Tag: general principles of metallurgy

Questions Related to general principles of metallurgy

In the equation,


$4M + 8 CN^- + 2 H _2O + O _2 \longrightarrow 4[M(CN) _2]^- + 4 OH^-$

the metal M is:

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

  1. Copper

  2. Silver

  3. Gold

  4. Zinc

Show answer
Correct Option: B,C
Explanation:

Cyanide process, also called Macarthur-Forrest Process, method of extracting silver and gold from their ores by dissolving them in a dilute solution of sodium cyanide or potassium cyanide. 


The process was invented in 1887 by the Scottish chemists John S. MacArthur, Robert W. Forrest, and William Forrest.

$4Ag + 8 CN^- + 2 H _2O + O _2 \longrightarrow 4[Ag(CN) _2]^- + 4 OH^-$


$4Au + 8 CN^- + 2 H _2O + O _2 \longrightarrow 4[Au(CN) _2]^- + 4 OH^-$


Hence options B & C are correct.

Select the correct statement(s) :

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

  1. Gravity separation method is used in concentration of oxide ore and carbonate ore

  2. Magnetic separation method is used for separation of non-magnetic rutile and magnetic impurity of chlorapatite

  3. $Fe _3O _4$ is magnetic and impurities non-magnetic

  4. $MnO _2$ is non-magnetic and impurities magnetic

Show answer
Correct Option: A,C
Explanation:
A) Gravity separation is an industrial method of separating two components, either a suspension, or dry granular mixture where separating the components with gravity is sufficiently practical: i.e. the components of the mixture have different specific weight. All of the gravitational methods are common in the sense that they all use gravity as the dominant force. The working principle is to lift the material by vacuum over an inclined vibrating screen covered deck.So by gravity separation we remove impurities present in oxides and carbonates there by oxides and carbonates are concentrated.

B) Magnetic separation is a process in which magnetically susceptible material is extracted from a mixture using a magnetic force. But non magnetic substances are not separated.

C) $Fe _3O _4$, is magnetic and impurities non-magnetic.

D) $MnO _2$, is magnetic substance.

Hence options A  &C are correct.

All minerals are not the ore but all ores are minerals. The extraction of a particular metal depends upon several factors and overall it has to be convenient and economical.


Which of the following statement is true?

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

  1. Na-ethyl xanthate is used as frother exclusively.

  2. Levigation cannot be applied for sulphide in any condition.

  3. Froth floatation can be applied for non-sulphide ore also using suitable activator.

  4. Impurities like S and As are removed as elemental vapor in roasting.

Show answer
Correct Option: C
Explanation:

(A) Sodium ethylxanthate acts as collector and not frother.


(b) Levigation can be used for sulphide ore to remove majority of gangue when density difference is high.

(C) Froth floatation can be used for non-sulphide ores having sulphide impurities, and the ore is recovered by using suitable activator.

(D) During roasting, impurities such as S and As are removed as their volatile oxides $SO _2$ and $As _2O _3$, respectively.

Hence, only option C is true.

Leaching method is used to concentrate the ores of:

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

  1. Gold

  2. Silver

  3. Aluminium

  4. All of these

Show answer
Correct Option: D
Explanation:
Leaching
It involves treatment of ore with leaching agents (like NaOH, NaCN, KCN or other reagents) due to which ore becomes soluble and their impurities remain insoluble. The leaching Process is basically done in the extraction of Al from Alumina.
$Al _2O _3 + 2 NaOH \rightarrow 2NaAlO _2 +  H _2O$ + Impurities

If leaching process is done in case of Ag and Au with NaCN (0.4 to 0.8%) then the process is called as Mac-Arthur Forrest cyanide Process.
$Ag + NaCN \rightarrow NaAg(CN) _2 + $ Impurities
$Au + NaCN \rightarrow NaAu(CN) _2 + $ Impurities

In the leaching of gold by cyanide process, the following reaction takes place: 
$\displaystyle aAu+bKCN+cH _{2}O+dO _{2}\rightarrow eKAu(CN) _{2}+fKOH$
$\displaystyle uAu+vKCN+wH _{2}O+xO _{2}\rightarrow yKAu(CN) _{4}+zKOH$
Identify the correct statements with respect to the stoichiometric coefficients when these reactions are balanced using simplest natural numbers.

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

  1. $d, c, x, u$ are in anthmetic progression

  2. $c, y, w, b$ are in arithmetic progression

  3. $f, b, z, v$ are in geometic progressinon

  4. $d, c,a, b$ are geometnic progression

Show answer
Correct Option: A,B,D
Explanation:

$\displaystyle 4Au+8KCN+2H _{2}O+O _{2}\rightarrow 4KAu(CN) _{2}+4KOH$
$\displaystyle 4Au+16KCN+6H _{2}O+3O _{2}\rightarrow 4KAu(CN) _{4}+12KOH$
$a = 4$      $ b = 8$       $c = 2$      $ d = 1$        $e = 4$               $f = 4$
$u = 4$     $ v = 16$       $ w = 6$       $ x = 3$     $ y = 4$           $ z = 12$ 

The principle behind froth floatation is:

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

  1. preferential wetting of ore and gangue particles.

  2. difference is specific gravity of ore and gangue particles.

  3. magnetic properties of ore and gangue.

  4. electrical properties of gangue particles.

Show answer
Correct Option: A
Explanation:

Froth flotation commences by comminution (that is, crushing and grinding), which is used to increase the surface area of the ore for subsequent processing and break the rocks into the desired mineral and gangue in a process known as liberation, which then has to be separated from the desired mineral. The ore is ground into a fine powder and mixed with water to form a slurry. The desired mineral is rendered hydrophobic by the addition of a surfactant or collector chemical. The particular chemical depends on which mineral is being refined. As an example, pine oil is used to extract copper. This slurry (more properly called the pulp) of hydrophobic mineral-bearing ore and hydrophilic gangue is then introduced to a water bath which is aerated, creating bubbles. The hydrophobic grains of mineral-bearing ore escape the water by attaching to the air bubbles, which rise to the surface, forming a foam or a scum (more properly called a froth). The froth is removed and the concentrated mineral is further refined.

Iron ores are concentrated by:

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

  1. froth floatation method

  2. magnetic separation method

  3. amalgamation method

  4. none of these

Show answer
Correct Option: B
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.

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

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

  1. bleaching

  2. leaching

  3. roasting

  4. calcination

Show answer
Correct Option: B
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.

Bayer's process is used for the concentration of ______ ore.

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

  1. aluminium

  2. zinc

  3. copper

  4. iron

Show answer
Correct Option: A
Explanation:

Bayer's process is used for the concentration of aluminium ore, bauxite. In this process, the impurities like iron oxide and silica are removed.

Enrichment of ore is also known as:

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

  1. concentration of ore

  2. ore dressing

  3. both $A$ and $B$

  4. none of the above

Show answer
Correct Option: C
Explanation:

Concentration of ore is also k/a enrichment of ore or one dressing. All the method depend on some difference in physical or chemical properties of gangue.