Which reducing agent is employed to get copper from the leached low-grade copper ore ?

Explanation

Copper can be obtained from low-grade ore through the process of leaching using acid or bacteria (leaching is a proces in which ore is treated with suitable reagent that dissolves ore but not impurities).
The solution containing copper can be reduced with the help of reducing agents such as scrap iron or `H_(2)` to get copper metal.
`Cu^(2+)(aq)+Fe to Cu (s) + Fe^(2+)(aq)`
`Cu^(2+)(aq)+H_(2)(g) to Cu (s) + 3H^(+)(aq)`