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BCCL OVERMAN EXAM 2024 PAPER WITH ANS KEYS

BCCL Jr OVERMAN EXAM-2024 PAPER WITH OFFICIAL ANS KEYS

    Drilling in a stone drift 3 mm × 4 m in cross-section in a coal mine produces 0.5 gm of dust of 5 µm size every minute. If the respirable dust has a free silica content of 8% and the intake air has a respirable dust load of 0.8 mg/m3 , the airflow rate required to dilute the dust to the TLV stipulated by CMR- 2017 is ………………..
    17.5 m3/s
    18.5 m3/s
    20.5 m3/s
    None of the above

    A gas mixture contains 75% CH4, 15%  C2H6 and 10% H2. The lower explosibility limits of CH4, C2H6 and H2 and 5% , 3.3% and 4.2% , respectively. The lower explosibility limit of the gas mixture is …………………
    5.34%
    3.72%
    4.56%
    None of the above

    Graham’s and Young’s ratios from the air sample containing CO2 = 4.8% , CH4 = 50.01% , o2 = 0.6% , N2 = 43.62% and CO = 0.036% collected from an area sealed off due to an outbreak of fire are ………………. and ……………., respectively.
    0.03% and 43.56%
    0.06% and 53.46%
    0.04 and 48.43%
    0.04% and 51.34%

    In an underground mine, a miner inhales the normal air and exhales the air containing 15.5% O2 and 3.5% CO2. The respiratory quotient of breathing for the worker is …………
    0.84
    0.74
    0.64
    0.54

    A plain concrete dam will be constructed in a gallery of 4 m × 3 m cross-section against a water head of 90 m. If the shear strength of coal is 500 kg/cm2 , the actual thickness of the water dam should be ……………
    2.25 m
    1.98 m
    1.89 m
    2.07 m

    Mine water having the flow rate of 1.5 m3/s and dissolved oxygen of 2 mg/l is mixing with the river water having the flow rate of 7 m3/s and dissolved oxygen of 6 mg/l. The dissolved oxygen concentration of the mixture is ……………
    3.89 mg/l
    4.3 mg/l
    5.3 mg/l
    4.2 mg/l

    The percentage of blackdamp in a mine air where the air sample contains CO2 = 0.26%, O2 = 19.10%, N2 = 79.04% and CO = 0.02% is …………….
    6.91%
    6.70%
    7.14%
    None of the above

    Which of the following is not a continuous mining technology for open-cast mines?
    Bucket-wheel excavator
    Shovel-Dumper combination
    Bucket chain excavator
    Conveyor bridge

    In an experiment to study the coal dust explosibility, it was found that at least 3 gm of limestone dust should be added to a sample of 2 gm of coal dust to ensure that propagation of flame does not take place. The explosibility index of coal dust is …………..
    1.5
    2.0
    2.5
    3.0

    The Bord and Pillar panels worked in conjunction with hydraulic stowing; the preferred line of extraction is ……………..
    Step Diagonal
    Diagonal
    Steep diagonal
    Straight

    Contiguous seam means the parting between two seams is within ………..
    10m
    7m
    11m
    9m

    The height of the caving zone varies typically in the function of extraction height………….
    2 to 8 times the extraction height
    4 to 16 times the extraction height
    5 to 20 times the extraction height
    7 to 9 times the extraction height

    The ratio of length of explosive column to the hole diameter which will work as a spherical charge, is ……………….
    L/D<6
    L/D>6
    L/D<4
    L/D>4

    The incubation period is not related to………….
    Crossing point temperature
    Panel size
    Seam thickness
    Explosibility of coal dust

    Coalification has taken place in the order of…………
    Peat, Lignite, Bituminous, Anthracite
    Lignite, Peat, Bituminous, Anthracite
    Peat, Lignite, Anthracite, Bituminous
    Bituminous, Peat, Lignite, Anthracite

    Which one of the following is the most likely mode of slope failure for waste dump?
    Circular
    Wedge
    Plane
    Toppling

    A non-electric detonating relay does not contain……….
    Delay element
    Fuse head
    Metal sleeve
    Neoprene connecting tube

    The automatic contrivance shall be provided in each shaft exceeding a depth of………
    70m
    90m
    50m
    100m

    The point beyond which the mineral/coal can not be extracted economically, is called.
    Stripping ratio
    Cost of stripping ratio
    Break-even point
    Limit of extraction

    The oxygen concentration in the underground working should not be less than ………..
    21%
    20%
    19%
    18%

    In the Coward flammability diagram, the respective percentage of methane and oxygen at the nose limit are………….
    14.2, 0
    14.1, 18.2
    5.8, 12.1
    5.0, 19.2

    The maximum wet bulb temperature in underground mines is…………
    30 deg. C
    30.5 deg. C
    33 deg. C
    33.5 deg. C

    A gas mask does not include……………
    Check valve
    Warning device
    Facepiece assembly
    Coolant canister

    The chemical Hopcalite used in…………..
    Self-contained breathing apparatus
    Gas mask
    CO detector
    MSA-methanometer

    Stink damp is Synonymous with ………….
    H2S
    CH4
    NO2
    SO2

    The lag on ignition in terms of ignition of CH4 is because of the following fact………….
    It takes the time of absorption of N2
    It takes the time of adsorption of N2
    It starts dissociating and burns only after absorbing a certain quantity of heat
    It depends on its maximum saturation

    Natural ventilation cab be caused by ………..
    Auto-compression in downcast shaft
    Differences in air densities in upcast and downcast shafts
    Auto-expansion in upcast shaft
    Moisture content in the mine

    In the underground mine, if the Graham’s ratio at particular space is found to be 3%, then it is indicating ………….
    Existence spontaneous heating
    Active fire
    Heating in advance stage
    Normal condition

    Effective temperature is estimated from …………
    Wet-bulb temperature, relative humidity, and air velocity
    Dry-bulb temperature, relative humidity, and air velocity
    Dry-bulb temperature, Wet-bulb temperature, and air velocity
    Dry-bulb temperature, Wet-bulb temperature, and relative humidity

    A developed panel for a coal seam with an incubation period of 9 months has 35 square pillars under extraction, which are 30m in size and 3.6m in height. The density of coal is 1.6 tonnes/m3. The extraction ratio during depillaring is expected to be 70%. To depillar the panel within the incubation period, assuming 25 working days in a month, the production from the panel in tonne/day is …………..
    565
    665
    765
    865

    An underground coal mine employing 1500 persons experiences 5 fatal injuries, 16 serious injuries, and 20 reportable injuries during the year 2023. The total injury rate per 1000 persons employed for the year is………….
    27.33
    24.49
    31.67
    29.37

    A drill’s rotational speed and cutting velocity are 400 rpm and 75 m/min, respectively. The diameter of the rotary drill bit in mm is ………….
    60
    65
    70
    75

    In a coal mine, the depth of working 450m, the gallery’s width is 4.2m, the gallery’s height is 3.6m, and the distance of the square pillar from center to center is 25m. What is the strength of the pillar?
    126.83 kg/cm2
    128.53 kg/cm2
    138.53 kg/cm2
    122.53 kg/cm2

    Five benches are being worked by the opencast mining system. The height, width, and face angle for each bench are 20 m, 50 m, and 60 deg, respectively. The overall slope angle of the benches in degrees is ………….
    19.25
    16.27
    21.21
    22.30

    In a mine, for one shovel, five trucks are assigned. The shovel loading time per truck is 6 mins, and the truck cycle time is 20 min. Calculate the match factor.
    1.5
    2.5
    3.0
    2.0

    If the value of ore is 800 per tonne, production cost Rs. 500 per tonne, and cost of overburden removal is Rs. 60 per m3, the break-even stripping ratio in m3 /tonne is ……………
    4:1
    1:4
    3:1
    5:1

    A surface mine blast design has 12 holes in a row, each 7m long and 180mm in diameter. The spacing and burden are 6m and 5m, respectively. The length of subgrade drilling is 1m, and the density of in-situ rock is 2.43 t/m3. Considering the explosive density of 0.9 t/m3 and steaming length of 2.5m, the powder factor from the blast in t/kg is………
    4.9
    4.32
    5.21
    3.41

    In an opencast mine deploying shovel and dumper, the distance from the crest of the bench to the centre of the dumper including safety berm and clearance is 7.5m, the dumping radius and the cutting radii of the shovel are 15m and 12m respectively. The width of the working bench of the mine in m is ………….
    32.5
    30.5
    36.5
    34.5

    20 m3 /s of airflow is through a longwall panel having 1000 tpd of production. Between the intake and return of the panel, the firedamp increases from 0 to 0.2%. The rate of firedamp emission is …………..
    3.45 m3 /t
    3.45 m3 /day
    3.45 m3 /sec
    3.45 l/g

    Mean air temperature of a 450 m deep downcast shaft is 29 deg C and that of the upcast shaft is 37 deg C. the height of the motive column in m is…………
    8.2
    9.5
    11.6
    12.8

    A mine fan delivers 50 m3 /sec of air at a fan drift of 10 mm of w.g. It is proposed to increase the quantity to 60 m3 /sec of air; the required w.g. shall be …………..
    12.00 mm
    14.40 mm
    13.60 mm
    20.20 mm

    The mean velocity of air current through an airway of 9 m2 cross-sectional area is found to be 1.5/sec. if the mean methane content of the air current is 0.6 , the layering index will be …………..
    3.10
    2.71
    2.15
    1.80

    A delay detonator has a delay element introduced between ………..
    Primary charge and base charge
    Detonator tube and fuse head
    Neoprene plug and neoprene sleeve
    Fuse head and primary charge

    Samples of air collected in the intake and return gate roads of an advancing longwall face show 0.25% and 0.75% of CH4, respectively. The panel has a production of 400 t in an 8 hours shift when an air quantity of 18 m3/s passes through it. Then, the methane emission in m3/te of coal mined is …………..
    0.02
    0.81
    2.25
    6.48

    A centrifugal fan rotating at 600 rpm delivers 80 m3/sec of air. If the speed is reduced to 200 rpm, the quantity of air delivered in m3/sec will be …………
    26.67
    28
    27.65
    29

    In a mine ventilation system, the resistance of two splits A and B are 0.5 Ns2m^(-8)  and 2 Ns2m^(-8) , respectively. The combined resistance of two shafts and trunk airways is 0.7 Ns2m^(-8) , A quantity of 20 m3/sec of air passes through split A. The total air quantity passing the mine in m3/sec is …………
    30
    27
    25
    17

    A fan circulates 24 m3/sec of air at a pressure of 1200 Pa in a ventilation district. It is intended to reduce the air quantity to 16 m3/sec by replacing a regulator. Assuming the pressure remains unchanged, the size of the regulator in m2 is …………
    1.48
    0.74
    0.37
    0.18

    For a Drop Shaft with ‘G’ as the weight of the caisson and ‘F’ as the frictional resistance, the following condition has to be fulfilled…………..
    G = F
    G > F
    G < F
    G + F = 0

    The maximum permissible gradient for the operation of an LHD machine in dry floor conditions is ……………
    1 in 12
    1 in 7
    1 in 6
    1 in 10

    The switch type used to cut off power in case of low oil levels in the tank of an SDL machine is ………….
    Deadman switch
    Thermal Overload Protection (TOL) switch
    Oil switch
    Float switch

    Exploration drilling is best done by …………..
    Diamond drilling
    Churn drilling
    Percussion drilling
    None of the above

    A cowl is provided behind the cutting drum of a shearer……………
    To safeguard the cutting drum
    To spray water on the cutting picks
    To divert cut coal to AFC
    All of the above

    The transformers used in mines are normally …………
    Star-delta-star connected
    Delta-star connected
    Star-delta connected
    None of the above

    The voltage requirement for the operation of machines such as LHD and SDL is ………….
    110 V
    1.1 kV
    250 V
    550 V

    An intrinsically safe apparatus ………….
    Usually does not require a flame-proof structure
    Requires flames-proof structure to prevent spark generation
    Is a flame proof structure
    None of the above

    In a hand-held drill machine, for providing electrical supply, which equipment is used to supply 550 V to the drill motor?
    Gate end box
    Drill Panel
    Both (a) and (b)
    None of these

    Choose the correct one.
    Jack hammer drill is a rotary drill machine
    DTH is a rotary-percussive drill machine
    DTH is a percussive drill machine
    All of these

    A 20/90 dragline machine specifies…………
    20 cu. M bucket and 90 m boom
    20 m boom and 90 m dragline length
    20 m boom and 90 cu. M bucket
    20 cu. m bucket and 90 m dragline length

    The operation of moving the dipper handle out or in to control the depth of cut and when positioning to dump is called…………
    Swing mechanism
    Crowd mechanism
    Propel mechanism
    Hoist mechanism

    Which sensors are most commonly used in autonomous haul trucks for obstacle detection?
    Pressure sensor
    Temperature sensor
    Acoustic sensor
    LIDAR sensor

    How many bones are there in the human body?
    198
    200
    206
    218

    Who discovered electron?
    Rutherford
    James Chadwick
    Newton
    None of these

    Which is a water soluble Vitamin?
    Vitamin A
    Vitamin C
    Vitamin D
    Vitamin K

    Tropic of cancer does not pass through which of the following Indian states?
    Uttar Pradesh
    Gujarat
    Madhya Pradesh
    Jharkhand

    When was Coal India Limited (CIL) established?
    1974
    1975
    1976
    1977

    First Women Sainik School of the Country has been opened in which state?
    Madhya Pradesh
    Gujarat
    Uttar Pradesh
    Bihar

    How many medals did India win in the Olympic Games 2024?
    6
    2
    3
    7

    Who has been awarded the Penn Pinter Prize 2024 for literary contribution?
    Usha Thakur
    Shashi Tharur
    Preeti Sudan
    Arundhati Roy

    Which team has won the title of the recently held Women’s Asia Cup 2024?
    India
    Sri Lanka
    Afghanistan
    Pakistan

    Who is the current Chief of Army Staff of India?
    Manoj Pandey
    Dinesh Kumar Tripathi
    Upendra Dwivedi
    Kamal Tiwari

    Find the missing number. 7, 9, 12, 17, 24, 35, …………………….?
    52
    45
    47
    18

    If FUN = 41, ROSE = 57 then WHITE = ?
    65
    63
    62
    66

    Five persons are standing in a row. ‘J’ is behind ‘N’ but ahead of ‘P’ Both ‘L’ and ‘M’ are ahead of ‘N’. Who is standing in the middle?
    L
    N
    P
    M

    A was born 5 years before B. B is 4 years older than C and 3 years younger to D. If the present age of A is 17 years then what is the age of D?
    15 years
    13 years
    12 years
    8 years

    Pointing to a girl, Mohan said, “She is the only daughter of my grandfather’s only child”. How is that girl related to Mohan?
    Daughter
    Aunt
    Mother
    Sister

    A train having length of 200 meter is running with a speed of 72 km/hr. How much time it will take to will cross a 200 meter long platform?
    10 seconds
    30 seconds
    20 seconds
    None of these

    The average of 50 numbers is 38. If two numbers 45 and 55 are removed then what will be the average of the remaining numbers?
    37.5
    36
    33
    35.5

    Ramesh completes a piece of work in 10 days. Suresh completes the same work in 15 days. In how many days will they together complete the work?
    4
    5
    6
    7

    The simple interest accrued on an amount of Rs. 15000 in 3 years is Rs. 5400. Find the rate of interest.
    11.5%
    12%
    12.5%
    11%

    The ratio of the number of boys and girls in a school is 3 : 2. The number of boys is 500 more than the girls. What is the number of girls?
    500
    800
    1000
    1300

    If respirable dust in an underground coal mine contains 4.8% free silica, then the maximum allowable respirable dust concentration in the mine working environment as per CMR 2017 is ………..
    2 gm/m3
    2 mg/m3
    3 gm/m3
    3 mg/m3

    The permissible limit of Nitrous Fumes for 8 hrs exposure is …………
    50 ppm
    10 ppm
    7 ppm
    5 ppm

    The number of persons in any rescue team using breathing apparatus shall be not less than ………….. and not more than ……….
    4 & 5
    5 & 6
    6 & 7
    7 & 8

    If the respirable dust has a free silica content of 4% and its concentration is 2.5 mg/m3, the interval of dust sampling should be ……………
    One month
    Three months
    Five months
    Six months

    The maximum CO2 concentration in the Self-Contained Self Rescuer at any times of its use is ………..
    0.3%
    0.5%
    1.5%
    3%

    When two or more auxiliary fans are installed in a gassy seam, the maximum allowable percentage of methane in the air entering the auxiliary fan is ………..
    0.3%
    0.5%
    0.75%
    1.25%


    MSA W65 model of self-rescuer over protection against CO does not work if the concentration of CO exceeds
    1%
    2%
    3%
    4%

    Which of the following is not a closed-circuit apparatus?
    Filter type self-rescuer
    Chemical type self-rescuer
    Reviving apparatus
    BG-4 breathing apparatus

    The noise levels measured during the operation of 3 drill machines are 85 dBA, 88 dBA, and 85 dBA, respectively. The equivalent noise level for the above three machines is …………
    86 dBA
    88 dBA
    87 dBA
    91 dBA

    Exposure to loud, impulsive noise may lead to…………..
    Tinnitus
    Nystagmus
    Siderosis
    Stannosis

    Stone dust barriers in underground coal mines are used to arrest …………..
    Blackdamp explosions
    Air blast
    Firedamp explosions
    Coal dust explosions

    When the risk score is 500, the risk hazards need ……………
    Immediate attention
    Management action
    Management in ongoing manner
    Both (b) & (c)

    A source of potential harm, injury or loss is known as ………………
    Danger
    Risk
    Hazard
    All of the above

    Which gas was detected by taking lal munias to underground mines?
    CO
    CH4
    CO2
    H2S

    The threshold limit value of SO2 for short-term exposure level (STEL) ……………
    5 ppm
    6 ppm
    7 ppm
    10 ppm

    Which of the following works on the principle of an analytical method of separating, identifying, and estimating quantitatively mixtures of gases?
    Multigas detector
    Gas chromatograph
    Toximeter
    Flame safety lamp

    The disease caused by inhalation of silica particles is known as …………
    Pneumoconiosis
    Siderosis
    Silicosis
    Black lung

    The injury, which results in enforced absence of the injured persons form work for a period of 72 hours or more, is known as…………..
    Serious bodily injury
    Reportable injury
    Minor injury
    All of the above

    As per Regulation 166 of CMR 2017, when shall inflammable gas be deemed to have been found or detected in a mine having 2nd degree gassy seam?
    Inflammable exceeding 0.5%
    Inflammable exceeding 0.75%
    Inflammable exceeding 1.25%
    Inflammable exceeding 0.1%

    To detect spontaneous heating in the early stages, the air in the return airway of every depillaring district and of every goaf shall be tested by an automatic CO monitor at minimum intervals of …………….
    30 days
    15 days
    7 days
    Daily