Low temperature oxidation of stored coal results in the

To avoid fire by spontaneous combustion of coal due to its low temperature oxidation, it should be stored in

A

Shallow and small piles

B

Fine sizes without the presence of any lump

C

Closed space without any ventilation facility

D

Large heaps with small surface to volume ratio

Rate of low temperature oxidation of coal due to bad storage conditions

A

Decreases with increase in surface area

B

Does not vary with increase in surface area

C

Is more for low volatile coal compared to high volatile coal

D

Is accelerated by storage in large heaps with small surface to volume ratio

Low temperature oxidation and spontaneous combustion of freshly mined coal is accentuated, if

A

It contains large amount of volatile matter

B

It is stored in tall heaps

C

Smaller fines are stored in large quantity

D

All of the above

Low temperature oxidation of coal is accelerated by the

A

Storage in large heaps

B

Storage in compressed piles

C

Absence of porous or friable particles

D

All of the above

Low temperature oxidation of coal during storage does not decrease its

A

Oxygen content

B

Caking power

C

Calorific value

D

None of these

Low temperature oxidation of coal resulting from bad storage conditions does not decrease its

A

Caking power

B

Calorific value

C

Hydrogen content

D

Oxygen content

Calorific value of coal middling generated in coal washeries during washing of coal may be around __________ Kcal/kg.

A

1000

B

4000

C

6000

D

8000

Coal mines drainage waste water (acidic in nature) results from the earth's water percolating through the voids created in coal bed during mining. This polluted water which either drains out naturally to water courses or are removed before starting the mining is

A

Neutralised by alkali treatment

B

Left as such without any treatment

C

Diluted with fresh water to reduce its acidity

D

None of these

A coal having high ratio of volatile matter to fixed carbon as compared to a coal having low ratio of volatile matter to fixed carbon

A

Is less liable to spontaneous combustion on storage

B

Is more difficult to ignite and produces a shorter flame

C

Requires smaller combustion space and less secondary air

D

None of these

The bright glow of a combustion process is the characteristic of __________ temperature oxidation of coal.

A

Fast & high

B

Slow & low

C

Slow & high

D

Fast & slow

Low temperature oxidation of stored coal results in the

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