How is copper extracted from low grade copper ores?

(N/A) Copper is extracted from low grade ores using the process of hydrometallurgy,specifically leaching.
$1$. The ore is treated with an aqueous solution of acid or bacteria,which dissolves the copper ions into the solution while leaving the impurities behind.
$2$. The resulting solution containing $Cu^{2+}$ ions is then treated with scrap iron $(Fe)$ or hydrogen gas $(H_2)$ to reduce the copper ions to metallic copper.
$3$. The chemical reaction involved is: $Cu^{2+}(aq) + H_2(g) \rightarrow Cu(s) + 2H^+(aq)$ or $Cu^{2+}(aq) + Fe(s) \rightarrow Cu(s) + Fe^{2+}(aq)$.