Lithium Extraction from Phosphate via Selective Precipitation
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Solution Overview
Problem
Conventional methods for producing lithium carbonate from lithium phosphate are economically inefficient due to high energy costs, low lithium recovery rates, excessive raw and supplementary material consumption, and complex processes, making them unsuitable for large-scale production of lithium secondary batteries.
Innovation Solution
A method involving the dissolution of lithium phosphate and impurities in an acid, followed by the addition of an alkaline earth metal oxide or hydroxide to precipitate phosphate anions and impurities, resulting in a basic lithium-containing solution that is then treated with a carbonate to produce lithium carbonate, thereby increasing lithium recovery rates and reducing energy and material costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If natural evaporation and concentration process is used to produce lithium carbonate, then lithium carbonate can be precipitated, but the process requires long time (more than a year) and causes large loss of lithium
Solution Approach 1:
The patent changes the chemical parameters by using lithium phosphate extraction instead of natural evaporation. The process uses phosphate to precipitate lithium at high concentration (60 g/L or higher) without requiring long-term evaporation, thereby reducing the time parameter from over a year to a much shorter period while maintaining effective lithium carbonate production
Solution Approach 2:
The patent extracts lithium from brine using lithium phosphate precipitation method, separating the lithium extraction step from the time-consuming natural evaporation process. This allows lithium to be concentrated and precipitated directly without waiting for natural evaporation to occur
2Loss of substance
If lithium phosphate extraction method is used to minimize evaporation process, then lithium recovery rate increases, but lithium phosphate must be converted to lithium carbonate requiring additional processes
Solution Approach 1:
The patent merges the lithium extraction and lithium carbonate production into a single integrated process. By using phosphate to precipitate lithium and then directly treating with carbonate, the method combines what were previously separate steps (extraction and conversion) into one continuous flow, reducing overall process complexity despite the conversion requirement
Solution Approach 2:
The patent performs preliminary concentration of lithium to 60 g/L or higher using phosphate precipitation before the carbonate conversion step. This preliminary action ensures high lithium recovery is achieved upfront, making the subsequent conversion to lithium carbonate more efficient and reducing the complexity of the overall process
3Manufacturing precision
If high-temperature heating and evaporation are used to convert lithium phosphate to lithium carbonate, then conversion can be achieved, but energy costs increase significantly
Solution Approach 1:
The patent changes the temperature parameter from high-temperature heating to room temperature or mild heating conditions. The method uses chemical reactions (phosphate precipitation followed by carbonate treatment) that proceed effectively at lower temperatures, thereby achieving lithium carbonate conversion while dramatically reducing energy costs
4Loss of substance
If acid dissolution followed by pH adjustment is used to remove impurities, then metal ions can be removed, but heavy metal ions may not be completely removed and process becomes complicated
Solution Approach 1:
The patent takes out impurity removal from the conventional acid dissolution-pH adjustment sequence and replaces it with selective phosphate precipitation. The phosphate selectively precipitates metal ions including heavy metals at controlled pH levels, ensuring complete removal without the complications of multi-step pH adjustment and achieving higher purity in the lithium-containing solution
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 achieves a high lithium recovery rate of 75% or more, significantly reducing energy consumption, raw material costs, and equipment investment while simplifying the production process, making lithium carbonate production more economically feasible.
Implementation Method 1
dissolving the lithium phosphate and impurities in an acid
Implementation Method 2
adding an alkaline earth metal oxide or hydroxide to precipitate phosphate anions and impurities
Implementation Method 3
the basic lithium-containing solution is then treated with a carbonate to produce lithium carbonate
Data Source
AI summary
The lithium extraction method includes providing lithium phosphate containing impurities of an alkaline earth metal; dissolving the lithium phosphate and the impurities in an acid; and preparing a lithium-containing solution by adding an additive to a solution prepared by dissolving the lithium phosphate and the impurities in the acid. The additive is a substance capable of simultaneously precipitating phosphate anions and the impurities, and the lithium-containing solution prepared through addition of the additive is basic.