3098. ‘Fat’ coal means a coal having
Low calorific value
High volatile matter
Low ash content
Non smoking tendency
✅ The correct answer is option B.
3065. Coke oven gas burns with an yellowish flame, because of the presence of
CO₂
CH₄
H₂
NH₃
✅ The correct answer is option B.
3070. Hardgrove grindability index of four coal samples are given below. Which of them is the easiest to grind?
50
70
85
100
✅ The correct answer is option D.
3075. Dust content in raw blast furnace gas is about __________ gm/Nm³ , hence it is cleaned to the dust level of about < 10 mg /Nm³ before use.
15-30
1-Feb
70-100
150-200
✅ The correct answer is option A.
3079. Coking coals are invariably
Lignites
Bituminous coals
Semi-anthracites
Anthracites
✅ The correct answer is option B.
3084. Which is the most matured coal?
Lignite
Bituminous
Semi-anthracite
Anthracite
✅ The correct answer is option D.
3090. Froth floatation is used for
Washing fine coal dust (< 0.5 mm size)
Washing lump coal (> 80 mm size)
Removing ash from the coal based on difference in specific gravity of coal and ash
All of the above
✅ The correct answer is option A.
3095. Critical Air Blast (CAB) value of coke is a direct measure of its
Reactivity
Hardness
Strength
None of these
✅ The correct answer is option A.
3100. Combustion of pulverised fuel
Requires larger combustion chamber than rich gaseous fuel
In a metallurgical furnace does not contaminate the product in the furnace by ash from fuel
Suppresses the discharge of fine dust and grit into atmosphere
All of the above
✅ The correct answer is option A.
3067. In low temperature carbonisation (as compared to high temperature carbonisation) of coal
Ammonia yield is more
Aliphatic tar is produced
Free carbon in tar is more
All of the above
✅ The correct answer is option B.