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Surface Mining > Quiz 2 > Flashcards

Quiz 2 Flashcards

1
Q

Dig Limits: Why the initial block classification might not be held during operations?

A

The block will be discretized into many sub-blocks in short-term
planning, and these sub-blocks will be re-classified according to the
information obtained from blast holes.

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2
Q

Dig Limits:Why applying a cut-off and classifying sub-blocks will not be sufficient for orewaste classification?

A

because this ignores blast movement causing loss/dilution
and shovel arm length.

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3
Q

Dig Limits:Why does the shovel arm length affects ore – waste separation?

A

because a shovel cannot separate ore from waste sharply

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4
Q

Dig Limits:What is dilution?

A

the waste material that is not separated from the ore during the operation and is mined with ore. This waste material is mixed with ore and sent to the processing plant

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5
Q

Dig Limits: Give dilution formula.

A
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6
Q

Dig Limits: What are the 2 types of dilution?

A

Internal dilution & External dilution

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7
Q

Dig Limits: What is internal dilution?

A

There can be waste inclusions or low-grade occurrence within a mining block
that cannot be separated and are inevitably mined with the mining block

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8
Q

Dig Limits: What is external dilution?

A

Also called contact dilution, refers to the waste outside of the
ore boundaries

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9
Q

Dig Limits: Draw internal/external dilution

A
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10
Q

Dig Limits: When does loss occur?

A

When ore is included in waste due to equipment capability or blast movement, loss occurs

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11
Q

Dig Limits: Complete sentence: As ________ and dilution increase due to fragmentation, there would be an ___________ effect. As homogenization increases, ore quantity _________, but average grade ____________

A

As loss and dilution increase due to fragmentation, there would be an homogenization effect. As homogenization increases, ore quantity increases, but average grade decreases

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12
Q

Dig Limits: What is recoverability?

A

percentage of the in-situ (in place) metal that can be actually extracted and processed from the ore body limited due to contraints and dilution

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13
Q

Dig Limits: Name 5 categories and examples of Parameters affecting Blast Movement.

A
  1. Blast pattern dimensions: Burden, Spacing, Delay, Sequence, Pattern Type
  2. Blast hole: depth, inclination, stemming, sub-drill
  3. Explosive: Velocity of detonation, density, powder factor
  4. GEOMETRY AND BENCH CONDITIONS: Heterogenous movement depending on free face availability
  5. ROCKMASS PROPERTIES : Mechanical Properties, Structural Properties
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14
Q

Dig Limits: Name the 2 Blast Movement Dynamics and explain them.

A
  1. Compressive waves reflect off the free face as tensile waves which fragments rock. Nonideal detonation leads to lateral expansion.
  2. Gas expansion: acceleration of the burden and adjacent rock fragments. A higher borehole pressure, more fragmentation, but higher acceleration and randomness in movement.
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15
Q

Dig Limits: Name 2 active measurement techniques and 2 general drawbacks about these techniques.

A
  1. Magnetic gradiometers and Radio Frequency Identification (RFID)
  2. Blast Movement Monitors (BMM)

high cost and time consuming

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16
Q

Bed-blending: What is bed-blending?

A

A specific operation managed through special equipment called stacker and reclaimer where crushed ore is stockpiled to reduce material variance and ensure homogeneity (precision).

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17
Q

Bed-blending: Explain the 2 phases of bed-blending.

A
  1. a stacker traverses the ground at a constant velocity along the stockpile, during which process materials are laid down on the same level as the stacker. As the stacker gradually reaches the end of the stockpile, it decelerates until it finally stops, before starting again to travel back in the opposite direction.
  2. a reclaimer (either a bucket-wheel or a harrow-type scraper) cuts slices of the stockpile perpendicular to the direction of stacking
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18
Q

Bed-blending: When can bed-blending be conducted (2)?

A
  • After primary or secondary crushing
  • Before shipping to the port
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19
Q

Bed-blending: Name the 2 objecteives of Bed-blending.

A
  • Homogenize or reduce temporal variability of input grades
  • Compose ore for meeting the requirement of processing head grade/shipment
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20
Q

Bed-blending: Name the 4 staking types sytems and draw them.

A
  1. chevron system
  2. windrow system
    3.
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21
Q

Bed-blending: What is the main issue with chevron stacking? which method compensates for this issue

A

Particle segregation:
-If particle size distribution of ore is wide, large particles will move the sides of the pile. - If large particles are high- or low-grade compared to small particles, ore cannot be
homogenized.

In this case, windrow method is more appropriate.

22
Q

Bed-blending: Give the name of the measure for the stockpiling efficiency and its formula.

A
23
Q

Bed-blending: Name the 10 design parameters of bed-blending.

A
  1. The ore quantity per layer
  2. The quantity in a slice
  3. The number of layers (N)
  4. Desired output variability
  5. The geometric configuration the bed-blending system
  6. Stockpile capacity (M)
  7. Stacker Capacity
  8. Critical sampling quantity and optimal sampling frequency
  9. Equipment characteristics and types
  10. Physical ore properties
24
Q

Gap analysis/Reconciliation: Define Reconciliation and its objective.

A

Reconciliation is a process that compares predictions and actual qualities
and quantities in the mining industry. Objective is to measure if the technical and economic models built on predictions are valid

25
Q

Gap analysis/Reconciliation: Name the 4 stages of Reconciliation in mining

A
  1. Mine reconciliation
  2. Mill reconciliation
  3. Mine to mill reconciliation
  4. Resource/reserve-to-product reconciliation
26
Q

Gap analysis/Reconciliation: What is the gap?

A

Discrepancy between the predicted and actual

27
Q

Gap analysis/Reconciliation: What are the 3 important issues to detect in gap analysis?

A

1 The sources of the gap
2 If discrepancy between the prediction and actual will even out in long term
3 If discrepancy between the prediction and actual is associated with a bias

28
Q

Gap analysis/Reconciliation: Name 6 Gap Analysis Design Aspects.

A
  1. Drilling and blasting design
  2. Slope Stability
  3. Loading and Hauling
  4. Dewatering
  5. Mineral processing
  6. Waste and tailing management
29
Q

Gap analysis/Reconciliation: Name the steps of root-cause analysis (RCA).

A
  1. Problem definition
  2. Determination of causal relationships
  3. Identification of possible solutions
  4. Implementation of solutions
30
Q

Gap analysis/Reconciliation: Name and and breifly explain 3 Bases for reconciliation practice

A
  • Area-based: actual and forecasted values are compared on a bench or an orebody sector
  • Time-based: actual and forecasted values are compared on weekly, monthly and annual bases
  • Process-based: actual and forecasted values are compared on various process pairs; for example, resource model to mining production, mining production to plant feed, mining production to shipping.
31
Q

Gap analysis/Reconciliation: What are the 2 main sources of error of reconcialiation in many mines?

A
  1. Inaccurate estimation of mineral resources and/or ore reserves.
  2. Ineffective classification of ore and waste. He called this ineffectiveness the “short range model” because short term mine planning.
32
Q

Gap analysis/Reconciliation: Give the F1 Factor formula.

A
33
Q

Gap analysis/Reconciliation: Give the F2 factor formula.

A
34
Q

Gap analysis/Reconciliation: GIve the F3 factior formula.

A
35
Q

Gap analysis/Reconciliation: Give the F4 Factor formula.

A
36
Q

Gap analysis/Reconciliation: Give the 5 Reconciliation steps

A
  1. Gather data for reconciliation
  2. Report the deviations from targets on bench or time (monthly, quarterly, annually) base
  3. Detect if trends are presented in terms of the deviations from the quality and quantity targets.
  4. Interpret and justify the reasons behind the deviations.
  5. Modify design such that deviations from targets are reduced
37
Q

Gap analysis/Reconciliation: Name 6 possible operational topics to reconciliation that can be added.

A
  1. The relationship between particle size distribution and loading performance (packing characteristics of broken materials)
  2. The changes of pre- and post-blast ore – waste boundaries due to blast movements and fragmentation.
  3. Differences between target and actual production due to equipment availability, reliability, utilization, and maintainability.
  4. Unexpected high energy consumption in communition process
  5. The differences between planned and actual recovery and throughput
  6. Inaccuracies in water balance calculations.
38
Q

Strip (Opencast) and Oil Sands: What is the ration used in oil sands?

A

TV:BIP

The total volume of oil sands mined (TV) to the total amount of bitumen in-place (BIP)

39
Q

What is marginal stripping ratio?

A

Marginal stripping ratio is the ratio of change in total waste quantity when coal production is increased by one unit to the change when coal production is increased by one unit.

40
Q

Name the 4 complexities in stripping ratio

A
  1. Multiple seams
  2. Quality fluctuations within seams and inter-seams
  3. Inconsistent thicknesses or irregular shape of ore deposits
  4. Variations in equipment availabilities
41
Q

Name 10 Advantages of Strip Mining

A
  1. Highest productivity of all methods
  2. Low cost
  3. Near maximum output of all methods
  4. Short preproduction period
  5. Low labor intensity
  6. Relatively flexible
  7. Amenable to intense mechanization
  8. Simple development and access
  9. Good ore recovery
  10. Minimizes overburden haulage
42
Q

Name 7 Disadvantages of Strip Mining

A
  1. Depth limitation-economics and technology
  2. Economic stripping ratio limitation
  3. Large surface area disturbance
  4. High capital intensity
  5. Large near surface deposits to justify investments
  6. Large reclamation capital
  7. Requires careful sequencing of operations
43
Q

Name the 6 steps of Strip Mining

A
  1. Clearing and topsoil removal
  2. Fragmentation
  3. Waste removal
  4. Waste placement (including soil restoration and initial revegetation)
  5. Coal mining
  6. Mine restoration, maintenance, and eventual closure
44
Q

When can Dozer Ripping be used as a fragmentation method?

A

For relatively thin overburden of less than 4 m and where rock strength allows, a
dozer-ripping process may be used for fragmentation

45
Q

What is area mining?

A

Area mining is a type of strip mining conducted on flat terrain

46
Q

Name the 3 contour mining methods.

A
  1. haulback
  2. box-cut
  3. block-cut
47
Q

Explain box-cut method

A

Box-cut contour mining is practiced in moderately sloping terrain. It is essentially the same as area mining where the total number of strips is limited to two or three.

48
Q

Explain Haulback Method

A

“Haulback” mining is based on a loader and truck operation. It refers to the fact that the waste is ‘hauled’ (transported) and dumped ‘back’ into the previously mined out area.

49
Q

Give the 7 steps to extract a Oil sands deposit

A
  1. Set up
  2. Remove muskeg
  3. Remove groundwater using a submersible pump
  4. Remove overburden
  5. Extract sand
  6. Finish removing overburden and extract more sand right on different elvations
  7. Backfill using mined-out pit with tailings and waste
  8. Put vegetation back
50
Q

OP to UG: Why is a crown pillar used( 2)?

A
  • To protect open-pit employees and infrastructure from ground instability problems
  • To protect u/g employees and infrastructure from water inflow
51
Q

OP to UG: Name the 7 most variables in crown pillar design.

A
  1. Water infows through groundwater or precipitation
  2. Rock mass characteristics
  3. Dip and width of orebody
    * Possible failure modes and mechanisms of crown pillar, the hanging wall and footwall rocks
  4. Weights of infrastructure (e.g., mining and processing equipment) on the crown pillar
  5. Characteristics of pillar and wall rocks
  6. Geotechnical characteristics affecting crown pillar stability
    7 Effects of open pit mining activities on crown pillar (e.g., seismicity and vibration)

Surface Mining (3 decks)

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