Fume Products Research Articles

Concurrent reduction of the fume and Cr (VI) concentrations of inhalable and respirable particle using a new covered stainless-steel SMAW electrode

In this work, a new covered electrode was developed for a SMAW process by the concurrent use of two fume reduction techniques viz; nano-arc stabilizer coating on welding core wire and nano-particle substitution on the welding flux. The experimental core electrode wires were coated with nano-zirconium to improve the electrode’s arc stability and reduce the effective oxygen concentration in the arc atmosphere. To further improve the arc stability, size-reduced synthetic rutile was mixed with the electrode flux. Total fume formation from experimental and conventional electrodes was evaluated and compared. Compared to the conventional electrode, the experimental electrode showed an 82 % reduction in fume production and an 85 % reduction in breathing zone concentration. The combined effect of nano zirconia and size-reduced synthetic rutile increased the reactivity of the arc atmosphere and favoured the reduction of inhalable and respirable fume mass concentration by improving arc stability and reducing spatter formation. The experimental electrodes showed a significant reduction in Cr(VI) concentration in fume up to 68 %. The Cr (VI) concentration in the inhalable and respirable fumes was also reduced by 36 % and 52 % in that order.

Biosorption of aqueous Pb(II) by H3PO4-activated biochar prepared from palm kernel shells (PKS)

The conversion of palm kernel shells (PKS), a major agricultural waste from the palm oil sector, into a potentially high-value biosorbent for heavy metals-contaminated wastewater treatments was explored in this work. Following carbonization, the activated PKS was chemically activated by soaking the biochar in a phosphoric acid (H3PO4) solution at 25 °C. The low-temperature approach benefits from less dangerous acid fume production and operational challenges when compared to the high-temperature procedure. The properties of the biochar were characterized by BET, FTIR, and SEM. The effects of H3PO4 dosage, initial Pb(II) concentration, and adsorbent dosage on removing Pb(II) from synthetic wastewater were investigated in the adsorption study. The activation of PKS biochar with high H3PO4 concentrations led to enhanced removal efficiency. The pseudo-second-order (PSO) kinetic model fitted the experimental data well (R2 0.99), indicating that chemisorption was likely involved in the adsorption of Pb(II) onto activated PKS. Pb(II) sorption was possibly promoted by the presence of phosphate moieties on the adsorbent surface. The Langmuir isotherm best described the sorption of Pb(II) onto the activated PKS (R2 0.97), giving the calculated maximum adsorption capacity (qm) of 171.1 μg/g. In addition to physical sorption, possible adsorption mechanisms included functional group complexation and surface precipitation. Overall, activating PKS biochar with H3PO4 at room temperature could be a promising technique to improve the adsorbent's adsorption efficiency for Pb(II) removal from wastewater.

Interactions of microwaves with alumina surface in microwave-enhanced laser-induced breakdown spectroscopy

In laser-induced breakdown spectroscopy (LIBS), when the target material is radioactive, the total amount of ablated materials presents a challenge. High-efficiency particulate air (HEPA) filters prevent the release of the fumes of radioactive materials into the atmosphere. Microwave enhances LIBS without increasing the number of laser shots, potentially reducing the production of fumes. In this study, we analyzed the interaction of microwaves with an alumina target surface during laser ablation. Time-series images of the plasma evolution on the surface of an alumina target were captured. Moreover, the ablation crater characteristics and temporal temperature profiles were measured to evaluate the non-equilibrium plasma characteristics of the microwave-enhanced laser-induced plasma. The results show no direct correlations of the ablation crater depth and volume with the microwaves, and the number of laser shots primarily influences the volume of the crater. The absorption of microwaves by the plasma took 100 µs after the laser shot, suggesting that microwaves did not contribute to the ablation process. Although laser ablation was not influenced by the microwave input, it is the primary cause of the volume expansion of the plasma.

Development of CO2 efficiency index for evaluating sustainability of microelectrical discharge drilling process

Recently, there has been a growing awareness of environmental issues, and the concept of sustainability has been introduced. This concept applies to different fields, including the manufacturing industry. This study focuses on the sustainability of the micro-electrical discharge machining (EDM) drilling process. In EDM technology, the critical aspects of sustainability are consumed energy, electrode wear, gas emissions, and generated waste. The operational conditions impact consumption and emissions. The aim of this study is to develop a CO2 efficiency index for evaluating the environmental–economic efficiency of the micro-EDM drilling process. The index was calculated as the emissions that occurred during machining and logistic activities divided by the added value, and it was expressed as the kg equivalent CO2 per unit money. For the emissions, all process activities that have an environmental impact were considered, such as transportation, absorbed energy generation, production of fumes by the dielectric during machining, and emissions attributed to the production of nonconforming pieces. The proposed index was applied to a medical case study in which titanium bone plates were produced for fractures of small body parts. It was found that the process performance significantly depended on the operation conditions of the dielectric fluid and electrode. The material removal rate (MRR) significantly influenced the index. Quality problems and scraping influenced the overall performance significantly, whereas dielectric management had a moderate effect. The optimum conditions were determined by varying the dielectric fluid, electrode material, and process parameters. Demineralized water was the best dielectric because it facilitated a high MRR, whereas hydrocarbon oil resulted in a high quality and a low scrap rate. Vegetable oil caused problems, resulting in a low MRR and poor quality. Further investigations should be conducted to improve its performance in microdrilling applications.

Carbonization‐dominated synergistic behaviors of ammonium hypophosphite/EG composite in improving flame retardancy of flexible polyurethane foam

AbstractDeveloping flexible polyurethane foam (FPUF) with good anti‐ignition and self‐extinguishing performance is the fundamental way to prevent fire hazards in application. A binary composite system containing ammonium hypophosphite (NHP) and expandable graphite (EG) was applied to prepare flame‐retardant FPUF. The co‐action of NHP and EG exhibited high‐efficiency synergistic effect in improving the anti‐ignition, self‐extinguishing, and carbonization performance of FPUF. The analysis of micromorphology, element retention and chemical structure character on charring residue, reveals the physical–chemical synergistic carbonization mechanism of NHP/EG composite. The real‐time tracing on thermal‐decomposition volatiles, discloses the behaviors of NHP/EG composite in suppressing volatile fuel supply and toxic fume production. With an addition of 11 wt.% NHP and 7 wt.% EG, 11NHP/7EG achieved a limited oxygen index value of 30.3%, passed horizontal burning class HF‐1, and retained 55.6 wt.% charring residue. The peak of heat release rate and total heat release of 11NHP/7EG were both reduced by more than 50%, compared with that of pristine FPUF. The synergistic flame‐retardant mechanism of NHP/EG composite provides a valuable reference for high‐performance flame‐retardant FPUF manufacturing.

Asphalt Fume Generation-Enrichment Device Development and Fume Production Estimation Model

Abstract Although indoor asphalt fume production tests are widely used because of their convenient operation, good controllability, and high reliability, because of differences in asphalt morphology during heating, the experimental data from an indoor test cannot accurately reflect outdoor conditions. This article proposes an asphalt fume generation-enrichment system that can correlate indoor and outdoor fume production results. At the same time, we develop a reliable detection process, which is used to analyze the correlation between asphalt fume production and its heating temperature, heating time, and exposure area. We then summarize the applicable rules for asphalt-mixture fume production research. The present study shows that the conversion link between indoor asphalt fume production and asphalt mixture fume production is the rate of fume production, which is affected by the heating temperature, heating time, and exposed area of the asphalt. Because of differences in the threshold of the asphalt’s volatile organic compounds and the chemical reaction’s starting temperature, the asphalt fume production rate has a multiple function relationship with temperature, and because of the difference in the size of the fume generation channel, it has a linear function relationship with the asphalt’s exposed area. Thus, this study proposes prediction models for the fume production of two asphalts under different heating environments and provides a reference for calculating fume production of the asphalt and asphalt mixtures.

Measurement of welding fume production in welding with high-alloy electrodes

Due to their good structural properties, stainless Cr-Ni steels have a very wide application in various branches of technology. During the welding of stainless Cr-Ni steels with high-alloy coated electrodes, welding fumes of complex chemical composition are generated, which is very harmful for welders and the environment. For the purposes of this experiment, two variants of one rutile Cr-Ni commercial electrode, designated E 23 12 2 LR 12, were designed and fabricated. Higher production of welding fume particles also means greater danger to humans and the environment. In order to show the influence of the base material on the production of welding fume particles, an experiment for measuring the production of welding fume particles was performed in which two different steels were used as the base material, general structural steel S235JRG2 and stainless steel X6CrNiTi18.10.

An overview of studies on the hazards, component analysis and suppression of fumes in asphalt and asphalt mixtures

As the main building materials for highway construction, asphalt and asphalt mixture will release large quantities of highly hazardous fume at high temperatures. Due to possible genotoxicity, carcinogenicity and teratogenicity, asphalt fumes present not only a threat to human and animal health but also cause serious environmental degradation. To provide pollution control of asphalt pavement production and technical support for environmentally-friendly transportation construction, existing study chiefly considers asphalt fume hazards, composition analysis, fume suppression and post-purification. This study aims to provide a new perspective and direction for the relevant academic study on asphalt fume suppression and purification. At present, the main deficiencies in the research are: 1) instant on-site detection of asphalt fume is weak, 2) lack of study on diffusion of asphalt fume, 3) a weak theoretical understanding of asphalt fume production and composition, 4) the absence of a working mechanism and directionality of fume suppressants, and 5) little study on the portable asphalt fume collection and purification equipment.

Optimization of friction stir welding parameters during joining of AA3103 and AA7075 aluminium alloys using Taguchi method

This paper investigates the optimization of input parameters for the friction stir welding of AA3103 and AA7075 aluminium alloys. The properties of base materials AA3103 are non-heat-treatable alloy, which is having good weldability while AA 7075 is having higher strength. Therefore, the welding of these aluminium alloys will produce superior mechanical properties. Friction stir welding is a rapidly growing welding process which is being widely used in marine, automobile and aerospace industries. Rather than its widespread use, this type of welding has several advantages over normal welding processes like low production of fume, no consumable electrodes are used and can be used in any position. In this paper, optimization of input parameters were conducted based on Taguchi method using the L9 orthogonal array. There were nine experimental runs in total after creating the L9 orthogonal array table in MINITAB software. The input parameters selected for optimization are tool rotation speed, feed rate, tool pin profile the output parameters which are optimized hardness, tensile strength, impact strength. The ANOVA analysis was carried out in the Qualitek 4 software to find out the percentage influence of input parameters on the output parameters. This research work was carried out to find the optimized condition to carry out friction stir welding of above mentioned aluminium alloys.

Novel Fire Extinguisher Method Using Vacuuming Force Applicable to Space Habitats

The existing extinguishment device used in spacecraft is an inert gas (CO2) extinguisher or water mist which is a promising technique to suppress flames, however, the remained production of fume (harmful) gas in the enclosed space was paid little attention, although its removal from the cabin is not an easy task. We propose novel methodology, which can completely resolve this problem; namely, flame is extinguished by “a vacuuming operation” driven by the pressure difference between the suction box and the cabin, whereby toxic gases and even the fire source is drawn into the box, where an effective extinguishment procedure can be separately operated. To convince the effectiveness of this methodology and investigate its performance, a specially-designed test device is developed and an extinction test is examined in this paper. The main experimental parameters are the suction flow rate and the distance between the end of the suction pipe and the burning specimen. The burning specimen used in this study is a small scale electric wire with a polymer sheath. The extinction process via suction operation has been observed carefully. In addition to the direct observation, velocity measurement induced by suction operation as well as the use of the Schlieren imaging technique are introduced. It is found that the vacuuming extinction can be categorized into three types based on the mechanism leading to the extinction. The model of the extinction procedure is proposed and corresponding three non-dimensional numbers as a function of vacuuming volume flow rate (Q) are developed to predict the mode on vacuuming extinction. Afterall, this paper successfully show the concept of a vacuum extinction and how it works.

Detonation Characteristics of a NOx-Free Mining Explosive Based on a Sensitised Mixtures of Low Concentration Hydrogen Peroxide and Fuel

Mining explosives based on ammonium nitrate(V) are safe and effective, however, the risk of NOx fume production during blasting is still present. In 2013, a project to eliminate NOx fumes from blasting began and hydrogen peroxide was chosen to replace ammonium nitrate(V) as the oxidiser. Previous work in this area demonstrated that hydrogen peroxide/fuel-based mixtures were able to detonate, provided that they are initiated under a situation of high confinement and also using hydrogen peroxide at relatively high concentrations. In contrast, a comprehensive study was conducted to determine the detonation properties of hydrogen peroxide/fuel-based mixtures that used hydrogen peroxide at lower concentrations (below 50 wt.%), detonated in unconfined conditions and used void sensitisation to achieve an efficient detonation reaction. This article presents the results of the influence of the density, water content, critical diameter and type of void sensitisation on the velocity of detonation (VOD) of hydrogen peroxide/fuel-based explosive mixtures. The results indicate that the mixtures can achieve a different VOD which depends on the size of the sensitising voids and more importantly, the mixtures behave as non-ideal explosive, similarly to ammonium nitrate-based explosives, but with the advantage of being a NOx-free explosive.

Heat transfer through glassfiber fabrics coated with silicone resin

Coatings can improve the performance of textiles, including flame retardants, water repellents and for heat resistance and weather resistance. Experimental methods are used normally to prepare heat insulation fabrics using coating technology. But there are many problems such as long processing time, high energy consumption, and the production of fumes. As computer technology develops, it is important to use numerical methods to predict the heat transfer performance of the coated fabrics. In this work, based on the yarn paths and their cross-sectional shapes, geometry models of the coated fabrics have been established. The finite element method was used to solve the heat transfer equations, and the numerical model was established to predict heat transfer performance. It was found that: (1) when comparing with the SEM images, the geometry model can represent well the structure and appearance of the coated fabric; (2) validation of the experimental data indicates that the numerical simulation model of heat transfer through the coated fabric is reliable and useful to predict the heat transfer performance, and the average relative deviation between the numerical data and experimental data was less than 7.0%; (3) when the thickness of the silicone coating layer is less than 0.50 mm, the temperature of the back face of fabric rapidly increased between 1 and 10 s, and it remained more than 510 °C as the heating time was extended. When the coating thickness is between 0.75 and 2 mm, the rising tendency of the temperature becomes gradually slower, and their temperatures remained 489, 455, 369 and 281 °C when the thickness of the coating layer is 0.75, 1.00, 1.50 and 2.00 mm, respectively.

The environmental credentials of hydraulic lime-pozzolan concretes

This research considers the compressive strength, embodied CO2, embodied energy and binder intensity of hydraulic lime-pozzolan concretes, in comparison with those of Portland-cement based concretes of equivalent 28-day compressive strength.Production of a lime-pozzolan concrete with a 28-day cube strength of approximately 50 MPa and an elastic modulus of 20 GPa has demonstrated the feasibility of producing modern, structural grade hydraulic lime-pozzolan concretes. Furthermore, construction and testing of two reinforced lime-pozzolan concrete beams has demonstrated the possibility of producing structural elements with a finished appearance and flexural behaviour similar to Portland cement concrete. This paper reflects on the value of this new material's technological progress in the context of the industry wide search for low carbon cements.Results of the research reported in this paper demonstrate that the use of aluminosilicate by-products, specifically ground granulated blastfurnace slag and silica fume, in combination with naturally hydraulic lime can realise savings in environmental impact; but that the savings are both future-orientated and highly dependent on the boundaries of the analysis. When considering only the secondary impacts of ground granulated blastfurnace slag and silica fume production, a ternary combination was observed to result in a lime-pozzolan concrete with a 28-day cube strength of 33 MPa and an embodied-CO2 of 95 kgCO2/m3, 64% lower than a CEMI, and 41% lower than a CEMIII/A concrete of equivalent strength. Both mass and economic allocation procedures were, however, shown to have a very detrimental effect on the environmental credentials of silica fume and thus also on hydraulic lime-concretes containing this pozzolanic addition.It is recognised that technical performance alone cannot be used to assess or compare the merits of any new material. This paper focus on the production, environmental impact and long-term availability of individual constituents of this novel binder, with a view to addressing important questions about the viability and desirability of re-producing this novel cementitious system in a commercial setting. Such information is acknowledged to be critical in the dialogue about the potential adoption and development of this emerging binder technology.

Metal Vapour in Atmospheric-Pressure Arcs

Metal vapour has a significant, and in some cases dominant, influence in many applications of atmospheric-pressure plasmas, including arc welding, circuit interruption and mineral processing. While the influence of metal vapour has long been recognized, it is only recently that diagnostic and computational tools have been sufficiently well-developed to allow this influence to be more thoroughly examined and understood. Some unexpected findings have resulted: for example, that the presence of metal vapour in gas–metal arc welding leads to local minima in the temperature and current density in the centre of the arc. It has become clear that the presence of metal vapour, as well as having intrinsic scientific interest, plays an important role in determining the values of critical parameters in industrial applications, such as the weld penetration in arc welding and the extinction time in circuit breakers. In gas–tungsten arc welding, metal vapour concentrations are formed by evaporation of the weld pool, and are relatively low, typically at most a few per cent. Moreover, the convective flow of the plasma near the weld pool tends to direct the metal vapour plume radially outwards. In gas–metal arc welding, in contrast, metal vapour concentrations can reach over 50%. In this case, the metal vapour is produced mainly by evaporation of the wire electrode, and the strong downwards convective flow below the electrode concentrates the metal vapour in the central region of the arc. The very different metal concentrations and distributions in the two welding processes mean that the metal vapour has markedly different influences on the arc. In gas–tungsten arc welding, the current density distribution is broadened near the weld pool by the influence of the metal vapour on the electrical conductivity of the plasma, and the arc voltage is decreased. In contrast, in gas–metal arc welding, the arc centre is cooled by increased radiative emission and the arc voltage is increased. In low-voltage circuit breakers, metal vapour is formed by evaporation of the electrodes (runners) and the splitter plates, and can have a major influence on the dynamics of arc motion. While the influence of metal vapour on arcs is now understood in general terms, there are many unresolved questions. Areas in which improvements and new insights are required include: diagnostic techniques for measurements of arc properties in the presence of metal vapour, and understanding of the possible deviations from local thermodynamic equilibrium and their influence on such measurements; measurements of the influence of metal vapour in circuit breakers, in which the arc occurs within a solid enclosure, and in gas–metal arc welding, in which the formation of metal droplets and arc instabilities can disrupt standard techniques; determination of the concentration of metal vapour species in different types of arcs; understanding of the relative importance of the different effects of metal vapour (such as increased radiation and electrical conductivity, and the rapid influx of relatively cold gas) on the arc for different configurations; the influence of metal vapour on the electrode boundary and sheath regions; the treatment of radiative and mass transport in computational models; understanding and treatment of the vaporization, condensation and nucleation of metal species, and methods of incorporation of these processes in computational models. In this cluster issue, many of these and related issues are addressed. The twelve contributions cover gas–metal arc welding, gas–tungsten arc welding and low-voltage circuit breakers, and include both experimental and computational studies, in some cases with striking results. A review of the influence of metal vapour in welding arcs is followed by three accounts of spectroscopic measurements of gas–metal arc welding, which are difficult to perform and until recently have rarely been attempted. The application of spectroscopic techniques to determine Stark widths of spectral lines is discussed in a further contribution. Two papers address the calculation of important plasma data sets, in particular net radiative emission coefficients and diffusion coefficients, which are vital input for computational models. Four sophisticated computational modelling studies of the influence of metal vapour on gas–metal arc welding, gas–tungsten arc welding, and arc splitting in low-voltage circuit breakers are then presented. The final contribution describes the application of a multiscale computational model to investigate the important occupational health problem of the production of fume from the metal vapour produced in welding arcs. Overall, the papers presented give an overview of the state of the art of research into metal vapour in atmospheric-pressure arcs, and at the same time constitute real progress in this topical and important field.

A Study of nozzle angle in stone surface treatment with water jets

The stone surface treatment with water jet is a recently introduced method. It is used to increase the roughness to improve its antislip properties while preserving esthetic appearance of the stone without having thermal shock, mechanical stress and the production of fumes and dust. Nozzle angle is one of the important parameters affecting treatment of surface. This study is an attempt to assess the effect of nozzle angle on surface treatment quality with water jet and to determine the most suitable nozzle angle value. For this purpose, surfaces of Sardinian Basalt samples are treated with pure water jet in six different nozzle angles (15°, 30°, 45°, 60°, 75° and 90°). The roughness is measured on all the treated surfaces by various roughness parameters. The experimental studies showed that treatment with nozzle angle between 30° and 75° gives the surfaces with similar regular variation.

The Experimental Study on the Road Asphalt Fumes Suppressive Effect of SBS and Nano Calcium Carbonate

In order to study the fume suppressive effect of SBS and nano calcium carbonate， this paper studied the fume suppression laws of SBS and nano calcium carbonate， and carried out ratio test of SBS and nano calcium carbonate, and got the conclusions that: With the increasing adding level of SBS and nano calcium carbonate, the asphalt fume productive rate will reduce gradually and will reach a condition of stability. The adding level of 4% of SBS is a turning point. When less than 4%, the asphalt fume production rate decreased rapidly; and more than 4%, the asphalt fume production rate decreased slowly; when adding nano calcium carbonate at the level of 5%, the asphalt fume won’t decrease. The best ratio of SBS and nano calcium carbonate is 6% of SBS and 6% of nano calcium carbonate, with which asphalt fume reductive rate was up to 30%.

Schadstoffemissionen bei der Entfernung von Knochenzement mit Ultraschallgeräten in der Revisionsendoprothetik - Fume Emission During Removal of PMMA Bone Cement Using Ultrasonic Instruments in Revision Hip Arthroplasty

The use of ultrasonic instruments to remove PMMA bone cement during revision hip arthroplasty results in the production of fumes. These emissions were analysed under standardized laboratory conditions, when it was found that the MMA concentration measured was only 1/10th of the MAC value. In terms of occupational safety, the MMA fumes emitted may therefore be considered non-hazardous for the medical personnel.

An analysis of heat transfer and fume production in gas metal arc welding. III

A two–dimensional dynamic theory for predictions of arc and electrode properties in arc welding has been used to investigate heat transfer phenomena in the welding wire in gas metal arc welding (GMAW). The theory is a unified treatment of the welding wire, the plasma and the workpiece and includes a free surface treatment for the welding drops, accounting for the effects of inertia, gravity, surface tension, arc pressure, magnetic forces, and viscous drag by the gas flow around the drop. Also, the theory accounts for the variation of the surface tension coefficient with temperature and includes thermal and dynamic phenomena within the solid and liquid phases of the wire, together with a detailed treatment for the electrode sheath regions. Calculations are made for arcs in argon with wires of mild steel at currents between 150 and 325 A. Results of calculations for heat fluxes within the wire suggest that evaporation from the surface of the droplet during droplet growth has an important influence on the heat balance of the wire. The calculated evaporation rates from the droplet surface during droplet growth at the tip of the wire are found to be much higher than measured rates of fume formation in GMAW, suggesting an important recondensation process at the surface of the workpiece.

Applying Ausmelt processing to complex copper smelter dusts

Ausmelt technology opens up new opportunities for the economic processing of complex copper smelter dusts. Not only can the technology separate more of the unwanted elements to produce a clean blister copper for refining, but it can also allow production of fume and precious metal products that can be readily upgraded to produce high-grade, valuable products. Developments in the processing of copper-bismuth-gold flue dusts left over after the smelting of bismuth-bearing concentrates in flash furnaces are described, including pilot-plant trials and process and equipment development. Design considerations and capital and operating costs for the proposed plant are discussed.

Cytotoxic, irritant and fibrogenic effects of metal-fume particulate materials investigated by intramuscular injection in the rat and guinea pig.

Fume products from metal-working processes are complex mixtures of metals and other elements, often potentially toxic and inhalable, e.g. fumes from welding ferrochromium steels. Previous investigations (Hicks et al. 1983) indicated that the toxic effects most usually exercised by such fumes when inhaled were irritancy, fibrogenicity and cytotoxicity. For simple comparative purposes, intramuscular administration was used as a means of producing particle deposits, being precise in dosage and location and not subject to aggressive translocation mechanisms. Toxic effects of ferrochromium metal products were compared, in particular, fume particles from manual metal-arc welding of stainless steel. Such fumes are rich in chromium in the hexavalent, highly reactive form. Fume particles from an innovative ‘low-fume’ electrode, welding product were also tested.KeywordsMild SteelManganese DioxideMild SteelFume ParticleWelding ProductThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.