“Down to Zero”:

Processing challenges and solutions for

recovering and realising the value of fines.

Ross Garling - FAusIMM & Member ACPS

Wednesday, 19 Oc“Down to Zero”:Processing challenges and solutions for recovering and realising the value of fines.tober 2016

Royal on the Park, Brisbane

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Topics

Raw Coal

One of the Problems – start at the beginning

Commercialising High Inherent Ash Coals, eg Fort Cooper Coal

Measures

Achieving low ash coal products

Developments in Tailings

Testing & Evaluation

Re-Mining

Re-Processing

Agglomeration

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“Coals ain’t Coals”

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Fine Grained Coal

Grey is vitrinite

Coarse Grained Coal

To maximise high grade product yield:-

1. Evaluate,

2. Liberate

3. Selectively Process

4. Dewater

5. Briquette

NB These are exactly the same steps that

have been followed for many years with

the evaluation and development of all

mineral deposits

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Information for reading the

following photographs

• Vitrinite – grey; lightens with increasing coal rank

• Inertinite – higher reflecting than vitrinite, grey to yellowish

white and commonly showing cell structure

• Liptinite – darker grey (rare)

• Minerals – generally black (clays), some with brownish colour

tones with some minerals ranging from grey (calcite) to very

highly reflecting yellowish white (e.g. pyrite)

• Magnification – see the blue bar scale

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Example of

Coarse

Grained Coals

Large particle

comprised of vitrinite

and a few small mineral

grains.

Courtesy - Ray Smith,

Coal Petrology Services

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Example of

Fine Grained

Coals

Vitrinite lamellae with

abundant layers of clay

minerals and a few

small particles of

inertodetrinite (white).

Photomicrograph taken

in oil.

Courtesy - Ray Smith,

Coal Petrology Services

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Processing Fine Grained Coal

• The first reaction is grind and achieve liberation.

• Not so fast – it is well known that flotation recovery

is poor in ultra-fine particles.

• We can look at nano-bubbles and other techniques

• Tradd has done over 2,300 pilot trials including large scale trials.

• Many in the Fort Coopers, Fair Hills, and Burngroves, Girrah

• Achieving:-

• <10% ash,

• premium coking coals,

• 90% combustible recoveries

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Comparison

- Standard Testing Yields

Fine Grained Techniques

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Maximise Coking Coal Recovery from

Moatize

9

A client asked Tradd to achieve 1% ash coal for an alternative market

To date Tradd has:-

• selected various coarse

grained coals

• Utilised its Fine Grain

Techniques

• Repeatedly achieved products

in the range 0.85% to 1.1%

ash(db)

• Other technologies now

emerging

Reasons for not getting 0% ash:-

• Impurities

• Organically bound minerals

Achieving low ash coal products

Ross GarlingBE(Mining), MBA, Mine Mgr’s Cert., FAusIMM

25 years - specialized in the evaluation, re-mining, and re-

processing of tailings – see www.green4ever.com.au .

Some tails/rejects worked on:-

Grasberg, Irian Jaya

Anchor Tin

Gympie Gold

Rhondda

Hexham

South Blackwater

German Creek

Hebburn

Wambo

Westcliff

Metropolitan

Huntley

Bloomfield

Liddell

Collinsville

Catherine Hill Bay

Jellinbah East

Kestrel

Lake Vermont

Meandu

Oaky Creek

Peak Downs

South Walker Creek

Jeebropilly

Austar

Integra

Invincible

Mount Thorley

Warkworth

Ulan

West Cliff

Cleveland Tin

Norwich Park

Saraji

Cook

Gregory

Dawson

Ayrefield

Aberdare East

Neath

Merrywood

Southland

Abermain

Richmond Main

Pelaw Main

Elrington

Bellbird

St. Ives, Kalgoorlie

Testing & Evaluation

No Assumptions Please – This is where the mistakes are made

For an industry that is so meticulous, the lack of knowledge of the volume, grade, and extraneous materials in the tailings dams, is

amazing.

Tailings dams are highly variable resources

To consider a tailings business, requires a JORC reserve

Sampling methods:-

Coring – lose sample

Auger – contamination

RC – running sands

Vibracore – 100% core recovery

Vibracore Drilling

100% Core Recovery

Soft Terrain

Drill Through Water

Re-Mining Alternatives

Depending on Throughput the costs & factors are:-

Hydraulic Mining $1.00 - $1.50/t(db):-

Constant high density

Work in any weather, near 100% mining recovery, accurate control

Dredging $1.50 - $2.50/t(db):-

High density fluctuation (0% - 40%)

Low labour, high pond evaporation, poor mining recovery (back off stumps, etc)

Dry Mining $3.00 - $5.00/t(db):-

High labour (1 man per truck or digger)

Soft floor – bogging + problem unloading trucks

Tailings then need slurrying to process

Hydraulic Re-Mining

Recycled

Water

Pressure

Pumps

Hydraulic Monitor

- remote

controlled,

tracked, semi-

Mine straight

faces

Slurry drains to

Pump

Modern Hydraulic Mining

High pressures (20 to 40 bar) – depending on material

High pressure converts tailings into dense oil like solution

Fine tailings can drain for kilometres to slurry pump

High constant densities 30-40% in coal, 50-60% in say gold

Monitors remote controlled, tracked, semi-automatic

Production rates up to 500 tph per 150 mm unit

or 1,000 tph/200mm

Low ground bearing pressures

Low evaporation

High mining recovery

Trash

cleaned

& left

Hydraulic Mining

Hunter Valley Coal Gold Tails, South

Africa

Bowen Basin

Re-Processing

The fine particle size of tailings dictates that flotation should be included

Many flotation devices, some with pre-treatment

Combustible recoveries 60% - 95% depending on circuit & feed ash

Product ashes – eg 5% to 10% ash (depends target & coal)

Coking properties retained

Dewatering an issue:- vacuum (30-35%TM), pressure (20-25%TM)

Agglomeration:– briquetting (with or without binder), pelletisation

Drying after agglomeration – moistures 2% (no re-wetting)

Alternative Processing

Spirals plant built for $1.3m

Slurry-making Circuit

Coal

refuse

WaterVibratory

de-slime

screens

Agitated slurry

hopper

High shear

mixer

1

2 3

5Dewatering and extrusion Flotation circuit

Agitated hopper

for froth de-aeration

6

Flotation columns

7Extrusion

89 Coating circuit

10

Carbon pellet storage pile

4

11

Ash pellet storage pile

Vacuum filtration

drums

Drying circuit

Nanotech solution

Alternative

720,000 tpa(pdt)

plant.

90% comb. rec,

5% ash,

2% moisture.

$50m capital

$20/t(pdt) opex

Agglomeration

To be avoided if possible as adds $10-$15 / tonne product,

Sometimes part or all of the product can be added to the host

mines product.Briquetting - 150 year history

& Pelletising - Binderless – originally 0% surface moisture, now increasing

- Binder regime depends on:- - Clay content

- Product heat

- Duty of Briquette

- Lowest cost alternative

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Likely Products

Briquettes

(technology is 150

years old), with or

without binders @ 2

to 20% TM

Filter Cake @ 20 to

25% TM can be

added to mine

product

Extruded pellets

made recently for

Australian major @

2% TM, & will not re-

wet