Addition Of Electric Arc Furnace Dust Research Articles

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.

Influence of alkali addition on the setting and mechanical behavior of cement pastes and mortars with electric arc furnace dust

Abstract The use of electric arc furnace dust (EAFD) in cementitious mixtures is gaining popularity. However, an arguable retardant effect in cement setting is often observed when this dust is used in proportions higher than 3%. This problem is the principle reason why high-volume addition of EAFD is typically hindered in cementitious materials; hence, this study was undertaken to isolate the effect of alkalis addition used as set-accelerant of blended cement pastes with EAFD. Mechanical properties of mortars including 10% and 20% EAFD on cement weight and with increasing alkali contents were investigated. Results indicated that increasing the alkali content was effective on shortening the setting time of blended pastes with EAFD. Final setting time of pastes with 10% and 20% EAFD was less than 6 h, and when the EAFD content was 5%, setting time was almost the same of the cement paste. Results also showed that an increase of alkali content in EAFD mortars resulted in a noticeable increase in compressive and flexural strength at 1 and 3 days, but it led to a reduction at later ages (7 and 28 days).

The effect of EAF dust and waste PVC on moisture sensitivity, rutting resistance, and fatigue performance of asphalt binders and mixtures

Considering the increase in the amount of industrial waste in recent years, the reuse of recycled materials has become commonplace in various industries. In the pavement industry, such recycled materials can be used as a modifier of the asphalt mixtures. Electric arc furnace dust (EAFD) and waste polyvinyl chloride (PVC) are two industrial waste materials that are hazardous to the environment. This study aimed to investigate the effect of EAFD and PVC materials on the physical, mechanical, and chemical properties of asphalt binders and mixtures. For this purpose, chemical properties, microstructural characteristics, fatigue life, and rutting resistance of EAFD and PVC modified asphalt binders were studied using FTIR, SEM, LAS, and MSCR tests, respectively. In addition, the effect of PVC and EAFD additives on tensile strength, moisture sensitivity, and rutting performance of asphalt mixtures were evaluated. The results of the FTIR test showed that the addition of EAFD and PVC additives to asphalt binder significantly reduce the carbonyl index of neat asphalt binder and improve the moisture sensitivity and aging resistance of asphalt binders and mixtures. The results of the MSCR test indicated that EAFD and PVC additives reduce asphalt binder strain and subsequently increase rutting resistance, especially at high stress levels. Also, according to the results of the LAS test, adding PVC and EAFD powders to neat asphalt binder increase the fatigue resistance of asphalt binder against micro-crackers at low strain levels. The results of experiments on asphalt mixtures showed that EAFD and PVC additives improve tensile strength, moisture susceptibility, and rutting performance of asphalt mixtures. Overall, the results of this study illustrated that using EAFD and PVC waste materials in pavement industry, not only eliminate environmental problems caused by these materials and reduce the cost of stabilizing them, but also improve the technical performance of asphalt binders and mixtures.

Marshall stability and flow tests for asphalt concrete containing electric arc furnace dust waste with high ZnO contents from the steel making process

Metallurgical industries worldwide produce many hazardous wastes with terrible consequences for the environment. In this research, Electric Arc Furnace Dust (EAFD) has been mixed in asphalt concrete. EAFD is a hazardous waste containing heavy metals. EAFD modified asphalt was fabricated by mixing asphalt binder 60/70 with in 1, 5, 10 and 20 wt%. Asphalt concrete samples were fabricated with EAFD modified asphalt and mineral aggregates with 0.0 (neat asphalt), 10, and 20 wt% of EAFD. Marshall stability tests were used to evaluate stability, flow, stiffness, bulk specific gravity, maximum theoretical gravity, density, air voids percentage, voids in mineral aggregate, and voids filled with binder. The optimum asphalt content for mixtures with 10 and 20 wt% of EAFD was found at 6.0 and 5.45 wt%, respectively, while for the mix without EAFD the optimum asphalt content was at 5.61 wt%. Stability, stiffness, bulk specific gravity, and air voids contents, increased with the addition of EAFD. Maximum theoretical gravity and voids filled with binder decreased with the addition of EAFD content. Voids in mineral aggregates increased and then decreased with the increase of EAFD content. Flow and density decreased and then increased with the addition of EAFD content. MANOVA analysis was conducted to study the effect of each factor. All data was adjusted, and the corresponding model equations are presented and can be easily applied in industry.

Effects of electric arc furnace dust (EAFD) addition on setting and strength evolutions of cement pastes and mortars

The purpose of this work is to study the effects of including high dosage of electric arc furnace dust (EAFD) on both setting behaviour of cement pastes, and on strength evolution of eco-friendly mortars. Particularly, in this research, dust was taken in as-received conditions from the collection system of a carbon steelmaking factory. Setting time of blended cement pastes with varying EAFD content and water/binder ratios was monitored through Vicat test. In addition, physical and mechanical properties of fresh and hardened mortars including EAFD up to 20% on cement weight were investigated. Results indicate that the use of low w/b ratio is effective in shortening the setting time of blended cements, also at high EAFD content, limiting the setting time below 24 h in most of the analysed mixtures. Additionally, an improvement of fresh mortar properties is obtained using EAFD, whereas strength evolution is slightly delayed due to EAFD addition.

The influence of EAF dust on resistivity of concrete and corrosion of steel bars embedded in concrete

Essentially, when electrical current flows easily in concrete that has large pores filled with highly connective pore water, this is an indication of a low resistivity concrete. In concrete, the flow of current between anodic and cathodic sites on a steel reinforcing bar surface is regulated by the concrete electrical resistance. Therefore, deterioration of any existing reinforced concrete structure due to corrosion of reinforcement steel bar is governed, to some extent, by resistivity of concrete. Resistivity of concrete can be improved by using SCMs and thus increases the concrete electrical resistance and the ability of concrete to resist chloride ingress and/or oxygen penetration resulting in prolonging the onset of corrosion. After depassivation it may slow down the corrosion rate of the steel bar. This indicates the need for further study of the effect of electric arc furnace dust (EAFD) addition on the concrete resistivity. In this study, concrete specimens rather than mortars were cast with different additions of EAFD to verify the electrochemical results obtained and to try to understand the role of EAFD addition in influencing the corrosion behaviour of reinforcing steel bar embedded in concrete and its relation to the resistivity of concrete. The results of these investigations indicated that the corrosion resistance of steel bars embedded in concrete containing EAFD was improved, which may link to the high resistivity found in EAFD-concrete. In this paper, potential measurements, corrosion rates, gravimetric corrosion weight results and resistivity measurements will be presented and their relationships will also be discussed in details.

Effects of Electric-Arc Furnace Dust Application on Soil Properties, Sorghum Growth, and Heavy-Metal Accumulation

This study investigated the possibility of using electric-arc furnace dust (EAFD) as an acidic soil amendment. The experiments were conducted using incubation and pot experiments. In the incubation experiment, various rates of EAFD were added to an acidic soil and properties such as pH; electrical conductivity of the saturation extract (ECse); and available phosphorus (P), potassium (K), iron (Fe), zinc (Zn), copper (Cu), manganese (Mn), lead (Pb), and cadmium (Cd) were determined. In the pot experiment rates of EAFD incorporated with soil were 0.25%, 0.5%, 1%, and 2%. The results showed that with increasing the rate of EAFD application, soil pH, EC, and available P and K were enhanced. However, addition of EAFD more than 2% caused high salinity and alkalinity; hence, it is not recommended for reclamation of this acidic soil. A pot experiment was carried out to determine its effects on sorghum (Sorghum bicolor L.) dry matter and heavy-metal accumulation. Plant dry matter was enhanced with increase the EAFD rates. The concentrations of Fe, Zn, Cu, Cd, and Pb were enhanced with the increasing rate of applied EAFD in root and shoot. However, content of these elements in plant shoot were in the normal range.

Geopolymerization of coal fly ash in the presence of electric arc furnace dust

The results of synthesis of fly ash based geopolymers and the experimental investigations of the geopolymerization of fly ash in the presence of eclectic arc furnace dust were presented. The electric arc furnace dust (EAFD) is a hazardous solid waste formed during remelting processes of iron and steel scrap in an electric arc furnace. In this work, the possibility of immobilization of Zn (as a most abundant toxic metal in EAFD) from EAFD and the influence of EAFD addition and alkaline dosage on the mechanical and microstructural properties of fly ash based geopolymers was investigated. Our result show that the best mechanical properties of FA and FE geopolymers were obtained using 10M NaOH and 10wt.% EAFD. The X-ray phase analysis confirmed the presence of aluminosilicate and oxide phases in investigated samples of FA, EAFD, as well as FA and FE geopolymers. SEM–EDS results have revealed the presence of Zn in an amorphous aluminosilicate phase. This material is considered as mesoporous and the change of porosity is greatly dependent on the alkaline dosage. The efficiency of immobilization of Zn from EAFD was evaluated using TCLP, EN 12457-2 and EPA Method 1313 leaching tests. Results of TCLP and EN 12457-2 tests have shown that the increase of alkaline dosage leads to the more effective immobilization of Zn and other toxic metals present in EAFD. On the other hand, the results of EPA method 1313-pH dependent leaching test have indicated that FE geopolymers are relatively stable in neutral and alkali environment while in a pH range 2–5.5, solubility of Zn and Pb is a concern for this type of materials.

Immobilization of Electric Arc Furnace dust toxic elements within the matrix of concrete based products

Electric Arc Furnace Dust (EAFD) generated through the production of carbon and alloy steel products is classified as environmentally hazardous waste mainly because of its relatively high levels of Pb, Cd and Cr. The aim of the present work was to investigate the effect of the EAFD addition on the properties of concrete building products (e.g concrete bricks) and to stabilize the toxic elements contained in EAFD in order to get environmentally accepted products. Concrete specimens were prepared by vibration and press-forming of mixtures containing cement, sand, dolomite, calcium stearate with water and the addition of different percentages of EAFD. For the immobilization of the toxic elements of EAFD within the matrix of the specimens, different percentages of each one of NaH2PO4, H3PO4 and of a mixture of H3PO4 - FeSO4.7H2O were added successively to each one of the mixtures as stabilizing materials. Modulus of rupture (MOR) and water absorption (WA) tests showed that the specimens produced had specifications within accepted limits for relevant products. Leaching tests applied on the specimens proved the compliance with imposed leachate Maximum Acceptable Limits (MAL), since the practiced stabilizing materials effectively immobilize toxic elements within the prepared specimens.

Recycling of Electric Arc Furnace Dust by Adding to Hot Metal

This research aims to study the process of incorporation of the metal iron contained in electric arc furnace dust (EAFD), by addition in hot metal at a temperature of 1,400 degrees Celsius altering experimental conditions such as how to add the EAFD (“as received” and in the form of briquettes), the percentage of EAFD to be added (10, 20 and 30% of initial weight of sample pig iron). The time of withdrawal of the sample of pig iron and slag (30 minutes after the addition of EAFD). Previously, the EAFD will be characterized using the following techniques: chemical analysis, particle size analysis, X-ray diffraction, scanning electron microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) microanalysis. After characterization, the electric arc furnace dust to be added to the bath of liquid iron, will be divided into 2 types: the first order of addition will be in the form "as received" from the plant and the second is through the agglomeration of EAFD in the form of briquettes. The achievement of fusion experiments in laboratory scale will take place in a vertical tubular furnace with temperature control. The fusion experiments to assess the incorporation of the metal iron will use graphite crucibles. A flow of inert gas (argon) will be maintained inside the furnace during the experiments. It is expected that the results obtained at the end of the research allow the evaluation of the iron metal incorporation of electric arc furnace dust in pig iron bath.

인공경량골재의 EAF dust 첨가에 따른 초경량화에 관한 연구

제철공업에서 부산물로 발생되는 EAF(Electric Arc Furnace) dust는 유해한 철분 성분을 다량 함유하고 있어 환경파괴를 일으킬 위험이 있는 지정폐기물이다. EAF dust의 자원화를 위하여 석탄화력 발전소에서 발생되는 바닥재와 준설토에 EAF dust를 첨가하여 세라믹 다공체의 제조 가능성을 연구하였다. 또한 등유는 비교적 저온에서 발포기구에 작용하는 탄소(C)의 효과를 보기위해 첨가하였다. 혼합은 건식 공정으로 했으며, 소결 방법은 <TEX>$1050^{\circ}C$</TEX>부터 <TEX>$1200^{\circ}C$</TEX>까지 <TEX>$50^{\circ}C$</TEX> 간격으로 10분간 직화소성 하였다. 소결된 시편의 비중, 흡수율 및 미세구조를 관찰한 결과, EAF dust는 시편 내의 발포 현상을 용이하게 하여 초경량 다공체 골재를 얻을 수 있었다. <TEX>$1150{\sim}1200^{\circ}C$</TEX>의 소결온도에서 10 wt% EAF dust를 첨가한 인공경량골재는 비중 1.0 g/<TEX>$cm^3$</TEX> 이하의 초경량 인공 경량 골재를 만드는 것이 가능할 것으로 판단되었다. EAF dust from steel industry used as primary materials for the production of lightweight aggregates. Fe compounds in EAF dust plays an important role in the bloating reaction. This study was conducted to evaluate the feasibility of using bottom ash and dredged soil from coal power plant and EAF dust. The effect of different raw material compositions and sintering temperatures on the lightweight aggregate properties were evaluated. The characteristic of thermal bloating of bottom ash and dredged soil were mainly influenced by ferrous materials. The specific gravity of aggregate was decreased with the addition of EAF dust and kerosene was reduced sintering temperature on the bloating formation. Lightweight aggregate containing 10% EAF dust having apparent density under 1.0 g/<TEX>$cm^3$</TEX> were produced at <TEX>$1150{\sim}1200^{\circ}C$</TEX>.

Stabilization of electric-arc furnace dust in concrete

Electric-arc furnace dust (EAFD) is a by-product of steel production and recycling. This fine-grained material contains high amounts of zinc and iron as well as significant amounts of potentially toxic elements such as lead, cadmium and chromium. Therefore, the treatment and stabilization of this industrial residue is necessary. Concrete is a well-known suitable environment for stabilization/solidification of materials which have leachable elements in need of fixation. The effect of the EAFD content on the mechanical and chemical performance of Portland cement concrete is investigated in this paper. The effect of the EAFD content on the setting time of cement slurry was also analyzed. The axial compressive strength of the concrete samples increases with the EAFD addition in the range of 10 to 20 wt. (%) EAFD; also the tensile strength increases with the EAFD addition. An increase in EAFD content significantly increases the setting time of the concrete. The acetic acid leaching and water solubilization tests indicate low mobility of the potentially toxic elements from the EAFD concrete composite. The results of the immersion tests show that the addition of EAFD to the concrete seems to reduce chloride penetration, which may help prevent pitting corrosion in reinforced concrete.

Effect of electric arc furnace dust on the properties of OPC and blended cement concretes

This paper presents results of a study conducted to evaluate the mechanical properties and durability characteristics of ordinary Portland cement (OPC) and blended cement (silica fume and fly ash) concrete specimens prepared with electric arc furnace dust (EAFD). Concrete specimens were prepared with and without EAFD. In the silica fume cement concrete, silica fume constituted 8% of the total cementitious material while fly ash cement concrete contained 30% fly ash. EAFD was added as 2% replacement of cement in the OPC concrete and 2% replacement of the total cementitious content in the blended cement concretes. Mechanical properties, such as compressive strength, drying shrinkage, initial and final setting time, and slump retention were determined. The durability characteristics were evaluated by measuring water absorption, chloride permeability, and reinforcement corrosion. The initial and final setting time and slump retention increased due to the incorporation of EAFD in both OPC and blended cement concretes. The drying shrinkage of EAFD cement concrete specimens was more than that of concrete specimens without EAFD. The incorporation of EAFD was beneficial to OPC concrete in terms of strength gain while such a gain was not noted in the blended cement concretes. However, the strength differential between the blended cement concretes with EAFD and the corresponding concretes without EAFD was not that significant. The water absorption and chloride permeability, however, decreased due to the incorporation of EAFD in both the OPC and blended cement concretes. The corrosion resistance of OPC and blended cement concrete specimens increased due to the addition of EAFD.

Utilization of Electric Arc Furnace Dust as Raw Material for the Production of Ceramic and Concrete Building Products

The up to 20 wt% addition of the Electric Arc Furnace Dust (EAFD) hazardous waste on the properties of extruded clay-based ceramic building products fired at various temperatures (850 to 1050°C), as well as of dolomite-concrete products was investigated. Chemical, mineralogical and particle size distribution analyses were performed in order to characterize the used EAFD. The results showed that the ceramic specimens prepared had water absorption, firing shrinkage, apparent density, mechanical strength, colour and leaching behaviour within accepted limits. Addition of 7.5 to 15 wt% EAFD presented improved properties, while 20 wt% seems to be the upper limit. Dolomite-concrete specimens were prepared by vibration and press-forming of mixtures containing cement, sand, dolomite, EAFD and water. Modulus of rupture values were significantly increased by the addition of EAFD. The leaching tests showed stabilization of all toxic metals within the sintered ceramic structure, while the leaching behaviour of lead in dolomite-concrete products needs further detailed study.