Concentration Reactions

$4Au + 8NaCN + 2H_2O + O_2 \rightarrow 4Na[Au(CN)_2] + 4NaOH \quad \text{(gold leaching)}$ $2Na[Au(CN)_2] + Zn \rightarrow Na_2[Zn(CN)_4] + 2Au \quad \text{(Zn displacement)}$ $Al_2O_3 + 2NaOH \rightarrow 2NaAlO_2 + H_2O \quad \text{(Bayer's leaching)}$ $2Al(OH)_3 \xrightarrow{\Delta} Al_2O_3 + 3H_2O \quad \text{(calcination of Al(OH)}_3\text{)}$

Extraction Reactions

$2ZnS + 3O_2 \xrightarrow{\Delta} 2ZnO + 2SO_2 \quad \text{(roasting of ZnS)}$ $ZnO + C \xrightarrow{\text{high T}} Zn + CO \quad \text{(carbon reduction of ZnO)}$ $Fe_2O_3 + 3CO \rightarrow 2Fe + 3CO_2 \quad \text{(blast furnace reduction)}$ $CaCO_3 \xrightarrow{\Delta} CaO + CO_2 \quad \text{(limestone decomposition)}$ $CaO + SiO_2 \rightarrow CaSiO_3 \quad \text{(slag formation)}$ $2Cu_2S + 3O_2 \rightarrow 2Cu_2O + 2SO_2 \quad \text{(Bessemer step 1)}$ $Cu_2S + 2Cu_2O \rightarrow 6Cu + SO_2 \quad \text{(self-reduction step 2)}$

Net Reaction — Cu Self-Reduction

$Cu_2S + O_2 \rightarrow 2Cu + SO_2 \quad \text{(net Bessemer reaction)}$

Hall-Heroult Reactions

$Al_2O_3 \xrightarrow{\text{cryolite melt, electrolysis}} Al + O^{2-}$ $Al^{3+} + 3e^- \rightarrow Al \quad \text{(cathode)}$ $C + 2O^{2-} \rightarrow CO_2 + 4e^- \quad \text{(anode)}$

Refining Reactions

$Ni + 4CO \xrightarrow{330-350\text{ K}} Ni(CO)_4 \xrightarrow{450-470\text{ K}} Ni + 4CO \quad \text{(Mond process)}$ $Ti + 2I_2 \xrightarrow{\sim 870\text{ K}} TiI_4 \xrightarrow{\sim 1700\text{ K, W filament}} Ti + 2I_2 \quad \text{(Van Arkel)}$ $HgS + O_2 \xrightarrow{\Delta} Hg + SO_2 \quad \text{(cinnabar roasting)}$