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Investigation into the Use of Cement Kiln Dust (CKD) for Wastewater Treatment (PCA Index Investigation into the Use of Cement Kiln Dust (CKD) for Wastewater Treatment (PCA Index No. M 06 -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 1

Project Overview Purpose: To investigate a potential new market avenue for CKD as a 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 Aug 07 Sept 07 – Aug-08 Aug 08 – May 09 2

Research at Dalhousie University • Founded in 1818 in Halifax, Nova Scotia • Atlantic Research at Dalhousie University • Founded in 1818 in Halifax, Nova Scotia • Atlantic Canada's leading research centre • $115 M 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 3

Task 1: Literature Review and Market Assessment Initial report completed in 2007 Broad overview 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 4

Proposed CKD Reuse Application • Increase p. H > 9. 0 • Metal contaminants Proposed CKD Reuse Application • Increase p. H > 9. 0 • Metal contaminants become insoluble & precipitate out of solution (Ca. O)CKD + H 20 Proposed Lime Slurry lead from (Ex) For removal of (Ca(OH)2) liquid phase: CKD Application (Dalhousie University) Wastewater Polymer Reactor Clarifier N-Viro CKD Application Treated Effluent Sludge 5

Task 2: CKD Characterization Study CKD sampled from six different plants: Lafarge Canada Inc: 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 (Ca. O): Laboratory grade Commercial vendor Knoxville 6

Analysis of Major Oxides Calcium oxide (Ca. O) content • CKD samples 39 to Analysis of Major Oxides Calcium oxide (Ca. O) content • CKD samples 39 to 58 % • Commercial quicklime 90 % Potential “interfering” oxides • CKD: 9 to 23 % Si. O 2 • Commercial quicklime 4 % Si. O 2 Other potential “interfering” oxides: Al 2 O 3, K 2 O, Mg. O 7

Particle Size Distributions Commercial Quicklime Alpena Ash Grove 8 Particle Size Distributions Commercial Quicklime Alpena Ash Grove 8

Slaking of CKD to Produce Ca(OH)2 CKD or Quicklime (0. 2 – 0. 8 Slaking of CKD to Produce Ca(OH)2 CKD or Quicklime (0. 2 – 0. 8 g Ca. O/L) 1 L H 20 (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 10

CKD Slaking Experiments 11 CKD Slaking Experiments 11

CKD Slaking Experiments 12 CKD Slaking Experiments 12

Path Forward Task 1: Literature Review & Market Assessment Proposal for literature review submitted 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 13

Path Forward Task 3: Bench-Scale Chemical Conditioning Trials Focus will be on CKD treatment 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 14

Acknowledgements Portland Cement Association & Cement Association of Canada Colin Dickson, CD, PEng: Director 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 15

Thank you for your time. QUESTIONS? Contact Info: M. E. Walsh, Ph. D, PEng Thank you for your time. QUESTIONS? Contact Info: M. E. Walsh, Ph. D, PEng Assistant Professor Department of Civil and Resource Engineering Dalhousie University 1360 Barrington St. , Bldg. D, Rm. D 215 Halifax, Nova Scotia, B 3 J 1 Z 1 Tel: (902) 494 8430 Email: mwalsh [email protected] ca 16