Lithium Extraction from Brine Using Phosphate Precipitation
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Solution Overview
Problem
Current methods for extracting lithium from brine are inefficient and economically unfeasible, particularly due to high impurity content, which leads to lithium loss and increased costs, and the need for extensive processing and sludge generation, limiting the use of brines with high magnesium and calcium content.
Innovation Solution
A method involving the addition of a phosphorus source material to a lithium solution containing alkaline earth metal cations, allowing for the production of a lithium precipitate that includes magnesium, calcium, and phosphorus without prior impurity removal, followed by stirring and filtration to achieve a high lithium dissolution rate, enabling the economical and efficient extraction of lithium and its conversion into lithium hydroxide or carbonate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium is extracted from brine using conventional solar evaporation, then lithium concentration increases from 0.5-1.5 g/L to 60 g/L, but the process takes about 18 months and lithium co-precipitates with other elements causing loss
Solution Approach 1:
The invention changes the chemical parameter by adding phosphate to precipitate lithium as lithium phosphate instead of relying on slow solar evaporation. This chemical transformation accelerates the concentration process from 18 months to a much shorter timeframe while achieving the same or higher lithium concentration.
Solution Approach 2:
The invention extracts lithium selectively by precipitating it as lithium phosphate through chemical reaction with phosphate, separating it from other elements in the brine. This selective extraction prevents co-precipitation losses that occur in conventional solar evaporation methods.
2Quantity of substance
If phosphate is added to brine to precipitate lithium as lithium phosphate, then lithium can be precipitated at low concentration, but phosphorus preferentially reacts with impurities such as magnesium, calcium, and strontium to produce their phosphates
Solution Approach 1:
The invention performs preliminary removal of interfering impurities (magnesium, calcium, strontium, aluminum, iron) before adding phosphate. This preliminary action ensures that when phosphate is subsequently added, it reacts selectively with lithium to form lithium phosphate precipitate without competing reactions with other metal ions.
Solution Approach 2:
The invention removes interfering impurities from the brine before the phosphate precipitation step. By extracting these competing metal ions first, the process ensures high selectivity of phosphorus reaction with lithium, preventing formation of other metal phosphates that would reduce lithium recovery efficiency.
3Productivity
If impurities such as magnesium and calcium are removed before adding phosphorus, then lithium phosphate precipitation efficiency increases, but the process complexity and cost increase due to additional processing steps
Solution Approach 1:
The invention merges the impurity removal step with the phosphate precipitation step into a unified process flow. By removing interfering impurities first and then immediately proceeding to phosphate addition without separate intermediate processing, the method achieves high extraction efficiency while minimizing process complexity and operational costs.
4Quantity of substance
If conventional solar evaporation is used to concentrate lithium, then lithium carbonate precipitates, but most lithium co-precipitates with other elements and is lost
Solution Approach 1:
The invention changes the precipitation chemistry by using phosphate instead of relying on natural carbonate equilibrium during solar evaporation. Lithium phosphate has extremely low solubility (0.39 g/L) compared to lithium carbonate, enabling complete precipitation at much lower concentrations and preventing co-precipitation losses with other elements.
Solution Approach 2:
The invention converts the low solubility of lithium phosphate from a potential disadvantage into a benefit, achieving near-complete lithium precipitation at low concentrations. This transforms what could be seen as a limitation (need for precise solubility control) into an advantage (high recovery efficiency with minimal loss).
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 allows for the efficient extraction and conversion of lithium with minimized phosphorus elution, reducing process complexity and costs, and enabling the use of lithium-rich brines with high impurity content, thereby meeting the increasing demand for lithium.
Implementation Method 1
adding a phosphorus source material to a first solution containing a lithium cation (Li+) and an alkaline earth metal cations to produce a lithium precipitate including magnesium, calcium, and phosphorus
Implementation Method 2
stirring and filtration to achieve a high lithium dissolution rate
Data Source
AI summary
Provided are a method of extracting lithium, which includes adding a phosphorus source material to a first solution containing a lithium cation (Li+) and an alkaline earth metal cation to produce a precipitate containing lithium, magnesium, calcium, strontium, and phosphorus, wherein the total concentration of the alkaline earth metal cations in the first solution is 100,000 mg/L or more, a method of preparing lithium carbonate using the same, and a method of preparing lithium hydroxide using the same.