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surface mining > test 2 > Flashcards

test 2 Flashcards

1
Q

Explosives release energy as

A

gas, shockwave, heat

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2
Q

explosives initiated by

A

heat, impact, friction, or shock

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3
Q

RoR

A

rate of reaction

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4
Q

Detonation

A

RoR is higher than the speed of sound, creates shockwave

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5
Q

shock

A

rapid change in attributes such as density, temp, etc

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6
Q

detonation velocity

A

1500-8000 m/s

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7
Q

deflegration

A

slow RoR, no shockwave

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8
Q

3 types explosives

A

high, low, blasting agents

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9
Q

blasting agents

A

cannot be detonated by #8 cap, insensitive

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10
Q

detonator sensitive

A

high explosives set off by #8 cap

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11
Q

free face

A

volume being blasted that has air as neighbor

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12
Q

blast hole length

A

longer than bench height

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13
Q

cheapest way to break rocks

A

blasting

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14
Q

how explosives break rocks

A

shockwave creates micro fractures, gas pressure extends fractures radially to free face, pressure pushes out broken rocks

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15
Q

tensile strength of rock

A

10% of compressive strength

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16
Q

compressive wave becomes _ after reflection on free face

A

tension wave, further breaks rocks

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17
Q

confinement balance

A

too much=too large rocks, too little=fine rock/thrown material

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18
Q

most common explosive

A

ammonium nitrate fuel (ANFO)

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19
Q

emulsion

A

mixtures of two liquids that do not normally mix, droplets of one (discontinuous phase) suspended in another continuous phase. AN dissolved in water and mixed with oil.

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20
Q

why is emulsion heavier than water?

A

difficult to load light explosives in watery holes

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21
Q

what are emulsions used for?

A

wet holes

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22
Q

3 types of initiation

A

chem, mech, electrical

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23
Q

how detonator works

A

primary expl sets off secondary (like PETN)

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24
Q

PETN

A

pentaerythritol tetranitrate

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25
Q

why explosive timing is important

A

fragmentation depends on delay from neighbor, multiples of 25 MS

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26
Q

percussive drilling

A

breaks by hammering, best for hardest rocks

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27
Q

rotary drilling

A

breaks rocks by twisting+downward pressure

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28
Q

type of rock consumes most bits

A

abrasive rocks

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29
Q

burden

A

distance to free face, aspect used for spacing example: (S=1.4B)

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30
Q

subgrade drilling amount

A

1/3 burden

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31
Q

powder factor

A

ratio of explosives used per ton of rock broken

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32
Q

stemming material size

A

ideally 1/8 hole diam

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33
Q

bench height to burden

A

3-4 times burden

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34
Q

less burden means

A

more holes per sq area

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35
Q

things to change particle size distribution (PSD)

A

B, S, stemming, explosive type/quantity

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36
Q

why control grade?

A
  1. meet metal production target 2. meet mill grade target
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37
Q

grade sample linked to

A

particle size of blasthole cuttings

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38
Q

bad sample means

A

holes near cutoff grade get misclassified

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39
Q

choke

A

muck from previous blast not loaded and prevents movement of freface

40
Q

features of strip mines

A

shallow dipping bedded deposits

41
Q

spoil volume

A

space for overburden (cross sectional area based on angle of repose) should be `1.35 times what dragline removes based on expansion

42
Q

width of drag line strip

A

depends on truck/shovel, reach of dl, narrow pros: shortens cycle for dl, spoil peaks easily leveled for reclamation.

43
Q

2 types of production loaders

A

rope shovels and hydraulic excavators (front loading and back hoe)

44
Q

rope shovel toughness

A

heavier and more protected buckets, can handle abrasive material

45
Q

mobility of rope shovel

A

requires electric cable, managing power supply can be prohibitive

46
Q

rope shovel vs h excavator

A

HE has higher production rates, RS have higher capitol cost but lower service cost. become cost effective in 5 years

47
Q

of passes to load

A

3 to 4

48
Q

productivity measured via

A

truck cycle time

49
Q

time to load truck is a

A

kpi

50
Q

guide to slope stability

A

design slopes properly, execute design, monitor slopes, maintain health of slopes

51
Q

linear feature description

A

trend/ plunge

52
Q

planar feature description

A

dip/strike

53
Q

planar failure

A

dip direction similar to slope but flatter dip, greater than friction angle, due to structure

54
Q

wedge failure

A

structure controlled, 2 structures intersect, intersection line is less than dip of slope but more than friction angle, rapid/slow

55
Q

toppling failure

A

structure controlled, strike within 20 deg of face, steeply dipping, slabs form with large height to thick ratio, cog must shift to hapen

56
Q

circular failure

A

not structure controlled, low soil strength

57
Q

raveling failure

A

basic weathering, rain, freeze/thaw, usually minor

58
Q

slope failure leads to

A

equilibrium

59
Q

slopes dont fail without

A

reason

60
Q

tension cracks

A

material is moving into pit leaving cracks, visit bench crest

61
Q

scarps

A

material is moving vertically, material unstable

62
Q

abnormal water flow

A

can be sign of slope failure, more/less

63
Q

bulges/creep

A

slow failure indication, veg can be a clue, live trees grow with abnormal curve

64
Q

rubble at toe

A

indicates failure

65
Q

EDM

A

electronic distance measuring, robotic total station, control point, monitoring beacon, first 2 must not move

66
Q

point clouds

A

area scanned periodically for movement, radar for about to happen failure

67
Q

gps monitoring

A

in pit may not have coverage all day

68
Q

pre splitting

A

use to minimize back break of explosives for final pit wall, not effective in closely jointed rock

69
Q

line drilling

A

last row of holes uncharged to promote splitting, line of weakness, holes close together, construction/stone

70
Q

vegetation must

A

achieve 70% reveg and survive 3 growing seasons since last seeding

71
Q

5 themes of reclamation

A

dealing with lefotvers/harmful material, erosion/sed control, gentle/stable slopes, veg, appropriate land use

72
Q

4 parts of topsoil reclamation

A

ID, salvage, stockpile, replace

73
Q

pedestals

A

top soil reference, dozer rip after salvage to verify

74
Q

topsoil stockpile

A

dont mix with OB, prevent erosion/loss, less than 5H:1V angle

75
Q

drainage goals

A

reduce speed/erosion, control seds, water flow as should be

76
Q

water/sed control structures

A

sed basin, diversion ditch, drop structures, backfill impound

77
Q

sed basin design

A

2:1 L:W and L:D, 2-3 ft of permanent pool above storage,

78
Q

check dams

A

internal dams like wall of rock in sed basin o catch big particles and slow water

79
Q

turbidity curtains/baffles

A

slow water and increase distance it must flow, help drop sed from suspension

80
Q

flocculants

A

chemical that help drop seds

81
Q

diversion ditches

A

prevent mixing of runoff from undisturbed area with mine runoff

82
Q

diversion stability

A

rock rip rap, grass lined, check dams

83
Q

drop structures

A

used in ditches through steep gradients to protect channel

84
Q

alternative sed control

A

straw/hay bales, water not supposed to flow over, not ideal for steep/narrow, catch seds, degrade

85
Q

rock check dams

A

for steep and defined drainages

86
Q

weir

A

built to monitor water flow, uniform cross section

87
Q

backfill settling

A

3 to 10 ft

88
Q

in situ leaching

A

for uranium/copper/etc, metal leached w/ lixiviant, 5/7 spot patterns

89
Q

ISU deposit requirements

A

deposit is porous and saturated, chemistry good for leaching, impermeable layers above/below, economic value

90
Q

excursion

A

escape of solutions outside mining layer, unplugged exp holes, excess pressure, blocked aquifer

91
Q

controlling leach

A

more solution pumped out than in, neg pressure, up to 5%

92
Q

well patterns

A

overlapping flows

93
Q

monitoring wells

A

closely spaced, above/below mine layer

94
Q

restore mining layer phases

A
  1. stop inj/pump out solution/h2o enters, 2. pumped out solution is treated w/ rev osmosis and injected, 3. pump out aquifer and chemically remediate solution and inject, 4. pump out and in to mix it all
95
Q

mining layer restoration times

A
  1. 7 months, 2. 9 months,
96
Q

ISU recommended best pract

A

compreh understanding of aquifer/subsurf enviro, strong disposal plan, demonst of capability

97
Q

placer mining

A

mining on streams or shallow beds, artisinal scale common, soft alluvial sands, grav separation

surface mining (2 decks)

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