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The ore Calamine contain ${ZnCO}_{3}$. The Calamine on heating produces $ZnO$.${ZnCO}_{3}\overset{∆}{\to}ZnO + {CO}_{2}$

Cyanide process, also called Macarthur-forrest Process, method of extracting silver from impure ores by dissolving them in a dilute solution of sodium cyanide in the presence of oxygen. The complex formed in the above process reduced to silver metal by the treatment with zinc.

${O}_{2} + {H}_{2}O + Ag + NaCN\overset{}{\to}Na\left[Ag{\left(CN\right)}_{2}\right] + NaOHNa\left[Ag{\left(CN\right)}_{2}\right]\overset{Zn}{\to}{Na}_{2}\left[Zn{\left(CN\right)}_{4}\right] + Ag$

${SiO}_{2}$ (Silica) is a flux material. It removes impurities as slag. Here, slag consists of Iron in Sulphide ore of $Cu$, here impurity is $FeO$.

$FeO + {SiO}_{2}\overset{}{\to}{FeSiO}_{3}$

Malachite green is ${CuCO}_{3} . Cu{\left(OH\right)}_{2} and cuprite is${Cu}_{2}O$. The ore malachite green on heating gives cupric oxide but not cuprous oxide.</p><p>${CuCO}_{3} . Cu{\left(OH\right)}_{2}\overset{∆}{\to}2CuO + {CO}_{2} + {H}_{2}O$