# Mine Tailings Valorization by Electrochemically Stimulated Mineralization from Mildly Acidic Conditions

## TL;DR

A new electrochemical method efficiently turns mine tailings water into calcium carbonate, using CO2 and controlled voltages.

## Contribution

A novel electrochemical process for selective calcite precipitation from mine tailings under mildly acidic conditions.

## Key findings

- Electrochemical pH control achieved >1 mol CaCO3 per mol e– at potentials between −1.4 and −1.6 V vs Ag/AgCl.
- Calcite and vaterite phases were selectively produced by adjusting the applied potential.
- Selective calcite precipitation was confirmed in real mine tailings water despite sulfate and trace elements.

## Abstract

This study presents a high-efficiency electrochemical
process for
the mineralization of calcium carbonate (CaCO3) from mildly
acidic mine tailing supernatant water. Electrochemical pH control
was used to promote carbonate speciation and precipitation from CO2-saturated solutions, achieving >1 mol CaCO3 precipitated
per mol e– at applied potentials between −1.4
and −1.6 V vs Ag/AgCl. Product morphology and polymorph selectivity
were tunable via applied potential, yielding calcite and vaterite
phases. Experiments using real mine tailings water confirmed selective
calcite precipitation, despite the presence of sulfate and other trace
elements. These results highlight a viable route for coupling CO2 utilization with mine tailings valorization.