The following describes a selection of mineral deposits. For the deposit the candidate chooses (Note only choose 1) the candidate is required to select a suitable mining method for the deposit based on the information given and to describe the mining system in detail. For whichever mineral deposit is selected the candidate should include in their answer the following as required:
1. Describe suitable surface connection(s).
2. Detail development requirements
3. Detail Production requirements including a full description of the method selected.
4. Number of production unit’s required/rate of production.
5. Describe loading/haulage requirements
6. Equipment
7. Briefly describe ventilation/drainage/power requirements
8. Personnel
9. Safety
10.Detail permitting and other requirements as required by the local regulator (students can select which jurisdiction the mine is located in from any Australian state or territory)
Students should also report on other salient points as required by the mining system. For economic analysis, use current market prices in A$ for the commodity as required. Accurate costings are not an essential aspect to the project but some notional costings should be undertaken to illustrate the viability of the method detailed.
Underground Mining project
A massive silver/lead/ zinc deposit approximately 250 m in width and 1,500m long ranging in depth from 300m below surface to 900m below surface. Angle of dip is 70°.
Surface Mining Project
A copper-gold-silver mine is located in a desert at an elevation of 3,050 m above sea level.
Current level of production is 127,000 t/d ore throughput. Production f 46.9 Mt/y of sulphide ore grading 1.9% copper, containing 776,400 t of copper, 129,000 oz of gold and 3.28 Moz of silver. The mine also treats 12.6 Mt of oxide ore grading 1.08% copper, with an output of 140,300 t of electro-won cathode copper.
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The deposit is related geologically to three porphyry bodies intruded along a major fault system. Primary hydrothermal sulphide ore grades at between 0.2% and 1% copper. Subsequent weathering and uplifting created a barren, leached cap, up to 180 m thick, over a high-grade supergene enriched ore, both overlying the primary sulphides. Primary sulphide mineralisation includes pyrite, chalcopyrite and bornite, with covellite and chalcocite in the enriched zone. Some areas contain significant oxide copper oxides overlying the sulphides.
Proven and probable reserves estimated at1, 990 Mt grading 1.23% copper. Initial mining reserves totalled 662 Mt grading 2.12% copper. The stripping ratio will average around 1.7:1 over the full life of the project, for a current 127,000 t/day of ore.
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ENMIN 7110
Questions
50% of course total marks
1. What are the processes for developing a new mine in Western Australia?
2. Schedule production for the mine detailed below to optimize copper concentrate at minimum mining cost using a maximum of five stopes operating at a time. Assume each month consists of 21 operating days. The mine has the following stopes with the characteristics as outlined.
Stope
Available
Stope Reserves (tonnes)
Stope Performance (tonnes/day)
Stope Grade
% Cu
Mining Cost
K1
Now
19,000
85
9.8
8.35
K2
Now
28,000
115
8.7
6.15
K3
1 Month
60,000
300
4.2
3.60
K4
Now
90,000
285
4.0
4.10
K5
2 Months
300,000
560
3.4
2.45
L1
Now
47,000
300
7.6
5.10
L2
Now
97,000
400
3.3
3.66
L3
6 Months
500,000
900
3.5
2.00
L4
8 Months
430,000
800
4.1
2.90
L5
Now
150,000
240
7.9
4.86
M1
9 Months
655,000
1,600
2.9
1.51
M2
3 Months
175,000
1,000
5.3
2.80
The schedule must aim for the following as far as possible:
a) Maximum, constant tonnage per month
b) Constant grade
c) Constant cost
3. What are strategic risks? How would you manage these risks?
4. Define short, medium and long term planning?
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5. Discuss some of the factors that an engineer needs to account for when planning a mining operation
6. What techniques of pit optimisation are available?
7. Define the following in relation to network techniques (CPM and PERT)
a. Earliest start time
b. Latest start time
c. Earliest finish time
d. Latest finish time
e. Slack
f. Float
8. A project is defined by the list of activities detailed in Table 1.
i. Draw the network as an activity on the arc network
ii. Find the critical path
iii. Find the slack for each activity
Table 1
Activity
Immediate predecessors
Duration days
A
-
3
B
-
4
C
-
3
D
C
2
E
B
1
F
A
5
G
B
2
H
B
3
I
C
11
J
D, E
3
K
F, G
1
L
K
4
M
J, H
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9. The network shown in the next diagram is to be used in the planning of the installation of an underground crusher station. Determine the total project time and the critical path.
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10.A 10,000 tpd underground coal mine is in the planning stages. It is anticipated that salaried and supervisory staff will constitute 20% of the work force. Each production crew will consist of 8 miners and 1 foreman. Several of the other mines operated by the company have been averaging 10 tonnes per person per day and 200 tonnes per unit shift. However there is no reason not to believe that the new mine will average 15 tonnes per person per day and 300 tonnes per unit shift. Determine the size of the required labour force for both rates of productivity.
11.Calculate the Net Values for gold ore containing 1.3 g/t, 4.5 g/t , 8.0 g/t and 15.7 g/t. Use the input values given below.
Input Values
Mill Recovery Rate
93%
Mill Concentrate Grade
20g/t Au
Smelter Loss
0.7 g/t of Au pulp
Refining Loss
0.25 g/t of Au dory
Head Grade
1.3 g/t, 4.5 g/t , 8.0 g/t , 15.7 g/t
Au price
$12.50 /g
By-product credit (Ag)
$45.00/t
Production costs (excluding stripping)
$103.00/t
Mining costs
$25.20/t
Milling costs
$95.00/t
General/Administration
$3.20/t
Shipment of mill pulp to mint
$8.20/t of Au pulp
Smelting cost
$45/t of Au dorey
Shipment of dorey to refinery
$45/t of dorey Au
Refining cost
$12.00/t of dorey Au
Selling & Delivery costs
$3.20/g Au metal
General Plant costs
$0.84/g of Au
12.Cut-off Grade
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a. Following are the variables for choosing the "Optimum Cut-off Grade":
M = maximum amount of material that the mine can produce in any given time (mine capacity)
C = maximum amount of ore that can be put through the concentrator in any given time (mill capacity)
R = maximum amount of final product that can be produced in the given time period (production capacity)
m = mining costs, $/t of material mined
c = concentrator cost, $/t of ore milled
r = smelting, refining, packaging, insurance cost, $/kg of final product
f = fixed cost
s = selling price
y = recovery
T = length of production period
Qm = quantity of material to be mined
Qc =quantity of ore sent to the concentrator
Qr = amount of product actually produced over this production period
a. Using these above variables, develop the basic equations for
i. total cost, Tc
ii. revenue, R
iii. profit, P
b. Develop the equations for cut-off grade assuming that
i. mining rate is the governing constraint
ii. concentrating rate is the governing constraint
iii. refining rate is the governing constraint
13. Define the following terms used with respect to the Lerchs-Grossmann 3D algorithm
a) Directed arc
b) Edge
c) Weight
d) Node
e) Graph
f) Directed graph
g) Sub graph
h) Closure
i) Maximum closure
j) Circuit
k) Chain
l) Cycle
m) Path
n) Tree
o) Root
p) Branch
q) Twig
14.Discuss the floating cone process
15.Describe three problems with regard to the application of the floating cone technique. What are the positive aspects of the floating cone technique?
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16.Summarise the steps in the Lerchs-Grossmann 2D algorithm
17.Define the terms:
a) Project year
b) Production year
c) Calendar year
18.Summarise the basic concepts behind Lane’s algorithm