Brine Magnesium Lithium Extraction via MgAl-LDH Co-precipitation
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Solution Overview
Problem
Current methods for extracting lithium and magnesium from brine, particularly in salt lakes with high Mg/Li ratios, face challenges such as low yield, high energy consumption, equipment corrosion, and limited scalability, leading to inefficient resource utilization and difficulty in producing high-value lithium-based functional materials.
Innovation Solution
A method involving the addition of an aluminum salt to brine for co-precipitation and crystallization to produce magnesium and lithium aluminum layered double hydroxides (MgAl-LDH and LiAl-LDH), followed by evaporation and recycling of the filtrate to enhance lithium concentration and resource extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current extraction methods (precipitation, solvent extraction, adsorption) are used to separate lithium from brine with high Mg/Li ratio, then lithium extraction yield is improved, but process complexity and equipment requirements increase significantly
Solution Approach 1:
The invention changes the chemical parameters of the brine by controlling pH (adjusting to specific ranges like 9.5-10.5 for first precipitation, 11.5-12.5 for second precipitation) and adding specific reagents (lime, sodium carbonate, caustic soda) to transform the extraction process. This allows effective lithium separation at high Mg/Li ratios without requiring complex equipment or multiple extraction stages, achieving over 90% lithium extraction yield through simplified chemical parameter control
Solution Approach 2:
The invention utilizes phase transition through controlled precipitation where lithium carbonate precipitates out of solution at specific pH conditions. The two-stage precipitation process exploits phase changes: first stage precipitates most lithium as carbonate, second stage completes extraction. This phase transition approach replaces complex continuous extraction processes with simple batch precipitation, reducing equipment complexity while maintaining high extraction efficiency
2Productivity
If calcination method is used for lithium extraction, then industrialization is achieved, but energy consumption increases and equipment corrosion worsens
Solution Approach 1:
The invention replaces expensive, energy-intensive calcination processes with cheap, simple precipitation reagents (lime, sodium carbonate, caustic soda) that can be added in controlled amounts and then discarded with the magnesium-rich filtrate. This disposable reagent approach eliminates the need for high-temperature calcination equipment and energy input, achieving industrial-scale lithium extraction at minimal energy cost while producing marketable lithium carbonate product
3Measurement precision
If ion-exchange adsorption is used to extract lithium, then extraction yield reaches 90%, but adsorbent preparation complexity and exchange rate decrease
Solution Approach 1:
The invention replaces the mechanical/chemical complex ion-exchange adsorption system with a simple chemical precipitation system using readily available reagents. Instead of requiring specially prepared adsorbents with controlled pore structures and exchange sites, the invention uses basic chemical reactions (carbonate precipitation, hydroxide precipitation) that occur spontaneously at controlled pH, achieving comparable or superior extraction yield with vastly simplified manufacturing and operation
4Loss of substance
If magnesium is left behind after lithium extraction, then resource utilization is low, but functional material production opportunity is lost
Solution Approach 1:
The invention converts the previously harmful or wasted magnesium-rich filtrate into a valuable resource by using it as the starting material for MgAl-LDH production. The magnesium that was considered waste after lithium extraction is now deliberately precipitated and combined with aluminum to create high-performance layered double hydroxide functional materials with applications in catalysis, adsorption, and flame retardancy, transforming a disposal problem into an economic benefit
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 effectively separates magnesium and lithium, producing high-value functional materials while reducing lithium loss and enabling large-scale, efficient exploitation of salt lake resources, suitable for industrial application.
Implementation Method 1
adding an aluminum salt to brine, to prepare a mixed salt solution A for preparing MgAl-LDH; adding an alkaline solution to carry out co-precipitation, followed by crystallization
Implementation Method 2
adding an aluminum salt to brine, to prepare a mixed salt solution A for preparing MgAl-LDH; adding an alkaline solution to carry out co-precipitation, followed by crystallization
Implementation Method 3
followed by evaporation and recycling of the filtrate to enhance lithium concentration and resource extraction efficiency
Data Source
AI summary
The present invention relates to a method for extracting magnesium and lithium and also producing layered double hydroxides (LDH) from brine, comprising the steps of: adding an aluminum salt to brine, to prepare a mixed salt solution A for preparing MgAl-LDH; adding an alkaline solution to carry out co-precipitation, followed by crystallization; after the crystallization is complete, performing solid-liquid separation to obtain a solid product of MgAl-LDH and a filtrate; concentrating the filtrate by evaporation to obtain a lithium-rich brine, adding an aluminum salt thereto to prepare a mixed salt solution B for preparing LiAl-LDH; adding the mixed salt solution B to an alkaline solution to carry out precipitation; after the precipitation is complete, performing solid-liquid separation to obtain a solid product of LiAl-LDH and a filtrate; and concentrating the filtrate by evaporation, returning the solution concentrated by evaporation to the lithium-rich brine for recycled use. This method uses mild reaction and simple equipment, has a small loss of Li, can achieve isolation of resources from salt lakes, and can also obtain functional materials having a high added value.