Lithium Recovery from Phosphate Minerals via Acid Leaching
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Solution Overview
Problem
Current methods for recovering lithium from amblygonite-rich ores are inefficient due to high operating costs and energy requirements, and struggle with separating lithium from phosphate, leading to lithium losses and high pH precipitation issues.
Innovation Solution
A process involving acid leaching of lithium and phosphate-rich minerals, followed by low pH impurity removal at elevated temperatures to precipitate impurities like alunite, with minimal lithium co-precipitation, and subsequent high pH steps to remove base metals and precipitate lithium carbonate, utilizing sulfuric acid and carbonate salts for efficient lithium extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high pH precipitation is used to remove phosphate impurities, then phosphate removal is effective, but lithium is co-precipitated as lithium phosphate causing lithium losses
Solution Approach 1:
The patent applies parameter changes by precisely controlling the pH range (8.5-9.5) and temperature (80-100°C) during precipitation to selectively remove phosphate as calcium phosphate while preventing lithium phosphate formation. This optimized parameter window allows effective phosphate removal without lithium co-precipitation losses.
Solution Approach 2:
The patent uses calcium carbonate as an intermediary substance to remove phosphate impurities. Calcium carbonate reacts with phosphate to form calcium phosphate precipitate, serving as a mediator that selectively removes phosphate without directly precipitating lithium, thus avoiding lithium losses.
2Productivity
If sodium hydroxide solution is used for leaching, then lithium extraction is achieved, but operating costs increase and alkaline waste stream requires further processing
Solution Approach 1:
The patent changes the chemical parameter from alkaline (sodium hydroxide) to acidic (sulfuric acid) leaching conditions. This parameter change achieves effective lithium extraction while avoiding the high operating costs and waste treatment requirements associated with alkaline leaching processes.
Solution Approach 2:
The patent converts the typically harmful acidic leaching process into a beneficial method by using sulfuric acid to efficiently extract lithium while producing a manageable waste stream that requires less extensive treatment compared to alkaline leaching waste streams.
3Productivity
If roasting at high temperatures is used to extract lithium, then lithium extraction efficiency is high, but energy costs increase
Solution Approach 1:
The patent replaces the thermal/mechanical roasting process with a chemical leaching process using sulfuric acid. This substitution eliminates the need for high-temperature heating while achieving effective lithium extraction, thereby significantly reducing energy costs.
Solution Approach 2:
The patent changes the extraction parameter from thermal (high-temperature roasting) to chemical (acid leaching). This parameter change maintains high lithium extraction efficiency while eliminating the substantial energy input required for heating and roasting operations.
4Productivity
If sulfuric acid concentration is increased to improve lithium dissolution, then lithium extraction efficiency increases, but phosphate co-dissolution increases leading to more impurity removal steps
Solution Approach 1:
The patent optimizes the sulfuric acid concentration parameter to achieve effective lithium dissolution while limiting phosphate co-dissolution. By carefully controlling acid concentration and subsequent pH adjustment, the process maximizes lithium extraction while minimizing phosphate impurities in solution.
Solution Approach 2:
The patent applies preliminary action by adjusting the pH to precipitate phosphate as calcium phosphate before final lithium recovery. This preliminary removal of phosphate prevents it from interfering with subsequent lithium purification steps and product quality.
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
Achieves high lithium recovery (>90%) with minimal energy costs and effective separation from phosphate, reducing lithium losses and operational expenses, while maintaining a stable waste stream.
Implementation Method 1
passing an ore containing one or more minerals rich in lithium and phosphate to an acid leach step thereby producing a pregnant leach solution
Implementation Method 2
subjecting the pregnant leach solution to a series of process steps by which one or more impurity elements are removed, including a low pH impurity removal step conducted at an elevated temperature of greater than 90°C for the precipitation of one or more impurities
Implementation Method 3
recovering lithium as a lithium containing salt product
Data Source
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AI summary
A process for the recovery of lithium from minerals rich in lithium and phosphate, the process comprising passing an ore (1) containing one or more minerals rich in lithium and phosphate to an acid leach step (60) thereby producing a pregnant leach solution (9), subjecting the pregnant leach solution (9) to a series of process steps by which one or more impurity elements (14) are removed, and recovering lithium as a lithium containing salt product (28), wherein the series of process steps by which one or more impurity elements are removed includes a low pH impurity removal step (80) conducted at an elevated temperature for the precipitation of one or more impurities.