1. Low Frequency Noise Ian Reynolds – Project Manager – Wolf Minerals
Process Plant overview
How it works
Screens
Options Register
Mitigations and possible solutions
Option development
Option evaluation

2. Process Plant Overview

3. Process Plant Overview Areas 110, 120, 130, 140 and 150

4. Process Plant Overview Areas 160, 180 and 200

5. Process Plant Overview Product Screen

6. Process Plant Overview Horizontal and Banana Screens

7. Process Plant Overview Horizontal and Banana Screens
The following matrix describes the relationship between mitigations and items.

8. Mitigations The Mitigations to be considered are as follows.
UP: Underpan
There is a possible relationship between the size of the underpan and its internal structure and the creation of LFN. Two modifications are being considered; increasing the volume of the underpan and also installing a grating arrangement within the underpan.
VT: Venting
The pressure waves created above and below a screen deck are 180 degrees out of phase; this natural phenomenon suggests that it’s possible to limit LFN by allowing these out of phase pressure waves to interact and cancel each other out. The cancelling effect will require the lower pressure wave to reach the upper pressure wave by either venting either through the screen deck, by removing panels and or removing the screen to underpan seal (peripheral)
RL: Relocation
Relocation of specific screens may improve the production of low frequency pressure waves; screen relocation to lower levels within the processing facility building is to be considered along with examining the relocation of screens outside of the existing processing facility building.
SY: Synchronisation
This mitigation is founded on the same phenomena being addressed through screen venting (VT) however in this instance the sound pressure waves from adjacent screens are run in anti-phase to each other in an attempt to cancel out overall low frequency noise.

9. Mitigations AC: Active Noise Control
Active noise control also takes advantage of the noise cancelling potential achieved through anti-phase sound pressure waves. In this instance a sound pressure generator is mounted above the screen being considered. The generator is linked to the screen deck in such a way that the generator creates a pressure wave out of phase with that generated by the screen deck, thus resulting in pressure cancellation.
SP: Split Screen
Replacing screens with two smaller screens has the potential of reducing overall low frequency noise, couple this with the ability to synchronise the screens has the potential to achieve a significant reduction in LFN.
AE: Acoustic Enclosure
The provision of an acoustic enclosure for an individual screen is considered to be a viable mitigation. The enclosure is designed to provide stiffened walls that limit the ability of the low frequency pressure waves to transmit into the environment.
BD: Bunding
Bunding to provide a barrier to prevent the transmission of low frequency pressure waves is being considered in strategically position locations near to the processing facility and at distance as dictated by the ground contours.
SO: Separate Operation
Consideration is being given to relocating the ‘front end’ of the processing facility to take advantage of the local geography to limit low frequency pressure wave transmission.

10. Process Facility Units
The following items are being addressed with respect to the mitigations described previously.
120SN01: Scrubber Screen SN02: Product Screen
140SN01: DMS Preparation Screen
140SN02-03: DMS Sink Screen

11. Process Facility Units
140SN04-05: DMS Floats Screen

12. Process Facility Units
140SN04-05: DMS Floats Screen

13. Process Facility Units
Processing Plant

14. Process Facility Units
Crushing-Screening