Heavy Metals in Steel Mill Electric Arc Furnace Dust

U okviru gospodarenja otpadom, koje obuhvaća i odabir rješenja za njegovo zbrinjavanje, bilo uporabom u vlastitim tehnološkim procesima, bilo prerađen u drugim industrijskim granama ili odgovarajućom obradom prije eventualnog odlaganja na propisanim odlagalištima, u Željezari Sisak se pristupilo sustavnom istraživanju fizikalno-kemijskih karakteristika metalurškog otpada kao i njegovog ponašanja u interakciji sa okolišem. Elektropećna prašina, kao metalurški otpad, razvrstana je prema US EPA klasifikaciji iz 1980. godine u opasni tehnološki otpad oznake K061. Elektropećna prašina Željezare Sisak svrstana je u opasni otpad na temelju ispitivanja fizikalno-kemijskih karakteristika od strane za to ovlaštenog laboratorija i dodijeljen joj je ključni broj *10 02 03, sukladno pravnim propisima Republike Hrvatske. Kako zbrinjavanje opasnog otpada nije moguće izravnim odlaganjem na tlo, ukazala se potreba pronalaženja rješenja za zbrinjavanje elektropećne prašine na ekološki prihvatljiv i ekonomski opravdan način. Naime, elektropećna prašina iz procesa proizvodnje čelika u čeličani Željezare Sisak, svojedobno je služila kao dodatak pri izradi sinter-mješavine za potrebe proizvodnje sirovog željeza visokopećnim postupkom. Zbrinjavanje elektropećne prašine na taj način bilo je jedino ekonomski opravdano radi iskorištavanja njezinog željezonosnog dijela, dok ekološka prihvatljivost tog načina zbrinjavanja opasnog otpada nije bila zadovoljena. Naime, teške kovine od elektropećne prašine kao toksični sastojci samo su mijenjali svoju matičnu osnovu tj. iz elektropećne prašine bivali preseljeni i ukoncentrirani u mulj ispirača visokopećnih otpadnih plinova. Zatvaranjem proizvodnje sirovog željeza u visokim pećima, napušten je i taj, ionako nepotpun način zbrinjavanja elektropećne prašine, a novonastale količine se otada privremeno odlažu u krugu tvornice i svakim su danom sve veća opasnost za okoliš. Radi pronalaženja mogućnosti i odabira optimalnog postupka zbrinjavanja nagomilanih količina opasnog metalurškog otpada provode se sustavna istraživanja od kojih je ovdje prikazan samo dio koji se odnosi na ispitivanje sadržaja teških kovina u elektropećnoj prašini, kao i međusobne povezanosti udjela teških kovina Zn, Pb, Cd s masenim udjelom željeza čiji oksidi čine osnovu tog otpada. Ostale kovine poput bakra, kroma i nikla nisu istraživane na isti način kao Zn, Pb i Cd s obzirom da je ispitivana prašina nastala u postupcima proizvodnje ugljičnih čelika te su u njoj koncentracije tih kovina vrlo niske.Within the scope of corporate waste management, Sisak Steelworks initiated a thorough and systematic examination of physical and chemical properties of metallurgical waste and of its behaviour in interaction with the environment. Electric arc furnace (EAF) dust has been categorized as hazardous technological waste and it can not be directly disposed of to the ground / in a land fill. Therefore, it is necessary to find a way to dispose of it in an environmentally friendly and economically acceptable manner. In order to elaborate different options and chose the optimal practice for the disposal of the accumulated volumes of hazardous metallurgical waste, comprehensive and systematic research has been conducted. This paper provides only a partial survey of the research of the heavy metal Zn, Pb, Cd content in electric arc furnace dust as well. Qualitative chemical analysis of samples of electric arc furnace dust was conducted on all observed samples and the presence of Fe, Zn, Pb, Mn, Cu, Al, Ca, Mg, K, S, P, C, O and Cl was established. The results of qualitative chemical analysis of monthly average samples of electric arc furnace dust obtained by other methods established that the mass fraction of iron was between 41.08 and 48.58 %, zinc between 3.75 and 8.10 %, lead between 0.94 and 2.07 %, and cadmium between 0.010 and 0.027 %. The results of the Zn, Pb, Cd fraction analysis in the observed samples of electric arc furnace dust are considerably lower, than the content of those metals in EAF dusts presented in the available references, where the mass fraction of zinc varies between 0.14 and 50 %, lead between 0.03 and 6.8 %, and cadmium between < 0.01 and 1.8 %. Quantitative analysis of Fe, Zn, Pb and Cd fraction was carried out in grain-metrical fractions of individual samples of EAF dust as well. The results have shown that the concentrations of Fe tend to increase with smaller fraction grains compared to an average sample, whereas concentrations of Zn, Pb and Cd in the same proportion display a descending tendency. Results of the Zn, Pb and Cd fraction analysis in the EAF dust samples from Sisak Steelworks compared to the mass fraction of those metals in EAF dust from other steel mills imply that the measured concentrations of zinc, lead, and cadmium are much higher. Therefore, it is not economically viable to recycle this dust for the lead, zinc or cadmium recovery. Consequently, the disposal of this kind of hazardous metallurgical waste must first be handled in another, environmentally acceptable and economically justifiable way. Additional investigations must be carried out before the final decision is made

Electric Arc Furnace as a Source of Emission of Polychlorinated Dibenzo-p-Dioxins and Polychlorinated Dibenzofurans in Perspective of the Council Directive 96/61 EC Concerning Integrated Pollution Prevention and Control

Jedan od vrlo istaknutih dokumenata iz zakonodavstva Europske unije relevantan za područje zaštite okoliša koji se odnose na industrijska postrojenja je Direktiva 96/61 EC o cjelovitom sprječavanju i kontroli onečišćenja (engl.: Integrated Pollution Prevention Control, IPPC). Ta direktiva objedinjuje kontrolu emisija i kompletan učinak koje industrija ima na okoliš, što podrazumijeva prepoznavanje svih utjecaja koje pojedini industrijski procesi imaju na okoliš (zrak, voda, tlo, otpad, buka, uporaba sirovina, energetska učinkovitost, sprječavanje nezgoda itd.). Direktiva uvodi sustav dodjele "ekoloških" dozvola za obavljanje djelatnosti i upravljanje procesima uz uporabu najboljih raspoloživih tehnika (engl.: Best Available Techniques, BAT). Metalurška postrojenja svojim katastrima emisija obuhvaćaju uz dobro poznata onečišćenja kao što je prašina, SO2, NOx, NH3, H2SO4, HCl, HF, HCN, H2S, CO, CO2, CH4, teške metale i niz organskih onečišćenja poput benzena, fenola, policikličkih aromatskih ugljikovodika, polikloriranih bifenila, polikloriranih dibenzo-p-dioksina (PCDD) i polikloriranih dibenzofurana (PCDF). Kako je primjena Direktive IPPC kompleksan postupak koji zahtijeva izobrazbu stručnog kadra, velika investicijska ulaganja u postojeći proces i njegovu modernizaciju, a ponekad čak i zamjenu, to se i čeličane, kao potencijalni emiteri iz grupe metalurških procesa, trebaju pravodobno pripremiti za obveze koje ih očekuju. Nužno je pristupiti analizi propisanih zahtjeva direktive, razmotriti korake koje treba poduzeti uz prethodno utvrđivanje troškova i razdoblja potrebnog za usklađivanje postojećih elektropećnih procesa proizvodnje čelika sa zahtjevima Direktive IPPC. U radu su prikazani zahtjevi Direktive IPPC koji se odnose na čeličane, s osvrtom na problem emisije polikloriranih dibenzo-p-dioksina i dibenzofurana, kao i načini na koje je moguće ispuniti zahtjeve kako bi se osigurali uvjeti sprječavanja i kontrole onečišćenja prijeko potrebnih za ishođenje "ekološke dozvole" za obavljanje djelatnosti proizvodnje elektročelika u okviru Europske unije, odnosno u uvjetima stupanja na snagu Direktive IPPC.As the accumulation of PCDDs/Fs in the natural environment poses a great threat, and the pollution of the environment with these highly toxic compounds from various emitters needs to be prevented, many countries have conducted an inventory of industrial sources and their emissions in order to obtain better insight into the share of particular sources in the total emission of PCDDs/Fs and to develop strategies to reduce these emissions. Metallurgical processes like sintering of iron ore, production of steel and non-ferrous and light metals from scrap material belong to a group of stationary PCDDs/Fs emitters and their share in the total PCDDs/Fs emission into the environment is very significant. The relative significance of particular metallurgical processes varies from country to country, depending on the nature of a particular process, installed capacities and annual output levels. As the modern approach to observing the environment includes preventive measures, as opposed to corrective post-event measures that were common practice in the past, the owners/operators of metallurgical processes are developing and introducing pollution monitoring and surveillance systems, based on which they take appropriate measures. One of the frequently applied measures is to build and implement the ISO 14001 environmental management system that very efficiently runs production processes along with maintenance of environmental protection on a daily basis. Since the adoption of the ISO 14001 environmental management system is a voluntary decision to be made by each organization, in 1996 the European Union adopted, for the purpose of environmental protection and pollution prevention, the Directive 96/61 EC or IPPC Directive on Integrated Pollution Prevention and Control (IPPC) requiring from industrial installations, depending on their type and output level, to obtain environmental permits to run production processes using best available techniques, thus maintaining daily care for environmental protection and preservation. This Directive integrates control of emissions and overall impact of industrial installations on the environment, meaning recognition of the entire impact from particular industrial processes on the environment (air, water, soil, waste, noise, use of raw materials, energy efficiency, prevention of accidents, etc.). The IPPC Directive has introduced a system of authorization (environmental permit) that needs to be obtained in order to perform business activities and run processes using the best available techniques (BAT). Taking into account the harmful impact of PCDDs/Fs on the environment, and their unavoidability in metallurgical processes, a series of methods has been developed for their partial prevention or at least reduction of their concentration in smoke gas discharge, and thus prevent environmental pollution through these very harmful compounds. In order to prevent the occurrence of PCDDs/Fs metallurgical processes often use methods based on the principle of selective catalyst reduction. For removal of the already generated PCDDs/Fs from waste gases methods of thermal decomposition at high temperatures or various sorption, i. e. "dry" and "wet" cleaning techniques are used. As the implementation of the IPPC Directive is a complex procedure requiring highly educated experts, significant investments into production processes and their modernization, or sometimes even replacement, steel shops need to timely prepare themselves for the obligations in order to harmonize the existing regulation with the requirements of the IPPC Directive. The requirements of the Directive have to be studied thoroughly. The required steps have to be carefully thought through, previously identifying the cost and time frame necessary to bring the existing electric arc furnace (EAF) steel production processes into conformance with the requirements of the IPPC Directive. The paper discusses the requirements of the IPPC Directive that are imposed on the steel business owners/operators, with a special review of the PCDDs/Fs emission. It also presents the ways in which the IPPC Directive requirements concerning these highly toxic pollutants can be fulfilled, ensuring conditions to obtain environmental permits to run this activity once the Directive has entered into force

Importance of Polychlorinated Dibenzo-p-dioxins and Dibenzofurans Emissions from Iron and Steel Production Processes

Razvoj metalurgije i metalurških procesa praćen je duljim ili kraćim razdobljima intenzivnog onečišćenja okoliša, što je uzrokovalo neposredno ili posredno ugrožavanje zdravlja ljudi, pojedinih biljnih i životinjskih vrsta, vodnih sustava, tla, povećane erozije materijalnih dobara, kao i niza drugih negativnih učinaka društvene i ekonomske prirode. Tako je npr. koncepcija integriranih željezara uvjetovala veliko povećanje broja izvora emisija i povećanje koncentracije štetnih tvari u okolišu, a najveći onečišćivači su oduvijek bili pogoni proizvodnje metalurškog koksa, postrojenja za aglomeraciju željezne rude, visoke peći, čeličane, ljevaonice i termoenergetska postrojenja. Brojna fundamentalna znanstvena istraživanja dokazala su čitav niz negativnih učinaka nekontrolirane emisije štetnih tvari iz tih postrojenja. Uz znatne količine uobičajenih i dobro poznatih onečišćenja poput sumporovog (IV) i ugljikovih oksida, fluorovodika, amonijaka, benzena, teških metala, fenola, cijanida, ulja i masti, troske, iskorištenog vatrostalnog materijala, metalnih strugotina, muljeva, prašine i ogorina, javljaju se i onečišćenja u relativno malim količinama čije dugotrajno djelovanje predstavlja opasnost i od njihovih niskih koncentracija kojima se uvijek ne posvećuje dužna pozornost. Tu skupinu onečišćenja čine postojana organska onečišćenja čiji su predstavnici policiklički aromatski ugljikovodici, poliklorirani bifenili, poliklorirani dibenzo-p-dioksini i poliklorirani dibenzofurani. Od svih poznatih onečišćenja kojima su izvor metalurški procesi, do sada su sa stajališta utjecaja emisije onečišćenja iz metalurških procesa u okoliš, najmanje istraženi upravo ti spojevi. U radu su izračunate prosudbe emisija polikloriranih dibenzo-p-dioksina i polikloriranih dibenzofurana u Hrvatskoj u razdoblju od 1960. do 2005. godine. Pri izračunu su poslužila iskustava razvijenih zemalja koje su ujedno i najveći proizvođači željeza i čelika. Dobiveni rezultati su pokazali da je ukupna emisija tih spojeva od metalurških procesa u okoliš u razdoblju 1960.- 2005. bila od QI-TEQ = 0,153-2,888 g a-1, dok je u razdoblju 1990. - 2000. ova emisija bila od 0,153-1,284 g a-1. Kako se ne smije zanemariti udjel metalurških procesa u ukupnoj emisiji polikloriranih dibenzop- dioksina i polikloriranih dibenzofurana u okoliš, to je nužno u nastavku istraživanja provesti mjerenja njihovih emisija od svih aktivnih metalurških procesa u Hrvatskoj, te odrediti udjel tih spojeva u svim vrstama otpada nastalog za vrijeme odvijanja procesa.Metals and metallic products are fundamental to a large number of modern industries and steel is certainly one of the most significant metallurgical products. Steel and steel castings as universal production material, that provided the grounds for the contemporary industrialization process, will have a continuously irreplaceable role in the future, regardless of the fact that nowadays steel materials are often replaced by other materials (ceramics, polymers, etc.), whenever it is technically required and cost-justified. The development of metallurgy and metallurgical processes is accompanied by pollution of the environment that directly or indirectly endangered the health of humans, certain animal and plant species, water resources systems, and soil. It also lead to increased erosion of material goods and caused many other adverse social and economy-related effects. The integral steelworks concept has, for example, set off a significant increase in the number of emission sources and the increase of harmful substances concentration in the environment. The largest polluters have always been coking plants, iron ore agglomeration facilities, blast furnaces, steel mills, foundries and thermal energy plants. Numerous fundamental scientific research works have proven a series of adverse effects caused by uncontrolled emissions of harmful substances from these plants. Beside the considerable quantities of usual and well-known polluting substances such as sulfur and carbon oxides, fluorides, ammonia, benzene, heavy metals, phenols, cyanides, oil and grease, slag, used refractory material, metallic scrapings, sludge, dust, and scale, there are also relatively small pollutions with long-lasting effects that are hazardous even in their low concentrations and they rarely receive due attention. This polluting substance group consists of persistent organic pollutions represented by polycyclic aromatic hydrocarbon (PAH), polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs), and polychlorinated dibenzofurans (PCDFs). These compounds are the least explored of all known pollutions generated in the metallurgical processes, in terms of the impact of their emissions to the environment. The paper provides elementary toxicity data for these compounds and a survey of reference data on the currently completed listings of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans in the world and in Croatia, illustrating that the metallurgical process account for most of the total emission of these compounds into the environment. Based on the experience of the developed countries that are at the same time the largest iron and steel producers, we calculated an estimate of potential emissions of dibenzo-p-dioxins and polychlorinated dibenzofurans from metallurgical processes in Croatia. The calculation took into account the coking processes, iron ore sintering processes, pig iron production, cast iron, openhearth steel and EAF steel production. The estimated total emission of dibenzo-p-dioxins and polychlorinated dibenzofurans from metallurgical processes to the environment in the time period between 1990 and 2000 in Croatia was m = 3.987 g I-TEQ and annual emission in the same period ranged from QI-TEQ = 1.284 g a-1 in 1990 to QI-TEQ = 0.153 g a-1 in 1995. Emissions of these compounds from metallurgical processes that were active in less recent past were also calculated and the values in the time period between 1960 and 2000 ranged from m =2.888 g I-TEQ in 1980 to m = 0.153 g I-TEQ in 1995. Based on the data on the existing facilities for steel production in electric arc furnaces we estimated that annual emission of dibenzo-p-dioxins and polychlorinated dibenzofurans could amount to QI-TEQ ~ 0.260 g a-1, whereas the future emission of these compounds from the existing cast iron facilities could be QI-TEQ ~ 0.100 g a-1. In the research follow-up for the impact of metallurgical processes on the overall emission of these compounds to the environment, it is required to measure their emissions from all active metallurgical processes. For the sake of better comprehension of emission flows of dibenzo-p-dioxins and polychlorinated dibenzofurans from metallurgical processes it is necessary to determine the contents of these compounds in all kinds of waste generated in the observed metallurgical processes and to select technical solutions to improve each individual process and to reduce their emissions to the environment

Importance of Polychlorinated Dibenzo-p-dioxins and Dibenzofurans Emissions from Iron and Steel Production Processes

Razvoj metalurgije i metalurških procesa praćen je duljim ili kraćim razdobljima intenzivnog onečišćenja okoliša, što je uzrokovalo neposredno ili posredno ugrožavanje zdravlja ljudi, pojedinih biljnih i životinjskih vrsta, vodnih sustava, tla, povećane erozije materijalnih dobara, kao i niza drugih negativnih učinaka društvene i ekonomske prirode. Tako je npr. koncepcija integriranih željezara uvjetovala veliko povećanje broja izvora emisija i povećanje koncentracije štetnih tvari u okolišu, a najveći onečišćivači su oduvijek bili pogoni proizvodnje metalurškog koksa, postrojenja za aglomeraciju željezne rude, visoke peći, čeličane, ljevaonice i termoenergetska postrojenja. Brojna fundamentalna znanstvena istraživanja dokazala su čitav niz negativnih učinaka nekontrolirane emisije štetnih tvari iz tih postrojenja. Uz znatne količine uobičajenih i dobro poznatih onečišćenja poput sumporovog (IV) i ugljikovih oksida, fluorovodika, amonijaka, benzena, teških metala, fenola, cijanida, ulja i masti, troske, iskorištenog vatrostalnog materijala, metalnih strugotina, muljeva, prašine i ogorina, javljaju se i onečišćenja u relativno malim količinama čije dugotrajno djelovanje predstavlja opasnost i od njihovih niskih koncentracija kojima se uvijek ne posvećuje dužna pozornost. Tu skupinu onečišćenja čine postojana organska onečišćenja čiji su predstavnici policiklički aromatski ugljikovodici, poliklorirani bifenili, poliklorirani dibenzo-p-dioksini i poliklorirani dibenzofurani. Od svih poznatih onečišćenja kojima su izvor metalurški procesi, do sada su sa stajališta utjecaja emisije onečišćenja iz metalurških procesa u okoliš, najmanje istraženi upravo ti spojevi. U radu su izračunate prosudbe emisija polikloriranih dibenzo-p-dioksina i polikloriranih dibenzofurana u Hrvatskoj u razdoblju od 1960. do 2005. godine. Pri izračunu su poslužila iskustava razvijenih zemalja koje su ujedno i najveći proizvođači željeza i čelika. Dobiveni rezultati su pokazali da je ukupna emisija tih spojeva od metalurških procesa u okoliš u razdoblju 1960.- 2005. bila od QI-TEQ = 0,153-2,888 g a-1, dok je u razdoblju 1990. - 2000. ova emisija bila od 0,153-1,284 g a-1. Kako se ne smije zanemariti udjel metalurških procesa u ukupnoj emisiji polikloriranih dibenzop- dioksina i polikloriranih dibenzofurana u okoliš, to je nužno u nastavku istraživanja provesti mjerenja njihovih emisija od svih aktivnih metalurških procesa u Hrvatskoj, te odrediti udjel tih spojeva u svim vrstama otpada nastalog za vrijeme odvijanja procesa.Metals and metallic products are fundamental to a large number of modern industries and steel is certainly one of the most significant metallurgical products. Steel and steel castings as universal production material, that provided the grounds for the contemporary industrialization process, will have a continuously irreplaceable role in the future, regardless of the fact that nowadays steel materials are often replaced by other materials (ceramics, polymers, etc.), whenever it is technically required and cost-justified. The development of metallurgy and metallurgical processes is accompanied by pollution of the environment that directly or indirectly endangered the health of humans, certain animal and plant species, water resources systems, and soil. It also lead to increased erosion of material goods and caused many other adverse social and economy-related effects. The integral steelworks concept has, for example, set off a significant increase in the number of emission sources and the increase of harmful substances concentration in the environment. The largest polluters have always been coking plants, iron ore agglomeration facilities, blast furnaces, steel mills, foundries and thermal energy plants. Numerous fundamental scientific research works have proven a series of adverse effects caused by uncontrolled emissions of harmful substances from these plants. Beside the considerable quantities of usual and well-known polluting substances such as sulfur and carbon oxides, fluorides, ammonia, benzene, heavy metals, phenols, cyanides, oil and grease, slag, used refractory material, metallic scrapings, sludge, dust, and scale, there are also relatively small pollutions with long-lasting effects that are hazardous even in their low concentrations and they rarely receive due attention. This polluting substance group consists of persistent organic pollutions represented by polycyclic aromatic hydrocarbon (PAH), polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs), and polychlorinated dibenzofurans (PCDFs). These compounds are the least explored of all known pollutions generated in the metallurgical processes, in terms of the impact of their emissions to the environment. The paper provides elementary toxicity data for these compounds and a survey of reference data on the currently completed listings of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans in the world and in Croatia, illustrating that the metallurgical process account for most of the total emission of these compounds into the environment. Based on the experience of the developed countries that are at the same time the largest iron and steel producers, we calculated an estimate of potential emissions of dibenzo-p-dioxins and polychlorinated dibenzofurans from metallurgical processes in Croatia. The calculation took into account the coking processes, iron ore sintering processes, pig iron production, cast iron, openhearth steel and EAF steel production. The estimated total emission of dibenzo-p-dioxins and polychlorinated dibenzofurans from metallurgical processes to the environment in the time period between 1990 and 2000 in Croatia was m = 3.987 g I-TEQ and annual emission in the same period ranged from QI-TEQ = 1.284 g a-1 in 1990 to QI-TEQ = 0.153 g a-1 in 1995. Emissions of these compounds from metallurgical processes that were active in less recent past were also calculated and the values in the time period between 1960 and 2000 ranged from m =2.888 g I-TEQ in 1980 to m = 0.153 g I-TEQ in 1995. Based on the data on the existing facilities for steel production in electric arc furnaces we estimated that annual emission of dibenzo-p-dioxins and polychlorinated dibenzofurans could amount to QI-TEQ ~ 0.260 g a-1, whereas the future emission of these compounds from the existing cast iron facilities could be QI-TEQ ~ 0.100 g a-1. In the research follow-up for the impact of metallurgical processes on the overall emission of these compounds to the environment, it is required to measure their emissions from all active metallurgical processes. For the sake of better comprehension of emission flows of dibenzo-p-dioxins and polychlorinated dibenzofurans from metallurgical processes it is necessary to determine the contents of these compounds in all kinds of waste generated in the observed metallurgical processes and to select technical solutions to improve each individual process and to reduce their emissions to the environment

Teške kovine u čeličanskoj elektropećnoj prašini

Within the scope of corporate waste management, Sisak Steelworks initiated a thorough and systematic examination of physical and chemical properties of metallurgical waste and of its behaviour in interaction with the environment. Electric arc furnace (EAF) dust has been categorized as hazardous technological waste and it can not be directly disposed of to the ground / in a land fill. Therefore, it is necessary to find a way to dispose of it in an environmentally friendly and economically acceptable manner. In order to elaborate different options and chose the optimal practice for the disposal of the accumulated volumes of hazardous metallurgical waste, comprehensive and systematic research has been conducted. This paper provides only a partial survey of the research of the heavy metal Zn, Pb, Cd content in electric arc furnace dust as well. Qualitative chemical analysis of samples of electric arc furnace dust was conducted on all observed samples and the presence of Fe, Zn, Pb, Mn, Cu, Al, Ca, Mg, K, S, P, C, O and Cl was established. The results of qualitative chemical analysis of monthly average samples of electric arc furnace dust obtained by other methods established that the mass fraction of iron was between 41.08 and 48.58 %, zinc between 3.75 and 8.10 %, lead between 0.94 and 2.07 %, and cadmium between 0.010 and 0.027 %. The results of the Zn, Pb, Cd fraction analysis in the observed samples of electric arc furnace dust are considerably lower, than the content of those metals in EAF dusts presented in the available references, where the mass fraction of zinc varies between 0.14 and 50 %, lead between 0.03 and 6.8 %, and cadmium between < 0.01 and 1.8 %. Quantitative analysis of Fe, Zn, Pb and Cd fraction was carried out in grain-metrical fractions of individual samples of EAF dust as well. The results have shown that the concentrations of Fe tend to increase with smaller fraction grains compared to an average sample, whereas concentrations of Zn, Pb and Cd in the same proportion display a descending tendency. Results of the Zn, Pb and Cd fraction analysis in the EAF dust samples from Sisak Steelworks compared to the mass fraction of those metals in EAF dust from other steel mills imply that the measured concentrations of zinc, lead, and cadmium are much higher. Therefore, it is not economically viable to recycle this dust for the lead, zinc or cadmium recovery. Consequently, the disposal of this kind of hazardous metallurgical waste must first be handled in another, environmentally acceptable and economically justifiable way. Additional investigations must be carried out before the final decision is made

Značaj emisije polikloriranih dibenzo-p-dioksina i dibenzofurana iz procesa proizvodnje željeza i čelika (Importance of Polychlorinated Dibenzo-p-dioxins and Dibenzofurans Emissions from Iron and Steel Production Processes)

Metals and metallic products are fundamental to a large number of modern industries and steel is certainly one of the most significant metallurgical products. Steel and steel castings as universal production material, that provided the grounds for the contemporary industrialization process,will have a continuously irreplaceable role in the future, regardless of the fact that nowadays steel materials are often replaced by other materials (ceramics, polymers, etc.), whenever it is technically required and cost-justified.The development of metallurgy and metallurgical processes is accompanied by pollution of the environment that directly or indirectly endangered the health of humans, certain animal and plant species, water resources systems, and soil. It also lead to increased erosion of material goodsand caused many other adverse social and economy-related effects.The integral steelworks concept has, for example, set off a significant increase in the number of emission sources and the increase of harmful substances concentration in the environment. The largest polluters have always been coking plants, iron ore agglomeration facilities, blast furnaces, steel mills, foundries and thermal energy plants.Numerous fundamental scientific research works have proven a series of adverse effects caused by uncontrolled emissions of harmful substances from these plants. Beside the considerable quantities of usual and well-known polluting substances such as sulfur and carbon oxides, fluorides,ammonia, benzene, heavy metals, phenols, cyanides, oil and grease, slag, used refractory material, metallic scrapings, sludge, dust, and scale, there are also relatively small pollutions with long-lasting effects that are hazardous even in their low concentrations and they rarely receivedue attention.This polluting substance group consists of persistent organic pollutions represented by polycyclic aromatic hydrocarbon (PAH), polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins(PCDDs), and polychlorinated dibenzofurans (PCDFs). These compounds are the least explored of all known pollutions generated in the metallurgical processes, in terms of the impact of their emissions to the environment.The paper provides elementary toxicity data for these compounds and a survey of reference data on the currently completed listings of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans in the world and in Croatia, illustrating that the metallurgical process account for most of the total emission of these compounds into the environment.Based on the experience of the developed countries that are at the same time the largest iron and steel producers, we calculated an estimate of potential emissions of dibenzo-p-dioxins and polychlorinated dibenzofurans from metallurgical processes in Croatia. The calculation took into account the coking processes, iron ore sintering processes, pig iron production, cast iron, openhearth steel and EAF steel production.The estimated total emission of dibenzo-p-dioxins and polychlorinated dibenzofurans from metallurgical processes to the environment in the time period between 1990 and 2000 in Croatia was m = 3.987 g I-TEQ and annual emission in the same period ranged from QI-TEQ= 1.284 g a-1 in 1990 to QI-TEQ = 0.153 g a-1 in 1995.Emissions of these compounds from metallurgical processes that were active in less recent past were also calculated and the values in the time period between 1960 and 2000 ranged from m =2.888 g I-TEQ in 1980 to m = 0.153 g I-TEQ in 1995.Based on the data on the existing facilities for steel production in electric arc furnaces we estimated that annual emission of dibenzo-p-dioxins and polychlorinated dibenzofurans could amount to QI-TEQ ~ 0.260 g a-1, whereas the future emission of these compounds from the existing cast iron facilities could be QI-TEQ ~ 0.100 g a-1.In the research follow-up for the impact of metallurgical processes on the overall emission of these compounds to the environment, it is required to measure their emissions from all active metallurgical processes. For the sake of better comprehension of emission flows of dibenzo-p-dioxins andpolychlorinated dibenzofurans from metallurgical processes it is necessary to determine the contents of these compounds in all kinds of waste generated in the observed metallurgical processes and to select technical solutions to improve each individual process and to reduce their emissions to the environment

Structural modifications of Cu(II) 12-tungstophosphoric acid salit studied by IR and Raman spectroscopy

In this paper local processes and structural phase transformations of the copper salt of 12-tungstophosphoric acid are investigated. The structural phase transformations were followed through bands, characteristic for the host lattice, in the IR and Raman spectra. The results of these investigations, as well as those of XRPD analysis and impedance measurements as a function of temperature show that some local processes provoke the change in the secondary structure of the Keggin anions.12th Yugoslav Conference on General and Applied Spectroscopy, Oct, 1999, Belgrade, Yugoslavi