Concepts

Question 1

To prevent flooding, the main sump is how many meters below the decking level of the pit bottom

Answer 1

3 - 4m

Question 2

The most harmful dust in silicosis comes from drilling rock containing more than —— per cent of free silica (SiO2) and resulting in concentrations of airborne dust from 0.2 to 5 microns in size that are higher than 2 mg/m3

Answer 2

10

Question 3

The extremely rapid liberation of energy in the chemical transformation is a

Answer 3

Explosion

Question 4

High speeds of disintegration produce

Answer 4

Detonation

Question 5

Low speeds of disintegration produce

Answer 5

Explosive burning

Question 6

An abrupt change of pressure in an explosion propagated in a medium at supersonic speed is a

Answer 6

Shock wave

Question 7

Methane can ignite when mixed with air in proportions between ——– percent

Answer 7

5 - 14

Question 8

Methane ignition being started by contact with a body at 650 degree or hotter. At 650 degree it requires how much time?

Answer 8

10 seconds

Question 9

Very fine coal dust suspended in the air in quantities of not Iess than ———-, is also capable of exploding

Answer 9

30-40 g/m3

Question 10

Coal dust explodes in contact with a body at —— heat

Answer 10

700-800 degrees

Question 11

The strength of the explosive shall correspond with the strength of

Answer 11

Rock

Question 12

Explosives which easily detonate with spark or flame and are used for the detonation of high explosives are

Answer 12

Initiators

Question 13

When the detonating fuse is ignited by a detonator, the core detonates at a very high speed of

Answer 13

6,800-7,200 m/sec