Solar Salt Recrystallization for Bromide Removal
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Solution Overview
Problem
Current methods for producing high purity solar salt from sea and sub-soil brines are either costly, energy-intensive, or ineffective in removing trace element impurities like bromine and iodine, which are detrimental to industrial applications, and often result in salt loss and high capital investment.
Innovation Solution
A cost-effective process involving solar recrystallization of solar sea salt using seawater to achieve high purity salt with reduced impurities, where salt is mixed with seawater to saturation, evaporated, and then washed to produce high purity salt without additional equipment or energy sources, allowing for the reuse of saturated brine and reduction of impurities below 10 ppm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional purification methods are used to remove impurities from solar salt, then salt purity is improved, but production cost and energy consumption increase significantly
Solution Approach 1:
The patent applies preliminary action by removing impurities during the solar evaporation process itself rather than after salt production. By controlling evaporation conditions and using pre-treated brine, impurities are eliminated in advance, avoiding the need for energy-intensive post-purification processes while maintaining high salt purity
Solution Approach 2:
The patent replaces mechanical/thermal purification systems with a chemical process approach. Instead of using mechanical filtration or thermal evaporation for purification, the invention uses chemical reactions during solar evaporation to selectively remove impurities, thereby reducing energy consumption while achieving high purity
2Manufacturing precision
If conventional purification methods are used to remove impurities from solar salt, then salt purity is improved, but capital investment and equipment complexity increase
Solution Approach 1:
The patent implements preliminary action by integrating impurity removal into the solar evaporation process itself. By preparing brine in advance and controlling evaporation conditions, the system achieves high purity salt without requiring complex post-purification equipment, thereby reducing capital investment and equipment complexity
Solution Approach 2:
The patent applies self-service by using the solar evaporation process itself to perform purification. The system leverages the natural evaporation process and chemical reactions to remove impurities automatically, eliminating the need for additional purification equipment and reducing both capital investment and operational complexity
3Reliability
If trace element impurities like bromine and iodine are removed from salt, then industrial applicability is improved, but production cost increases
Solution Approach 1:
The patent applies preliminary action by removing trace element impurities during the brine preparation and evaporation process rather than after salt production. By using pre-treated brine and controlling evaporation conditions, the system eliminates bromine and iodine at the source, achieving high industrial applicability without increasing production cost
Solution Approach 2:
The patent converts the harmful effect of trace element impurities into a beneficial process by using them as indicators to control evaporation timing. The presence of these impurities helps determine the optimal evaporation point, allowing their removal through controlled solar evaporation while maintaining cost-effectiveness and improving industrial applicability
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 process achieves high purity solar salt (>99.5% NaCl) with impurities below 10 ppm, reducing downstream purification costs and minimizing waste, while being environmentally friendly and scalable, without salt loss or significant capital investment.
Implementation Method 1
spreading the saturated brine as obtained in step (i) in a pre-crystallizer to effect solar evaporation till 27° Be′ saturated brine
Implementation Method 2
solar recrystallization of solar sea salt using seawater to achieve high purity salt
Data Source
AI summary
The invention discloses an improvement over the existing process of producing solar salt of high purity from seawater and minimizes the need for downstream purification. More particularly, the invention teaches the practical utility of recrystallization of salt in solar salt pans using seawater itself as the dissolving medium. The resultant recrystallized salt is obtained with a yield up to 80% and with much reduced levels of impurities. Special mention is made of the bromide level which is reduced 7-10 fold. The invention is most ideal for trace impurities which reside in the salt crystal lattice and are difficult to dislodge by conventional methods adopted for salt purification and where conventional recrystallization would be cost ineffective and scalability would pose a problem. The invention can be practiced by solar salt works based on seawater and where spare land is available to set up additional crystallizers required for the purpose of recrystallization.