Assessment criteria for all students
1.
(20%) Presentation and layout—includes the general appearance of the document or assignment,
attention to document detail and quality to provide an easily legible document.
2.
(80%) Content—includes the accuracy and relevance of answers, application of knowledge,
language and grammar used in answering the questions.
Assignment 2
Due date:
Monday, Week 8, 5:00 pm
Weighting:
35%
ASSESSMENT
2
Objectives
Note:
1.
Students will submit their own work in their own words. All assignments will be submitted via
Turnitin to be checked for copying of content.
2.
Answers will be well organised and well presented. Marks will be deducted for poorly organised
or poorly explained solutions. Refer to the relevant section in the course material for appropriate
presentation, setting out and formatting of answers.
3.
Answers will be relevant. Students should refer to the marking criteria information to ensure their
answers are relevant and correctly address the question.
4.
Relevant diagrams and pictures will be used, where possible, to help explain your answers.
5.
All work will be referenced correctly. Material that is not correctly referenced using the Harvard
style guide will not be awarded any marks.
Question 1
(10 marks)
The following data applies to a working bench being mined as part of a truck and shovel
operation in an open pit mine:
 Bench height = 12.5 m,
 a safety berm is required,
 minimum clearance between the outer truck tire and the safety berm = 1.2 m,
 single spotting is used,
 bench face angle = 70˚,
 loading is done with a 6.5 m3 shovel,
 haulage is by 90 tonne capacity trucks,
 truck widths = 4.8 m,
 tyre rolling radius = 1.5 m,
 dumping radius at minimum height (B) = 14.5 m,
 maximum dumping height (A) = 9.5 m,
 radius of level floor (G) = 11.0 m,
 diameter of drill hole (De) = 34 cm,
 ANFO explosive used for blasting.
Find
a) working bench dimension of shovel (WB),
b) maximum cutting width of shovel (WC),
c) safety bench width (SB),
d) burden and spacing.
Question 2
(5 marks)
Discuss the design of a typical catch or safety bench. (Max 500 words)
Question 3
(10 marks)
A rock slope contains a potential failure plane. Develop a spreadsheet based on the following
table. The cells under the heading “Values” should contain formulas to calculate the
corresponding components of force acting on the block.
Variables
Data
Units
Force Components
Cohesion (c)
Area (A)
MN/m2
m2
Friction Angle (fa)
Water affected
friction angle (faw)
Discontinuity angle
(b)
Weight of block
(W)
Deg. not rad
Degrees
Force resisting sliding due to cohesion.
Force resisting sliding due to weight
and friction angle.
Force inducing sliding due to weight.
Factor of Safety (Dry).
Uplift (U)
MN
Horizontal force
(V)
MN
Values
Degrees
MN
Water affected force resisting sliding
due to weight and water affected
friction angle.
Force inducing sliding due to weight
and horizontal force.
Factor of Safety (wet).
Enter the following data into the spreadsheet to calculate the factors of safety for a dry and wet
rock slope:
 cohesion c = 0.1688 MN/m2,
 Area of the failure plane A = 115 m2,
 Friction angle ф = 45˚,
 Friction angle affected by water фa = 41˚,
 Angle of the discontinuity β = 35˚,
 Block weight W = 80 MN,
 Uplift force U = 25 MN,
 Horizontal force V = 18 MN.
Print a copy of the spreadsheet showing formulas and another copy showing values.
Question 4
(10 marks)
Why is the simplest mining sequence not necessarily the most cost effective? (500 words)
Question 5
(10 marks)
A polygon map produces the following table of data,
Hole Area Coal
Vol Tonnes O/burden
Thickness
Thickness
1
105.5
1.85
62.5
2
98.7
1.79
62.6
3
112.3
2.01
60.4
4
101.7
1.76
61.5
5
104.6
1.90
60.3
6
99.3
1.85
61.4
7
87.5
1.87
62.5
8
104.2
1.92
61.8
Vol
Tonnes
SR for the
hole
Total
Assuming
 a coal density of 1310.5 kg/m3
 an overburden density of 2415 kg/m3
 a mining recovery of 92% and
 a preparation plant recovery of 88%
Calculate
a) the missing data in the table
b) The stripping ratio for the deposit taking into account the mining and preparation
plant recoveries.
Question 6
(5 marks)
List the four important elements of dragline pit design and give a brief explanation for each.
Question 7
(10 marks)
Consider a dragline operation with the following parameters:
 Highwall slope angle β = 85˚,
 Spoil pile slope angle θ =40˚,
 Overburden depth D = 30 m,
 Spoil pile swell factor S = 25%,
 Pit width W = 45 m,
 Coal thickness T = 1.9 m,
 Spoil pile toe height t = 1.1 m.
Determine the
 dragline Reach factor (RF),
 Height of spoil pile (h) and
 stacking height.
Question 8
(10 marks)
A dragline is operating with the following parameters:
 Highwall slope angle β =74˚,
 Spoil pile slope angle θ = 34˚,
 Overburden depth D = 41 m,
 Spoil pile swell factor S = 21%,
 Pit width W = 55 m,
 Coal thickness T = 1.5 m,
 Spoil pile toe height t = 0 m,
 Cycle time C = 64 s,
 Dragline availability A = 84%,
 Dragline utility U = 90%,



Bucket fill factor B = 90%.
Bucket weight = 1.3 t/m3,
Material weight = 1.8 t/m3.
Find the bucket capacity and the maximum suspended load (MSL) of bucket?
Assume the loading operation will be conducted 5 days per week at a clean coal production rate
of 6000 t/day. Also the dragline will be operated 345 days per year, 24 hours per day. All coal
losses amount to 20%. Density of coal = 1.2 tonnes/m3.
Question 9
(10 marks)
For a coal stockpile
 angle of repose (Q) is 45˚,
 density of coal (ρ) 1.2 t/m3,
 Length (L) = 160 m,
 width (W) = 60 m and
 height (h) = 12 m.
Calculate the total tonnage of coal reserved in the stockpile?
Question 10
(10 marks)
For a blast design, the following parameters apply:
 Rock density (ρR) = 2.6 t/m3,
 The explosive is ANFO (ρe = 800 kg/m3, Weight strength of ANFO = 1),
 Bench height (H) = 14 m,
 Hole diameter (D) = 0.25 m,
 Staggered drilling pattern,
 vertical holes,
 5 rows of 6 holes make up one blast.
 Assume, KB = 25, KS = 1.15, KT = 0.7, KJ = 0.3.
Find the following:

Burden (B),

Spacing (S),

Stemming length (T),

Length of sub-drill (J),

Length of drill hole (L),

KH,

amount of explosive required (TEXP),

Total rock produced (TR), and

Powder factor of ANFO explosive (PFANFO).
Question 11
(10 marks)
Write short notes describing the application of the following explosives:
(a) ANFO
(b) Watergels
(c) Emulsions
(d) Gelignites