The impurities of iron present with copper are removed as iron silicate.
$$FeO + Si{O_2} \to \mathop {FeSi{O_3}}\limits_{{\text{Slag}}} $$

\[\begin{align} & 2C{{u}_{2}}S+3{{O}_{2}}\to 2C{{u}_{2}}O+2S{{O}_{2}} \\ & 3C{{u}_{2}}O+\underset{\begin{smallmatrix} \text{(From green} \\ \text{logs of wood)} \end{smallmatrix}}{\mathop{C{{H}_{4}}}}\,\to 6Cu+2{{H}_{2}}O+CO \\ \end{align}\]

Pyrolusite is an oxide ore of $$Mn$$  i.e., $$Mn{O_2}.$$

$$PbO\,\& \,PbS{O_4}$$   get reduced by $$PbS$$  itself which is already present in mixture so because the reduction took place by itself, hence is known as self reduction.
\[\begin{align} & 2PbO+PbS\xrightarrow{\Delta }3Pb+S{{O}_{2}}\uparrow \\ & PbS{{O}_{4}}+PbS\xrightarrow{\Delta }2Pb+2S{{O}_{2}}\uparrow \\ \end{align}\]

Roasting involves heating the ore strongly in presence of excess of air $$\left( {{O_2}} \right).$$

Liquation or distillation is used for purification of metals with low boiling or melting point.

Metals of high reactivity such as $$Na,Mg,Al$$   etc. are extracted from their ores by electrolytic reduction.

$$2C{u_2}O + C{u_2}S \to 6Cu + S{O_2}$$

When $${H_2}{O_2}$$  is reacted with hydrogen sulphide $$\left( {{H_2}S} \right),$$  it form $$S$$  and water. In this reaction $${{H_2}S}$$  is oxidised to sulphur. $${H_2}{O_2}$$  act as oxidising agent.
$${H_2}{O_2} + {H_2}S \to S + 2\,{H_2}O$$

Zone refining is used for metals which are required in very high purity. Semiconductor grade silicon is purified by this method $$(Si, Ge).$$