Magnesium Chloride Production With In Situ Acid-Alkali Generation
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Solution Overview
Problem
The Dow method for producing magnesium from seawater requires large quantities of alkali and hydrochloric acid, leading to high chemical costs.
Innovation Solution
A system comprising a crystallization unit, precipitation unit, removal unit, acid-alkali generation unit, and reaction unit, which efficiently uses sodium hydroxide and hydrochloric acid generated in situ to produce magnesium chloride aqueous solution, reducing chemical consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the Dow method is used to produce magnesium from seawater, then magnesium can be recovered, but large quantities of alkali and hydrochloric acid are required increasing chemical costs
Solution Approach 1:
The system uses an acid-alkali generation unit that produces sodium hydroxide and hydrochloric acid from reaction liquid generated during the magnesium recovery process. This self-generated acid and alkali are then reused in the crystallization and reaction units, making the system self-sufficient and eliminating the need to purchase large quantities of external chemicals, thereby reducing chemical costs
Solution Approach 2:
Instead of discarding the reaction liquid containing divalent cations after the precipitation unit, the system recovers and utilizes it by feeding it to the acid-alkali generation unit. This recovered reaction liquid is then used to generate the acid and alkali needed for subsequent processing steps, transforming waste into a valuable resource and reducing overall chemical consumption
2Productivity
If large quantities of alkali and hydrochloric acid are used in the Dow method, then magnesium hydroxide and magnesium chloride can be produced, but chemical costs increase
Solution Approach 1:
The system establishes a continuous cycle where the reaction liquid from the precipitation unit is continuously fed to the acid-alkali generation unit, which continuously produces sodium hydroxide and hydrochloric acid for reuse in the crystallization and reaction units. This continuous regeneration and reuse of chemicals maintains high productivity while significantly reducing the net quantity of chemicals required from external sources
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
Reduces chemical costs by generating sodium hydroxide and hydrochloric acid within the system, thereby lowering overall production expenses.
Implementation Method 1
the crystallization unit crystallizes magnesium hydroxide by adding a sodium hydroxide aqueous solution to water to be treated using seawater as a raw material, and generates reaction slurry in which particles of the magnesium hydroxide are dispersed
Implementation Method 2
the precipitation unit stores the reaction slurry to precipitate the particles, and separates the reaction slurry into a recovered slurry containing the particles at a high concentration and a separated liquid containing the particles at a low concentration
Implementation Method 3
the removal unit removes divalent cations from the water to be treated or the separated liquid to generate a reaction liquid
Implementation Method 4
the acid-alkali generation unit generates a sodium hydroxide aqueous solution and hydrochloric acid from the reaction liquid
Implementation Method 5
the reaction unit adds the hydrochloric acid to the recovered slurry and generates a magnesium chloride aqueous solution
Data Source
AI summary
A system for producing a magnesium chloride aqueous solution includes a crystallization unit configured to generate reaction slurry in which particles of magnesium hydroxide are dispersed by adding a sodium hydroxide aqueous solution to water to be treated, a precipitation unit configured to store reaction slurry, precipitate particles and separate the reaction slurry into recovered slurry and a separated liquid, a removal unit configured to remove divalent cations from the water to be treated or the separated liquid to generate a reaction liquid, an acid-alkali generation unit configured to generate a sodium hydroxide aqueous solution and hydrochloric acid from the reaction liquid, and a reaction unit configured to generate a magnesium chloride aqueous solution by adding hydrochloric acid to the recovered slurry. The acid-alkali generation unit has a main body section configured to generate a sodium hydroxide aqueous solution and hydrochloric acid from the reaction liquid.