In order to refine "blister copper" it is melted in a furnance and is strirred with green logs of wood. The purpose is

Blister copper is melted in a furnance and is strired with green logs of wood. It is done to reduce the metallic copper with oxide of copper by the reduction of carbon of wood. This process is called poling.

$$\begin{gathered} 2\mathrm{CuS} +3{\mathrm{O}}_2\to 2{\mathrm{Cu}}_2\mathrm{O}+2{\mathrm{SO}}_2 \\ 3{\mathrm{Cu}}_2\mathrm{O} +{\mathrm{CH}}_4\to 6\mathrm{Cu}+2{\mathrm{H}}_2\mathrm{O}+\mathrm{CO} \end{gathered}$$