Urea Hydrothermal Precipitation for Salt Lake Brine Separation
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Solution Overview
Problem
Current methods for extracting lithium and magnesium from salt lake brine face challenges due to their similar chemical properties, high Mg/Li ratios, and environmental concerns, with existing technologies being complex, energy-intensive, and prone to equipment corrosion and pollution.
Innovation Solution
A method using urea as a precipitant for hydrothermal precipitation to selectively separate magnesium ions from lithium ions, allowing for the efficient extraction of high-purity magnesium oxide and battery-grade lithium carbonate without introducing other metal ions or diluting the brine solution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If coprecipitation method is used to extract lithium from salt lake brine, then lithium can be extracted, but other metal ions are introduced and strong adsorption occurs on solid product surface making filtration and washing difficult
Solution Approach 1:
The patent extracts only magnesium ions from the brine solution using urea precipitation, leaving lithium ions and other beneficial ions in the solution. This selective extraction avoids the coprecipitation problem where multiple ions precipitate together, making the solid product easy to filter and wash without strong adsorption of other ions.
Solution Approach 2:
Urea acts as an intermediary precipitant that selectively binds with magnesium ions to form magnesium carbonate precipitate, while not interfering with lithium ions. This intermediary substance enables selective separation without introducing harmful side effects or strong adsorption properties that would complicate filtration.
2Reliability
If calcination technology is used for lithium extraction, then the process is mature and can be applied to industrial production, but energy consumption is high and equipment corrosion is serious
Solution Approach 1:
The patent changes the chemical parameters of the precipitation process by using urea instead of traditional hydroxide precipitants. This parameter change allows magnesium to precipitate as carbonate at milder conditions, reducing energy consumption and equipment corrosion while maintaining process reliability and industrial applicability.
3Productivity
If solvent extraction is used, then lithium can be extracted, but the concentration of hydrochloric acid is very high which seriously corrodes the equipment
Solution Approach 1:
The patent uses urea, a cheap and environmentally benign substance, as the precipitant instead of concentrated hydrochloric acid. Urea decomposes safely and does not cause severe equipment corrosion, making the process more sustainable and reducing maintenance costs while maintaining effective lithium extraction.
4Ease of manufacture
If ion sieve adsorption method is used, then the method is low cost and pollution-free, but the ion sieve is usually in powdered form with poor fluidity and permeability which is difficult to be applied in industry
Solution Approach 1:
The patent replaces the mechanical adsorption system (ion sieve in powdered form) with a chemical precipitation system using urea. This substitution transforms the separation mechanism from physical adsorption to chemical precipitation, producing a solid product with good filtration properties that is suitable for industrial application while maintaining low cost and environmental friendliness.
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 method achieves high extraction rates of lithium ions (>94%) and produces high-purity magnesium oxide (>99.5%) and lithium carbonate (>99.5%) with a simple process, reducing environmental impact and operational complexity.
Implementation Method 1
adding urea into the brine to dissolve; placing the solution into the reactor for hydrothermal reaction, the magnesium ion will precipitate
Implementation Method 2
the magnesium ion will precipitate and enter the solid phase; the solid-phase product obtained is white fluffy powder
Implementation Method 3
the solid-phase product obtained is white fluffy powder, which is easy to filter, and the separation process is simple; simultaneously preparing high-purity magnesium oxide
Data Source
AI summary
This invention provides a method for efficiently separating magnesium and lithium from salt lake brine, and simultaneously preparing high-purity magnesium oxide and battery-grade lithium carbonate. The detailed processing steps are as follows: (1) adding urea into the brine to dissolve, (2) placing the solution into the reactor for hydrothermal reaction, the magnesium ion will precipitate and enter the solid phase; (3) filtering and drying the production to get the magnesium carbonate solid, while the lithium ion remains in the liquid phase; (4) after directly concentration and precipitation, the battery-grade lithium carbonate can be obtained, while the calcination of solid-phase product results in the high-purity magnesium oxide. In this method, urea is used as the precipitant to separate magnesium and lithium in salt lake without introducing any new metal ion, and the brine solution is not diluted. The solid product is white and fluffy powder, which is easy to filter and separate. The extraction rate of lithium is high than 94%, and the purity of MgO obtained by calcination is higher than 99.5%.