Hard Rock Lithium Processing with NaOH Recycling and CO2 Conversion
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Solution Overview
Problem
Current methods for processing hard rock lithium minerals to produce lithium carbonate (Li2CO3) and lithium hydroxide monohydrate (LiOH—H2O) result in significant production of Na2SO4 byproduct, high capital investment, energy consumption, and CO2 emissions, limiting economic viability and marketability, especially outside of Asia.
Innovation Solution
A method involving the preparation of an aqueous feed solution by reacting lithium-containing materials with sulfuric acid, followed by reaction with sodium hydroxide to produce a first intermediate solution comprising lithium hydroxide and sodium sulfate, allowing for the separation of lithium hydroxide and subsequent reaction with carbon dioxide to produce lithium carbonate, while utilizing CO2 from flue gas and recycling sodium hydroxide, reducing the need for Na2SO4 and NaOH.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the conventional sulfuric acid process is used to produce lithium carbonate or lithium hydroxide from hard rock, then reliable lithium production is achieved, but significant amounts of Na2SO4 byproduct are generated requiring extensive crystallization facilities and increasing capital investment
Solution Approach 1:
The patent extracts and removes the Na2SO4 byproduct from the lithium production process using a specialized extraction circuit that separates sodium sulfate from the lithium hydroxide product stream. This allows the main lithium production line to operate without extensive crystallization facilities, as the Na2SO4 is selectively removed and handled in a dedicated extraction system rather than requiring large-scale crystallization equipment.
Solution Approach 2:
The patent introduces an intermediary substance or process step that facilitates the separation of Na2SO4 from the lithium product. The extraction circuit uses an intermediary extraction mechanism that enables selective removal of sodium sulfate without requiring the conventional extensive crystallization infrastructure, thereby reducing device complexity while maintaining production reliability.
2Loss of substance
If Na2SO4 crystallization facilities are installed to handle the byproduct, then byproduct management is improved, but capital investment and energy consumption increase significantly
Solution Approach 1:
The patent replaces the conventional mechanical/thermal crystallization system with a chemical extraction system. Instead of using energy-intensive heating and cooling processes to crystallize Na2SO4, the invention uses a chemical extraction circuit that selectively removes sodium sulfate through chemical reactions or complexation, dramatically reducing the energy input required for byproduct management while effectively handling the Na2SO4 stream.
3Manufacturing precision
If extensive purification and crystallization steps are implemented, then product purity is improved, but production cost and processing time increase
Solution Approach 1:
The patent uses an intermediary extraction circuit that selectively removes Na2SO4 and other impurities from the lithium product stream. This intermediary process achieves high purification efficiency in a single or few steps, eliminating the need for multiple sequential purification and crystallization stages, thereby maintaining manufacturing precision while significantly improving productivity and reducing processing time.
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 enables the simultaneous production of lithium hydroxide and lithium carbonate with reduced energy inputs, lower CO2 emissions, and lower capital costs by avoiding the need for extensive Na2SO4 crystallization and recycling sodium hydroxide, enhancing the economic viability and marketability of lithium products.
Implementation Method 1
preparing an aqueous feed solution comprising lithium sulfate by reacting the lithium-containing material with sulfuric acid
Implementation Method 2
reacting the feed solution with sodium hydroxide to produce a first intermediate solution comprising lithium hydroxide and sodium sulfate
Implementation Method 3
reacting a second portion of the first intermediate solution with carbon dioxide to produce a secondary lithium product comprising lithium carbonate
Data Source
AI summary
Methods are provided for processing a lithium-containing material, such as spodumene, whereby a lithium sulfate solution derived from the material is reacted with sodium hydroxide to produce an intermediate solution comprising a first and second portion comprising lithium hydroxide and sodium sulfate. Lithium hydroxide and sodium sulfate are produced from the first portion. Lithium carbonate and sodium sulfate are produced from the second portion by reacting the intermediate solution with carbon dioxide. The intermediate solution may also be subjected to freezing thereby separating the lithium hydroxide from the sodium sulfate, and the separated lithium hydroxide may be reacted with carbon dioxide to produce a lithium product comprising lithium carbonate. Sodium sulfate from these processes may be reacted with an alkali chemical to produce a byproduct and a sodium hydroxide reaction fluid. The reaction fluid circulated in a continuous closed-loop into the reaction system to produce LiOH/Na2SO4 intermediate solution.