate phases with superior crystallinity compared to traditional purification methods
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 purity and crystallinity of the metal salts, using minimal chemical additives and producing minimal effluents, while valorizing carbon dioxide as a waste product.
Implementation Method 1
Contacting the suspension obtained in step a) with CO2, preferably gaseous CO2, to obtain a solution or a suspension
Implementation Method 2
Crystallizing at least one carbonate-containing metal salt by desorbing CO2 from the liquid phase recovered in step c)
Implementation Method 3
Crystallizing at least one carbonate-containing metal salt by desorbing CO2 from the liquid phase recovered in step c) to obtain a suspension
Implementation Method 4
recovering step c) is implemented by solid/liquid separation, such as by filtration or centrifugation
Implementation Method 5
recovering step c) is implemented by solid/liquid separation, such as by filtration or centrifugation
Data Source
AI summary
The present application relates to a process for purifying metal salts, and to a process for separating a metal from a polymetallic mixture by crystallizing a metal salt. The processes according to the invention allow obtaining crystallized carbonate-containing metal salts with high purity and high crystallinity.