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WorksheetsCoal & Coal Dust
Total questions: 29
Worksheet time: 15mins
What is the general specific gravity of West Virginia Coal?
about one and thirty-five hundredths (1.35)
About one and three tenths (1.3)
About thirteen hundredth (.130)
About thirteen (13.0)
What is the average weight of solid coal per cubic foot?
About fifty (50) pounds
About one hundred (100) pounds.
about eighty (80) pounds.
about seventy-five (75) pounds.
How many net tons (2,000 pounds) are generally considered to be in a foot acre?
approximately one thousand eight hundred (1,800) tons.
approximately one thousand five hundred (1,500) tons.
approximately one hundred (1,000) tons.
approximately two hundred thousand (2,000) tons.
How is heating value of coal usually expressed?
by the number of B.T.U per pound of coal.
by the number of B.T.U per ton of coal.
by the number of B.T.U. per cubic foot of coal.
by the number of B.T.U. per foot of coal.
What is the average weight of loose coal per cubic foot?
about 80 pounds
about 65 pounds
about 100 pounds
about 50 pounds
What is the principle gas contained in coal?
Cabon Monoxide
Sulfur Dioxide
Methane
Hydrogen Sulfide
What causes the propagation of explosions throughout large areas of mines?
Coal dust
Insufficient rock dust
Extremely dry mines
Usually happens when fans stops
How does coal dust contribute to the severity of an explosion?
by being raised in clouds and ignited, the explosion is propagated through the mine.
coal dust is highly volatile
by being raised in clouds
coal dust is scarred throughout the mines in ventilating current
When is it possible to have an explosion in a coal mine with no methane present?
when hydrogen is present
when carbon monoxide is present
when quantities of coal dust are raised in a sufficiently dense cloud in the presence of a source of ignition
when mining close to gas wells
Under what circumstances does coal dust explode?
when combined with methane
in a temperature exceeding on thousand and two hungred (1,200) degrees Fahrenheit
When the particles are suspended as a cloud in the presence of flame or spark
in all circumstances
What are the main causes of coal dust explosions?
Nonpermissible explosives
poor ventilation
human error
explosions of methane, electric arcs and explosives
How much coal Duse is sufficient to propagate a coal dust explosion?
One(1) cubic foot per one hundred (100) square feet
One(1) cubic foot per two hundred(200) square feet
about eight hundredth (.08) or one twelfth (1/12) of an ounce per cubic foot of air
about eight tenths (.8) of an ounce per cubic foot
What are the largest size particles of coal dust which will start an explosion?
any particle of coal dust which will pass through a twenty (20) mesh screen
any particle of coal dust which will pass through a fifteen (15) mesh screen
any particle of coal dust which will pass through a one-half (1/2) inch screen
any particle of coal dust which will pass through a one eighth (1/8) inch screen
How can the explosibility of coal dust be reduced?
by applying rock dust
by increasing the air flow
by keeping line brattice to within ten(10) feet of face
by the addition of incombustible material
What is the maximum amount of moisture that coal dust will retain?
about ten(10%) percent
about fifteen (15%) percent
about twenty (20%) percent
about five (5%) percent
What shall be done with accumulations of fine, dry coal dust in a mine?
Fine dry coal dust shall be removed from the mine
cleaned up with loading machine
cleaned up with scoop
must be rock dusted
What benefit is derived from rock dusting?
keeps coal dust out of atmosphere
not necessary for miners to wear respirator
the explosibility of coal dust and the danger of an explosion being propagated is reduced
gas explosion is not likely
only one (1%) percent silica allowed
What is the maximum percentage of silica in rock dust?
a maximum of five (5%) percent
a maximum of two(2%) percent
a maximum of three (3%) percent
a maximum of one (1%) percent
What is the required size of rock dust?
one hundred(100%) percent must pass through twenty (20) mesh screen
all will pass a twenty (20) mesh screen and not less than seventy (70%) percent will pass a two hundred (200) mesh screen
one hundred(100%) percent must pass through one hundred (100) mesh screen
seventy (70%) percent must pass through twenty(20) mesh screen
How close to working faces must rock dust be applied?
within twenty(20) feet to face
within twenty-five (25) feet to face
within fifty (50) feet to face
in and beyond the last open breakthrough to within forty(40) feet of face
What entries shall be rock dusted?
all intake airways, trackways, beltlines, and return airways
only active working entries
only intake entries
all entries
What shall be the minimum percentage of incombustible material after rock dust has been applied (other than return entries)?
forty(40%) percent
fifty (50%) percent
sixty (60%) percent
eighty (80%) percent
What shall be the minimum percentage of incombustible material after rock dust has been applied to return entries?
sixty (60%) percent
eighty (80%) percent
seventy-five (75%) percent
sixty-five (65%) percent
What should be done before coal dust is loaded from haulageways?
a test for methane gas must be made
all electrical gas must be made
water, calcium chloride or other dust allaying materials should be applied
a clean-up plan must be posted
How shall unusual quantities of coal be kept out of suspension?
by keeping the air velocity low
by sprinkling or other dust allaying devices
sprays must be operative
water must be piped to all sections
Who shall approve methods of allaying dust in mines?
United States Bureau of Mines
United States Mining Board
Inspector-At Large
The Director of Miners' Health & Safety Training
Who shall be required to wear respirators?
Apprentice miners
Miner helpers
Roof bolters
Miners exposed for short periods to gas, dust, fumes, and mist
After applications of rock dust are made in coal mine, how may incombustible content of the mine be determined?
Entire area must be white
at least quarter (1/4) inch must be measured along ribs
by collecting samples of dust from the sides, roof, and floor and analyzing them for total incombustibility with a device know as "voltmeter", or proximate analysis
by collecting samples of dust from the sides, roof, and floor and analyzing them for total incimbustibility with a device know as "volunteer", or by proximate analysis
What effect does the presence of small amounts of methane have upon the explosibility of coal dust?
it decreased the explosibility
it increased the explosibility
less than five(5%) percent methane will not explode
has no effect on coal dust
