This set of Extractive Metallurgy Multiple Choice Questions & Answers (MCQs) focuses on “Mineral Dressing”.
1. Raw materials are processed to get marketable products and waste by some means without destroying the physical and chemical properties of the minerals. The process is known as _____
a) oxidation
b) reduction
c) mineral dressing
d) ore dressing
View Answer
Explanation: Mineral Dressing is an important method of beneficiation. This technique helps to remove substantial portions of gangue and upgrade the raw material. This does not destroy the physical and chemical properties of the minerals. When the mineral dressing is applied to ores it is known as Ore Dressing.
2. Which process liberate valuable components by detaching dissimilar mineral particles from each other?
a) Comminution
b) Concentration
c) Sizing
d) Coagulation
View Answer
Explanation: Comminution serves two purposes, one is detaching dissimilar mineral particles from each other to liberate valuable components. The other purpose of comminution is producing small-sized mineral particles.
3. The percentage of the mineral occurring as free particles to the total of mineral occurring as free and locked forms is called ______
a) degree of locking
b) degree of liberation
c) degree of hardness
d) degree of reduction
View Answer
Explanation: For a certain mineral or phase the degree of liberation is defined as the percentage of the mineral occurring as free particles to the total of mineral occurring as free and locked forms. The converse of this is known as the degree of locking.
4. The particles of an ore consisting of two or more minerals are known as locked particles.
a) True
b) False
View Answer
Explanation: The statement is true. The particles of an ore consisting of a single mineral are called free particles and locked particles when consisting of two or more minerals.
5. In liberation by size reduction process, for the abundant phase to be freed, the particles must be ______
a) coarser in composition than the original grain size
b) equal to the size of the original grain size
c) greater than the size of the original grain size
d) finer in composition than the original grain size
View Answer
Explanation: According to Gaudin’s analytical procedure to show that when a mixture of two phases is crushed, the less abundant phase is freed only when the particles are finer in composition than the original grain size.
6. The majority of concentration processes require particles of which size?
a) Large-sized particles
b) Huge lumps
c) Small-sized particles
d) Medium-sized lumps
View Answer
Explanation: In nature, ores are often available as big lumps which are not suitable for most of the extraction processes. So, there are crushed and ground into small-sized particles.
7. What is the maximum size, approximately, to which comminution of ore is done?
a) 10 mm
b) 8 mm
c) 6 mm
d) 4 mm
View Answer
Explanation: Comminution of ore is done to a maximum of 6 mm and the process is referred to as crushing. When the comminution is done less than 6 mm, it is referred to as grinding.
8. Grinding is carried out mostly in which of the following machines?
a) Ball mill
b) Jaw crushers
c) Gyratory crushers
d) Rolls
View Answer
Explanation: The Grinding process is slower than crushing and is usually carried out in a ball mill or equipment similar to it.
9. Which of the following forces does not act on ore particles in a ball mill?
a) Cataracting
b) Tension force
c) Cascading
d) Frictional forces
View Answer
Explanation: In a ball mill, the ore particles are subjected to forces like Cataracting, cascading, interparticle collisions, rubbing and frictional forces but not tension force.
10. In ore beneficiation method, when mineral particles are subjected to force fields such as magnetic, gravitation and electrical, their behaviour depends on their size.
a) True
b) False
View Answer
Explanation: The statement is true. When minerals are subjected to force fields, it is not only the intrinsic properties like density and magnetic permeability which affects them. The extrinsic properties like mass and size also play an important role in the process.
11. The volume of the particle having dimensions a, b, c can be determined using which of the following equations?
a) V (a, b, c) = π*(diameter of a sphere)3/3
b) V (a, b, c) = π*(diameter of a sphere)3/6
c) V (a, b, c) = π*(diameter of a sphere)2/3
d) V (a, b, c) = π*(diameter of a sphere)3/6
View Answer
Explanation: The volume of the particle can be determined using the equation, V (a, b, c) = Π*(diameter of a sphere)3/6, where the diameter of the sphere whose volume is equal to that of the particle.
12. Which of the following is the most widely used sizing technique in the laboratory?
a) Grinding
b) Crushing
c) Gravity separation
d) Sieving
View Answer
Explanation: Sieving is a mechanism of separating particles by size. In this process, the particles are subjected to mechanical force in a vertical and horizontal direction with the help of a container. The container’s design contains screens with different mesh sizes to separate particles of different size.
13. A crude method in which the coarser particles are selected from an orebody is called ______
a) screening
b) sieving
c) handpicking
d) crushing
View Answer
Explanation: Hand-Picking which is also known as sorting process yields particles which are ideal for certain unit processes and may also contain a high concentration of mineral.
14. What is the basis of separation of ‘screening’ process?
a) Particle size
b) Particle weight
c) Particle mass
d) Particle shape
View Answer
Explanation: The more scientific method of sizing is a screening rather than sorting, whose basis of separation is ‘particle size’. The particles can be separated into two groups, oversized and undersized, using this method.
15. The capacity of ‘screen’ depends on which of the following factors?
a) Size of ore
b) Area of screening surfaces
c) Shape of screen
d) Weight of particle
View Answer
Explanation: The capacity of the screen depends primarily on following factors – the area of screening surface, size of the opening on screening surface, characteristics of ore like specific gravity, moisture content, temperature etc. and type of screening mechanism used.
Sanfoundry Global Education & Learning Series – Extractive Metallurgy.
To practice all areas of Extractive Metallurgy, here is complete set of Multiple Choice Questions and Answers.
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