matthew hayward, spraying systems co pty ltd - improving dust management from pit to port

Spraying Systems Co. Pty Ltd

A.B.N 64 065 383 253

Improving Dust Management

from

Mine to Port

Presented By

Matthew Hayward

Spraying Systems Co Pty Ltd

Improving Dust Management from Mine to Port of 11

Ore Movement equals Dust With the mining process every movement of mined Ore generates dust. Below are twelve of the

most common areas that created dust from ROM Bin to the Ship loader.

ROM Bins

Grizzly / Apron Feeders /

Crushers

Conveyors

Transfer Chutes

Screen Houses Stackers

Stockpiles

Reclaimers Train Load outs

Ore Dumpers Belt Wash Stations Ship Loaders



Water to control Dust

• Water is the one of the most effective options to control dust.

• Water is the most economical solution rather than using Surfactants, Foam and Binders.

• For water to be effective and maximise results it is a matter of the right setup.

• A better understanding of Spray Technology by personnel will ensure the correct results are

achieved using water.

• Understanding droplet size and its importance to control airborne dust.

Using Water to supress dust from an emptying Haul Pac into ROM Bin

Understanding Dust Control • To maximise Dust management you need prevention and suppression.

• Dust prevention uses water to make the dust particle heavier so that it cannot become

airborne.

• Dust Suppression uses water to capture airborne dust particles by combining – which

becomes heavy and it falls down.



How Dust Suppression works

• In order for dust suppression to work the droplet size has to be of approximate equal size

to the dust particle size.

• If droplet size is larger than dust particle all you achieve is turbulence.

Understanding Nozzles Sprays

• Air atomizing nozzles produce the smallest drop sizes followed by fine spray, hollow cone, flat fan

and full cone nozzles.

Air Atomizing Nozzle

Fine Spray Nozzle Hollow Cone

Nozzle Flat Fan Nozzle Full Cone Nozzle



Understanding Droplet Size

• High pressures yield smaller drops and lower pressure yield larger drops.

• Lower flow nozzles produce the smallest drops and higher flow nozzles produce the largest

drops.

Pressure and

Flow

Smaller Droplets

Pressure and

Flow

Larger Droplets

Drop Velocity

• Drop velocity is dependent on drop size. Small drops may have higher initial velocity, but

velocity diminishes quickly. Larger drops retain velocity and travel further.

• Increases in surface tension increase drop size.

• Hard Water – Calcium and Magnesium.



Droplet Size

• Droplet size - VMD is the Volume Medium Diameter – Middle Range.

• Droplets are 50% larger and 50% smaller.

VMD

50% Smaller Drops

50% Larger Drops

• New nozzles are ideal – correct droplet size, spray pattern, litre output at given pressure.

• As nozzle wears – droplet size increases (more larger droplets than smaller), spray pattern

distorts and output increases.

Droplet size Angle Output

Droplet size Angle Output



Nozzle Maintenance

• Maintenance is usually low on priority list, on shutdowns the majority of maintenance repairs in done around the rest of the plant and not enough time is available for nozzle replacement.

• Poor understanding of nozzle technology and detecting worn nozzles ensures no maintenance is performed by mine personnel.

• Assumption that as long as water is still spraying there is no need for maintenance.

• It’s important through visual detection to identify nozzles erosion, caking, corrosion and damage.

Maintenance Timeline

• 1 Day

24 Hours

1 Week

168 Hours

1 Month

672 Hours

2 Months

1344 Hours

3 Months

2013 Hours

• Nozzle wear is not obvious • Excess water use • Minimal Dust Suppression • Replace nozzles 2-3 months

New Nozzle Worn Nozzle



New vs Worn Nozzle

• With nozzle wear for every 1% wear 5% additional volume output.

• As volume output increases from the nozzle due to wear the fundamental factors of dust

suppression/prevention such as, spray pattern, drop size, and coverage are compromised.

Common Sprays Used in Mining

Air Atomiser Nozzle

Hydraulic Nozzle

WhirlJet Nozzle

VeeJet Nozzle

FlatJet Nozzle

FullJet Nozzle

FogJet Nozzle

SpiralJet Nozzle



The Importance of Filtration

• Poor quality water blocks nozzles • Internal corrosion block nozzles • Nozzles wear quicker • Distorted spray patterns

The right setup Strainers should be placed by the pump and before the spray bar – in many original

engineering designs strainers are placed in the circuit, though it is not taken into account the length of piping and long term corrosion effects.

Pump Strainer Piping Strainer Spray Bar

Dust Control, Cleaning and Ore Conditioning

<= Ore Level Moisture

• When determining all the sprays across the site they need to be calculated so the total water used does not exceed the maximum moisture level in the Ore.

• Total allowable moisture • Starting moisture • Ore tonnage per hour • Recycled – re-screened Ore • Loss to evaporation • End moisture level

<=

All Site Sprays

Over wetting = Incorrect nozzles, calculations and worn nozzles



Belt Washing Stations

• Belt Washing stations are part of process though can create dust which requires control especially at the end of conveyors where Ore flicks off creates dust.

• Poor Belt Cleaning increases wear and tear to belts, rollers and bearings, increased vibration harmonics through conveyors and entire plant structure.

• Sprays that are over wetting Ore will stick to the belts which in turn end up

on conveyor belt assemblies.



Common Problems from Mine to Port• Common issues found from Mine to Port

– Blocked nozzles

– Missing nozzles

– Wrong nozzles types – incorrect angles and capacity sizes

– Poorly positioned sprays

– Distorted spray patterns

– Solenoids and test functionality not working

– Water supply not available

– Damaged spray bars

– Damaged and leaking hoses

– Poor Pressure

– Poor water flow

matthew hayward, spraying systems co pty ltd - improving dust management from pit to port

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