25 research outputs found
SEM, AES, WDS i korozijsko testiranje oksidnih i nitridnih zaÅ”titnih slojeva oblikovanih toplinskom obradom nerÄajuÄeg Äelika
Protective oxide and/or nitride layers on AISI 321 stainless steel were prepared by thermal treatment in air and two controlled atmospheres in a laboratory simulation of an actual technological procedure. Samplesā surface was imaged by Scanning Electron Microscopy (SEM), elemental composition of the substrates was checked by Wavelength Dispersive Spectroscopy (WDS) and depth profiles of the samples were measured by Auger Electron Spectroscopy (AES). Since protective layer thicknesses were found to be of the order of hundreds of nanometers an attempt was made to obtain some fast averaged information about layers composition by Wavelength Dispersive Spectroscopy (WDS) with appropriately adjusted primary beam energy. Electrochemical corrosion testing was also performed on samples.ZaÅ”titne oksidne i/ili nitridne slojeve na AISI 321 nerÄajuÄem Äeliku pripremljen toplinskom obradom materijala na zraku i u 2 kontrolirana tipa atmosfera kao laboratorijsku simulaciju stvarnog tehnoloÅ”kog procesa. Slike povrÅ”ine uzoraka dobijene tehnikom SEM, sastav substrata metodom WDS a za profilnu analizu upotrijebljena je spektroskopija Augerovih elektrona (AES). Kako je ustanovljeno da su debljine formiranih zaÅ”titnih slojeva reda veliÄine nekoliko stotina nanometara pokuÅ”alo se doÄi do ocjene o prosjeÄnom sastavu unutar sloja upotrijebom tehnike WDS uz odgovarajuÄe odabranu energiju primarnog elektronskog snopa. Na uzorcima je provjereno i korozijsko testiranje
IR AND X-RAY PHOTOELECTRON SPECTROSCOPY OF V 2 O 5 , TiO 2 AND V/Ti-OXIDE SOL-GEL DERIVED FILMS INFRARDE^A IN RENTGENSKA FOTOELEKTRONSKA SPEKTROSKOPIJA V 2 O 5 , TiO 2 IN V/Ti-OKSIDNIH SOL-GEL FILMOV
Prejem rokopisa -received: 1998-12-06; sprejem za objavo -accepted for publication: 1998-12-14 V/Ti-oxide films were prepared by dip-coating from sols made by mixing of V-oxoisopropoxide and Ti-propoxide in V:Ti molar ratio in precursors 3:1, 1:1 and 1:3. Amorphous films were obtained after annealing at 300Ā°C (1 h). IR spectroscopic analysis revealed that V=O stretching modes appeared at 1020 cm -1 in the IR spectrum of powder (V:Ti=1:1). However, in the IR spectra of a film with the same molar ratio the bands at 1008 and 914 cm -1 appeared suggesting the presence of V 4+ -O bonds. The new band at 790 cm -1 signalled the V-O-Ti bridging bonds connecting V-O and Ti-O polyhedra. XPS measurements confirmed that initial-state films contained V 5+ , V 4+ and Ti 4+ species, but at the film surface only V 5+ species existed. Sequential depth analysis of films performed with Ar + sputtering showed that the vanadium is reduced to 3+ oxidation state with progressive exposure while titanium is not affected. Key words: electrochromic (EC) devices, oxide films, IR spectroscopy, XPS, oxidation states, sputtering, sol-gel V/Ti-oksidne filme smo pripravili iz koloidnih raztopin V-oksoizopropoksida in Ti-propoksida v 2-propanolu s tehniko potapljanja. Molska razmerja V:Ti v prekurzorjih so zna{ala 3:1, 1:1 in 1:3. Amorfni filmi so nastali po segrevanju na 300Ā°C (1h). V IR spektru pra{kastega vzorca (V:Ti = 1:1) so se valen~na nihanja V=O pojavila pri 1020 cm -1 . V IR spektru filma z istim molskim razmerjem pa se pojavita trakova pri 1008 c
Heavy Metals in Steel Mill Electric Arc Furnace Dust
U okviru gospodarenja otpadom, koje obuhvaÄa i odabir rjeÅ”enja za njegovo zbrinjavanje, bilo uporabom u vlastitim tehnoloÅ”kim procesima, bilo preraÄen u drugim industrijskim granama ili odgovarajuÄom obradom prije eventualnog odlaganja na propisanim odlagaliÅ”tima, u Željezari Sisak se pristupilo sustavnom istraživanju fizikalno-kemijskih karakteristika metalurÅ”kog otpada kao i njegovog ponaÅ”anja u interakciji sa okoliÅ”em.
ElektropeÄna praÅ”ina, kao metalurÅ”ki otpad, razvrstana je prema US EPA klasifikaciji iz 1980. godine u opasni tehnoloÅ”ki otpad oznake K061. ElektropeÄna praÅ”ina Željezare Sisak svrstana je u opasni otpad na temelju ispitivanja fizikalno-kemijskih karakteristika od strane za to ovlaÅ”tenog laboratorija i dodijeljen joj je kljuÄni broj *10 02 03, sukladno pravnim propisima Republike Hrvatske. Kako zbrinjavanje opasnog otpada nije moguÄe izravnim odlaganjem na tlo, ukazala se potreba pronalaženja rjeÅ”enja za zbrinjavanje elektropeÄne praÅ”ine na ekoloÅ”ki prihvatljiv i ekonomski opravdan naÄin. Naime, elektropeÄna praÅ”ina iz procesa proizvodnje Äelika u ÄeliÄani Željezare Sisak, svojedobno je služila kao dodatak pri izradi sinter-mjeÅ”avine za potrebe proizvodnje sirovog željeza visokopeÄnim postupkom.
Zbrinjavanje elektropeÄne praÅ”ine na taj naÄin bilo je jedino ekonomski opravdano radi iskoriÅ”tavanja njezinog željezonosnog dijela, dok ekoloÅ”ka prihvatljivost tog naÄina zbrinjavanja opasnog otpada nije bila zadovoljena. Naime, teÅ”ke kovine od elektropeÄne praÅ”ine kao toksiÄni sastojci samo su mijenjali svoju matiÄnu osnovu tj. iz elektropeÄne praÅ”ine bivali preseljeni i ukoncentrirani u mulj ispiraÄa visokopeÄnih otpadnih plinova.
Zatvaranjem proizvodnje sirovog željeza u visokim peÄima, napuÅ”ten je i taj, ionako nepotpun naÄin zbrinjavanja elektropeÄne praÅ”ine, a novonastale koliÄine se otada privremeno odlažu u krugu tvornice i svakim su danom sve veÄa opasnost za okoliÅ”.
Radi pronalaženja moguÄnosti i odabira optimalnog postupka zbrinjavanja nagomilanih koliÄina opasnog metalurÅ”kog otpada provode se sustavna istraživanja od kojih je ovdje prikazan samo dio koji se odnosi na ispitivanje sadržaja teÅ”kih kovina u elektropeÄnoj praÅ”ini, kao i meÄusobne povezanosti
udjela teÅ”kih kovina Zn, Pb, Cd s masenim udjelom željeza Äiji oksidi Äine osnovu tog otpada. Ostale kovine poput bakra, kroma i nikla nisu istraživane na isti naÄin kao Zn, Pb i Cd s obzirom da je ispitivana praÅ”ina nastala u postupcima proizvodnje ugljiÄnih Äelika 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
Specola 2000
Progetto di recupero, inventariazione e informatizzazione degli archivi astronomici italiani realizzato dal Ministero dei Beni Culturali e dalla Societ\ue0 Astronomica Italian