120402 Beneficial use of CKD-Holcim(NZ) Ltd

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© Holcim (New Zealand) Limited 2011

A Local Solution for a Local Problem

Cement Kiln Dust as a valued by-productHarvey Tyler (Technical Sales Manager)

Grant Anderson (Environmental Manager)

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Presentation overview

• Cement Manufacture, Cement Kiln Dust(CKD) generation and the generation journey

• Environmentally appropriate approach and waste hierarchy progression

• Key benefits to Holcim (New Zealand) Ltd

• Void Stowing with Controlled Low Strength Fill (CLSF)

• CLSF mix design technology

• Acid Mine drainage reduction and management

• Industrial Ecology and Symbiosis

• Future Use

• Summary

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CKD

Cement production

1. Raw materials – HG limestone, marl, iron

2. Raw material milling & slurry production

3. Slurry injection into kiln system

4. Clinker production

5. Cement milling

6. CKD generation

Cement Production1. Journey begins in the quarry where 760,000 T pa of high grade(205,000 T pa @ 350+ LSF) and blend limestone(485,000T pa marl/clays) is combined with iron correctives(ironsand)Blended on a truck by truck basis (60 T per truck), primary crusher, delivered to incline feeders2. Raw material milling in 3 open circuit raw mills , output target 15% @ 90 micron blended with 35% water to slurry, 3 cascading basins; total volume = 11,000T, This constitutes wet process3. Slurry injected onto kilns, 3700 T/day, 670,000 T pa slurry throughput4. Kiln decarbonation calcium carbonate process via sintering at 1500 deg C(liquid temp) and 2100 deg c(gas temp), drying-calcining-sintering-rapid cooling, liquid phase that is rapidly cooled in planetary coolers to lock in chemistry of strength forming compound C3S, C2S, C3A & C4AF, to form Portland cement clinker5. Clinker is milled in two ball mills(CMM1 60.5T/hr, CMM2 12T/hr) 3-5% gypsum, up to 10% limestone addition.6. CKD generation is a kiln byproduct, ESP’s captures CKD particles across charge field, particle size 2-40 micron, plates vibrate to discharge CKD to drag chain, then silo andinsulfflation – collects 8000T/day 5-6% clinker production pa

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Cement production – CKD generation

CKD

Kiln temp profile = 100m length, 3 zones, tilted, 20m burning zone, planetary coolers – CKD outlet

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1958 1975 1991 1993 2005 2011

CKD and the generation journey

DUMP TO LAND FILL

ESP’s

NSD FERTILISER

INSULFLATION

ACID MINE MANAGEMENT

MINE VOID STOWING

1958 - cement production commenced (Guardian/NZ Cement Holdings/Milburn Cement) – kiln dust discharged to air and landfilled (~50,000 T pa)1975 – electrostatic precipitators installed on all 3 kilns,1991 – CKD Nodulised(NSD) for fertilizer production, ~20,000 T pa1993 – insulfflation system installed(5000 T pa) , consented landfill disposal with leachate monitoring program2005 – CKD utilised in mine restoration/rehabilitation for acid mine drainage (AMD) runoff management.2011 – All fresh CKD produced utilised in CLSF for void stowing plus legacystockpiles of CKD from ground storage (5 + 5 year program/contract); THE ULTIMATE SOLUTION!

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Environmental Appropriateness

Least Preferred

1974-1988

1988-1995

2011

Most Preferred2015+(tbc)New Kiln Project

CKD Void Stowing

Fertiliser

Landfilling

Insufflation 1993

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Waste Hierarchy and Holcim’s Response

Disposal

Material Recovery

Recycling

Reuse

Minimisation

PreventionThe Holy Grail!

Process Control

Void Stowing

Dust Insufflation

Land-filling

Fertiliser

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Waste Hierarchy and Solid Energy’s Response with CLSF

Disposal

Material Recovery

Recycling

Reuse

Minimisation

PreventionResource Utilisation

Overburden material use

CLSF as Engineered Cap

Contaminated Coal (OB)

Fire mitigation

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Void stowing process with CLSF

Overburden (-35) + Sand(-7)

H20

OPC

CKD

CLSFGROUND

UNDERGROUND MINE

Void stowing process with CLSF•Overburden processed to 35mm max agg size and granite sand 0-7mm •Water supply – mine catchment/management area (annual rainfall 3.5 metres)•Ordinary Portland Cement (GPC) – Holcim Ultracem storage in 110 T

horizontal silos, delivered via bulk tanker•CKD - 110 T horizontal silos, delivered via bulk tanker•Co-processed in constant flow double axle paddle track mounted processing

plant and discharge via gravity flume to 250-350 dia borehole. Void tight filled, monitored for filling, then moved to next borehole approx 15-20m away, re-filled. Boreholes can be 5 – 25m depth

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Controlled Low Strength Fill (CLSF) composition

52% Screened overburden waste nominal -35mm (onsite)

20% Water (onsite)

7% CKD (Holcim Westport Works)

3% OPC (Holcim Westport Works)

18% Screened granite sand nominal -7mm (onsite)

Min 10% binder

CLSF composition, by weight•~52% screened overburden waste – nominal -35mm granite gravel (ONSITE)•20% water (ONSITE)•~18% screened granite sand -7mm (ONSITE)•~7%ave CKD(5-15% depending on required characteristics) - Holcim•~3% Ultracem – Holcim

Minimum binder content of 10% to achieve; flowability, low viscosity, economiccementing capacity, required cohesion (prevent segregation), tight filling ability and required hardening. Water tightly dispensed to maintain required fresh propertiesAll materials sourced either onsite or Holcim 45km away!

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CLSF Processing Plant – Blair Athol, Clermont – QLD(Holcim Australia – 1.8 million m3 voids stowed over 7 years)

•CLSF plant at Blair Athol, Clermont, QLD – Holcim Australia (formerly Ready Mix owned by CEMEX)

•Material flow from processed overburden for coarse and fine aggregate, cement via plant mounted silo, constant flow blending, gravity fluming into boreholes

•1.8 million m3 over ~6 year stowing period•Holcim Australia consulted on SE void stowing operation - grateful

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Exposed opencast cut face – Blair Athol (Holcim Australia)

§ Waste minimisation, reduced OB contamination

§ Sets/structures locked into CLSF

§ Reused as engineered OB cap (2nd life)

§ Safe heavy machinery operation

§ Extinguishes underground fires

Opencast cut face1. 10m profile showing well performance CLSF(strength and tight-filling);

• waste minimisation with reduced OB contamination of coal resource• sets and existing mining structures set into the CLSF• 2nd life as an engineered cap for restoration and AMD management

2. safe operating environment for heaving machinery operating on overburden3. Assists in the extinguishing of historical underground fires by eliminating

air(one key aspect for fire propagation)

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Millerton Block mine workings - 1.25 million m3 known voids

1 km

Millerton Block•First mined in 1870’s, beset by major fires ever since, spontaneous

combustion, ceased mining 1960’s, reported temperature in excess of 1000 deg C, flares continue to occur to much lesser frequency

•1.25 million m3 of known voids. Mapping of historical miningoperation coupled with x-ray scan of voids. Scale. Estimate10+million tonnes coal reserves, high grade coking coal for export

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Solid Energy – Big Yellow CLSF processing plant

Solid Energy (Big Yellow)•Arrows indicate material flow to twin axle constant flow paddle mixer

then dispensed to gravity flume•17 m long, track mounted, weighs 115 tonne•Engine, hydraulics and track assembly are from a 100T Komatsu digger•Some parts made from 40m plate•Designed by Graeme Ashby of Hokitika, built in Westport by Buller

Industrial (Jim Rae Engineering Co)

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Solid Energy – Big Yellow CLSF processing plant

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CLSF as an engineered cap

• Acid mine treatment (Pyrite, acid forming water run-off)

• Second life as an engineered cap

• Assists in pH management of water run-off

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Industrial Ecology (Kalundborg Eco-park) – The Ideal…

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Holcim’s Industrial Ecology

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Industrial Symbiosis

35km

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Summary and acknowledgements• Value and use of an industrial by-product in a two tier lifecycle

• Promotion through the waste hierarchy

• Evolution of CKD management utilising the most environmentally appropriate solution available

• Industrial symbiosis with complementary industry

• Possible future use;

- Sewage sludge treatment- Contaminated ground remediation

Acknowledgements

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Don’t be afraid to take a big step when one is indicated. You can’t cross a chasm in two small steps. David Lloyd George

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Date post:	18-Aug-2015
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120402 Beneficial use of CKD-Holcim(NZ) Ltd

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