Waste Sagger Recycling for High-Purity Lithium Phosphate Recovery
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Solution Overview
Problem
There is no effective method for recovering high-purity lithium compounds from waste saggars discarded after high-temperature firing in the production of lithium secondary battery positive electrode active materials, leading to significant waste generation and increased production costs.
Innovation Solution
A method involving crushing, alkali leaching, anion exchange, carbonation, and lithium phosphate precipitation steps to recover high-purity lithium phosphate from waste saggars, with specific conditions for each step to enhance recovery efficiency and purity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional methods are used to recover lithium from waste sagger, then some lithium can be recovered, but the purity is insufficient and trace lithium in wastewater is lost
Solution Approach 1:
The patent applies parameter changes by adjusting pH values at different stages (pH 9-10 for initial precipitation, pH 1.5-2.0 for acidification, pH 10-11 for final lithium phosphate precipitation), temperature (90-100°C for carbonation), and concentration levels to selectively precipitate different compounds and achieve 99.9% purity while recovering trace lithium
Solution Approach 2:
The patent extracts lithium from waste sagger through multiple separation stages: first extracting lithium from the solid matrix via dissolution, then separating it from impurities through selective precipitation, and finally concentrating trace lithium from wastewater through evaporation and re-precipitation
2Manufacturing precision
If multiple purification steps are added to achieve high purity lithium phosphate, then purity increases, but process complexity and cost increase
Solution Approach 1:
The patent segments the purification process into distinct functional stages: dissolution of waste sagger, selective precipitation of impurities (Al(OH)3, Fe(OH)3, SiO2), carbonation to form Li2CO3, acidification to LiCl, and final precipitation of Li3PO4. Each stage targets specific impurities or lithium compounds, achieving 99.9% purity through systematic division of the complex purification task
Solution Approach 2:
The patent uses parameter changes (pH adjustment, temperature control, concentration variation) to achieve selective precipitation and separation at each stage, allowing high purity to be obtained through controlled chemical reactions rather than complex physical separation equipment
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
The method achieves a lithium recovery rate of 99.9% purity lithium phosphate, maximizing the recovery of valuable lithium compounds from waste saggars and reducing production costs by recycling them into lithium-ion batteries.
Implementation Method 1
adding an alkali leaching agent and water to the waste sagger crushed material and then allowing a reaction to occur therebetween to prepare a waste sagger crushed material dissolution reaction slurry
Implementation Method 2
allowing a filtrate obtained in a liquid phase through the primary solid-liquid separation to flow through an anion exchange resin to perform an anion exchange reaction
Implementation Method 3
performing a carbonation reaction on a flow-through of the anion exchange reaction to prepare a carbonation reaction liquid
Implementation Method 4
performing reverse osmosis concentration on a filtrate obtained in a liquid phase through the secondary solid-liquid separation
Implementation Method 5
performing a heating fractional precipitation reaction on a concentration liquid obtained through the reverse osmosis concentration
Implementation Method 6
performing a lithium phosphate precipitation reaction on a filtrate obtained in a liquid phase through the tertiary solid-liquid separation
Data Source
AI summary
The present invention provides an optimized method for recovering high-purity lithium phosphate from a lithium-containing composite oxide deposited on an eroded surface of a waste sagger discarded. Therefore, when the method for producing high-purity lithium phosphate from a waste sagger of the present invention is used, it is expected not only to be able to produce high-purity lithium phosphate that can be used for manufacturing lithium secondary batteries by recycling a discarded waste sagger, but also to be able to recycle a positive electrode active material, iron oxide, alumina, silicate, and calcium carbonate obtained as by-products during the production process of the lithium phosphate.