Chemistry · Science General

Metallurgical Processes

1,403 Questions

This section explores key metallurgical processes including ore concentration, pyrometallurgy, and metal refining. It also covers corrosion and the properties of refractory materials. These chemistry questions are relevant for engineering and science entrance tests.

Pyrometallurgy furnacesMetal refining techniquesCorrosion protection methodsOre concentrationAuto reduction process

Metallurgical Processes Questions

Multiple choice chemistry principles of metallurgy concentration of ore concentration of ores general principles of metallurgy

Iron ores are concentrated by:

  1. froth floatation method

  2. magnetic separation method

  3. amalgamation method

  4. none of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Iron ores are concentrated by magnetic separation method.
In  magnetic separation method, ferromagnetic and nonmagnetic particles in the ore are separated by an electromagnetic separator.

Multiple choice chemistry principles of metallurgy concentration of ore concentration of ores general principles of metallurgy

Chemical method used in concentration of ore is known as ___________.

  1. bleaching

  2. leaching

  3. roasting

  4. calcination
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Leaching is a chemical method of concentration of ores. It involves the treatment of the ore with a suitable reagent so as to make it soluble while impurities remain insoluble. The ore is recovered from the solution by suitable chemical method. Copper is recovered from chemical solutions by leaching processes such as solvent extraction.

Multiple choice chemistry principles of metallurgy concentration of ore concentration of ores general principles of metallurgy

In Bayer's process, the crushed ore is treated with ______ .

  1. hot concentrated caustic soda (NaOH)

  2. cold dilute caustic soda (NaOH)

  3. hot concentrated caustic potash (KOH)

  4. cold dilute caustic potash (KOH)
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Bayer's process is the industrial refining process to refine bauxite to produce alumina. In this process, the crushed ore is treated with hot concentrated caustic soda (NaOH).

Multiple choice chemistry non-metals introduction to non-metals occurence of metals occurrence of metals and non metals

 Copper is extracted from sulphide ore using the method:

  1. Carbon reduction

  2. Carbon monoxide reduction

  3. Auto reduction

  4. None of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
The copper can be extracted from its sulphide ore by the auto reduction process.
The ore is reduced by heat alone.
 
$Cu _2S + O _2 \rightarrow 2Cu + SO _2$

The copper and the oxygen have been reduced (decrease in oxidation state). The sulphur has been oxidised (increase in oxidation state). The reducing agent is the sulphide ion in the copper(I) sulphide.

Hence, the correct option is $C$
Multiple choice chemistry non-metals introduction to non-metals occurence of metals occurrence of metals and non metals

 In the extraction of copper from copper pyrites, iron is removed as:

  1. $FeSO _4$
  2. $FeSiO _3$
  3. $Fe3O _4$
  4. $Fe _2O _3$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
The copper ($II$) ions in the copper pyrite are reduced to copper ($I$) sulphide (which is reduced further to copper metal in the final stage).
The iron in the copper pyrite ends up converted into an iron ($II$) silicate slag which is removed.
$CuFeS _2 + SiO _2 + 4O _2 \rightarrow Cu _2S + 2FeSiO _3 + 3SO _2$
Multiple choice chemistry non-metals introduction to non-metals occurence of metals occurrence of metals and non metals

 Silica is added to roasted copper ore during extraction in order to remove:

  1. cuprous sulphide

  2. ferrous oxide

  3. ferrous sulphide

  4. cuprous oxide
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
Silica is added during smelting in order to remove iron oxides from copper sulphide and oxides. During roasting the iron sulfides react with oxygen (in air or oxygen enriched air) to produce iron oxides (mainly as $FeO$, but with some magnetite $(Fe _3O _4))$ and sulfur dioxide. 
Copper sulfide and iron oxide can mix, but when sufficient silica is added, a separate slag layer is formed. 
The slag forming reaction is:
$FeO + SiO _2 \rightarrow FeO.SiO _2$
Slag is less dense than matte, so it forms a layer that floats on top of the matte.
Multiple choice chemistry non-metals introduction to non-metals occurence of metals occurrence of metals and non metals

Silver can be separated from lead by:

  1. fractional crystallization

  2. amalgamation

  3. cupellation

  4. addition of zinc
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
The Parkes process is a pyrometallurgical industrial process for removing silver from lead during the production of bullion. It is an example of liquid–liquid extraction.
The process takes advantage of two liquid-state properties of zinc. The first is that zinc is immiscible with lead, and the other is that silver is 3000 times more soluble in zinc than it is in lead. When zinc is added to liquid lead that contains silver as a contaminant, the silver preferentially migrates into the zinc. Because the zinc is immiscible in the lead it remains in a separate layer and is easily removed. 
Multiple choice chemistry non-metals introduction to non-metals occurence of metals occurrence of metals and non metals

Aluminium metal is purified by:

  1. Hoopes process

  2. Halls process

  3. Serpecks process

  4. Baeyers process
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

All processes are used in Aluminium metallurgy but the Hoopes process is a metallurgical process, used to obtain the aluminium metal of very high purity.
The Bayer process is the principal industrial means of refining bauxite to produce alumina (aluminium oxide).
The Hall–Héroult process is the major industrial process for smelting aluminium. 
Serpeck's process  is used for the purification of bauxite ore containing silica  as the main impurity
Multiple choice chemistry non-metals introduction to non-metals occurence of metals occurrence of metals and non metals

Heamatite ore is concentrated by:

  1. gravity separation method

  2. forth floatation

  3. amalgamation

  4. hand picking
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Heamatite is an iron oxide with a chemical composition of $Fe _2O _3$. Gravity Separation or Hydraulic Washing (Levigation)

Heamatite ore is concentrated by gravity separation method. This method of concentration of the ore is based on the difference in specific gravities of the metallic ore and gangue particles. Generally metal ores are heavier than the gangue associated with them.
By flowing the powdered ore in a current of water, the lighter rocky impurities can be washed away and the ore particles are left behind. For this, either wilfley table or Hydraulic classifier is used. Generally oxide and carbonate ores are concentrated by this method. i.e. haematite and cerussite.

Multiple choice chemistry chemical thermodynamics system and surroundings introduction to thermodynamics basics of thermodynamics

Which of the following factors is of no significance for roasting sulphide ores to the oxides and not subjecting the sulphide ores to carbon reduction directly?

  1. Metal sulphides are thermodynamically more stable than $CS _2$
  2. $CO _2$ is thermodynamically more stable than $CS _2$

  3. Metal sulphides are less stable than the corresponding oxides
  4. $CO _2$ is more volatile than $CS _2$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The reduction of metal sulfides by carbon reduction process is not spontaneous as the change in Gibb's free energy ($\triangle G$) for such a process is positive. 

The reduction of metal oxides by carbon reduction process is spontaneous as $\triangle G$ for such a process is negative.
Thus $CO _2$ is more stable than $CS _2$ and the metal sulfides are more stable than the corresponding oxides.
Hence, factor listed in $(3)$ is of no. significance.

Multiple choice evs experiments with water water and its types hard and soft water what floats - what sinks

The brownish-white deposit on kettles, heating elements and utensils formed by boiling water is due to:

  1. moisture in the air

  2. temporary hardness of water

  3. permanent hardness of water

  4. reaction of sulphur dioxide in the air with hot water
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The temporary hardness of water is due to the presence of calcium or magnesium bicarbonates. 

The brownish-white deposit on kettles, heating elements, and utensils formed by boiling water are due to the temporary hardness of water. 
It can be removed from water by heating due to which the hydrogen carbonate decomposes to original insoluble carbonate.