Lithium Carbonate Production via Low-Acidity Double Decomposition
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Solution Overview
Problem
Current methods for preparing lithium carbonate from lithium fluoride are cumbersome, costly, and hazardous due to the use of corrosive hydrofluoric acid, requiring repeated decomposition and a severe acid environment, which complicates equipment protection and operator safety.
Innovation Solution
A method involving pulping crude lithium fluoride, followed by double decomposition in a calcium chloride solution with an alkaline substance, and subsequent lithium carbonate precipitation in a low-acidity environment, allowing for single-step fluoride removal and decomposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional acidolysis is used to decompose lithium fluoride, then lithium carbonate can be produced, but the process consumes a lot of acid, has low decomposition rate, and requires repeated decomposition leading to long technological process and high cost
Solution Approach 1:
The patent changes the chemical parameters of the decomposition process by using sulfuric acid instead of conventional acids, and by controlling the pH value within a specific range (0.5-3). This parameter change enables complete decomposition in a single step with high decomposition rate, eliminating the need for repeated decomposition operations and significantly shortening the technological process.
Solution Approach 2:
The patent performs preliminary pulping of crude lithium fluoride before decomposition, creating an optimal physical state for the subsequent decomposition reaction. This preliminary action ensures that the decomposition proceeds efficiently in a single step, preventing the need for repeated operations and reducing overall process time.
2Productivity
If conventional acidolysis is used to decompose lithium fluoride, then lithium carbonate can be produced, but the process consumes a lot of acid and requires enormous investment for corrosion prevention equipment
Solution Approach 1:
The patent changes the acid selection parameter to sulfuric acid, which has lower volatility and less severe corrosivity compared to conventional acids like hydrofluoric acid. By controlling the pH within the range of 0.5-3, the process achieves high decomposition efficiency while significantly reducing the requirements for corrosion prevention equipment and lowering investment costs.
Solution Approach 2:
The patent uses a relatively inexpensive acid (sulfuric acid) that can be readily available and does not require expensive specialized handling equipment. This approach replaces the need for costly corrosion-resistant materials and complex safety systems required when using highly corrosive acids, thereby reducing device complexity and investment requirements.
3Productivity
If conventional acidolysis is used to decompose lithium fluoride, then lithium carbonate can be produced, but the process produces highly corrosive and volatile hydrofluoric acid making it difficult to protect operators
Solution Approach 1:
The patent changes the chemical parameter of the acid used from conventional volatile and highly corrosive acids to sulfuric acid, which has lower volatility and less severe corrosivity. By maintaining pH within the controlled range of 0.5-3, the process achieves complete decomposition capability while dramatically reducing the generation of harmful volatile acids, thereby protecting operator safety and eliminating the need for extremely stringent protective measures.
Solution Approach 2:
The patent converts the potentially harmful decomposition process into a safer operation by selecting sulfuric acid, which transforms the harmful volatile hydrofluoric acid production into a controlled process with minimal harmful emissions. This parameter change turns a hazardous process into a safer operation while maintaining full decomposition capability.
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 simplifies the process, reduces costs, and enhances operator safety by achieving high lithium recovery rates in a low-acidity environment, with a single-step fluoride removal and decomposition process.
Implementation Method 1
double decomposition by adding the crude lithium fluoride pulp-like material obtained in the step a into a boiling calcium chloride solution, and then adding an alkaline substance to prepare a lithium chloride solution
Implementation Method 2
lithium carbonate precipitation by heating the lithium chloride solution obtained in the step b, adding a carbonate solution according to the mass of lithium in the lithium chloride solution, stirring at a constant temperature, and filtering, wherein a filter cake is a lithium carbonate product
Data Source
AI summary
A method for preparing industrial grade lithium carbonate from crude lithium fluoride includes the following steps: a, pulping by stirring crude lithium fluoride into a pulp, and adding an acid to prepare a crude lithium fluoride pulp-like material; b, double decomposition by adding the lithium fluoride pulp-like material obtained in the step a into a boiling calcium chloride solution, and then adding an alkaline substance to obtain a lithium chloride solution; c, lithium carbonate precipitation by heating the lithium chloride solution obtained in the step b, adding a carbonate solution according to the mass of lithium in the lithium chloride solution, stirring at a constant temperature, and filtering, wherein the filter cake is a lithium carbonate product. The lithium fluoride is decomposed at one time in a low-acidity environment; fluoride ions are removed; and a double decomposition reaction is used to decompose the lithium fluoride into lithium ions and calcium fluoride precipitates.