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Portland Cement Association

Manufacturing Technical Committee Meeting

May 19, 2008

M.E. Walsh and C.B. LakeDepartment of Civil and Resource Engineering

Dalhousie University

Investigation into the Use of Cement Kiln Dust (CKD) for Wastewater Treatment

(PCA Index No. M06-04 )

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Project OverviewPurpose: To investigate a potential new market avenue

for CKD as a reuse material

Start Date May 2007

End Date May 2009

Budget (2-yrs) $117,528 US

Project Sub-TasksTask 1: Literature Review & Market AssessmentTask 2: CKD Characterization StudiesTask 3: Bench-scale Chemical Conditioning Trials

Completed Aug07Sept07 – Aug-08Aug08 – May 09

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Research at Dalhousie University

Dalhousie University• Founded in 1818 in Halifax, Nova Scotia

• Atlantic Canada's leading research centre

• $115M annual R&D grants & awards

• Dalhousie has been ranked as the top university, outside the United States, to work and conduct scholarly research by The Scientist Magazine

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Task 1: Literature Review and Market Assessment

Initial report completed in 2007Broad overview of treatment methods for various types

wastewater Focused on use of lime for chemical precipitation of target

contaminantsMarket assessment found that most promising application is in

mine effluent treatmentLime neutralisation with quicklime most widely applied treatment

methodMetal commodities in demand/prices high, WW volumes are large

& environmental discharge concerns

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Proposed CKD Reuse Application

N-Viro CKD Application

OHCaOHCaOHCaO 222)(2

)(2)(22 sOHPbOHPb (Ex) For removal of lead from liquid phase:

• Increase pH > 9.0 • Metal contaminants become insoluble & precipitate out of solution

Lime Slurry (Ca(OH)2)

WastewaterReactor

Treated Effluent

Polymer

Clarifier

Sludge

Proposed CKD Application(Dalhousie University)

(CaO)CKD + H20

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Task 2: CKD Characterization StudyCKD sampled from six different plants:

Lafarge Canada Inc: Brookfield, NSAsh Grove Cement Company: Clancy, MTSt. Lawrence Cement: Juliette, QCLafarge North America: Alpena, MICemex Inc: Xenia, OHCemex Inc: Knoxville, TN

Quicklime (CaO): Laboratory grade Commercial vendor

Ash Grove

Knoxville

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Analysis of Major Oxides

0

20

40

60

80

100

Julie

tte

Ash G

rove

Alpena

Brookfi

eld

Knoxv

illeXen

ia

Quickli

me

CaO

, Wt %

Calcium oxide (CaO) content • CKD samples 39 to 58 %

• Commercial quicklime 90 %Potential “interfering” oxides

• CKD: 9 to 23 % SiO2

• Commercial quicklime 4 % SiO2

0

5

10

15

20

25

Julie

tte

Ash G

rove

Alpena

Brookfi

eld

Knoxv

illeXen

ia

Quickli

me

SiO

2, W

t %

Other potential “interfering” oxides:

Al2O3, K2O, MgO

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Particle Size Distributions

0

20

40

60

80

100

120

0 1 10 100 1000

Particle Diameter (µm)

% F

iner

CaO

Quicklime

Knoxvil le

Brookfield

Xenia

Ash Grove

Alpena

St Lawrence

Alpena Ash Grove

Commercial Quicklime

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Slaking of CKD to Produce Ca(OH)2

CKD or Quicklime(0.2 – 0.8 g CaO/L)

1L H20

(1) Rapid Mix for 30 minutes

(2) Analysis of Ca(OH)2 quality

• Neat solution (with solids)

• Filtered through 0.45 µm filter paper

• After 10 minute settling period

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CKD Slaking Experiments

10.0

10.5

11.0

11.5

12.0

12.5

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

Concentration of Sample (g CaO/L)

pH

Knoxville CKD

Laboratory Grade CaOCommercial Quicklime

Xenia CKDAlpena CKD

Brookfield CKD

Ash Grove CKDJuliette CKD

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CKD Slaking Experiments

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

Concentration of sample (g CaO/L)

Cond

uctiv

ity (m

S/cm

)

Laboratory Grade CaO

Commercial Quicklime

Xenia CKD

Brookfield CKD

Ash Grove CKD

Juliette CKD

Knoxville CKD

Alpena CKD

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Task 1: Literature Review & Market AssessmentProposal for literature review submitted on application of S/S technology

for treatment of mine tailings (CAC)Results would parallel with objectives of this study in terms of assessing

market potential for commercial applications

Task 2: CKD Characterization StudyBase properties: particle size & surface areaSlaking Experiments:

Temperature reactivity tests Possible blending trials (CKD & commercial quicklime)

Summer 2008

Path Forward

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Task 3: Bench-Scale Chemical Conditioning TrialsFocus will be on CKD treatment applications for

mine effluents 100% CKD vs Quicklime vs Blend RatiosExperiments will start in Sept. 2008

Path Forward

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Portland Cement Association & Cement Association of CanadaColin Dickson, CD, PEng:

Director Business Development, CACRichard Bohan, PE

Director Education and Technical Services, PCA CKD suppliers (Lafarge Canada Inc, Ash Grove Cement Company, St. Lawrence

Cement, Lafarge North America, Cemex Inc)Chris Petrie, EIT

Xstrata Zinc/Brunswick Mine, Bathurst, NB

Acknowledgements

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Contact Info:M.E. Walsh, PhD, PEng

Assistant ProfessorDepartment of Civil and Resource Engineering

Dalhousie University1360 Barrington St., Bldg. D, Rm.D215

Halifax, Nova Scotia, B3J 1Z1Tel: (902) 494 8430

Email: mwalsh2@dal.ca

Thank you for your time.

QUESTIONS?