Use Of Electric Arc Furnace Dust Research Articles

Analytical Study on the Effect of Electric Arc Furnace Dust (EAFD) on the Rutting of Asphalt Concrete Mixtures

As a byproduct of the steelmaking process, significant amounts of hazardous electric arc furnace dust (EAFD) are produced. Utilizing the solidification/stabilization technology with asphalt mix is one way to safeguard the environment from its negative effects. Rutting was used as an indicator to assess the asphalt mixture with EAFD since it is an important factor in pavement design. This study's major goal is to ascertain how EAFD affects the rutting of asphalt-concrete mixtures. To evaluate the ideal asphalt content, the Marshall test method was applied to asphalt concrete mixtures. EAFD was added to the asphalt cement in four different volume percentages as a binder addition. Then, using the Universal Testing Machine, participants were exposed to a replica of the rutting test (UTM). Experiments were conducted at 25, 40 and 55oC, and at frequencies of 1, 4 and 8 Hz. Rutting was measured for each specimen. Tests results showed that while rut depth has negative correlation with of EAFD% and positive correlation with the temperature. The use of EAFD has dual advantages, protecting the environment from the adverse impact of EAFD and reducing the cost of asphalt mix without jeopardizing the pavement performance.

Effect of freshly produced electric arc-furnace dust and chloride-free chemical accelerators on concrete performance

This study investigates the use of chloride-free calcium-based chemical accelerators in ordinary concrete incorporating freshly homogenized electric arc-furnace dust (EAFD). The utilization of calcium nitrite (CN) and calcium formate (CF) counteracts the negative impact of elevated zinc oxide content in fresh EAFD. The presence of ZnO dramatically delays the setting time of cement in paste and concrete. In this study, EAFD was used in different replacement levels varied from 0 to 12% of cement. The incorporation of EAFD in concrete increased the setting time of concrete by up to 68 h. However, the presence of chemical accelerators enabled a significant reduction in setting time. The hydration reaction formed around cement grains due to the reaction between ZnO in EAFD and portlandite (Ca(OH)2) is responsible for the delay in setting time. This delay could be overcome under the influence of a concentration gradient due to the effective chemical accelerator dosage. The use of EAFD in concrete showed similar strength to silica fume (SF) mixes. The efficiencies of CN and CF rely on their dosage and EAFD content. It is concluded that the effective chemical accelerator-to-EAFD ratio plays a vital role in mitigating the extensive delay in setting time to practically feasible values. The mixture containing 4% CN and 4% EAFD was identified as the best concrete mixture.

Development of a concrete set retarder utilizing electric arc furnace dust

Retarding admixtures are used to increase the setting time of concrete, especially under hot weather conditions. They provide longer time for concrete to be transported, placed and consolidated. Several commercial retarders are used to extend the setting time of concrete. However, they have a shorter shelf-life as they are commonly supplied in a liquid form. Consequently, there is a need to develop a solid (powder) set retarder that can be efficient in retarding the setting time of concrete and at the same time have a longer shelf-life. This paper presents the results of a study conducted to assess the possibility of developing a set retarder utilizing electric arc furnace dust (EAFD), a by-product of steel industry. The retardation efficiency of up to 6% EAFD, by weight of cement, was evaluated in comparison with other two commercial retarders. The effect of EAFD addition on the heat of hydration, slump retention, compressive strength, and drying shrinkage was evaluated. The experimental data indicated that EAFD is effective in increasing the initial and final setting time. The calorimetry data indicated that the hydration of cement was delayed due to the addition of EAFD. The 28-day compressive strength of concrete was not adversely affected by EAFD or the commercial retarders, and it was in the range of 46.5 MPa to 50.7 MPa. However, the drying shrinkage strain increased by 24 to 37%. It can be concluded that the performance of the solid retarder developed using EAFD was comparable to that of the commercial retarders. The use of EAFD, an industrial byproduct, as a retarder will result in technical, economic and environmental benefits.

Effect of Electric Arc Furnace Dust Treatment on the Properties of Fresh and Hardened Mortar

Electric arc-furnace dust (EAFD) is generated in considerable amounts by the electric arc steelmaking process. Use of EAFD in concrete improved many properties of concrete. Yet, the prolonged setting time even at low dosages of EAFD was a serious limitation. This phenomenon was attributed to the presence of transition metal in the material of EAFD. Therefore, it was necessary to stabilize the transition metal in an insoluble crystalline matrix. The calcination with high-temperature was done to fix the transition metal in a complex matrix with the cementitious properties. This material was called Engineered Dust (ED). The use of ED with different replacement levels of 0, 5, 10, 15 and 20% at w/b ratio of 0.5 was carried out. The results showed that the use of ED solved the prolonged setting time which the replacement up to 20% had a normal setting time of 5 to 6 hours. Furthermore, the material of ED was used up to 15% replacement level with the replacement of 20% ED that gave the lowest electric charge values in the RCPT.

Promotion of circular economy: steelwork dusts as secondary raw material in conventional mortars.

Among the actions proposed by the European Union for the implementation of Circular Economy is the use of waste as a secondary raw material (SRM). During the fusion of the scrap, a steel dust is generated, named electric arc furnace dust (EAFD). The EAFD is composed mainly of potentially leachable heavy metals and is classified as a "hazardous" waste. Worldwide, approximately 70% of EAFD is deposited in landfills, with a previous treatment through cement-based materials to prevent the metals' mobility. However, this action is not in accordance with the Circular Economy concept. The present investigation analyses the use of EAFD as SRM in conventional mortar production for its use as a construction material. Different substitution percentages (25, 50 and 100%) were used replacing the siliceous filler by EAFD. A preceding characterisation of the waste by X-ray fluorescence, X-ray diffraction, specific surface area, bulk density, electron microscopy and particle size distribution was performed. The investigation analysed the behaviour of conventional mortars by tests of workability, compressive strength, mineralogy, water absorption by capillarity, and leaching behaviour in granular and monolithic states. The results obtained indicate a slight improvement in mechanical behaviour with the incorporation of EAFD, the reason why its use as SRM in conventional mortars would benefit the construction industry and would encourage the Circular Economy. From an environmental point of view, the mechanisms of Pb fixation should be improved in a granular state.

Study of electric-arc furnace dust (EAFD) in fly ash and rice husk ash-based geopolymers

Electric-arc furnace dust (EAFD) is an industrial waste produced by the volatilization of metals during scrap melting in electric arc furnaces. This waste is classified as Class I – hazardous, because lead and cadmium concentrations are above the limits set in the leaching test. Processes are carried out in many countries to recover the metals contained in EAFD. In Brazil, these processes are usually not conducted in the industry because the low percentage of commercially valuable metals makes it economically unfeasible to recover them. One of the study alternatives is the use of EAFD in civil construction. Studies have shown that EAFD increases the mechanical strength of mortars and Portland cement-based concretes. However, EAFD delayed cement setting time, which can jeopardize its use in construction. Thus, this study aims to evaluate the effect of EAFD when added to fly ash (FA) and rice husk ash (RHA) based geopolymers. Geopolymer mortars were prepared at a ratio of 1:3 (FA+RHA: sand, four different granulations) and added with 0, 10, 15, and 20% EAFD in relation to the mass of FA+RHA. Compressive mechanical strength and leaching tests were carried out at the ages of 7, 28, and 91days. Microstructural analyses were performed using XRD, FTIR, and SEM/EDS. EAFD did not negatively influence the geopolymerization process. The highest compressive strength results for the mortars containing the waste were found for 20% of EAFD. All mortars, regardless of EAFD content, were classified as non- hazardous Class II at the age of 91days.

Method and Mechanisms of Soil Stabilization Using Electric Arc Furnace Dust

This paper reports the method and mechanism for improving the strength of marl and desert sand utilizing electric arc furnace dust (EAFD), an industrial by-product, in lieu of cement or lime. EAFD was used in conjunction with a small quantity (2%) of cement. The mechanical properties and durability characteristics of marl and sand mixed with 2% cement plus 5-, 10-, 20- or 30%-EAFD, by weight of the soil, were evaluated. The soil-cement-EAFD mixtures were used to determine their unconfined compressive strength (UCS), soaked California Bearing Ratio (CBR) and durability. The risk of leaching of toxic heavy metals, such as lead and cadmium, from the stabilized soils to the groundwater was also investigated. The mechanisms of stabilization of the selected soils due to the use of EAFD along with a small quantity of cement are also elucidated. The usage of 20 to 30% EAFD with 2% cement was noted to considerably improve the mechanical properties and durability of both marl and sand.

Oxide zinc addition in cement paste aiming electric arc furnace dust (EAFD) recycling

Large amounts of electric arc furnace dust (EAFD) are generated in steel production, highlighting the need for recycling alternatives like the use of EAFD in production of building materials. However, EAFD delays hydration reactions of concrete. This study presents a model of cement hydration using ZnO as admixture and analyzes phenomena associated with zinc oxide compounds in cement pastes. Cement samples were analyzed by X-ray diffraction (XRD) with Rietveld refined, scanning electron microscopy (SEM), and characteristic X-ray mapping 1, 2, 4, 7, and 14days into setting. Zn was present as ZnO on day 1. A new phase formed containing CaZn2(OH)6·2H2O on day 4, suggesting the transition of ZnO to Zn hydroxide, especially on day 7, when hydration reactions were visually detected and Zn was found only as hydroxide. CaZn2(OH)6·2H2O enables the hydration of cement with ZnO. A model to explain hydration reactions of cement admixed with ZnO was proposed.

Analysis of the Effect of Temperature on the Resilient Modulus of Asphalt Concrete Mixed with Electric Arc Furnace Dust (EAFD)

This research aims at solving an environmental issue caused by the electric arc furnace dust (EAFD), a hazardous waste produced as a by-product of steel-making industry. The research proposes the use of EAFD in road construction, through mixing it with asphalt concrete mixture. As the resilient modulus is one of the key parameters in pavement design, it was chosen as indicator to evaluate the asphalt concrete mixture with EAFD. Experiments were conducted at 25, 40, and 55 °C using three different loading frequencies, 1, 4, and 8 Hz, so that the results can benefit as many countries as possible with different climate conditions. Five contents of EAFD (0, 5, 10, 15, and 20 %) by volume of binder were studied. Results showed that the expected negative correlation between temperature and resilient modulus was not consistent. In particular, there was a higher response of resilient modulus for samples of asphalt concrete mixtures with more than 15 % of EAFD for temperature of 40 °C and loading frequency of 4 Hz as well as with more than 17 % of EAFD for temperatures of 40 and 55 °C and 8 Hz of loading frequency. Results also showed that the highest response of the resilient modulus was at 40 °C, both 4 and 8 Hz, and with percentages of EAFD higher than 15 %.

Investigations on the use of electric-arc furnace dust (EAFD) in Pozzolan-modified Portland cement I (MP) pastes

The use of electric-arc furnace dust (EAFD) in civil construction is not common. In countries where this waste is collected, it is used in the recovery process of heavy metals, such as Zn, Cd, Pb, and Cr. In Brazil, these processes are still not used, because the percentages of heavy metals of commercial value are not economically feasible (e.g. zinc with only 13% of mass). Thus, more studies are necessary aimed at making EAFD a subproduct for civil construction. For this reason, the waste behavior was evaluated in Pozzolan-modified Portland cement I (MP) pastes. Setting time and hydration heat were determined, as well as mineralogical and microstructural characterization, in order to better understand the residue's effect upon cement paste's properties, both in fresh and hardened states. The results showed that EAFD slows down the Portland cement's hydration reactions. This behavior is better verified using hydration heat curves as compared to the Vicat equipment. As of the mechanical performance, it was verified that even though the EAFD retards the hydration reaction of the cement in its initial ages, in more advanced ages the trend is having significant gain of resistance in pastes containing EAFD.

Use of EAF dust as heterogeneous catalyst in Fenton oxidation of PCP contaminated wastewaters

In this study, chemical oxidation tests using H 2O 2 were performed on a solution contaminated with 100 mg l −1 of pentachlorophenol (PCP). The effectiveness of electric arc furnace dust and hematite as heterogeneous catalysts was evaluated. Reactions were conducted at pH 2 for 24 h. Either H 2O 2 stabilized with KH 2PO 4 or un-stabilized H 2O 2 was used. Total organic carbon (T.O.C.) removal and chloride release from PCP molecule were monitored. Results showed that the maximum removal yields for electric arc furnace (EAF) dust (49.2% T.O.C., 56.7% Cl) were achieved when H 2O 2:PCP ratio was 10:1 and Fe:H 2O 2 = 1:5 for unstabilized H 2O 2 and when H 2O 2:PCP = 10:1 and Fe:H 2O 2 = 1:1 for stabilized H 2O 2 (48% T.O.C., 60.6% Cl). The maximum yield using hematite (45.2% T.O.C., 55.2% Cl) was obtained when H 2O 2:PCP ratio was 10:1 and Fe:H 2O 2 was 1:2. When EAF dust was used and Fe:H 2O 2 > 1:5, Cl release was higher than the one expected from T.O.C. removal.

The potential for agricultural use of EAF dusts in Canada

Abstract The potential for use of electric arc furnace (EAF) dusts as Fe and Zn supplements in Canadian agriculture was considered. EAF dusts contain a variety of toxic elements whose concentrations are regulated in feedstuff and fertilizer. Calculations with data for typical dusts containing 1% and 15.4% Zn indicated that neither would be satisfactory sources of Fe and Zn for feedstuff and that only the 15.4% Zn material would be a satisfactory source of Zn for fertilizer manufacture. Lead and Cd are the toxic elements that would most limit the use of EAF dust for fertilizer manufacture. Both dusts contained >3% Fe and might be satisfactory sources of Fe for fertilizer manufacture, however, Fe supplementation of Canadian soils is not necessary for agricultural crop production.