Formation and Release of POPs in the Cement Industry Second edition 23 January 2006 Page 2 of 200 Table of content Table of content .......................................................................................................................... 2 Acronyms and abbreviations ....................................................................................................... 5 Glossary ........................................................................................................................ 10 Executive summary..................................................................................................................... 12 1. Introduction ........................................................................................................................ 16 1.1 The Cement Sustainability Initiative ............................................................................. 16 1.2 What are PCDD/Fs?....................................................................................................... 18 1.2.1 Properties of dioxins....................................................................................... 20 1.3 Basic assumptions for this investigation........................................................................ 21 2. Cement production process ................................................................................................ 24 2.1 Main processes............................................................................................................... 24 2.1.1 Quarrying........................................................................................................ 25 2.1.2 Raw materials preparation.............................................................................. 26 2.1.3 Fuels preparation............................................................................................ 26 2.1.4 Clinker burning............................................................................................... 27 2.1.5 Cement grinding............................................................................................. 28 2.1.6 Mineral additions preparation......................................................................... 29 2.1.7 Cement dispatch............................................................................................. 29 2.2 Material technological characteristics in cement production ........................................ 29 2.2.1 Main Clinker Phases....................................................................................... 29 2.2.2 Raw mix components..................................................................................... 31 2.2.3 Fuels................................................................................................................ 32 2.2.4 Cement constituents........................................................................................ 32 2.3 The four main process routes......................................................................................... 33 2.4 Process technological characteristics of clinker production.......................................... 34 2.4.1 The dry process............................................................................................... 34 2.4.2 The semi-dry process...................................................................................... 36 2.4.3 The semi-wet process ..................................................................................... 38 2.4.4 The wet process .............................................................................................. 39 2.4.5 Vertical shaft kilns.......................................................................................... 40 2.4.6 Operating characteristics - a summary ........................................................... 41 2.5 Kiln exhaust gases ......................................................................................................... 41 2.6 Clinker coolers............................................................................................................... 44 2.7 Fuels preparation............................................................................................................ 45 2.8 Mineral additions preparation........................................................................................ 46 2.9 Environmental significance of cement production ........................................................ 47 2.9.1 Dust................................................................................................................. 47 2.9.2 Gaseous atmospheric emissions ..................................................................... 49 2.9.3 Normal emission levels .................................................................................. 54 2.9.4 Other emissions .............................................................................................. 55 2.9.5 Circulating elements ....................................................................................... 56 2.9.6 Inherent "scrubbing" of exit gases.................................................................. 57 2.9.7 Resources consumption .................................................................................. 58 2.10 Characteristics of the cement production process - a summary..................................... 59 Kåre Helge Karstensen [email protected] Page 3 of 200 2.11 Cement production in developing countries .................................................................. 62 3. Utilisation of alternative fuels and raw materials in cement production....................... 63 3.1 Theory of combustion.................................................................................................... 63 3.2 AFR use in the cement industry..................................................................................... 65 3.3 Co-processing of hazardous wastes ............................................................................... 66 3.3.1 Fate of the constituents in the hazardous waste fuel....................................... 67 3.3.2 Organic constituents ....................................................................................... 67 3.3.3 Results from trial burns conducted in the 1970s ............................................ 68 3.3.4 Results from trial burns conducted in the 1980s ............................................ 69 3.3.5 Results from trial burns conducted in the 1990s ............................................ 69 3.3.6 Results from newer trial burns........................................................................ 70 3.3.7 Results from trial burns that focused on PCBs............................................... 70 3.3.8 Trial burns – a summary................................................................................. 71 4. Regulatory framework........................................................................................................ 73 4.1 Background for legislation on PCDD/F emissions in the European Union ................. 73 4.1.1 PCDD/F emission limit values for cement kilns ............................................ 76 4.1.2 Sampling and analysis .................................................................................... 77 4.1.3 Detection/quantification limits and interferences........................................... 83 4.1.4 HCB and PCBs ............................................................................................... 84 4.2 PCDD/F emission standards in the US.......................................................................... 84 4.3 Regulatory framework in Developing countries............................................................ 86 5. Formation of PCDD/F......................................................................................................... 87 5.1 General theory of PCDD/F formation mechanisms in combustion............................... 87 5.2 Possible formation mechanisms in Cement Kilns ......................................................... 92 5.2.1 Effect of operating variables and the APCD temperature .............................. 92 5.2.2 Effect of combustion conditions..................................................................... 94 5.2.3 Effect of total hydrocarbons ........................................................................... 95 5.2.4 Effect of chlorine ............................................................................................ 96 5.2.5 Effect of waste fuel composition .................................................................... 96 5.2.6 Effect of feeding alternative fuels and secondary raw materials.................... 97 5.2.7 Effect of feeding alternative fuels to the preheater/precalciner...................... 98 5.2.8 Effect of catalysts ......................................................................................... 102 5.2.9 Effect of catalysts ......................................................................................... 103 5.2.10 Effect of carbon injection ............................................................................. 103 6. POPs releases from cement production........................................................................... 104 6.1 PCDD/F and PCB levels established by actual measurements ................................... 105 6.1.1 Australia.......................................................................................................