<p>Separation and enrichment of cobalt by using zinc powder under hydrothermal conditions were investigated by means of ICP, XRD, and SEM–EDS, and the reaction mechanism was revealed. A two-stage treatment process for cadmium and cobalt enrichment from cadmium-depleted liquid was developed: stage one cemented 99% of cadmium with &lt; 5% cobalt loss and &gt; 72% cadmium in precipitates, while stage two cemented 95.8% of cobalt, reducing cobalt concentration to &lt; 10&#xa0;mg/L. The cobalt precipitate content exceeded 4%, four times that of conventional zinc powder replacement. The improved cobalt cementation by zinc was due to the temperature effects on the H⁺/H₂ redox potential, which inhibits hydrogen evolution and promotes cobalt replacement.</p> Graphical Abstract <p>The separation and enrichment of cobalt from cadmium-depleted liquid in hydrothermal system</p> <p></p>