The Phase Composition of Electric Furnace Slag

Elementary and phase composition as well as micrography of the electric furnace slag were examined. The base of slag is made from phases containing Fe, Mn and Ca. Grains differ in size and shape, they cling together to form bigger or smaller agglomerates, depending on separated fractions. Relative distribution of identified phases in separated fractions is presented and the possibility of phase separation by means of successive fragmentation and sieve analysis was noticed. The slag defined in that way could find application in cement production and construction industry. The electric furnace slag deposits which pollute the water and ground as well as disfigure the environment can thus be reduced

Ion Chromatographic Analysis of Anion from Slag Elution

Anions from blast furnace slag (F~, Cl", Br", NO3, NO2 and SO|") significantly influence the environment, human health, and the stability of structures. Particular attention is paid to reactions between the slag and the solution of the anions in question (of defined concentration) in the duration of 1 hour to 30 days. The anions were determined by means of the ion chromatographic analysis modified for different proportions of anions in eluents. The results of elution within reactions between slag and media point to the inertness of the system. The fluoride saturation factors of the system were experimentally determined and calculated with the help of distribution coefficients

APPLICATION OF DIFFERENT ISOTHERM MODELS ON LEAD IONS SORPTION ONTO ELECTRIC FURNACE SLAG

The effect of temperature on the equilibrium sorption of Pb2+ from aqueous solution onto a low-cost electric furnace slag was investigated. In this paper, two-parameter isotherm models namely the Langmuir and the Freundlich and three-parameter isotherm model namely Redlich–Peterson were applied to describe the isotherms and to calculate their constants. The best estimation of the parameters of these models by a non-linear regression analysis was obtained. A comparison between two-parameter and three-parameter isotherms was reported. The characteristic parameters for each isotherms and related coefficient of determination (R2) have been determined using MATLAB 6.5. All the coefficients of determination (R2) of the non-linear method are close to unity. The Redlich−Peterson isotherm produced a higher coefficient of determination values in comparison to all the isotherms studied

Radioactivity Monitoring of Steel Processing in Croatian Steel Mills and Foundries

U posljednjih dvadeset godina zabilježen je značajan broj slučajeva radioaktivnog onečišćenja u metalurškim procesima, iako nije sigurno je li to posljedica porasta nekontroliranog odlaganja otpada koji sadržava radionuklide različitog podrijetla ili povećanog nadzora i kontrole radioaktivnosti u metalnom otpadu namijenjenom oporabi. Stoga su svjetski proizvođači metala pristupili sustavnomu praćenju radioaktivnosti u procesima proizvodnje. S obzirom na moguću prisutnost radioaktivnih elemenata u čeličnom otpadu, poluproizvodima i gotovim proizvodima domaće metalurške i metaloprerađivačke industrije, a na temelju iskustva najpoznatijih svjetskih i europskih proizvođača čelika, postalo je nužno i opravdano uvođenje sustava nadzora i kontrole radioaktivnosti u proizvodnim procesima hrvatskih proizvođača čelika. Svrha ovog rada bila je upozoriti na potrebu uvođenja sustava za nadzor i praćenje radioaktivnosti u procesima proizvodnje čelika i čeličnih odljevaka te upoznati stručnjake u hrvatskim čeličanama i ljevaonicama s mogućim rješenjima i postojećim sustavima. Zbog nedostatka vlastitih normi i propisa kojima bi se regulirala kontrola uvoznoga čeličnog otpada, poluproizvoda (sirovi čelik, toplo valjana i hladno valjana traka), kao i gotovih proizvoda te vlastitog otpada, poluproizvoda i gotovih proizvoda, nužno je započeti s uvođenjem sustava za nadzor i praćenje radioaktivnosti u procesima proizvodnje čelika i čeličnih odljevaka koristeći se postojećim međunarodnim preporukama i propisima, sve dok se ne izgradi vlastiti sustav nadzora i ne donese odgovarajuća legislativa na razini RH.The last twenty years have seen a number of cases of radioactive pollution in metallurgical industry. Therefore many metal producers have implemented systematic monitoring of radioactivity in their production processes, especially in steel processing, steel being the most applied construction material with the annual world output of over billion tonnes. Learning from the experience of the best known steel producers in Europe and the world Croatian steel mills have introduced radioactivity surveillance and control systems for radioactive elements in steel scrap, semi-finished and finished products. This paper argues in favour of radioactivity surveillance and control systems in steel and steel castings production in Croatia, and describes current systems and solutions available. Since we lack our own standards and regulations to control both domestic and imported steel scrap, semi-finished products (crude steel, hot and cold rolled strip) and finished products, we need to start implementing radioactivity surveillance and control systems in our steel and steel castings production applying the current international recommendations and guidelines, until we build up our own monitoring system and adopt legislation on the national level. This paper gives an overview of the basic types of radioactivity surveillance and control systems, the most frequent requirements to be met, as well as of the measurement and information flow in their application in steel and steel castings production

Influence of X-ray Radiation on the Phase Composition and Morphology of Electric Furnace Slag, Clinker, and Plaster

The effect of X-ray irradiation upon the structure and morphology of samples of clinker, plaster, and electric furnace slag was studied. Slag was obtained in the process of austenite manganese steel casting. The research objective was to determine the stability of these materials under radiation. The changes that occurred were analyzed by X-ray diffraction and scanning electron microscopy. The diffractograms show changes in the profile, number, relative intensity of diffraction lines, and measured width values at half the maximum height. The micrographs show swelling and cracking of grains. As the radiation time was prolonged, this phenomenon became more evident, which points to the apparent change in the size and shape of the slag, clinker, and plaster grains, i.e. the elementary components of cement

Aqueous Leachate from Electric Furnace Slag

In manufacturing manganese and carbon steel in the basic electric arc furnace, 70 to 80 kg of slag per tonne of steel is produced, whereas the grey cast production results in 30 to 40 kg of slag per tonne of grey cast. Such large slag volumes require special care for their disposal at landfills near steel and rolling mills. It is therefore necessary to examine the chemical stability of slag under various conditions. The paper reports examinations of the chemical and phase composition of slag, as well as the number of anions and cations. The number of anions and cations in water eluates was determined in order to define the influence of such material on the environment. The phase composition of slag was determined by the X-ray diffraction method. Eluated anions (F-, Cl-, NO2-, Br-, NO3- and SO42-) were determined by ion-chromatographic analysis. Eluated cations (Na+, K+, Ca2+ and Mg2+) were established by spectrometric atom absorption. Changes in pH, conductivity and chemical composition of water eluates were monitored for 96 hours. The results have shown that the examined slag material could, with regard to its chemical and phase composition, constitute a stable Fe-Mn-Ca silicate material. However, elution of the examined components, along with the change in conductivity and pH value, implies that slag is not chemically inert and that therefore the problem of slag disposal has to be approached paying special attention on its potential impact on the environment

Radionuclides in steel slag intended for road construction

The objective of this study was to describe the radiochemical characteristics of electric arc furnace (EAF) slag from Croatian EAF black steel slags, generated from carbon steel production process in CMC Sisak d.o.o., and steel mill in Split in order to enhance the understanding of possibilities for their use in road construction. This article presents the results of radionuclide in electric arc furnace steel slag. The presence of natural isotopes 40 K, 232 Th ( 228 Ra), 226 Ra and 238 U was established. The measured activity in slag natural isotopes lies within the Croatian legally permitted limits