How is leaching carried out in case of low grade copper ores?

(N/A) In the case of low-grade copper ores,leaching is carried out using acid or bacteria in the presence of air. In this process,copper dissolves into the solution as $Cu^{2+}$ ions.
$Cu_{(s)} + 2H^{+}_{(aq)} + \frac{1}{2}O_{2(g)} \to Cu^{2+}_{(aq)} + H_2O_{(l)}$
The resulting solution is then treated with scrap iron or $H_2$ gas to recover metallic copper.
$Cu^{2+}_{(aq)} + H_{2(g)} \to Cu_{(s)} + 2H^{+}_{(aq)}$