Amount Of Dust Research Articles

A Study on the Dust Retention Effect of the Vegetation Community in Typical Urban Road Green Spaces—In the Case of Ying Tian Street in Nanjing City

This study aimed to investigate the association between the plant community structure, leaf surface microstructure, nutrient element content, and the dust-retention capacity of garden plants in urban road green spaces. The plant community located along Ying Tian Street in Nanjing City was selected as the focal point of the investigation. Random sampling was performed on the urban road green spaces, determining the amount of dust trapped in plant leaves. Subsequently, the microstructure of the leaf surface was observed, and the content of nutrient elements in the plant leaves was determined. The study also entailed an analysis of the interrelationships between the leaf surface microstructure, plant nutrient element content, and the dust-retention ability of the plants. The findings of this study revealed notable variations in the dust-retention capacity of garden plants and the community structure observed along Ying Tian Street. Among the tree species, Cedrus deodara and Ginkgo biloba exhibited a remarkable dust-retention ability per unit leaf area. Among the shrub species, Abelia × grandiflora and Loropetalum chinense displayed a strong dust-retention capacity per unit leaf area. Similarly, Ophiopogon japonicus and Cynodon dactylon exhibited a robust dust-retention ability per unit leaf area among the herbaceous plants. Furthermore, the dust-retention ability of the plants exhibited a strong positive correlation with the dimensions of leaf stomata, specifically the length and width, while displaying a moderate positive correlation with the width of grooves on the upper and lower surfaces of the leaves. Conversely, the thickness of the leaves did not exhibit a significant correlation. Additionally, the nitrogen content of the leaves exerted a significant influence on the dust-retention ability of the plants (p < 0.05), although the phosphorus and potassium content factors did not exhibit a significant influence (p > 0.05). Based on the findings, it is recommended to prioritize the utilization of plants with robust dust-retention abilities, such as C. deodara, A. grandiflora, O. japonicus, and C. dactylon, and implement a mixed planting approach encompassing a combination of trees, shrubs, and herbaceous plants within urban road green spaces.

Evaluating silicosis risk: Assessing dust constitution and influence of water as a primary prevention measure in cutting and polishing of silica agglomerates, granite and marble

An increasing number of silicosis cases have been reported related to the use of silica agglomerates. Many studies agree on the severity of this disease, which often presents with severe clinical forms in young workers and after a short latency period.Are there differences in the composition of dust generated by cutting and polishing with silica agglomerates versus granite and marble? Does the use of water injection reduce the risk associated with the use of these materials?We carried out a comparative observational-analytical study, measuring the concentration of dust generated during different machining operations on three different materials: granite, marble, and silica agglomerates. The effect of water injection on dust generation was evaluated.Personal sampling pumps were used, connected to a cyclone with polyvinyl chloride filters. The flow rate of the pumps was adjusted using a piston flowmeter. Measurements with a cascade impactor were made to assess the size distribution of respirable crystalline silica particles within the respirable fraction. In addition, environmental measurements with a spectrometer were made.10 tests were carried out on granite and silica agglomerates for each procedure. In the case of marble, with very low silica content, only 2 tests of each type were carried out. Duration of each measurement was between 6 and 25 min. Cleaning times were set for each of the operations.The amount of dust collected in the respirable fraction was 70.85, 32.50 and 35.78 mg/m3 for dry cutting; 6.50, 3.75 and 3.95 mg/m3 for wet cutting; and 21.35, 13.68 and 17.50 mg/m3 for dry polishing, for granite, marble, and silica agglomerates respectively.Dry procedures in marble, silica agglomerates and granite showed higher dust concentration of particles smaller than 0.5 μm. Silica agglomerates showed higher concentrations of respirable crystalline silica particles than granite and marble, mainly with dry procedures. The greater production of small particles in dry and wet procedures with silica agglomerates shows that water injection is an insufficient preventive measure.

The minimum mass for star formation by dynamical fragmentation: dependence on epoch, dust abundance, and environment

ABSTRACT We estimate the minimum mass of a star formed by dynamical collapse and fragmentation, as a function of epoch, dust abundance, and environment. Epoch is parametrized by redshift, zred, through the variation in the temperature of the cosmic microwave background. The dust abundance is parametrized by the mass-fraction in dust, ZD, with the additional simplifying assumption that the intrinsic properties of dust do not change with ZD, only the amount of dust. Environment is parametrized by the energy-density of the ambient suprathermal radiation fields through a dilution factor ω⋆ (applied to a blackbody radiation field at $T_{\star }=10^4\, {\rm K}$). The critical condition is that a spherical proto-fragment should be able to cool, and therefore contract, fast enough to detach from neighbouring proto-fragments. The minimum mass increases with increasing redshift, increasing dust abundance, and increasing suprathermal background. Values in the range from $M_{{\rm MIN}}\sim 0.002\, {\rm M}_{\odot }$ to $M_{{\rm MIN}}\sim 0.2\, {\rm M}_{\odot }$ are obtained at the extremes of the parameter ranges we have considered (0 ≤ zred ≤ 8, 0.00016 < ZD < 0.04, and 10−15 ≤ ω⋆ ≤ 10−8). Our results agree quite well with the predictions of detailed numerical simulations invoking similar redshifts and dust abundances, but our estimates are somewhat lower; we attribute this difference to resolution issues and the small-number statistics from the simulations. The increased minimum masses predicted at high redshift and/or high suprathermal background result in significantly bottom-light initial mass functions, and therefore low mass-to-light ratios, provided that the dust abundance is not too low. The changes due to high suprathermal background may be particularly important for star formation in galactic nuclei and at high redshift.

Study on the property of self‐reactive colloidal dust suppressant and the synergistic dust suppressant mechanism

AbstractThe poor plasticity of coal results in a large amount of dust during the mining process, thereby posing a significant impact on mine safety and the health of workers. In order to address this issue, a method has been proposed to suppress dust by enhancing the plasticity of coal through injecting a reactive material, which forms a colloid within the coal. The results implicated that the self‐active colloidal dust suppressant, composed of sodium alginate, gluconolactone, calcium disodium EDTA, and sodium dodecyl sulfate, effectively improved the moisture content of coal seams and decreased the brittleness of coal. Scanning electron microscopy and specific surface area test revealed that the dust suppressant not only tightly adheres to the surface of the coal after the reaction, but also penetrates the coal pores and forms a colloid on both the inner and outer surfaces of the coal. The material is rich in carboxyl and hydroxyl groups, which forms hydrogen bonds with the carboxyl and hydroxyl groups present in coal. This interaction enhances the toughness of coal. Simultaneously, it has the ability to adsorb water and function as a moisturizer. The combined synergistic effect of these mechanisms fundamentally reduces dust production during the coal mining process.

The relationship between environmental factors and dust accumulation by machine learning

Abstract This study aims to explore the relationship between dust accumulation on a glass and various environmental factors including temperature, humidity, atmospheric pressure, and wind speed. The data was analyzed using Python, a popular language for data science and artificial intelligence, and regression algorithms from the scikit-learn library. The data was divided into training (80 %) and test (20 %) sets and different models were used, such as linear regression, decision tree, K-neighbor regression, random forest regression, and decision tree regression. The accuracy of the models was determined using R 2 scores, where a score of 1.0 indicates a perfect fit and negative values suggest that the model is worse than predicting the mean value. The accuracy of the selected models was calculated as a percentage by multiplying the obtained R 2 scores by 100. Graphs were used to visualise the data and determine the appropriate analysis model. The study found that the amount of dust is directly proportional to temperature and humidity. The accuracy levels of the linear models were suboptimal, leading to the use of nonlinear models like random forest regressor, decision tree regressor, and gradient boosting regressor, which showed improved performance.

The effect of particle size on aluminum dust dispersion based on numerical simulation

This study aimed to investigate the dispersion pattern of aluminum dust with different particle sizes in 20 L vessels by numerical simulations. Using coupled Eulerian and Lagrangian methods, the system of Navier–Stokes equations and DPM momentum balance equations were solved to obtain the dispersion process of aluminum dust with different particle sizes (25, 38, 45, 60, and 75 μm). A standard deviation of particle concentration (Spc) was proposed to characterize dispersity of dust; the smaller Spc is, the better the dispersity of dust is. On the basis of Spc, after the sample reached uniform distribution, the dust with large particle size could maintain uniform dispersion for a certain time period. By contrast, the dust with small particle size, which was more affected by the central turbulence than large dust particles, had difficulty in maintaining uniform dispersion. In addition, the use of rebound nozzles for dust dispersion led to a large turbulence intensity gradient, which significantly influenced the dust dispersion process, especially on the small particle sizes. A large amount of dust was concentrated in the near-wall region, resulting in the concentration of dust in the center of the chamber being lower than expected.

Chapter 3: The Origins and Evolution of Planetary Systems.

The materials that form the diverse chemicals and structures on Earth-from mountains to oceans and biological organisms-all originated in a universe dominated by hydrogen and helium. Over billions of years, the composition and structure of the galaxies and stars evolved, and the elements of life, CHONPS, were formed through nucleosynthesis in stellar cores. Climactic events such as supernovae and stellar collisions produced heavier elements and spread them throughout the cosmos, often to be incorporated into new, more metal-rich stars. Stars typically form in molecular clouds containing small amounts of dust through the collapse of a high-density core. The surrounding nebular material is then pulled into a protoplanetary disk, from which planets, moons, asteroids, and comets eventually accrete. During the accretion of planetary systems, turbulent mixing can expose matter to a variety of different thermal and radiative environments. Chemical and physical changes in planetary system materials occur before and throughout the process of accretion, though many factors such as distance from the star, impact history, and level of heating experienced combine to ultimately determine the final geophysical characteristics. In Earth's planetary system, called the Solar System, after the orbits of the planets had settled into their current configuration, large impacts became rare, and the composition of and relative positions of objects became largely fixed. Further evolution of the respective chemical and physical environments of the planets-geosphere, hydrosphere, and atmosphere-then became dependent on their local geochemistry, their atmospheric interactions with solar radiation, and smaller asteroid impacts. On Earth, the presence of land, air, and water, along with an abundance of important geophysical and geochemical phenomena, led to a habitable planet where conditions were right for life to thrive.

The Effect of Ultraviolet Photon Pumping of H2 in Dust-deficient Protoplanetary Disks

We perform radiation hydrodynamics simulations to study the structure and evolution of a photoevaporating protoplanetary disk. Ultraviolet and X-ray radiation from the host star heats the disk surface, where H2 pumping also operates efficiently. We run a set of simulations in which we varied the number of dust grains or the dust-to-gas mass ratio, which determines the relative importance between photoelectric heating and H2 pumping. We show that H2 pumping and X-ray heating contribute more strongly to the mass loss of the disk when the dust-to-gas mass ratio is D≤10−3 . The disk mass-loss rate decreases with a lower dust amount, but remains around 10−10−11 M ⊙yr−1. In these dust-deficient disks, H2 pumping enhances photoevaporation from the inner disk region and shapes the disk mass-loss profile. We thus argue that the late-stage disk evolution is affected by the ultraviolet H2 pumping effect. The mass-loss rates derived from our simulations can be used in the study of long-term disk evolution.

Dust around Massive Stars Is Agnostic to Galactic Environment: New Insights from PHAT/BEAST

Resolving the environments of massive stars is crucial for understanding their formation mechanisms and their impact on galaxy evolution. An important open question is whether massive stars found in diffuse regions outside spiral arms formed in situ or migrated there after forming in denser environments. To address this question, we use multiresolution measurements of extinction in the Andromeda galaxy (M31) to probe the interstellar medium surrounding massive stars across galactic environments. We construct a catalog of 42,107 main-sequence massive star candidates (M ≥ 8 M ⊙) using resolved stellar photometry from the Panchromatic Hubble Andromeda Treasury (PHAT) program, plus stellar and dust model fits from the Bayesian Extinction and Stellar Tool (BEAST). We quantify galactic environments by computing surrounding stellar densities of massive stars using kernel density estimation. We then compare high-resolution line-of-sight extinction estimates from the BEAST with 25 pc resolution dust maps from PHAT, measuring the total column density distribution of extinction. Our key finding is that, although the average total column density of dust increases with the density of massive stars, the average line-of-sight extinction toward massive stars remains constant across all environments. This suggests that massive stars have a uniform amount of dust in their immediate environment, regardless of their location in the galaxy. One possible explanation for these findings is that small molecular clouds are still capable of forming massive stars, even if they are not resolvable at 25 pc. These results indicate that massive stars are forming in the sparse regions of M31, as opposed to migrating there.

Treatment of chromium (VI) waste solutions with clay-based adsorbents after reduction with acid mine drainage

South Africa has one of the largest Cr-related industries in the world and generates large amounts of Cr-containing smelter dusts. It is normal practice to scrub Cr from the furnace off-gas in water, and to recover the Cr by adsorption, followed by recycling of the loaded adsorbent into the furnace. A study was conducted to find a low-cost adsorbent that is capable of removing sufficient Cr from the solutions generated by scrubbing. The test work focused on the evaluation of different clay minerals (attapulgite, bentonite, and kaolinite) as adsorbents for Cr. Cr(VI) could only be adsorbed after prereduction with e.g. ascorbic acid (ASA). An 80% removal of Cr(VI) could be achieved from a solution containing 20 mg/L Cr using bentonite clay after reduction with ASA. Attapulgite and kaolinite adsorbed less than 55% Cr after reduction with ASA. Both ASA and ferrous salts were found to be suitable reducing agents. The use of acid mine drainage (AMD) was also investigated as a low-cost alternative reducing agent, as AMD usually contains iron. The Cr(VI) reduction potential of the AMD was determined by redox titration against a solution containing 50 mg/L Cr(VI). Studies show that AMD can potentially be used as a reducing agent in a Cr removal process if it is available on site.

Serendipitous detection of the dusty Type IIL SN 1980K with JWST/MIRI

ABSTRACT We present mid-infrared (mid-IR) imaging of the Type IIL supernova (SN) 1980K with the JWST more than 40 yr post-explosion. SN 1980K, located in the nearby (D ≈ 7 Mpc) ‘SN factory’ galaxy NGC 6946, was serendipitously captured in JWST/MIRI images taken of the field of SN 2004et in the same galaxy. SN 1980K serves as a promising candidate for studying the transitional phase between young SNe and older SN remnants and also provides a great opportunity to investigate its the close environment. SN 1980K can be identified as a clear and bright point source in all eight MIRI filters from F560W up to F2550W. We fit analytical dust models to the mid-IR spectral energy distribution that reveal a large amount (Md ≈ 0.002 M⊙) of Si-dominated dust at $T_\rm {dust}\approx 150$ K (accompanied by a hotter dust/gas component), and also computed numerical SED dust models. Radiative transfer modelling of a late-time optical spectrum obtained recently with Keck discloses that an even larger (∼0.24–0.58 M⊙) amount of dust is needed in order for selective extinction to explain the asymmetric line profile shapes observed in SN 1980K. As a conclusion, with JWST, we may see i) pre-existing circumstellar dust heated collisionally (or, partly radiatively), analogous to the equatorial ring of SN 1987A, or ii) the mid-IR component of the presumed newly-formed dust, accompanied by much more colder dust present in the ejecta (as suggested by the late-time the optical spectra).

The geochemical evolution of basalt Enhanced Rock Weathering systems quantified from a natural analogue

Substantial quantities of fine-grained basaltic dust have fallen on South Iceland soils over at least the past 3300 years, making this region an ideal natural analogue to define the long-term consequences of current Enhanced Rock Weathering efforts. A relatively pristine South Iceland Gleyic/Histic Andosol, 3 m in height, receiving approximately 1250 mm of rainfall annually was selected for this study. This soil receives an estimated 500–800 g m−2y−1 of basaltic dust. The soil waters in this system were regularly sampled as a function of depth from May to November 2018. The fluid pH, alkalinity and the concentrations of most major elements increased with depth as the fluids became more reduced. In contrast, whereas numerous toxic trace metals are initially released to the fluid by the dissolution of the basalt near the surface they are scavenged at depth likely due to their uptake by secondary minerals. Equilibrium reaction path modelling suggests that 1) the added airborne basaltic dust dissolves throughout the soil column and 2) in total 0.26 cm3 of basalt dust dissolves per kg water in this soil–water system. Mass balance calculations indicate that the annual mass of basalt dissolved is less than 60 % of that added to the system, such that the mass of basaltic material in the soil column likely increases continuously over time. Basalt dissolution is maintained throughout the soil by the precipitation of Al-Si-minerals such as allophane, and organic anion ligands released from organic decay. These processes limit aqueous Al3+ activity and keep the soil waters undersaturated with respect to primary basaltic minerals and glass. The soil water pH is ∼6 and has a higher alkalinity than that of both Icelandic surface waters and the ocean. In contrast, if no basalt was present, the pH of the soil solutions would be 4.4, with zero alkalinity, illustrating the role of added basalt in drawing CO2 out of the atmosphere.

Attempts to apply fiber optic sensing technology to desert research: laboratory measurement and field observation on the movement of desert sand particles.

Sand particle movement can lead to sand collision, which may even generate large amounts of sand dust and finally trigger a sandstorm. However, there is a lack of effective observation methods for sand particle scale at present due to the harsh environment of the desert. In this article, we attempt to use fiber optic sensing technology to address the above issues. Based on that, laboratory measurement and field observation of sand particle motion are carried out. In the laboratory, the sand particle vibration is detected. In the field observation, the results we obtained are consistent with the actual movement of sand particles. The proposed technique exhibits high resolution and good repeatability for sand particle motion measurement and observation. This work will promote the application of optical fiber sensing technology as a new means for desert research.

Influence of Cement Kiln Dust on Long-Term Mechanical Behavior and Microstructure of High-Performance Concrete.

Cement production in the world market is steadily increasing. In 2000, it was 1600 million tons, while as of 2013, the annual amount exceeded 4000 million tons. The burning of cement clinker is associated with the generation of waste. It is estimated that the amount of cement kiln dust (CKD), during combustion, reaches about 15-20%, which means 700 million tons per year. However, not all types of by-products are reusable due to high alkali, sulfate, and chloride contents, which can adversely affect the environment. One environmentally friendly solution may be to use CKD in the production of high-performance concrete (HPC), as a substitute for some of the cement. This paper presents a study of the short- and long-term physical and mechanical properties of HPC with 5%, 10%, 15%, and 20% CKD additives. The experiments determined density, water absorption, porosity, splitting tensile strength, compressive strength, modulus of elasticity, ultrasonic pulse velocity, and evaluated the microstructure of the concrete. The addition of CKD up to 10% caused an increase in the 28- and 730-day compressive strengths, while the values decreased slightly when CKD concentration increased to 20%. Splitting tensile strength decreased proportionally with 5-20% amounts of CKD regardless of HPC age. Porosity, absorbability, and ultrasonic pulse velocity decreased with increasing cement dust, while the bulk density increased for HPC with CKD. Microstructure analyses showed a decrease in the content of calcium silicate hydrate (C-S-H), acceleration of setting, and formation of wider microcracks with an increase in CKD. From the results, it was shown that a 15% percentage addition of CKD can effectively replace cement in the production of HPC and contribute to reducing the amount of by-product from the burning of cement clinker.

From total destruction to complete survival: dust processing at different evolutionary stages in the supernova remnant Cassiopeia A

ABSTRACT The expanding ejecta of supernova remnants (SNRs) are believed to form dust in dense clumps of gas. Before the dust can be expelled into the interstellar medium and contribute to the interstellar dust budget, it has to survive the reverse shock that is generated through the interaction of the preceding supernova blast wave with the surrounding medium. The conditions under which the reverse shock hits the clumps change with remnant age and define the dust survival rate. To study the dust destruction in the SNR Cassiopeia A, we conduct magnetohydrodynamical simulations of the evolution of a supernova blast wave and of the reverse shock. In a second step, we use these evolving conditions to model clumps that are disrupted by the reverse shock at different remnant ages. Finally, we compute the amount of dust that is destroyed by the impact of the reverse shock. We find that most of the dust in the SNR is hit by the reverse shock within the first 350 yr after the SN explosion. While the dust destruction in the first 200 yr is almost complete, we expect greater dust survival rates at later times and almost total survival for clumps that are first impacted at ages beyond 1000 yr. Integrated over the entire evolution of the SNR, the dust mass shows the lowest survival fraction (17 per cent) for the smallest grains (1 nm) and the highest survival fraction (28 per cent) for the largest grains (1000 nm).

Recycling Blast Furnace Dust as Raw Material in Iron-Making

A large amount of dust is formed as one of the primary by-products during the blast furnace ironmaking process. Iron and carbon are mainly compositions in the dust. Blast furnace dust (BFD) is cycled to protect the environment and recover valuable components. In this study, BFD is used pelletization process with iron ore concentration for raw materials charging to the iron-making furnace. The mixture of BFD and iron ore (30; 40; 50 by mass %) with 2 % bentonite as a binder was used for making pellets. The produced pellets were tested drop strength and fired at 1200 °C for 30 minutes in the atmosphere environment. Fired pellets were examined compressive strength and reduced at 900; 1000; 1100 °C in 30 minutes. Mechanical, porosity and reduction degree properties of reduced pellets were analysed. The results show that green strength and compressive strength are acceptable values. Good porosity is observed when using a high amount of BFD so that it gives a high degree of reduction. XRD, SEM were used for characterization. Iron whiskers were observed in the sample, which was reduced at 1000 °C. It is clearly shown that the pellets using BFD are appropriated for charging to blast furnace as raw materials.

Resolving Clumpy versus Extended Lyα in Strongly Lensed, High-redshift Lyα Emitters

We present six strongly gravitationally lensed Lyα emitters (LAEs) at z ∼ 4–5 with Hubble Space Telescope (HST) narrowband imaging isolating Lyα. Through complex radiative transfer Lyα encodes information about the spatial distribution and kinematics of the neutral hydrogen upon which it scatters. We investigate the galaxy properties and Lyα morphologies of our sample. Many previous studies of high-redshift LAEs have been limited in Lyα spatial resolution. In this work we take advantage of high-resolution Lyα imaging boosted by lensing magnification, allowing us to probe subgalactic scales that are otherwise inaccessible at these redshifts. We use broadband imaging from HST (rest-frame UV) and Spitzer (rest-frame optical) in spectral energy distribution fitting, providing estimates of the stellar masses (∼108–109 M ⊙), stellar population ages (t 50 < 40 Myr), and amounts of dust (A V ∼ 0.1–0.6, statistically consistent with zero). We employ nonparametric star formation histories to probe the young stellar populations which create the Lyα. We also examine the offsets between the Lyα and stellar continuum, finding small upper limits of offsets (<0.″1) consistent with studies of low-redshift LAEs, indicating our galaxies are not interacting or merging. Finally, we find a bimodality in our sample’s Lyα morphologies: clumpy and extended. We find a suggestive trend: our LAEs with clumpy Lyα are generally younger than the LAEs with extended Lyα, suggesting a possible correlation with age.

Water Vapor Variability in the Thermosphere of Mars During Mars Years 32–36

AbstractUsing Mars Atmosphere and Volatile Evolution observations, we characterize the variability of water vapor in the Martian thermosphere during Mars Years 32–36. Near a fixed atmospheric pressure level of ∼5 × 10−7 Pa, the typical water density is 1.7 (±1.0) × 103 cm−3 and the typical water mixing ratio is 14.6 (±9.0) ppm. Thermospheric water levels are higher during the southern spring and summer seasons when Mars is near perihelion and there is significant dust loading in the lower atmosphere. However, the seasonal variation is not the same from year‐to‐year, likely due to annual differences in dust loading. Water vapor abundance is highly correlated with the amount of dust in the lower atmosphere, and increases during both regional and global dust storms. Additionally, there is a local time asymmetry with higher mixing ratios observed during morning local times, potentially caused by atmospheric circulation. Our results support previous work that found increased dust levels allow more water to be supplied directly to the thermosphere.

Mapping dust in the giant molecular cloud Orion A

ABSTRACT The Sun is located close to the Galactic mid-plane, meaning that we observe the Galaxy through significant quantities of dust. Moreover, the vast majority of the Galaxy’s stars also lie in the disc, meaning that dust has an enormous impact on the massive astrometric, photometric and spectroscopic surveys of the Galaxy that are currently underway. To exploit the data from these surveys we require good three-dimensional maps of the Galaxy’s dust. We present a new method for making such maps in which we form the best linear unbiased predictor of the extinction at an arbitrary point based on the extinctions for a set of observed stars. This method allows us to avoid the artificial inhomogeneities (so-called ‘fingers of God’) and resolution limits that are characteristic of many published dust maps. Moreover, it requires minimal assumptions about the statistical properties of the interstellar medium. In fact, we require only a model of the first and second moments of the dust density field. The method is suitable for use with directly measured extinctions, such as those provided by the Rayleigh–Jeans colour excess method, and inferred extinctions, such as those provided by hierarchical Bayesian models like StarHorse. We test our method by mapping dust in the region of the giant molecular cloud Orion A. Our results indicate a foreground dust cloud at a distance of 350 pc, which has been identified in work by another author.

Mechanism and kinetics study on waste acid leaching from copper smelting dust

AbstractCopper smelters generate large amounts of copper smelting dust (CSD) that has a high recycling value because it contains about 20% copper. Waste acid can be used to leach CSD. Here, the effects of different temperatures, times and liquid–solid ratios on copper, iron and arsenic leaching rates were investigated. The optimal conditions were determined to be a temperature of 95°C, leaching time of 3 h, and liquid–solid ratio of 7:1. Under these condition, the leaching rate of copper reached 96.37%, and the copper ion concentration was 32.71 g/L. The leaching kinetics date revealed that the leaching of copper and iron was controlled by two different reaction models. The leaching of copper conformed to the Johnson–Mehl–Avrami (JMA) model and was diffusion controlled, and the reaction was rapid in the first 60 min. In contrast, leaching of iron was controlled by a chemical reaction. Copper and iron activation energies were 2.579 and 62.791 kJ/mol, respectively. These results show that CSD waste acid is can be used to dispose of arsenic‐containing hazardous waste in a green, sustainable, and ecologically method.