Slag Fiber Research Articles

Preparation and characterization of TiO2 photocatalytic composites supported by blast furnace slag fibres for wastewater degradation

The carrier selection for photocatalytic materials is critical for photocatalytic degradation technology. In this study, blast furnace slag fibre (BFSF) prepared using metallurgical waste was employed as a carrier for TiO2. The photocatalytic activity of the resulting TiO2/BFSF composite and its influencing factors during the sol-gel process was systematically investigated via TG-DTA, XRD, SEM-EDS, BET, UV–Vis absorption spectroscopy, degradation of methylene blue (MB) experiments, and mass loss technology. The results showed that the crystal phase of TiO2 transformed from pure anatase to a mixture of anatase and rutile and then to pure rutile as the calcination temperature increased from 350 °C to 800 °C. When the number of TiO2 loading cycles increased from 1 to 6, the TiO2 film changed from thin to thick and from uneven to uniform, until cracking and spalling finally occurred. When the number of TiO2 loading cycles and calcination temperatures increased, the photocatalytic activity increased and then decreased. After loading TiO2 sol four times and calcining at 450 °C for 2.5 h, a uniform and dense anatase TiO2 film was observed to be wrapped on the BFSF, achieving the highest photocatalytic activity and a maximum degradation ratio of 95.3%. The TiO2/BFSF composite showed excellent reusability. After four reuse cycles, the degradation ratio remained at 66.2%. Three potential mechanisms were proposed for photocatalytic degradation. The water and alkali resistance of BFSF markedly increased after the TiO2 thin film was loaded. This study therefore provides strategies to improve the photocatalytic activity of TiO2 and expands the high-value-added application of BFSF.

Mechanical Properties of Alkali-Activated Slag Fiber Composites Varying with Fiber Volume Fractions.

The mechanical properties of alkali-activated slag fiber composites (ASFC) were investigated with varying volume fractions of PVA (Polyvinyl alcohol) fibers. Ground granulated blast furnace slag (GGBS) and alkali-activators were used as the main binders instead of cement, which emits a large amount of carbon dioxide during the manufacturing process. The measured slump flow of ASFC showed a high fluidity at a fiber content of 1.5 vol.% or less. The tensile, flexural, and shear strength of ASFC showed higher values as the amount of fiber increased. Compared to the existing high ductility fiber composites showing strain hardening behaviors with a fiber content of 2.0 vol.%, ASFC proved that it could exhibit high ductility characteristics due to multi-microcracks even at low fiber mixing rates of 1.0% and 1.25%. ASFC could be expected to lower the manufacturing cost with a low fiber content and provide improved workability with high fluidity. In addition, when manufacturing structural components using the developed ASFC, it is expected that the amount of fiber could be selected and used according to the required performance.

Effect of the Acidity Coefficient on the Properties of Molten Modified Blast Furnace Slag and Those of the Produced Slag Fibers.

The online preparation of fibers using molten modified blast furnace slag can not only achieve the high-value-added utilization of the slag but can also make use of the sensible heat of the slag. In this paper, blast furnace slag was modified using iron tailings, and was then used to prepare slag fiber online; the effects of the acidity coefficient on the properties of the molten modified blast furnace slag and modified blast furnace slag fiber were investigated. With an increase in the acidity coefficient from 1.2 to 1.6, the temperature range of the slag melt, with viscosity in the 1–3 Pa·s range, increased from 101.2 °C to 119.9 °C. The melting temperature increased from 1326.2 °C to 1388.7 °C, and the suitable fiber-forming temperature range increased from 70.7 °C to 82.9 °C. With the increasing acidity coefficient, the crystallization temperature of the molten modified slag decreased markedly. When the acidity coefficient was greater than 1.4, the slag system was still in a disordered glassy phase at 1100 °C. The hardening speed gradually reduced with the increasing acidity coefficient when the modified slag was cooled at the critical cooling rate, resulting in a gradual increase in fiber formability. The fibers prepared from the modified slag at different acidity coefficients had smooth surfaces, and were arranged in a crossed manner at the macroscopic level. Their color was white, and small quantities of slag balls were doped inside the fibers. With an increase in the acidity coefficient from 1.2 to 1.6, the average fiber diameter increased from 4.2 μm to 8.2 μm, and their slag ball content increased from 0.73% to 4.49%. Overall, the acidity coefficient of modified blast furnace slag should be less than 1.5 in actual production.

Torrefaction pretreatment facilitated solvents-resistant and stable wood-plastic composites

Solvents-resistant and stable wood-plastic composites have been successfully obtained via combined torrefaction pretreatment, extrusion, and injection molding processes that applied torrefied sweet sorghum slag (SS) fibers as reinforcing fillers and high-density polyethylene (HDPE) as thermoplastic polymer matrices. Comparing with intact SS fibers, torrefaction pretreatment caused deacetylation and severe decomposition of hemicellulose (decomposed nearly 95% under 300 °C) in SS fibers, which was favorable for the formation of porous structures on the surface of SS fibers and the increase in their hydrophobicity. Thus the resultant composites exhibited enhanced mechanical properties (max tensile strength of ~24.84 MPa, flexural strength of ~32.63 MPa, and toughness of ~2.50 MJ/10−3), and promising solvents resistance (e.g., H2O, acid, alkali, salt, and ethanol) and stabilities (e.g., thermal, and dynamic mechanical stabilities). The mechanical strength retention rates of HDPE/torrefied SS (300 °C) composites maintained above 95% after socking in common solvents for 7 days. Moreover, torrefaction took advantages of short processing time, energy-saving, low-cost, and high mass yield when compared to the traditional carbonization, which paved an efficient and scalable biomass fibers pretreatment strategy to construct highly stable wood-plastic composites and extended their application areas like constructing materials and some extreme circumstances.

Influence of Pet Fiber Geometry on Properties of Concrete Using Partial Replacement of Fine Aggregate with Copper Slag

In the last few years with the growth of population, development of industry and technology there has been rapid increment in the waste materials and by-products production. The basic strategy to decrease solid waste and plastic waste bottle disposal problems have been focused at the reduction of waste production and retrieval of usable materials from waste as raw materials . In present study, the PET fibers were achieved by manually hand cutting from Kinley polyethylene terephthalate (PET) plastic drinking water bottles. Three different geometrical shape Straight shape fiber, Flattened shape fiber and ‘O’ shape polyethylene terephthalate (PET) fibers 0.5% by weight of cement were used. Fine aggregate were partially replaced with copper slag at percentages of 0%, 20%, 40% and 60%. Effect of different geometry of PET fiber and copper slag on fresh and hardened properties of concrete was investigated. Test result revealed that geometry of fiber and copper slag has good effect on fresh properties of concrete. Without use of super plasticizer workability was increasing. The combination of O shape fiber with 60% copper slag demonstrate enhancement in compressive strength, split tensile strength and flexural strength up to 25.85%,26.39% and 28.09% respectively compared to standard mix M 25 grade concrete. With the Increment of copper slag enhancement in strength was observed it was due to the friction developed between copper slag and PET fiber surface. Development of friction was due to the angularity of copper slag particles and bridging action of PET fiber. From water absorption test result it was concluded that water absorption is less in O shape fiber. It is due to the less water absorption properties of PET fiber and copper slag and also the O shape fiber provide good interlocking property in concrete matrices compare to other two geometrical shape fiber.

Effect of process parameters on dry centrifugal granulation of molten slag by a rotary disk atomizer

Dry centrifugal granulation (DCG) experiments for blast furnace slag (BFS) were performed by means of a rotary disk atomizer since water quenching method can create a series of problems. The results showed that the DCG method can granulate the BFS, but the results are easily affected by the slag flow rate, disk rotating speed, disk radius, disk material and slag falling height. The granulating parameters with an excessive flow rate, low rotating speed, SiN–SiC disk, stainless steel disk and low slag falling height are detrimental to the granulation process. The most suitable parameters for granulation are a slag flow rate of 5.1 × 10−5 m3/s, a disk rotating speed of 1500–2300 r/min, a slag falling height of 0.8 m and a smooth graphitic disk with the radius of 0.1 m. In the absence of an off-center flow, the overall best granulating effect produces round particles with mean diameter of 3.43 mm without creating slag fiber. The vitreous content of the BFS particles granulated by graphite disks is 92%, which meets the requirements of cement raw materials. The Bond work index of dry granulated BFS is 18.4 kWh/t, and the grindability of dry granulated slag and water-quenched slag is similar.

Development of Porous Asphalt with Bitumen Emulsion, Electric arc Furnace Slag and Cellulose Fibers for Medium Traffic Roads

The construction of road infrastructure is one of the most polluting activities that exists today. Therefore, the use of waste from other industries is an excellent solution, since it reduces the consumption of raw materials, reduces CO2 emissions and avoids the disposal of waste in a landfill. In this study, electric arc furnace slag, cellulose fibers from the papermaking industry and bitumen emulsion were used for the conformation of sustainable and porous bituminous mixtures. Electric arc furnace slag was used as a high-resistance aggregate with a capacity sufficient to support traffic loads. Cellulose fibers were added to increase the percentage of binder in the mixture without bleeding problems, thereby achieving greater tensile strength. To do this, first the waste was physically and chemically characterized, then different mixtures were conformed and finally the mixtures were studied by means of the loss by wear and Marshall tests. The results reflected an optimal combination of materials that provided the best results in the mechanical tests, obtaining much better results than the mixtures with discontinuous grading and traditional bitumen emulsion. Therefore, a sustainable, porous and economical mixture for road use is obtained in this research.

Influence of polyvinyl alcohol–glutaraldehyde on properties of thermal insulation pipe from blast furnace slag fiber

AbstractThe development of an environmentally friendly binder can immensely benefit and promote the BF slag fiber industry. Accordingly, in this study, fiber insulation pipes were prepared using water glass, polyvinyl alcohol (PVA), and PVA–glutaraldehyde (GA); moreover, their bulk density, moisture absorption capacity, and thermal conductivity coefficient were measured and compared. The results demonstrated that the values of these three parameters depend on the binder concentration and dosage under certain fiber quality, pipe sizes, and manufacturing process conditions. The best binder composition was proven to be that of PVA–GA, prepared using 3 wt% PVA and 5 wt% GA herein, which facilitated reduction in the bulk density and improvement of the waterproof properties and insulation performance of the slag fiber pipes.

Comparison of water uptake behavior on tensile property of epoxy impregnated continuous basalt and slag filament composites

Slag fiber has economic and environmental advantages in that it converts a low-value-added material to a high-value-added material. However, although the slag fiber has a chemical composition similar to basalt fiber, its competitiveness in the fiber industry is significantly lower. Moreover, the slag fiber remains in the pre-commercial stage due to the uncertainty and instability of the basic properties. Therefore, in this study, the slag fiber customized through the fiberization process was compared with the existing basalt fiber to analyze the effect of the similarity of chemical composition on the environmental degradation characteristics and mechanical properties under tensile loading. As a result, the slag filament composites showed lower tensile strength due to the weaker interfacial bonding strength with the epoxy matrix than the basalt filament composites, but the difference in decreased tensile strength rate was not significant. In addition, long-term moisture absorption in fresh water and seawater demonstrated excellent moisture absorption resistance.

Tensile properties of mineral fibers determined with Sentmanat extensional rheometer

Within the presented research, we utilized a non-standard technique, i.e. Sentmanat Extensional Rheometer (shorter SER-tool), which can potentially provide tensile measurements (i.e. tensile strength and Young’s modulus) on relatively short and brittle fibrous materials such as slag mineral fibers. For easier transportation and fastening of the fibers, physical model of SER-tool was slightly modified. Consequently, modified technique was theoretically (through parametric error analysis) and experimentally (through mechanical characterization) evaluated on four different types of mineral fibers. Despite a fair, yet distinguishable scatter of tensile strength which cannot be theoretically evaluated due to size effect (related to thermo-mechanical histories), fiber’s weakest link (related to fiber defects), etc., mechanical response, which is universally presented by Young’s modulus, was reproducible. Parametrical error analysis, which determines the accuracy of modified SER-tool showed that the large part of the error arises from the combination of fiber diameter and error in fiber diameter, however by careful selection of fibers (related to the magnitude of the diameter and its error) the result remains within the predicted ranges. From the results different types of mechanical responses can be observed, which is related to ceramic content, i.e. SiO2+Al2O3, within the slag fiber. Utilized technique demonstrates the high performance and the capability of modified SER-tool to perform various studies, investigating the effects of thermo-mechanical histories, chemical composition and other parameters on mechanical properties of single fiber filaments.

Effect of B2O3 on the properties of ferronickel melt and mineral wool

To utilize both ferronickel slag and its sensible heat, the melting and viscosity-temperature behaviors of the B2O3 modified slags were studied first. Results show that the initial melting temperature reduces from 1612 K (1339 °C) to 1534 K (1261 °C), and the complete melting temperatures decreases from 1744 K (1471 °C) to 1696 K (1423 °C) with the increase of B2O3 from 3 to 9 wt%. However, the temperature span of the viscosity ranging in 0.5–2.5 Pa s increases from 10 K (°C) to 39 K (°C) with increasing B2O3. Then, the characterizations of the slag fibers prepared by the modified slags suggest that the addition of B2O3 decreases the mean diameter of the slag fibers from 5.6 ± 0.45 μm to 3.4 ± 0.27 μm, whereas increases their tensile strength from 1724 ± 80 MPa to 2114 ± 136 MPa. Moreover, both the glass transition temperature (Tg) and crystallization temperature (Tc) are delayed by the addition of B2O3 since boron works as network former in the slag melt structure.

전기로 환원 슬래그 미분말을 사용한 강섬유보강 모르타르의 역학특성과 섬유 분포 특성

전기로 환원 슬래그 미분말을 사용한 강섬유보강 모르타르의 역학특성과 섬유 분포 특성

Crystal-pit-cracking formation on composite modified slag fiber in long-term water immersion

Composite modified slag fiber (CMSF) has been widely used as insulation material for enclosures in the field of construction; however, its corrosion characteristics and crack formation are unclear. Therefore, the damage behavior of CMSFs with two acidity coefficients (ACs) immersed in water for 365 days was studied; the fiber structure and composition were measured. The crystalline phase on the fiber surface was identified as CaCO3 deposits that dissolved after long-term immersion, resulting in pits. Owing to continuous replacement of H+, Ca2+ continuously migrates from the inside to the outside of the fiber, resulting in a stepwise increase in the AC of the fiber cross-section; the surface pits significantly increased and joined together to form an axial crack. However, the Si-O-Si bond has no significant fracture during long-term immersion. These findings support the theory on the crack behavior of CMSFs during long-term immersion for practical applications.

Spinning properties of slag fiber according to viscosity model

Slag means residues that occur during the steelmaking process. Measuring the high temperature viscosity of the slag is difficult and high cost. So, viscosity models can be used to predict the trends in viscosity as a function of the key variables, and so assist in the selection of process conditions and the optimization of the performance of slag fibers. Slag fibers with compositions similar to glass/carbon fibers are also expected to be suitable for spinning at a log viscosity value of 2.8–3. The fiberizing temperature of glass fiber is more than [Formula: see text] and the fiberizing temperature of basalt fiber is more than [Formula: see text], while the slag fiber can be spun at a low temperature.

Dissolution behavior of a novel composite fiber made from blast furnace slag

A novel composite fiber was made from chemically modified blast furnace slag, it has been widely used in construction field of china, but the related dissolution behavior was unclear. Specimens of the fibers with different acidity coefficient (AC) by adding basalt, ranging from 0.93 to 1.19, were immersed into deionized water for 180 days. The surface morphology was studied by scanning electron microscopy (SEM). The element concentration on the surface and in aqueous phase was determined by Energy dispersive X-ray spectroscopy (EDS) and inductively coupled plasma spectroscopy (ICP), respectively. The results showed that the fiber surface newly formed calcite crystal when the AC was lower than 1.03. Portion of Al element was converted from four coordination forms to a combination of six coordinations. In the leaching experiment, as the AC increased, the concentration of Ca2+ in the aqueous phase decreased significantly, and the corresponding Mg2+ release increased slightly. As a result, the dissolution behavior was hindered by adjusting AC value and it was helpful to further improve the water-resistant quality of new slag fiber.

Study on the characteristics of grout material using ground granulated blast furnace slag and carbon fiber

This study aims to evaluate the applicability of a grout material that is mixed with carbon fiber, biogrout, ground granulated blast furnace slag (GGBS) powder and cement. Uniaxial compressive strength tests were performed on homo-gel samples at days of 1, 3, 7, 14 and 28. In addition, the variation of permeability with the mixing ratios was measured. Based on the uniaxial compressive strength test, it was confirmed that the uniaxial compressive strength increased by 1.2times when carbon fiber increased by 1%. In addition, as a result of the permeability test, it was found that when the GGBS increased by 20%, the permeability coefficient decreased by about 1.5times. Therefore, the developed grout material can be used as a cutoff grouting material in the field due to its strength and cut-off effect.

Environmental resistance and mechanical properties of glass, basalt and slag fibers

This study was evaluated by changing the mass loss ratio and the strength maintenance ratios of the fibers after treatment. The fibers were treated with sodium hydroxide and hydrochloric acid solutions for different amount of times. The environmental resistance was analyzed by changing the time of treatment in NaOH and HCl solutions. The fibers’ surface corrosion morphologies were analyzed using the optical microscope. The acid resistance was much better than the alkali resistance for the basalt and slag fibers. Nevertheless, the situation for the glass fibers was different: the acid resistance was almost the same as the alkali resistance. Between the two types of aqueous environments evaluated, the alkali solution is the most aggressive to the fibers’ surface.

Crystallisation behaviour of blast furnace slag modified by adding fly ash

Crystallisation of molten blast furnace (BF) slag can increase its viscosity, which can in turn affect the quality of slag fibres. Fly ash was added to BF slag to control its crystallisation and modify its chemical composition. FactSage simulation and analyses using X-ray diffraction (XRD), scanning electron microscope-backscattered electrons (SEM-BSE) coupled to an energy dispersive spectrometer (EDS), and single hot thermocouple technique (SHTT) were performed to explore the crystallisation behaviour of the modified BF slag. The relationship between temperature, mineral precipitation, and added fly ash content was investigated. The minerals contained in the modified BF were melilite, anorthite, clinopyroxene, and spinel. Variation in the fly ash content did not change the composition of the precipitate, but changed its content and the crystallisation temperature of the minerals, which affects the initial crystallisation temperature of the modified BF slag. It decreased as fly ash content increased, and was influenced by the crystallisation of melilite when the added fly ash content was between 5% and 20%. When the added fly ash content increased to 25%, the initial crystallisation temperature was influenced by the precipitation of anorthite. The initial crystallisation temperatures obtained by FactSage simulation, XRD analysis, and SHTT experiments differed due to kinetic effects. The modified BF slag with a fly ash content of 15% is considered suitable for manufacturing of slag fibres due to its low initial crystallisation temperature and cost.

Investigation on the effect of MgO content on the crystallization behavior of synthetic BF slag

ABSTRACTThe crystallization of molten blast furnace (BF) slag can increase its viscosity and reduce its liquidity; it can also affect the quality of slag fibers following their manufacture. The crystallization behavior of BF slag is influenced by its chemical composition. In this study, four synthetic BF slags with various MgO contents, ranging from 6 to 12%, were investigated. FactSage simulations were performed to predict the types of crystallized phases as well as their mass fractions that are developed within the synthetic BF slags during the cooling process. To verify the validity of FactSage simulation, X-ray diffraction and scanning electron microscope–backscattered electron imaging, where the equipment was coupled to an energy-dispersive spectrometer, were performed to explore the mineralogical compositions and morphologies of the synthetic BF slags. Experiments using the hot thermocouple technique were performed to identify the initial crystallization temperatures of the synthetic BF slags. The results indicate that the observed phases of the synthetic BF slags were primarily composed of akermanite (2CaO · MgO · 2SiO2) and gehlenite (2CaO · Al2O3 · SiO2), which could form a solid solution, melilite, and control the initial crystallization temperature. The initial crystallization temperature increased as the MgO content of the slag increased. A low initial crystallization temperature was achieved in the cases of the synthetic BF slag samples with MgO contents of 6–8%; these slags were considered suitable for the manufacture of slag fiber.

Crystallization behavior of blast furnace slag modified by adding iron ore tailing

Blast furnace (BF) slag is a by-product of the ironmaking process and could be utilized to manufacture slag fiber by adding iron ore tailing. The crystallization behavior of the modified BF slag is significant to the fibrosis process. To investigate the influence of basicity on the crystallization behavior, BF slag was modified by adding iron ore tailing at room temperature and melted at 1500 °C. FactSage simulation, X-ray diffraction, scanning electron microscopy backscattered electron imaging coupled to an energy dispersive spectrometer, and hot thermocouple technique analysis were performed to explore the crystallization behavior of the modified BF slag during the cooling process. It was found that the initial crystallization temperature increased with the increase in basicity. Melilite, anorthite, clinopyroxene, and wollastonite could be generated during the cooling process as basicity ranged from 0.7 to 0.9. Spinel could be found as one of the phases; however, wollastonite disappeared under a basicity of 1.0. The initial crystallization temperature was controlled by the crystallization of melilite during the cooling process when the basicity of the modified BF slag ranged from 0.7 to 1.0. Moreover, the cooling rate could also influence the crystallization of the modified BF slag.