Lithium Extraction Carbonate Leach Phosphate Removal
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Solution Overview
Problem
Existing methods for extracting lithium from minerals, such as spodumene, face challenges in separating impurities like phosphates from the lithium product, leading to lithium losses during further processing due to the solubilization of phosphoric impurities from gangue minerals like apatite, resulting in high phosphorus content in lithium carbonate products.
Innovation Solution
A method involving a carbonate leach process that includes a leaching step with an aqueous alkaline solution, a carbonization step with an alkali earth metal compound and CO2 to precipitate phosphates as insoluble compounds, and a solid-liquid separation step to isolate lithium bicarbonate or carbonate, thereby preventing phosphate reaction with lithium.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If an alkaline carbonate leach process is used to extract lithium from mineral concentrate, then lithium is solubilized and can be processed, but phosphoric impurities from gangue minerals also solubilize and react with lithium to form unwanted lithium phosphate compounds in the final product
Solution Approach 1:
The patent applies preliminary action by adding an alkali earth metal compound (such as calcium carbonate or magnesium oxide) before the carbonization step. This compound reacts with solubilized phosphoric impurities during the leaching process to form insoluble phosphate precipitates, which are then removed by filtration before lithium carbonate precipitation. This preliminary removal prevents phosphates from reacting with lithium during subsequent processing steps.
Solution Approach 2:
The patent extracts the harmful phosphoric impurities from the solution by precipitating them as insoluble compounds using alkali earth metal compounds. The precipitated phosphates are then separated from the lithium-containing solution through filtration, effectively removing the impurity before lithium carbonate formation.
2Device complexity
If phosphate impurities are not removed during the leaching process, then the process is simpler, but lithium losses occur during further processing due to phosphate reactions
Solution Approach 1:
The patent introduces an intermediary substance (alkali earth metal compound such as calcium carbonate or magnesium oxide) that mediates between the phosphoric impurities and the lithium. This intermediary reacts with phosphates to form insoluble precipitates, effectively separating the harmful impurities from the lithium without requiring complex separation processes.
3Manufacturing precision
If high-purity lithium products are targeted, then product quality is improved, but the separation of impurities from lithium becomes more challenging
Solution Approach 1:
The patent changes the chemical parameters of the leaching solution by adding alkali earth metal compounds, which alter the solubility characteristics of phosphoric impurities. This parameter change causes phosphates to precipitate as insoluble compounds that can be easily separated by filtration, achieving high-purity lithium products through a relatively simple process modification.
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 approach effectively reduces the phosphorus content in lithium carbonate products to less than 300 ppm, compared to the typical range of 500-2000 ppm, minimizing lithium losses and producing high-purity lithium compounds.
Implementation Method 1
a carbonization step, wherein the obtained leach slurry is reacted with an alkali earth metal compound in the presence of CO2, for obtaining a carbonated slurry containing lithium bicarbonate, and for precipitating phosphate(s) from the leach slurry as insoluble phosphate compound(s)
Implementation Method 2
a leaching step, wherein the lithium-containing mineral is leached in aqueous alkaline carbonate leach solution for liberating lithium and phosphate from the mineral
Implementation Method 3
a solid-liquid separation step, wherein the carbonated slurry obtained from the carbonization step is subjected to solid-liquid separation wherein undissolved mineral and the insoluble phosphate compound(s) are separated
Data Source
AI summary
A method and apparatus of preparing lithium compound(s) from lithium-containing mineral includes a) a leaching step, wherein the lithium-containing mineral is leached in aqueous leach solution containing alkaline carbonate, for liberating lithium and phosphate(s) from the lithium-containing mineral, thus obtaining leach slurry containing lithium carbonate and phosphate(s) leach slurry, b) a carbonization step, wherein the leach slurry containing lithium carbonate and phosphate(s), obtained from the leaching step, is reacted with an alkali earth metal compound in the presence of CO2 for obtaining a carbonated slurry containing lithium hydrogen carbonate, and for precipitating phosphate(s) contained in the leach slurry as insoluble phosphate compound(s), c) a solid-liquid separation step, wherein the carbonated slurry obtained from carbonization step is subjected to solid-liquid separation wherein the undissolved mineral and phosphate compound(s) are separated as solids that can be recovered or discarded, thereby obtaining a solution containing lithium hydrogen carbonate.