Doctoral thesis Processing of mercury-contaminated industrial wastes, particularly from former chlorine-alkali electrolysis facilities and acetaldehyde sites in soil washing plants (Die Aufbereitung quecksilberkontaminierter Industrieabfälle unter besonderer Berücksichtigung ehemaliger Chloralkalielektrolyse- und Acetaldehydstandorte in Bodenwaschanlagen) Dipl.-Ing. Dipl.-HTL-Ing. Rüdiger B. RICHTER Abu Dhabi, June 2011 The Chemical Factory Marktredwitz was the first large-scale mercury remediation project worldwide (photo: Harbauer) Supervisors (Gutachter): Univ.-Prof. Dr. mont. Helmut FLACHBERGER Chair of Mineral Processing Department Mineral Resources & Petroleum Engineering o.Univ.-Prof. Dr. techn. Karl LORBER Institute for Sustainable Waste Management and Technology DOCTORAL THESIS Processing of mercury-contaminated industrial wastes June 2011 To my dear wife Robinah for her tolerance and patience and to baby Caelyn Gerda – welcome to the world! Montanuniversität Leoben -i- Dipl.-Ing., Dipl.-HTL-Ing. Rüdiger B. Richter DOCTORAL THESIS Processing of mercury-contaminated industrial wastes June 2011 ACKNOWLEDGEMENTS This doctoral thesis would not have been possible without the support of many people. The author wishes to express his gratitude to his supervisor, Professor Dr. Helmut FLACHBERGER, holder of the Chair of Mineral Processing who was abundantly helpful and offered invaluable assistance, support and continual guidance but also excellent cooperation during the associated industrial project study. My appreciation is extended to Professor Dr. Karl LORBER, co-reviewing member of the thesis supervisory team, for a couple of fruitful discussions and for giving the permission to perform necessary tests under specific HSE and PPE conditions in his laboratory associated to the Institute for Sustainable Waste Management and Technology. I am also deeply indebted to my wife, Robinah, for her support and her patience all the way through when I worked on many weekends and during all my recent leaves on this thesis. The candidate wishes also to express his special gratitude to his passed away mother Gerda Waltraut Ingeborg, nee VOLLMER by supporting and encouraging him all the way with the intention of becoming an engineer, but also to his supervisor, when the author was an apprentice in crafts, Mr. Matthias GEIER, an excellent craftsman and one of the most well-read persons he ever met, but also to two very special professors during his basic engineering education at the technical college in Graz (Höhere Technische Lehranstalt) Arch. Prof. Dipl.-Ing. Hermann WORSCHITZ and to the current head master, Prof. Dipl.-Ing. Reinhold NEUMANN. The author also wants to express his gratitude to his earlier academic teacher Prof. Dr.rer.nat. Wolfgang SIMONIS (the „father of the free jet flotation‟), no longer with us, and formerly holder of the Chair of Mineral Processing and Beneficiation of the Technical University of Berlin and to Dr. Lutz ROLF, formerly assistant professor of the same department for the most creative time as an engineer in his life. Besides this I am also obliged to some of my former colleagues and co-workers in various mercury and soil/waste treatment projects performed in the past twenty years in various countries and in particular to my co-authors in diverse publications in particular to Dipl.-Berging. Andreas J. SCHMIDT and Dr.-Ing. Frank STAPELFELDT but also to my current employer TAKREER giving me the opportunity to write this thesis in parallel to my normal duties as a Department Manager of the BeAAT waste treatment facilities in the Ruwais Refinery Division/United Arab Emirates. Special thanks also to all the laboratory staff of the Chair of Mineral Processing in Leoben and of the Institute for Sustainable Waste Management and Technology, but especially to the lab technicians of the BeAAT plant laboratory in Ruwais/United Arab Emirates supporting me in completing the required chemical analysis for this thesis, but also to my secretary Khurram Maqsood, who helped me to format the entire document during the final phase of this work and to my friend and colleague Nayaz Sohale Sayed, Sr. Environmental Engineer for his review and advice. Last but not least the candidate wants to say „thank you‟ to his dear colleague Dipl.-Ing. Andreas SCHMID, he became a friend during the course of this thesis, for all his constructive and helpful assistance. The author would also like to convey thanks to the Administration Department of the Montanuniversität Leoben for their always helpful and competent support and their uncomplicated approach which is remarkable enough to be mentioned here. It is my dearest wish to thank honestly the „Republic of Austria‟ for their well-established school system, giving everybody a fair chance to learn and get access to higher education. Montanuniversität Leoben -ii- Dipl.-Ing., Dipl.-HTL-Ing. Rüdiger B. Richter DOCTORAL THESIS Processing of mercury-contaminated industrial wastes June 2011 ABSTRACT The PARCOM-decision 90/3 from 14 June 1990 recommends that all chlorine-alkali electrolysis facilities in Western Europe using the amalgam process shall be phased out for reasons of environmental protection at the latest by 2010. For the treatment of the demolition material from decommissioned chlorine plants in particular soil and rubble soil washing should be considered as a treatment option as an alternative to underground mine or mono dump disposal. Physical-chemical soil washing plants have proven to be suitable for the treatment of contaminated soils during the last 25 years. The first soil washing plants were based on the principle that soil was liberated by mechanical energy input and the contaminant-soil separation took place by applying subsequent combinations of classifying and separation processes. Because of the concentration of contaminants in the fine particle fraction, flotation becomes a significant separation process in the particle-size-fraction below 500 µm. In the past the successful application of soil flotation was mostly related to the treatment of organic contaminants such as Petrol Hydrocarbons (PHC) and Polycyclic Aromatic Hydrocarbons (PAH). Previous investigations regarding the flotation of heavy-metal contaminated soils were performed with material from a former steel works and rolling mills inner city site in Berlin. A recovery of maximum 75 % lead and 44 % zinc was obtained for a one step flotation. The recovery of the cleaned soil amounted to 92 %1. Preliminary tests performed with mercury-contaminated soil in a range of 1,000 mg/kg have shown that a removal of mercury from the soil under the given laboratory conditions in a particle size range of 25-500 µm is possible. The best results were received with KAX as a collecting agent at a pH of 8. In order to provide the best treatment for different soils from various chlorine-alkali electrolysis plants and acetaldehyde factories a categorization based on various samples selected from former and currently ongoing mercury remediation cases worldwide could be made, showing that the silt and clay fraction in very cohesive soils from chlorine-alkali plants have a much lower mercury content than sandy soils up to a concentration of fine in a range of 20 mass-%. Next to the positive effect of attrition for the enrichment of mercury in the fin particle range the importance of the removal of other with mercury closely linked soil components in chlorine-alkali soils such as carbon (mostly as graphite from the electrodes) was highlighted in this thesis. Owing to the different solubility of various mercuric sulphide species in aqueous systems such as in 2- particular the sulfur mercuric ion HgS2 a flotation method was developed using organic sulphidisation agents and xanthates in the same process. Performing tests rows with different mercury concentrations have proven that this process is applicable for solid high mercury wastes up to 1,000 mg/kg up to a particle size range of 500 µm and is capable to be implemented in existing or newly designed soil washing plants. All TCLP-tests performed with treated soil in laboratory scale were passing the leaching criteria for Hg < 0.2 mg/l. In the dry substance the target value “Zuordnungswert 2 (Z2)” of the German LAGA: Hg < 10 mg/kg DW could be reached. The thesis includes also experience made with other treatment options than soil washing such as in particular stabilization/solidification and thermal desorption. Keywords: Mercury, soil washing, solubility of mercury sulfide species, physical/chemical separation and froth flotation 1 STAPELFELDT F. AND RICHTER R.: Flotation von kontaminierten Böden und artverwandten mineralischen Abfällen in Bodenwaschanlagen (Flotation of contaminated soils and similar mineral waste materials in soil washing plants, Altlastenspektrum (04/2002), pp.: 188 - 192 Montanuniversität Leoben -iii- Dipl.-Ing., Dipl.-HTL-Ing. Rüdiger B. Richter DOCTORAL THESIS Processing of mercury-contaminated industrial wastes June 2011 KURZFASSUNG Die „PARCOM-Entscheidung 90/3“ vom 14. Juni 1990 empfiehlt, dass alle nach dem Amalgamverfahren arbeitenden Chloralkalielektrolyseanlagen der 176 Mitgliedstaaten aus Gründen des Umweltschutzes bis spätestens 2010 stillzulegen oder umzurüsten. Aufgrund der umfangreich vorgenommenen weltweiten Stilllegungen und des damit einhergehenden Rückbaus zahlreicher Chloralkalielektrolysen und Acetaldehydfabriken sind zuverlässige und kostengünstige Aufbereitungstechnologien zur Behandlung der quecksilberkontaminierten Abfälle aus dem Rückbau