Determine the optimum diameter for a ventilation shaft

Assignment Help Mathematics
Reference no: EM131673055

Question: 1.

For the following situations determine the effective noise level in dB(A)

a. A rock drill produces a sound pressure level of 90 dB(A) in a heading. If two more drills were to operate in the heading what would be the expected noise level?

b. Currently a conveyor operator works for a shift length of 8 hours and is subjected to a noise exposure of 85 dB(A) over the shift. If this worker works a double shift at his normal work station what will be his noise exposure for that day?

c. A continuous miner operator sitting on the machine is exposed to a noise level of 93 dB(A) when sat 3m from the noise source. If this operation were to be made a line of site remote operation with the operator being an equivalent distance of 18m away from the noise source what would his noise exposure be?

d. Determine the equivalent 8 hour noise exposure level for a worker exposed to an equivalent continuous sound pressure of 86dB(A) over a 12 hour shift?

Question: 2.

An analysis of air samples taken in a return airway indicates the following gas concentrations:

Carbon dioxide: 0.2 percent, Hydrogen Sulphide: 2 ppm, Sulphur Dioxide: 1 ppm. Determine the threshold limit values, TWA and STEL for the mixture.

Question: 3.

Using the Brief and Scala method determine the TLV-TWA for Carbon Dioxide for an 11 hour shift if the TWA-TLV for an 8 hour shift is 0.5%

Question: 4.

Develop a spreadsheet based application to determine the optimum diameter for a ventilation shaft for a ventilation flow rate of 200 m3/s. It may be assumed that the cost of power is Au$ 0.45 kWhr.

The following apply
Shaft sinking
Set up and decommissioning costs $ 1,000,000
Excavation cost $ 450/m3
Fittings and Lining $ 500/m
Shaft Data
Shaft depth 1000m
Friction factor 0.006 kg/m3
Air density 1.2 kg/m3
Fan efficiency 70%
Shaft life 20 years
Annual rate of interest 10%
Use Chapter 5 and 9 provided as a reference

Question: 5.

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 dorey

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

Verified Expert

The assignment is related to effective noise calculation and Cash flows. Effective noise level does not get added arithmetically , but there is a standard 3db gain for adding 2 same noise levels.As distance of exposure increases the effective noise decreases. When time exposure is doubled , the noise level is added to itself which shows a 3db gain. Cash flows are related to operating costs and profits in terms of present worth. The present worth is converted to equivalent annual worth and the net worth is calculated by adding the profits and deducting the operating costs related to it.

Reference no: EM131673055

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Reviews

inf1673055

1/13/2018 5:08:13 AM

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inf1673055

12/6/2017 5:00:14 AM

Some more reference material 25483716_112 Further evaluation techniques.pptx 25483716_2Runge Economics orkbook.xls 25483716_35150 Reference books.jpg Thanks for the solution, can you please convert question 4 into a spreadsheet with formulas etc as per the question outline, as I am hopeless at developing a spreadsheet, cheers.

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