Roasting and Calcination Questions in English

(A) Calcination is a process of heating an ore in a limited supply of air to convert carbonates or hydrated oxides into their respective metal oxides.
$ZnO$ and $MgO$ are already present in their oxide forms,hence they do not require calcination.

(C) The reduction of metal sulphides to metals is thermodynamically unfavorable compared to the reduction of metal oxides.
Metal oxides are generally easier to reduce using common reducing agents like $C$ or $CO$ because the formation of $CO_2$ is highly exothermic.
In contrast,the reduction of metal sulphides is difficult and often requires more energy.
Therefore,sulphide ores are first converted into metal oxides through a process called roasting,which makes the subsequent reduction to metal much more efficient.

(B) Roasting is a metallurgical process in which an ore is heated in a regular supply of air at a temperature below the melting point of the metal.
$I$. Roasting is used to convert sulfide ores into oxides. This statement is correct.
$II$. Roasting is generally an exothermic process because the oxidation of sulfide ores releases a significant amount of heat. This statement is correct.
$III$. Heating hydrated oxides and oxysalt ores to remove moisture and volatile impurities is known as Calcination,not Roasting. This statement is incorrect.
$IV$. Roasting is performed after the concentration of the ore to convert the concentrated ore into a form suitable for reduction. This statement is correct.
Therefore,statements $I, II,$ and $IV$ are correct.

(C) Calcination is a process of heating an ore in a limited supply of air or in the absence of air to remove volatile impurities or water of hydration,or to decompose carbonates into oxides.
$PbCO_3 \to PbO + CO_2$ is a calcination reaction.
$Fe_2O_3 \cdot 3H_2O \to Fe_2O_3 + 3H_2O$ is a calcination reaction (removal of water).
$PbS \to PbSO_4$ is an oxidation reaction (roasting),not calcination,as it involves the addition of oxygen to a sulfide ore.
$PbSO_4$ is already an oxidized form and does not undergo calcination under standard conditions.
Therefore,the reaction $PbS \to PbSO_4$ is a roasting process,not calcination.

(C) Calcination is the process of heating an ore strongly in the absence of air to remove volatile impurities or moisture and to convert carbonates or hydroxides into oxides.
$PbCO_3 \rightarrow PbO + CO_2$ (Calcination)
$Fe_2O_3 \cdot 3H_2O \rightarrow Fe_2O_3 + 3H_2O$ (Calcination)
$PbS + 1.5O_2 \rightarrow PbO + SO_2$ (Roasting)
$PbS + 2O_2 \rightarrow PbSO_4$ (Roasting)
$PbSO_4$ is typically formed during the roasting of sulfide ores,not calcination.
Therefore,the change $PbS \rightarrow PbSO_4$ is not observed during calcination.

(A) Calcination is a process of heating an ore in a limited supply of air or in the absence of air to a temperature below its melting point.
$1$. Carbonate ores decompose to form oxides (e.g.,$ZnCO_3 \rightarrow ZnO + CO_2$).
$2$. Moisture and volatile impurities are removed.
$3$. The process is kept below the melting point to prevent fusion.
$4$. Option $A$ is incorrect because the removal of impurities as elemental vapours is characteristic of roasting or specific distillation processes,not calcination.
$5$. Option $D$ is incorrect because calcination does not involve oxidation; in fact,it is often used for ores that are already in the desired oxidation state or to remove volatile components.

(D) The conversion of hydrated alumina $(Al_2O_3 \cdot 2H_2O)$ into anhydrous alumina $(Al_2O_3)$ is achieved by heating the ore in the absence of air or in a limited supply of air. This process is known as $Calcination$. The chemical reaction is: $Al_2O_3 \cdot 2H_2O(s) \xrightarrow{\Delta} Al_2O_3(s) + 2H_2O(g)$.

(D) Calcination is a process of heating an ore strongly in a limited supply of air or in the absence of air.
Its main functions are:
$1$. To remove moisture from the ore.
$2$. To remove volatile impurities and organic matter.
$3$. To decompose carbonates into oxides (e.g.,$CaCO_3 \rightarrow CaO + CO_2$).
Therefore,all the given options are correct.

(D) Calcination is the process of heating an ore strongly in the absence of air or in a limited supply of air to remove volatile impurities and moisture.
It is typically used for carbonate or hydroxide ores.
In the reaction $MgCO_3 \to MgO + CO_2$,magnesium carbonate is heated to produce magnesium oxide and carbon dioxide,which is a classic example of calcination.
Option $A$ represents a leaching process,while options $B$ and $C$ represent roasting processes.

(D) The process of heating a sulfide ore in the presence of excess air to remove sulfur as sulfur dioxide $(SO_2)$ is known as roasting.
For example,$2FeS_2 + \frac{11}{2}O_2 \rightarrow Fe_2O_3 + 4SO_2$.

(D) The process of heating an ore in the absence of air at a temperature below its melting point is known as $Calcination$.
$Calcination$ is typically used for carbonate and hydroxide ores to remove volatile impurities and moisture,and to convert the ore into its oxide form.

(D) Both $Roasting$ and $Calcination$ are metallurgical processes used to convert ores into their respective metal oxides.
$Roasting$ involves heating the ore in the presence of excess air (usually for sulfide ores).
$Calcination$ involves heating the ore in the absence or limited supply of air (usually for carbonate or hydrated ores).
Therefore,both processes result in the formation of metal oxides.

(B) Calcination is a process of heating an ore strongly in a limited supply of air or in the absence of air.
It is primarily used to remove volatile impurities like water (moisture) and carbon dioxide $(CO_2)$ from carbonate ores.
For example,$ZnCO_3 \xrightarrow{\Delta} ZnO + CO_2 \uparrow$.

(C) Copper pyrites is $CuFeS_2$. During the roasting process,$CuFeS_2$ is heated in the presence of air (oxygen).
The chemical reaction is: $2CuFeS_2 + O_2 \rightarrow Cu_2S + 2FeS + SO_2$.
Thus,the mixture obtained after roasting consists of $Cu_2S$,$FeS$,and $SO_2$ gas is evolved.

(B) Roasting is the process in which the ore is strongly heated in the presence of excess air.
In the extraction of copper,after crushing and concentration of the ore,it is heated in a reverberatory furnace.
Copper pyrites $(CuFeS_2)$ is partially oxidized,and a part of the sulfur in the ore is removed as sulfur dioxide $(SO_2)$.
The given equation $2CuFeS_2 + O_2 \rightarrow Cu_2S + 2FeS + SO_2$ represents the partial roasting of copper pyrites.

(N/A) The extraction of zinc from zinc blende $(ZnS)$ involves the following steps:
$(i)$ Concentration of ore: The ore is concentrated by the froth floatation process.
$(ii)$ Roasting: The concentrated ore is heated in a regular supply of air to convert it into zinc oxide.
$2 ZnS + 3 O_{2} \longrightarrow 2 ZnO + 2 SO_{2}$
$(iii)$ Reduction: Zinc oxide is reduced to zinc metal by heating it with coke.
$ZnO + C \xrightarrow{673 \ K} Zn + CO$
$(iv)$ Electrolytic Refining: The impure zinc is refined by electrolysis using an acidified solution of zinc sulphate $(ZnSO_{4})$ as the electrolyte,with impure zinc as the anode and pure zinc as the cathode.
Anode: $Zn \longrightarrow Zn^{2+} + 2e^{-}$
Cathode: $Zn^{2+} + 2e^{-} \longrightarrow Zn$

(N/A) Roasting is the process of converting sulphide ores to oxides by heating the ores in a regular supply of air at a temperature below the melting point of the metal. For example,sulphide ores of $Zn$,$Pb$,and $Cu$ are converted to their respective oxides by this process.
$2ZnS + 3O_2 \xrightarrow{\Delta} 2ZnO + 2SO_2$
$2PbS + 3O_2 \xrightarrow{\Delta} 2PbO + 2SO_2$
$2Cu_2S + 3O_2 \xrightarrow{\Delta} 2Cu_2O + 2SO_2$
On the other hand,calcination is the process of converting hydroxide and carbonate ores to oxides by heating the ores either in the absence or in a limited supply of air at a temperature below the melting point of the metal. This process causes the escaping of volatile matter leaving behind the metal oxide. For example,hydroxide of $Fe$,carbonates of $Zn$,$Ca$,and $Mg$ are converted to their respective oxides by this process.
$Fe_2O_3 \cdot 3H_2O \xrightarrow{\Delta} Fe_2O_3 + 3H_2O$
$ZnCO_3(s) \xrightarrow{\Delta} ZnO(s) + CO_2(g)$
$CaMg(CO_3)_2 \xrightarrow{\Delta} CaO(s) + MgO(s) + 2CO_2(g)$

(N/A) The concentrated ore should be converted into a form that is suitable for reduction. Generally,sulfide ores are converted into oxides before reduction because it is easier to reduce metal oxides than other compounds like sulfides or carbonates.

(N/A) There are two methods to convert concentrated ore into oxide: $(A)$ Calcination and $(B)$ Roasting.
$(A)$ Calcination: Calcination involves heating the ore in the absence of air or in a limited supply of air. This process removes volatile impurities and leaves behind the metal oxide.
$Fe_{2}O_{3} \cdot xH_{2}O_{(s)} \stackrel{\Delta}{\longrightarrow} Fe_{2}O_{3(s)} + xH_{2}O_{(g)}$
$ZnCO_{3(s)} \stackrel{\Delta}{\longrightarrow} ZnO_{(s)} + CO_{2(g)}$
$CaCO_{3} \cdot MgCO_{3(s)} \stackrel{\Delta}{\longrightarrow} CaO_{(s)} + MgO_{(s)} + 2CO_{2(g)}$
$(B)$ Roasting: In roasting,the ore is heated in a regular supply of air at a temperature below the melting point of the metal.
Some processes involving sulfide ores are:
$2ZnS + 3O_{2} \rightarrow 2ZnO + 2SO_{2}$
$2PbS + 3O_{2} \rightarrow 2PbO + 2SO_{2}$
$2Cu_{2}S + 3O_{2} \rightarrow 2Cu_{2}O + 2SO_{2}$
Copper sulfide ore is heated in a reverberatory furnace. If the ore contains iron,it is mixed with silica before heating. Iron oxide is removed as iron silicate 'slag' and copper is obtained in the form of 'copper matte' which contains $Cu_{2}S$ and $FeS$.
$FeO + SiO_{2} \rightarrow FeSiO_{3}$
The $SO_{2}$ gas produced is used in the production of $H_{2}SO_{4}$.

(N/A) There are two main methods to convert concentrated ore into oxide: $(A)$ Calcination and $(B)$ Roasting.
$(A)$ Calcination: Calcination involves heating the ore in the absence or limited supply of air. This process removes volatile impurities and leaves behind the metal oxide.
$Fe_2O_3 \cdot xH_2O(s) \xrightarrow{\Delta} Fe_2O_3(s) + xH_2O(g)$
$ZnCO_3(s) \xrightarrow{\Delta} ZnO(s) + CO_2(g)$
$CaCO_3 \cdot MgCO_3(s) \xrightarrow{\Delta} CaO(s) + MgO(s) + 2CO_2(g)$
$(B)$ Roasting: In roasting,the ore is heated in a regular supply of air at a temperature below the melting point of the metal.
Some processes involving sulfide ores are:
$2ZnS + 3O_2 \rightarrow 2ZnO + 2SO_2$
$2PbS + 3O_2 \rightarrow 2PbO + 2SO_2$
$2Cu_2S + 3O_2 \rightarrow 2Cu_2O + 2SO_2$
Copper sulfide ore is heated in a reverberatory furnace. If the ore contains iron,it is mixed with silica before heating. Iron oxide is removed as iron silicate slag $(FeSiO_3)$,and copper is obtained in the form of 'copper matte',which contains $Cu_2S$ and $FeS$.
$FeO + SiO_2 \rightarrow FeSiO_3$
The $SO_2$ gas produced is used in the production of $H_2SO_4$.

(N/A) The process of isolation of metals from concentrated ore involves two main steps:
$(i)$ Conversion to oxide
$(ii)$ Reduction of the oxide to metal
Step $1$: Conversion to oxide:
$(i)$ Calcination: Calcination involves heating the ore in the absence or limited supply of air. It removes volatile matter and moisture,leaving behind the metal oxide:
$Fe_{2}O_{3} \cdot xH_{2}O_{(s)} \stackrel{\Delta}{\longrightarrow} Fe_{2}O_{3_{(s)}} + xH_{2}O_{(g)}$
$ZnCO_{3_{(s)}} \stackrel{\Delta}{\longrightarrow} ZnO_{(s)} + CO_{2_{(g)}}$
$CaCO_{3} \cdot MgCO_{3_{(s)}} \stackrel{\Delta}{\longrightarrow} CaO_{(s)} + MgO_{(s)} + 2CO_{2_{(g)}}$
$(ii)$ Roasting: In roasting,the ore is heated in a regular supply of air in a furnace at a temperature below the melting point of the metal. This is commonly used for sulphide ores:
$2ZnS_{(s)} + 3O_{2_{(g)}} \rightarrow 2ZnO_{(s)} + 2SO_{2_{(g)}}$
$2PbS_{(s)} + 3O_{2_{(g)}} \rightarrow 2PbO_{(s)} + 2SO_{2_{(g)}}$
$2Cu_{2}S_{(s)} + 3O_{2_{(g)}} \rightarrow 2Cu_{2}O_{(s)} + 2SO_{2_{(g)}}$
The sulphide ores of copper are heated in a reverberatory furnace. If the ore contains iron,it is mixed with silica before heating. Iron oxide is removed as iron silicate slag $(FeSiO_{3})$,and copper is produced in the form of copper matte,which contains $Cu_{2}S$ and $FeS$.

(N/A) It is thermodynamically easier to reduce metal oxides than metal sulphides. The reduction of metal sulphides is difficult because the metal-sulphur bond is more stable and the process is less spontaneous compared to the reduction of metal oxides. Therefore,sulphide ores are first converted into oxide ores by roasting,which are then easily reduced to the metal.

(A) Calcination involves heating carbonate ores,which releases $CO_{2}$ gas,a primary greenhouse gas contributing to global warming.
Roasting involves heating sulfide ores,which releases $SO_{2}$ gas,a primary pollutant responsible for acid rain.
Therefore,calcination and roasting lead to global warming and acid rain,respectively.

(B) In the roasting process,metal sulphide $(MS)$ ores are converted into metal oxides,and sulphur is removed in the form of $SO_{2}$ gas.
$2 MS + 3 O_{2} \xrightarrow{\Delta} 2 MO + 2 SO_{2} \uparrow$

(A) $ZnCO_{3(s)} \xrightarrow{\Delta} ZnO_{(s)} + CO_{2(g)}$
Heating in the absence of air or limited supply of air is known as calcination.
$(B)$ $2ZnS_{(s)} + 3O_{2(g)} \longrightarrow 2ZnO_{(s)} + 2SO_{2(g)}$
Heating in the presence of excess air is known as roasting.
Therefore,$(A)$ is calcination and $(B)$ is roasting.

(A) The correct option is $A$.
The reaction is $2ZnS_{(s)} + 3O_{2(g)} \xrightarrow{\Delta} 2ZnO_{(s)} + 2SO_{2(g)}$.
This process is known as roasting,where the sulphide ore is heated in a regular supply of air to convert it into its oxide form at a temperature below the melting point of the metal.

(A) In metallurgy,sulphide ores are first converted into oxides by roasting because it is thermodynamically easier to reduce metal oxides than metal sulphides.
$2 ZnS + 3 O_2 \rightarrow 2 ZnO + 2 SO_2$
Metal oxides are easier to reduce using carbon because the formation of $CO_2$ is more favorable and $CO_2$ is a stable gas,whereas the reduction of sulphides with carbon is difficult and often leads to the formation of $CS_2$,which is less stable and harder to remove.
Therefore,both Statement-$I$ and Statement-$II$ are correct.

(D) Calcination is the process of heating an ore in the absence or limited supply of air to remove moisture and volatile impurities.
Option $A$ is the dehydration of limonite (calcination).
Option $B$ is the calcination of limestone.
Option $C$ is the calcination of dolomite.
Option $D$ $(2PbS + 3O_2 \xrightarrow{\Delta} 2PbO + 2SO_2)$ involves the reaction of sulfide ore with oxygen,which is the definition of roasting.

(B) The extraction of zinc from zinc blende $(ZnS)$ involves the following steps:
$1$. Roasting: Zinc blende is heated in the presence of excess air to convert it into zinc oxide $(ZnS + 3O_2 \rightarrow 2ZnO + 2SO_2)$.
$2$. Reduction: The zinc oxide $(ZnO)$ obtained is then reduced to metallic zinc using carbon (coke) as a reducing agent $(ZnO + C \rightarrow Zn + CO)$.
Therefore,option $B$ is correct.

(A) When sulphide ore is roasted,it is heated in the presence of excess air to form the gas $SO_{2}$.
$S + O_{2} \longrightarrow SO_{2} (X)$
For example: $2ZnS + 3O_{2} \longrightarrow 2ZnO + 2SO_{2}$
Thereafter,$X$ $(SO_{2})$ reacts with $Cl_{2}$ in the presence of activated charcoal to give $Y$ $(SO_{2}Cl_{2})$:
$SO_{2} + Cl_{2} \xrightarrow{\text{activated charcoal}} SO_{2}Cl_{2} (Y)$
Thus,$Y$ is $SO_{2}Cl_{2}$.

(D) The correct statement is given in option $(D)$.
- Roasting involves heating the ore in a regular supply of air.
- Calcination involves heating the ore below its melting point.
- Smelting is the process by which a metal is obtained at temperatures above its melting point.
- Calcination of calcium carbonate $(CaCO_3 \rightarrow CaO + CO_2)$ is an endothermic process as it requires heat to proceed.

(C) Calcination is the process of converting an ore into its oxide by heating it strongly below its melting point in the absence or limited supply of air. Carbonate ores are converted into their respective oxides by the loss of carbon dioxide.
$CaCO_{3} \stackrel{\Delta}{\longrightarrow} CaO + CO_{2} \uparrow$

(D) Roasting is the process of heating an ore in a regular supply of air in a furnace at a temperature below the melting point of the metal. $ZnS$ (zinc blende) is a sulfide ore,and sulfide ores are always subjected to roasting,not calcination,to convert them into their respective oxides. Therefore,the statement that zinc blende is subjected to calcination is false.

(B) Roasting is a metallurgical process in which a sulfide ore is heated in a regular supply of air or oxygen to convert it into its oxide form.
In the reaction $2 PbS + 3 O_2 \longrightarrow 2 PbO + 2 SO_2$,lead sulfide $(PbS)$ is heated in the presence of oxygen to form lead oxide $(PbO)$ and sulfur dioxide $(SO_2)$.
Therefore,this reaction is an example of roasting.
Option $A$ represents calcination,option $C$ represents reduction using carbon,and option $D$ represents slag formation.

(B) In the process of manufacturing wrought iron from cast iron,a reverberatory furnace is lined with limestone $(CaCO_3)$.
$CaCO_3$ acts as a flux to remove impurities like silicon,which is oxidized to $SiO_2$.
$CaO + SiO_2 \longrightarrow CaSiO_3$ (slag).
Thus,$CaCO_3$ is the flux used.

(A) Iron pyrite,i.e.,$FeS_2$,is also known as Fool's Gold.
It is not an ideal choice of ore for the extraction of iron because it produces polluting sulfur-containing gases,such as $SO_2$ and $SO_3$,during the roasting process.
Although it is thermodynamically feasible and stable,the environmental impact of these gases makes it undesirable.
Hence,option $(A)$ is the correct answer.

(C) Roasting is a metallurgical process in which sulphide ores are heated in the presence of excess air to convert them into their corresponding metal oxides.
In the given options,the reaction $2ZnS + 3O_2 \longrightarrow 2ZnO + 2SO_2$ represents the roasting of zinc sulphide $(ZnS)$ ore to form zinc oxide $(ZnO)$.

(D) Calcination is a process of heating an ore in a limited supply of air or in the absence of air to remove volatile impurities and moisture.
It is typically used for carbonate or hydrated oxide ores.
The reaction $Fe_2O_3 \cdot x H_2O \xrightarrow{\Delta} Fe_2O_{3(s)} + x H_2O_{(g)}$ represents the removal of water of hydration from limonite,which is a characteristic calcination process.