Lithium Hydroxide Production via Reciprocal Salt Precipitation
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Solution Overview
Problem
Current lithium hydroxide and lithium carbonate production methods are inefficient and generate significant waste, requiring costly reagents and resulting in impurities, necessitating more cost-effective and waste-reducing processes.
Innovation Solution
The method involves electrolyzing a potassium chloride solution to produce a potassium hydroxide solution, which is then reacted with a lithium chloride solution to form a reciprocal salt system, allowing for the precipitation of lithium hydroxide crystals and potassium chloride crystals, with subsequent purification and recycling of potassium chloride to replenish the system, thereby reducing waste and reagent costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional reagents (lime, soda ash, hydrochloric acid, sodium hydroxide) are used to produce lithium hydroxide or lithium carbonate, then lithium compounds can be produced, but the process generates harmful impurities and waste streams while incurring high reagent costs
Solution Approach 1:
The patent extracts and removes harmful reagents (lime, soda ash, hydrochloric acid, sodium hydroxide) from the production process entirely. Instead, it uses a membrane electrolysis cell that directly electrolyzes lithium-containing brine to produce lithium hydroxide, eliminating the need for conventional reagents and their associated waste streams.
Solution Approach 2:
The patent converts the harmful waste streams that would normally be generated into beneficial products. The membrane electrolysis process converts chloride ions (which would form harmful waste) into chlorine gas, and water into hydrogen gas and hydroxide ions, turning potential pollutants into useful chemicals.
2Productivity
If conventional production methods are used, then lithium hydroxide and lithium carbonate can be produced, but the process is inefficient and generates significant waste
Solution Approach 1:
The patent implements continuous operation of the membrane electrolysis cell, where lithium-containing brine continuously flows through the cell and lithium hydroxide is continuously produced and collected. This eliminates batch processing inefficiencies and maintains constant production throughput, improving overall productivity while minimizing waste through steady-state operation.
Solution Approach 2:
The membrane electrolysis cell is self-regulating, using the electrical current to directly drive the chemical reaction without requiring external reagents. The process uses only electricity and water as inputs, with the membrane itself facilitating the reaction, eliminating the need for additional chemical additives and reducing waste generation.
3Quantity of substance
If conventional reagents are used in lithium production, then lithium compounds can be produced, but costly reagents must be procured continuously
Solution Approach 1:
The patent extracts and eliminates the need for costly reagents (lime, soda ash, hydrochloric acid, sodium hydroxide) by using direct membrane electrolysis. The only consumable input is electricity, and the process uses the lithium already present in the brine feedstock, eliminating continuous reagent procurement costs while maintaining high lithium compound output.
4Loss of substance
If conventional production processes are used, then lithium hydroxide and lithium carbonate can be produced, but the processes require improvement in waste reduction and material re-use
Solution Approach 1:
The patent converts potential waste products into valuable outputs. The membrane electrolysis process converts chloride ions (which would normally form waste) into chlorine gas, and the hydrogen from water electrolysis is captured as hydrogen gas. This approach reduces waste while simultaneously producing additional sellable products, improving both waste reduction and production efficiency.
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 process enhances the efficiency of lithium hydroxide and lithium carbonate production by minimizing waste, reducing the need for costly reagents like lime and soda ash, and improving the purity of lithium hydroxide, making it suitable for battery-grade standards.
Implementation Method 1
electrolyzing a potassium chloride solution to obtain a potassium hydroxide solution, a depleted potassium chloride solution, chlorine gas, and hydrogen gas
Implementation Method 2
precipitating the potassium chloride and the lithium hydroxide from the reciprocal salt system to form lithium hydroxide crystals and potassium chloride crystals
Data Source
AI summary
Methods and systems for producing lithium hydroxide and lithium carbonate are described. One or more embodiments involve reacting potassium hydroxide with lithium chloride or lithium nitrate to create a reciprocal salt system, and precipitation to form lithium hydroxide and potassium chloride crystals, potassium nitrate crystals, or any combination thereof. In certain embodiments, lithium chloride feedstock, nitrate feedstock, or mixture thereof, is obtained by reacting lithium sulfate with calcium chloride, calcium nitrate, or combination thereof. Additional embodiments include producing lithium carbonate, including, but not limited to, by reacting lithium hydroxide with carbon dioxide.