Producing silica nanoparticles during mineral carbonation

Abstract

An integrated method to synthesize silica nanoparticles and recover critical metals from leachates produced from mineral carbonation. The method includes adding a zwitterion (e.g., an amino acid) into a Si-rich carbonation leachate, where the zwitterion instigates silica precipitation by complexing with aqueous Si species and serving as nucleation agents. During this process, the pH of the leachate is minimally affected, allowing the solution to be recycled for mineral carbonation. The resulting silica nanoparticles can be filtered out, washed with a mild acidic solution to remove impurities, and resuspended in a basic solution. The critical metals retained in the leachate after silica precipitation can be recovered using chemical precipitation or electrodialysis.

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