1. Environmental impact of ore smelting: the African & European experience Vojtěch ETTLER EGG – Environmental Geochemistry Group Institute of Geochemistry, Mineralogy and Mineral Resources Faculty of Science, Charles University in Prague Albertov 6, 128 43 Prague 2, Czech Republic

2. Number of colleagues and students: Charles University in Prague Martin Mihaljevič, Ondřej Šebek, Ladislav Strnad, Jan Jehlička, Martina Vítková & many students Czech Geological Survey Bohdan Kříbek, František Veselovský, Vladimír Majer BRGM Orléans, France Zdenek Johan, Patrice Piantone,… Université d´Orléans, France Jean-Claude Touray, Patrick Baillif,… People from Zambian & Namibian universities / geological surveys: B. Mapani, F. Kamona, I. Nyambe, G. Schneider,…

3. Number of companies: Funding: Czech Science Foundation (GAČR 210/12/1413) Ministry of Education, Youth and Sports of the Czech Rep. Granting Agency of the AS CR and Charles University IGCP project No. 594 („Assessment of impact of mining and mineral processing on the environment and human health in Africa“) Kovohutě Příbram CZ (Pb smelter) Zdeněk Kunický, Karel Vurm Ongopolo Mines – Tsumeb smelter (Namibia) Hans Nolte Chambishi and Mufulira smelters (Zambia) Tony Gonzáles and technical staff

4. Background information non-ferrous metal smelting large amounts of smelting waste silicate slag fly ash – air polution control (APC) residues high concentrations of inorganic contaminants high leachability of metals and metalloids in EU classified as hazardous materials soil pollution by smelter emissions (fly ash)

5. Outline of the presentation Examples from Czech and African smelting sites Long-term environmental stability of waste materials from the smelting activities (slags) – insights from mineralogy/geochemistry Fate of smelter-derived contamination in the environment (soils affected by smelter emissions)

6. Environmental stability of smelting slags Slags are silicate waste products resulting from extraction of metals from ores by reducing fusion. Slags contain high levels of contaminants.

7. Pb smelter (Příbram, CZ) operating 200 years Pb-Ag production processing of ores (1786-1974) processing of car batteries since 1974 1.8 Mt of slags on the dumps

8. Slag melt tipped off >>> Reducing fusion in shaft furnace temperature ~ 1350°C charge: Pb source (ore, Pb scrap), Fe scrap, calcite, Si source fuel (coal, coke)

9. Slag melt cooling 150-kg cone-shaped pots gravity separation during cooling 0.85-3.0 wt.% PbO 0.26-8.2 wt.% ZnO up to hundreds ppm As, Sb, Cu, Sn slag matte metallic residue

10. Tsumeb smelting site (Namibia) Tsumeb smelter (2007) ore mining/processing since 1907 (2 Mt Pb, 1 Mt Cu, 0.5 Mt Zn) 200 kt slags on the dumps Ettler et al. (2009): Appl. Geochem. 24, 1. Ettler et al. (2010): Comm. Geol. Survey Namibia 14, 3.

11. Nkana smelter (Kitwe, Zambia) in operation 1930-2009 Nkana old slag dumps 20 Mt of Cu slag 1.8 wt.% Cu, 2.4 wt.% Co crushing to 15 mm reprocessing and Co recovery

12. Chambishi smelter (Zambia) electric arc furnace Co recovery (alloy 14% Co) 60-t glassy slag pots evacuated to dumps

13. <<< Pb slag dumps Slag exposure to weathering >>> Příbram, Czech Republic

14. slag is milled and reused as a cover layer on mine tailing disposal site Tsumeb, Namibia

15. Fine slag particle wind dispersal slag crushers fine-grained slag particle dispersion in the environment (soils) Kříbek et al. (2010): J. Geochem. Explor. 104, 69. 20 μm

16. Slag mineralogy - solid speciation Ettler et al. (2001): Can. Mineral. 39, 873. Ettler et al. (2009): Appl. Geochem. 24, 1. Vítková, Ettler et al. (2010): Mineral. Mag 74, 581. high-temperature Ca-Fe alumosilicates spinel-family oxides silicate glass metallic fraction melt enriched in metals (18 wt.% Pb, 12 wt.% Zn, 12 wt.% Cu, 8 wt.% As) Zn, Cu, Co enter into the structures of silicates, oxides and glass Pb enters into the glass Mel Spl Ol+Glass

17. Alteration products Vítková, Ettler et al. (2010): Mineral. Mag. 74, 581.

18. Leaching experiments identification of dissolution and attenuation processes long-term simulations of waste/water interactions coupled to thermodynamic speciation-solubility modelling coupled to investigation of newly-formed phases batch test liquid-to-solid (L/S) ratio

19. Pb slag - long-term Pb leaching (batch) Ettler et al. (2003): Mineral. Mag. 67, 1269.

20. Mineralogical controls 20 µm 20 μm XRD – SEM – TEM leached samples geochemical modelling natural weathering cerussite PbCO 3 cerussite PbCO 3 HFO Ettler et al. (2003): Mineral. Mag. 67, 1269.

21. Pb slag - long-term Zn leaching (batch) Ettler et al. (2003): Mineral. Mag. 67, 1269.

22. Tsumeb slag – batch leaching Ettler et al. (2009): Appl. Geochem. 24, 1.

23. Natural alteration products bayldonite Cu 3 Pb(AsO 4 ) 2 (OH) 2 olivenite Cu 2 AsO 4 OH lammerite Cu 3 (AsO 4 ) 2 lavendulan NaCaCu 5 (AsO 4 ) 4 Cl·5H 2 O hydrocerussite Pb 3 (CO 3 ) 2 (OH) litharge PbO Ettler et al. (2009): Appl. Geochem. 24, 1.

24. pH-static leaching experiments paralel extractions at different pH values metal/metalloid leachability under various disposal scenarios (dumping, stabilization, reuse) pH-static leaching test

25. Leaching behaviour Vítková, Ettler et al. (2011): J. Hazard. Mater. 197, 417. not hazardous material according to EU limits potentially high release of Cu and Co in acidic environments dissolution of slag particles in soils (pH 4-5)

26. Conclusions #1 Environmental stability of slags understanding of metal-/metalloid-hosting phases in slags is essential for subsequent determination of possible environmental impacts natural alteration products are indicators of long- term weathering processes leaching experiments – accelerated weathering >>> understanding and prediction of the chemical processes

27. slag crushing and milling facilities generate highly reactive fine-grained dust high metal and metalloid release (mainly under low pH conditions) formation of secondary alteration products can lead to attenuation of contaminants highly soluble weathering products can be dissolved during thunderstorm rain events

28. Fate of smelter-derived contamination in the environment Soils in the vicinity of smelters are highly polluted with metals/metalloids originating from smelter stack emissions (fly ash).

29. Pb emissions from the Příbram smelter, CZ 1969: 624 t Pb y -1 1999: 1.2 t Pb y -1

30. Pb migration in soil profiles FOREST SOIL (700 m of the smelter) mobile Pb SEP and Pb isotopes: about 50% of Pb is very mobile calculated vertical Pb migration velocity 0.3-0.36 cm/year Pb concentration (mg/kg) Depth (cm) Ettler et al. (2005): Chemosphere 58, 1449., Ettler et al. (2004): ABC 378, 311.

31. Soil pollution in Copperbelt, Zambia topsoils/subsurface maximum values Cu 41900 ppm Co 606 ppm Pb 503 ppm Zn 450 ppm As 255 ppm Kříbek et al. (2010) J. Geochem. Explor. 104, 69-86

32. Fly ash reactivity – leaching tests fly ash sampled at bag-house filters in the smelter rapid dissolution of primary phases pH-stat pH-dependent release relevant for soil systems Ettler et al. (2008) ES&T 42, 7878. Vítková et al. (2009) J. Hazard. Mater. 167, 427.

33. Incubation of fly ash in soils 0.5 g fly ash sealed by welding testing bags – polyamide fabric (NYTREL TI) mesh size 1 μm double bags

34. Laboratory pot experiments 60% WHC pore water sampling in time

35. Metal release into soil water high and quick release of Cd into soil and soil water lower release of Pb – efficient attenuation processes

36. In situ experiments sampling of soil before experiment testing bag insertion

37. Soils and cadmium (Cd) distribution increase 51xincrease 250xincrease 46x for a given pH range mostly independent Cd release

38. Soils and lead (Pb) distribution increase 3xincrease 16x increase 1.4x strong pH-dependent release of Pb for given conditions

39. Chemical fractionation of metals shift towards more mobile forms after the fly ash exposure

40. Conclusions #2 Fate of smelter emissions in soils laboratory and in situ experiments help to decipher the processes affecting fly ash reactivity in soils direct comparisons with polluted soils smelter emissions are often composed of soluble phases low soil pH is accelerating the dissolution and influences subsequent mobility of contaminants in soil profiles

41. General conclusions smelter-affected environments are convenient natural laboratories for understanding the dynamics and fate of anthropogenic contaminants multi-method approaches needed knowledge of behaviour of smelter-derived contaminants can help to innovate smelting technologies to be more „environment-friendly“ indications for possible ways for recycling of smelting waste products

42. Thanks for your attention! ettler@natur.cuni.cz