International Conference Click to edit Master title style Click to edit Master title style STABILISATION/SOLIDIFICATION TREATMENT AND REMEDIATION Advances in S/S for Waste a member of the a member of the Click to edit Master text styles and Contaminated Land 12-13 April 2005 Cambridge University UK group Second level group Third level Fourth level La Floridienne La Floridienne Fifth level The First Large Scale The First Large Scale Immobilisation Project in Belgium Immobilisation Project in Belgium Contact: Contact: DEC DEC Stany Pensaert – R&D Manager DEC NV Haven 1025 Haven 1025 Scheldedijk 30 Scheldedijk 30 B- -2070 Zwijndrecht 2070 Zwijndrecht B Belgium Belgium 1 1 Tel: +32 3 250 54 11 Tel: +32 3 250 54 11 Fax: +32 3 250 52 53 Fax: +32 3 250 52 53 Info@decnv.com http://www.decnv.com
a member of the a member of the group group Contact: Contact: DEC DEC Haven 1025 Haven 1025 Scheldedijk 30 Scheldedijk 30 B- -2070 Zwijndrecht 2070 Zwijndrecht B Belgium Belgium 2 Tel: +32 3 250 54 11 Tel: +32 3 250 54 11 Fax: +32 3 250 52 53 Fax: +32 3 250 52 53 Info@decnv.com http://www.decnv.com
History of the site La Floridienne History of the site La Floridienne a member of the • Production facilities of inorganic metal a member of the compounds: group group – Ferro- and ferric cyanides → grey waste tip – Lead, lead chloride and lead carbonates → red waste tip • In operation between 1930 and 1961 • Pollution sources: – Grey waste tip: gypsum-lime nature. – Red waste tip: dust nature. – Ruins of former production plant Contact: Contact: – Storage and small disposal areas around the DEC DEC Haven 1025 Haven 1025 production plant. Scheldedijk 30 Scheldedijk 30 B- -2070 Zwijndrecht 2070 Zwijndrecht B Belgium Belgium 3 Tel: +32 3 250 54 11 Tel: +32 3 250 54 11 Fax: +32 3 250 52 53 Fax: +32 3 250 52 53 Info@decnv.com http://www.decnv.com
Pollution sources on the site Former plant area a member of the a member of the slurry wall group group Red waste Grey waste Quaywall combined with Contact: Contact: DEC DEC Black waste slurry wall Haven 1025 Haven 1025 Scheldedijk 30 Scheldedijk 30 B- -2070 Zwijndrecht 2070 Zwijndrecht B Belgium Belgium 4 Tel: +32 3 250 54 11 Tel: +32 3 250 54 11 Fax: +32 3 250 52 53 Fax: +32 3 250 52 53 Info@decnv.com http://www.decnv.com
Composition of the main sources Composition of the main sources a member of the a member of the Red waste Grey waste Immobilisation Concentration Leachability Concentration Leachability target mg/kg mg/l mg/kg mg/l group group (DIN 38414-S4) pH 4 - 13 3,82 4 12,5 12,7 ≤ 1 mg/l Arsenic 35000-40000 6-8 500-1000 0,01-0,05 ≤ 2 mg/l Lead 2000-10000 0,1-0,5 10000-25000 0,1-10 ≤ 10 mg/l Zink 500-5000 0,1-0,5 500-2000 0,05-0,5 ≤ 1 mg/l Cyanide 500 0,01-0,1 500-8000 10-300 total Contact: Contact: DEC DEC Haven 1025 Haven 1025 Scheldedijk 30 Scheldedijk 30 B- -2070 Zwijndrecht 2070 Zwijndrecht B Belgium Belgium 5 Tel: +32 3 250 54 11 Tel: +32 3 250 54 11 Fax: +32 3 250 52 53 Fax: +32 3 250 52 53 Info@decnv.com http://www.decnv.com
Soil contamination a member of the a member of the group group arsenic Contact: Contact: complex cyanides DEC DEC Haven 1025 Haven 1025 Scheldedijk 30 Scheldedijk 30 B- -2070 Zwijndrecht 2070 Zwijndrecht B Belgium Belgium 6 Tel: +32 3 250 54 11 Tel: +32 3 250 54 11 Fax: +32 3 250 52 53 Fax: +32 3 250 52 53 Info@decnv.com http://www.decnv.com
Groundwater contamination a member of the a member of the group group Arsenic –upper aquifer Contact: Contact: complex cyanides –upper aquifer DEC DEC Haven 1025 Haven 1025 Scheldedijk 30 Scheldedijk 30 B- -2070 Zwijndrecht 2070 Zwijndrecht B complex cyanides –deep aquifer Belgium Belgium 7 Tel: +32 3 250 54 11 Tel: +32 3 250 54 11 Fax: +32 3 250 52 53 Fax: +32 3 250 52 53 Info@decnv.com http://www.decnv.com
Headlines of the remediation Headlines of the remediation • Vertical and horizontal isolation of soil and a member of the a member of the groundwater within the site’s boundaries. group group • Immobilisation of the leachable waste products and storage within the isolation. • Removal of contaminated soil outside the site’s boundaries and storage within the isolation. • Pump-and-treat of the groundwater contamination outside the site’s boundaries. • Permanent lowering of the groundwater within the site’s boundaries in order to prevent contact Contact: Contact: with stored waste and soil, and prevent DEC DEC Haven 1025 Haven 1025 outward flow of contaminated water. Scheldedijk 30 Scheldedijk 30 B- -2070 Zwijndrecht 2070 Zwijndrecht B Belgium Belgium 8 Tel: +32 3 250 54 11 Tel: +32 3 250 54 11 Fax: +32 3 250 52 53 Fax: +32 3 250 52 53 Info@decnv.com http://www.decnv.com
Immobilisation of the red and grey Immobilisation of the red and grey waste: contractual obligations waste: contractual obligations a member of the a member of the • Contractor is responsible for the design and application of the immobilisation recipes: group group only one party involved. • Contractor has to guarantee the proposed target levels for immobilisation: - control samples with tender - ‘entrance exam’ of 200 m³ of red and grey waste. - 50 % of the contract award points on immobilisation. - High risk and liability for the contractor: extremely high penalties for non-conformance of Contact: Contact: immobilized waste. DEC DEC Haven 1025 Haven 1025 • Minimal geotechnical stability within 28 days: Scheldedijk 30 Scheldedijk 30 B- -2070 Zwijndrecht 2070 Zwijndrecht B Belgium Belgium 9 17 MPa compressibility modulus Tel: +32 3 250 54 11 Tel: +32 3 250 54 11 Fax: +32 3 250 52 53 Fax: +32 3 250 52 53 Info@decnv.com http://www.decnv.com
Contractors risks Contractors risks a member of the a member of the • DEC guaranteed the most stringent levels of group 1 mg/l for lixiviation of arsenic and cyanides. group • From a contractual side the guarantee remains valid irrespective the chemical quality of the waste that would be encountered in the waste tips. • The guaranteed execution period was very short: only 9 months for the total project, of which only 4 months for the immobilisation: - Parallel mixing of red and grey waste. Contact: Contact: - mixing plant capacities of 200 tons an hour. DEC DEC Haven 1025 Haven 1025 Scheldedijk 30 Scheldedijk 30 B- -2070 Zwijndrecht 2070 Zwijndrecht B Belgium Belgium 10 Tel: +32 3 250 54 11 Tel: +32 3 250 54 11 Fax: +32 3 250 52 53 Fax: +32 3 250 52 53 Info@decnv.com http://www.decnv.com
Immobilisation of the red waste Immobilisation of the red waste 2- or • Mobile form of arsenic is arsenate (H 2 AsO 4 - , HAsO 4 a member of the a member of the 3- in function of pH) or arsenite (AsO 3 AsO 4 3- ). group • In the presence of iron various interactions with these group arsenic compounds can occur: – adsorption and chemisorption of anionic arsenic compounds on the positively charged Fe(OH) 3 – Chemical reaction and crystallisation of iron-arsenic compounds on the iron oxides. • At the low pH of the red waste, ferric arsenate will be the most favourable compound to be formed: 3- → FeAsO 4 K = 5.3 x 10 20 Fe 3+ + AsO 4 Contact: Contact: DEC DEC Haven 1025 Haven 1025 Scheldedijk 30 Scheldedijk 30 zerovalent iron B- -2070 Zwijndrecht 2070 Zwijndrecht B Belgium Belgium 11 Tel: +32 3 250 54 11 Tel: +32 3 250 54 11 Fax: +32 3 250 52 53 Fax: +32 3 250 52 53 Info@decnv.com http://www.decnv.com
Immobilisation of the grey waste: Immobilisation of the grey waste: which cyanides? which cyanides? a member of the a member of the • Origin: Prussian Blue Fe 4 (Fe(CN) 6 ) 3 group group • At the high pH of the grey waste Prussian Blue is thermodynamically unstable and will dissociate into soluble 4- anions in hexacyanoferrate Fe(CN) 6 the pore water and Fe(OH) 3 . • Hardly no free cyanides are present 4- is a strong complex and since Fe(CN) 6 Contact: Contact: an excess of ferrous ions is present. DEC DEC Haven 1025 Haven 1025 Scheldedijk 30 Scheldedijk 30 B- -2070 Zwijndrecht 2070 Zwijndrecht B Belgium Belgium 12 Tel: +32 3 250 54 11 Tel: +32 3 250 54 11 Fax: +32 3 250 52 53 Fax: +32 3 250 52 53 Info@decnv.com http://www.decnv.com
Immobilisation of the grey waste: Immobilisation of the grey waste: options investigated. options investigated. a member of the a member of the • Lowering the pH of the mixture in order to group group stabilize the cyanides as insoluble Prussian Blue. • Fixing the cyanides with the addition of cationic exchange resins. Idea from the water treatment plant as there ionic exchange is used. • Transforming the waste matrix to an impermeable cemented matrix in order to reduce the cyanide mobility within this matrix substantially. Contact: Contact: DEC DEC Haven 1025 Haven 1025 Scheldedijk 30 Scheldedijk 30 Cement & water repellent additives B- -2070 Zwijndrecht 2070 Zwijndrecht B Belgium Belgium 13 Tel: +32 3 250 54 11 Tel: +32 3 250 54 11 Fax: +32 3 250 52 53 Fax: +32 3 250 52 53 Info@decnv.com http://www.decnv.com
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