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

Investigation into the Use of Cement Kiln Dust
(CKD) for Wastewater Treatment
(PCA Index No. M06-04 )
M.E. Walsh and C.B. Lake
Department of Civil and Resource Engineering
Dalhousie University
Portland Cement Association
Manufacturing Technical Committee Meeting
May 19, 2008
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Project Overview
Purpose: To investigate a potential new market avenue
for CKD as a reuse material
Start Date
May 2007
End Date
May 2009
Budget (2-yrs)
Project Sub-Tasks
Task 1: Literature Review & Market Assessment
Task 2: CKD Characterization Studies
Task 3: Bench-scale Chemical Conditioning Trials
$117,528 US
Completed Aug07
Sept07 – Aug-08
Aug08 – 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 2007
 Broad overview of treatment methods for various types
wastewater
 Focused on use of lime for chemical precipitation of
target contaminants
 Market assessment found that most promising
application is in mine effluent treatment
 Lime neutralisation with quicklime most widely applied
treatment method
 Metal commodities in demand/prices high, WW volumes
are large & environmental discharge concerns
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Proposed CKD Reuse Application
• Increase pH > 9.0
• Metal contaminants become insoluble & precipitate out of solution
CaO  H 2O (CaO)
Ca (CKD
OH+)H220 Ca 2  2OH 
Proposed CKD Application
Lime Slurry
2)
(Ex) For removal
of (Ca(OH)
lead from
liquid phase:
(Dalhousie University)
Polymer
Pb 2   2OH   Pb(OH
)2 (s)
Wastewater
Reactor
Clarifier
N-Viro CKD Application
Treated Effluent
Sludge
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Task 2: CKD Characterization Study
CKD sampled from six different plants:
 Lafarge Canada Inc: Brookfield, NS
 Ash Grove Cement Company: Clancy, MT
 St. Lawrence Cement: Juliette, QC
 Lafarge North America: Alpena, MI
 Cemex Inc: Xenia, OH
Ash Grove
 Cemex Inc: Knoxville, TN
Quicklime (CaO):
 Laboratory grade
 Commercial vendor
Knoxville
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Analysis of Major Oxides
Calcium oxide (CaO) content
• CKD samples 39 to 58 %
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• Commercial quicklime 90 %
CaO, Wt %
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Potential “interfering” oxides
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• CKD: 9 to 23 % SiO2
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• Commercial quicklime 4 % SiO2
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Other potential “interfering”
oxides:
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SiO2, Wt %
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Al2O3, K2O, MgO
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Particle Size Distributions
120
Commercial
Quicklime
100
80
CaO
% Finer
Quicklime
Knoxville
60
Brookfield
Xenia
Ash Grove
40
Alpena
St Lawrence
20
0
0
1
10
100
1000
Particle Diameter (µm)
Alpena
Ash Grove
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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
12.5
11.5
Brookfield CKD
pH
12.0
Laboratory Grade CaO
Commercial Quicklime
Knoxville CKD
Xenia CKD
Alpena CKD
Ash Grove CKD
Juliette CKD
11.0
10.5
10.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
Concentration of Sample (g CaO/L)
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CKD Slaking Experiments
4.0
Laboratory Grade CaO
Commercial Quicklime
Conductivity (mS/cm)
3.5
3.0
Knoxville CKD
2.5
Xenia CKD
2.0
Alpena CKD
1.5
Juliette CKD
1.0
Ash Grove CKD
Brookfield CKD
0.5
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
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Concentration of sample (g CaO/L)
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Path Forward
Task 1: Literature Review & Market Assessment
 Proposal 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 Study
 Base properties: particle size & surface area
 Slaking Experiments:
 Temperature reactivity tests
 Possible blending trials (CKD & commercial quicklime)
 Summer 2008
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Path Forward
Task 3: Bench-Scale Chemical Conditioning Trials
 Focus will be on CKD treatment applications for mine
effluents
 100% CKD vs Quicklime vs Blend Ratios
 Experiments will start in Sept. 2008
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Acknowledgements
 Portland Cement Association & Cement Association of Canada
 Colin Dickson, CD, PEng:
Director Business Development, CAC
 Richard 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
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Thank you for your time.
QUESTIONS?
Contact Info:
M.E. Walsh, PhD, PEng
Assistant Professor
Department of Civil and Resource Engineering
Dalhousie University
1360 Barrington St., Bldg. D, Rm.D215
Halifax, Nova Scotia, B3J 1Z1
Tel: (902) 494 8430
Email: [email protected]
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