Cl t C l Mi P j tClermont Coal Mine ProjectSelection of Tailings Paste Thickener

A IMM T h i l M tiAusIMM – Technical Meeting17 February 2010

Norris September / Rebecca Kirkwood

Topics

> Project Overview> Project Overview

> Metallurgical Design Considerations

> Tailings Disposal Study> Tailings Disposal Study

> Thickening Test Work (Outotec)

> Current Construction Activities> Current Construction Activities

Project Overview

• 15km north of Clermont TownshipClermont Township

• 15km east of Blair Athol Mine

• Open cut, truck/shovel operation and in pit p pcrushing & conveying system

• Planned production of• Planned production of 12Mtpa

• Expected mine life of 17 years

• High quality coal deposit with 192 Mt of proved open cut reserves• Contained within Wolfang Basin - an elongated north-south trending basin

approximately 5 km long by 1.5 km wideapproximately 5 km long by 1.5 km wide• Three major coal seams – the Gowrie, Prospect and Wolfang seams• Seams range from between 80 and 290 m below ground level

W lf i t l 40 thi k• Wolfang seam approximately 40 m thick• Approximately 17% of ROM coal will need to be washed over life of Project

Metallurgical Design ConsiderationsMetallurgical Design Considerations

Feed Rates

> CHP Nominal Feed Rate 2050 tph> CHP Nominal Feed Rate 2050 tph

> CHP Design Feed Rate 2500 tph

> CPP Design Feed Rate 300 tph

CPP – Equipment Utilised

> DMC: -50 + 2 mm

> Spirals: -2 + 0.1 mm

> TBS & Spirals were consider for the mid fractionTBS & Spirals were consider for the mid fraction

> Spirals were selected as they are better understood and appropriate for the required separating density

> Paste Thickener: -0.1mm

> Large proportion of the fine fraction is clay, hence disposal of th fi f ti d t ithe fine fraction does not compromise energy recovery

CPP Yields

Ci it Mi i N i l M iCircuit Minimum Nominal Maximum

Dense Medium Cyclone 22% 65% 96%

Spirals 47% 75% 95%

Tailings Disposal Study

Traditional Disposal Methods

Conventional Tailings Dam> Require large land areas.

Co-Disposal Dam> Disposal of coarse and fine reject

combined prior to pumping> Environmental challenges:

o Soil erosion;o Dust pollution;

combined prior to pumping.

> Finer fractions fill voids created by larger fractions, thereby creating a o Dust pollution;

o Water contamination.

> Dangerous – Fencing required.

g y gcompetent structure and can be driven on in a week.

> Smaller emplacement area requiredg g q

> Approval for dam not sought in mining application for Clermont, hence alternatives were explored

> Smaller emplacement area required than conventional tailings dam.

> Downsides include higher power & hence alternatives were explored. water consumption, pipeline wear

and emplacement management.

Background – Tailings Disposal

> At FS all rejects were to be co-disposedj p

> Co-disposal would require 636 ML / annum

> Initial groundwater studies reported that this water would beInitial groundwater studies reported that this water would be available from underground sources

> Later investigations found that this was incorrect

> New philosophy had to be adopted• Number of technologies investigated

Technologies Investigated

> Filter Press

> Vacuum Filters

> Belt Press FiltersBelt Press Filters

> Paste Thickeners

> Screen Bowl & Solid Bowl CentrifugesScreen Bowl & Solid Bowl Centrifuges• Rejected from study due to high maintenance and

power consumption &• Inability to dewater smaller fraction (-38µm) (Screen y ( µ ) (

bowl only)

Water Consumption

69%

70%

71%

66%

67%

68%

ving

(%)

63%

64%

65%

Wat

er S

av

61%

62%

Filter Presses Vacuum Filters Belt Press Filters Deep Cone Thickener

Power Saving – Total Installed Power

80%

90%

100%

50%

60%

70%

ving

(%)

20%

30%

40%

Pow

er S

av

0%

10%

Filter Presses Vacuum Filters Belt Press Filters Deep Cone Thickener

CPP co-disposal design had allowed for 1456 kW which includes 3 x co-disposal pumps, 2 x return water pumps & 1 x gland water pump.return water pumps & 1 x gland water pump.

Capital Cost

25%

30%

15%

20%

ase

(%)

5%

10%

pita

l Cos

t Inc

rea

0%Filter Presses Vacuum Filters Belt Press Filters Deep Cone

Thickener

Cap

Price comparison based on fixed plant only, does not include mobile equipment cost.Cost of Deep Cone Thickener is not much greater than a conventional thickener.Cost of Deep Cone Thickener is not much greater than a conventional thickener.

Maintenance

> Co-DisposalpReasonably maintenance intensive due to pumping coarse material

• Rotation of pipeline every month and replacement 3 times per year

• Frequent maintenance required on pumps

> Filter PressesMore maintenance friendly than older models

• Filter bags more reliableFilter bags more reliableRed Mountain CPP experienced cake discharge problems with their filter press and so replaced them with belt press filtersfilters

Maintenance Continued

> Vacuum Filters• Most common dewatering method for flotation product• Most economical unit to operate• Maintenance costs could possibly increase using this for

tailings

> Belt Press Filters• Installed & commissioned in some CPPs in CQ but• Installed & commissioned in some CPPs in CQ, but

experienced very high maintenance costs and much downtime

• Some of these units were replaced with more reliable unitsSome of these units were replaced with more reliable units which dropped maintenance costs significantly

> Deep Cone Thickener• Least moving parts of any other option• Robust and reliable• By their nature should require least maintenance

Criteria Evaluation

> Each option scored on a scale of 1-10p

> Each criteria equally weighted

> Scores for water and power were directly based on the savingsScores for water and power were directly based on the savings achievable compared with co-disposal

> Score for the capital cost based on the price rise expected

> Maintenance score was based on expected maintenance costs

> Maintenance and capital costs evaluated based on inverse

Comparison Matrix

Water Power Capital Maintenance TotalConsumption Consumption

pCost

Filter Presses 7 8 3 5 23

Vacuum Filters 7 7 2 6 22

Belt Press 7 9 8 2 26Belt Press filters

7 9 8 2 26

Deep Cone Thickener

6 9 9 8 32

Paste thickeners operate in a similar manner to conventional high rate thickeners but produce an underflow of paste consistency by: [Bedell et Aunderflow of paste consistency by: [Bedell et. A. UWA]

S l i h i fl l> Selecting the appropriate flocculant

> Using feed dilution systems

> Using a deep tank for compression

> Allowing for long bed residence times

> Using a 30-45° tank cone

> Using a specially designed rake system

> Using shear thinning principles

> Using a high degree of instrument and controlImage courtesy of FLSmidth

Thickening Test work

Test Work by Outotec

> Undertaken at Rio Tinto’s Technology & Innovation Laboratory in gy yMelbourne

> Test Equipment> Test EquipmentOutotec’s Supaflo High Rate Thickener

• 94 mm Diameter• 190 mm Diameter• 190 mm Diameter

> Test Material• Blair Athol Coal Tailings• SG: 1.7• Quantity: 16 bulky bins

Test Work by Outotec

> 94 mm Φ Test Method• Bed Height: 220mm• Rake Speed: 2.5 rpm• Stock slurry: Stored in 40 L agitated, baffled tub• Feed sent via variable speed peristaltic pump• Underflow pumped put by positive displacement pump

> Flocculant Screening (94 mm Φ Test Method)> Flocculant Screening (94 mm Φ Test Method)• Ciba Flocculants

Magnafloc X110, X125, 336, 1011 & 5250• Best settling performance by 1011 hence Magnafloc 1011Best settling performance by 1011, hence Magnafloc 1011

was selected for thickening test work

Test Work by Outotec

> 190 mm Φ Test Method• Bed Height: 220mm• Rake Speed: 2.5 rpmRake Speed: 2.5 rpm• Stock slurry: Stored in 2m3 agitated tank and fed at 3.7 – 4.3% w/w• Feed sent via variable speed peristaltic pump• Underflow pumped put by positive displacement pump

> To achieve an underflow solids density of 50% w/w, a solids loading rate of 0.23 t/m2h and flocculant dosage rate of 20 g/t were ideal conditions – as seen in Run 2.were ideal conditions as seen in Run 2.

Dynamic Thickening (190 mm Φ) Results

Run 1

> Solids LoadingTarget Rate: 0.31 t/m2hActual Rate: 0.30 t/m2h

> Underflow DensityCalculated Density: 48 % w/wActual Density: 47% w/wActual Rate: 0.30 t/m h

> Flocculant DosingTarget Rate: 30 g/tAct al Rate 31 g/t

Actual Density: 47% w/w

Actual Rate: 31 g/t

Dynamic Thickening (190 mm Φ) Results

Run 2

> Solids LoadingTarget Rate: 0.23 t/m2hActual Rate: 0.24 t/m2h

> Underflow DensityCalculated Density: 50% w/wAfter Feed Interruption: 57%Actual Rate: 0.24 t/m h

> Flocculant DosingTarget Rate: 20 g/tAct al Rate 19 g/t

After Feed Interruption: 57%

Actual Rate: 19 g/t

Dynamic Thickening (190 mm Φ) Results

Run 3

> Solids LoadingTarget Rate: 0.31 t/m2hActual Rate: 0.32 t/m2h

> Underflow DensityCalculated Density: 47 % w/wActual Density: 46.6% w/wActual Rate: 0.32 t/m h

> Flocculant DosingTarget Rate: 20 g/tAct al Rate 19 g/t

Actual Density: 46.6% w/w

Actual Rate: 19 g/t

Construction Activities

ST201 ( ROM Feed Bin & Apron Feeder)

Crushing Station – ST201

CPP & Portion of OLC

CPP

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