This set of Iron Making Multiple Choice Questions & Answers (MCQs) focuses on “Beneficiation of Iron Ore”.
1. Which category of iron ore can be separated using low intensity magnetic field (200-500 oersteds)?
a) Hematite
b) Magnetite
c) Limonite
d) Siderite
View Answer
Explanation: Magnetite ore of iron is paramagnetic in nature and hence strongly attracted by magnets. Hematite ores are weakly magnetic and require high intensity magnetic field to be separated (12000 oersteds).
2. What should be the density of the gravity separation media for separation to be carried out effectively?
a) Higher than iron oxide and gangue
b) Lower than iron oxide and gangue
c) In between that of gangue and iron oxide
d) Density is not an influential factor
View Answer
Explanation: The density of the gravity separation medium must be in between that of iron oxide and gangue. The heavier iron oxide sinks and the lighter gangue materials are carried over as tailings.
3. What type of magnetic separation will you use to beneficiate iron ore fines of size less than 150 mesh?
a) Wet magnetic separation
b) Dry magnetic separation
c) Magnetic separation along with jigging
d) The iron ores of size 150 mesh cannot be beneficiated
View Answer
Explanation: Wet magnetic separation is used to separate iron ores of size less than 150 mesh. The iron ore fines of size less than 150 mesh carry a risk of flying away during separation, hence they are wetted to minimize the loss of fines.
4. Petroleum, sulphonates and fatty acids are used as surface frothing agents for froth flotation process. How would iron ore particles behave in the presence of these surfactants?
a) Iron ore particles would settle at the bottom of the vessel
b) Iron ore particles remain unaffected by these surfactants
c) Iron ore particles would dissolve in the surfactants
d) Iron ores particles would float to the surface
View Answer
Explanation: The surfactants attach themselves to the surface of the iron ores and render the surface hydrophobic. As a result the iron ore particles float up to form froth.
5. What is the basic principle behind magnetic roasting?
a) Reduce hematite ores to magnetite by heating to 600°C
b) Oxidize magnetite to hematite by heating
c) Remove water vapour from the iron ore
d) Remove carbon dioxide from the iron ore
View Answer
Explanation: Magnetic roasting is carried out to reduce hematite to magnetite under reducing conditions at 600°C to make the ore amenable to magnetic separation.
6. Why is drying of beneficiated ores important before charging them into blast furnace?
a) To improve the strength of the charged ore
b) Effectively screen the differently sized particles
c) To ensure extra heat is not consumed in drying the ore in the BF
d) Wet ores can be charged in the BF
View Answer
Explanation: The ores need to be dried before charging to effectively carry out screening of different sized ores. Wet ores if charged in the BF gets dried due to the sensible heat present in the exit gas of the BF, however the screening of ores is not effective and may affect the operations adversely.
7. Which beneficiation process are you likely to use if the ores are carbonates/sulphides?
a) Roasting/Calcination
b) Magnetic separation
c) Crushing and washing
d) They can be directly charged in the BF
View Answer
Explanation: Ores containing carbonates or sulphides of iron can be detrimental to the hot metal chemistry and hence must be eliminated. Roasting/Calcination is used to eliminate the carbonate or suphides in the iron ore.
Sanfoundry Global Education & Learning Series – Iron Making.
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