Recovery Of Dust Research Articles

Evaluation of steel metallurgical dust management: combining treatment methods and resource attributes

The escalating challenges of resource scarcity and environmental pressures have drawn significant attention to heavy metal-containing dust generated during steel production. While previous research on heavy metals in steel manufacturing has primarily focused on emission inventories, health and ecological risks, and recycling technologies, the assessment of steel metallurgical dust management has been largely overlooked. To address this research gap, this study employed statistical entropy analysis to evaluate the effectiveness of dust treatment in the steel production process, aiming to identify potential issues in dust management. Furthermore, an evaluation framework was established to systematically assess the resource attributes of steel metallurgical dust, thereby supporting evidence-based decision-making in dust management. Results indicate that Cd, Pb, As, Zn, Cr, and Hg tend to accumulate in dust during steel production. Given its high resource attribute, converter dust should be prioritized for recovery. Further analysis suggests that the rotary kiln process plays a transitional role in dust recovery. This study provides a scientific foundation for dust management in the steel industry and offers guidance for the sustainable development of dust utilization.

Characterization of Respirable Coal Mine Dust Recovered from Fibrous Polyvinyl Chloride Filters by Scanning Electron Microscopy

The characterization of respirable dust on the basis of constituent fractions and particle sizes is increasingly of concern for evaluating exposure hazards. For high-resolution particle analysis, scanning electron microscopy with energy dispersive X-ray (SEM-EDX) can be an effective tool. However, it requires particles to be deposited on a smooth, uniform substrate such as a polycarbonate (PC) filter for optimal results. While direct sampling onto PC is possible, this is not the standard approach in many situations. For example, in coal mines, respirable dust samples have typically been collected onto polyvinyl chloride (PVC) filters because they are intended for gravimetric and/or infrared spectroscopy analysis. Such fibrous substrates are not ideal for SEM-EDX (or other microscopy), but an effective method to recover and redeposit the dust particles could render such samples suitable for the additional analysis. Here, we present a simple method and compare SEM-EDX results for paired samples analyzed directly on PC and following recovery from PVC and redeposition on PC. Both laboratory-generated dust samples (n = 10 pairs) and field samples of respirable coal mine dust (n = 44 pairs) are included in this study. Although some changes in particle size distributions were observed between samples analyzed directly and those that were recovered and redeposited prior to analysis, the results indicate the dust recovery method generally yields a representative sample in terms of mineral constituents. That said, results also highlighted the effects of high particle loading density on individual particle analysis. Considering all sample pairs, those with similar loading density between the directly analyzed and recovered sample tended to exhibit similar mineralogy distributions. This was generally the case for the lab-generated sample pairs, and the Freeman-Halton exact test of independence indicated that the samples in just three (of 10) pairs were in disagreement in terms of their mineralogy distributions. On the other hand, for the field samples, the directly analyzed sample often had higher loading density than the recovered sample; and the Freeman-Halton test showed that 25 (of 44) pairs were in disagreement. However, the effect of possible particle agglomeration on the directly analyzed samples cannot be ruled out—and exploration of this factor was beyond the scope of the current study.

Influence of particle size on the separation performance and flotation kinetics of foundry dust

The high-efficiency separation of foundry dust (FD) is imperative for its resource utilization, which contributes to promoting cleaner production and environmental protection in the foundry industry. In order to strengthen the flotation performance of high-quality coal dust in the FD, a systematized investigation was carried out to explore the influence of particle size on the contact angle, separation performance, and flotation kinetics of the FD. The results indicate that the pretreatment process increases the contact angle of the FD, and the liberation degree of coal dust decreases with the decrease of particle size. The fine particles of −53 µm can reduce the separation performance, resulting in a lower coal dust recovery of 60.79%. The coarse particles of −212 + 75 µm and intermediate particles of 75–53 µm possess better flotation results compared to the unclassified FD. The coal dust recovery in the coarse particles can reach up to 84.68%, and the obtained coal dust exhibits a pristine surface and splendid purity. The results of flotation kinetics analysis found that classical first-order model is suitable for characterizing flotation process of the FD with different particle sizes. The flotation rate constant drops as particle size reduces, revealing that the floatability of FD can be significantly improved via a classification method. This may provide a valuable method and scientific guidance for efficient separation and resource utilization of the FD.

Extracting zinc from ironworking dust having a high zinc content by vacuum silicothermic reduction

Zinc dust having a high ZnO content can be obtained after the preliminary treatment of zinc-bearing dust generated by the iron and steel industry by using a rotary kiln. However, this material has a high concentration of chloride salts that can affect the hydro-metallurgical extraction of metallic zinc. The present study used a vacuum distillation-vacuum thermal reduction process to recover zinc metal from this dust. This process first separated chloride and PbO by vacuum distillation and then extracted metallic zinc via the vacuum silicothermic reduction of ZnO. The results show that high-purity ZnO was prepared by vacuum distillation using the original zinc dust as a raw material. Both alkali metal chlorides and PbO in the dust could be removed with greater than 99 % efficiency by vacuum distillation at 1000 °C. Following this step, the slag contained more than 80 wt% Zn but less than 0.01 wt% chlorine and PbO. The vacuum thermal reduction process used the slag obtained from distillation as the raw material together with ferrosilicon alloy as a reducing agent. ZnO was reduced above 1000 °C and the recovery of this oxide exceeded 99 % using a reduction temperature of 1200 °C, reduction time of 2 h, and ferrosilicon mass ratio of 0.27. The main phase in the slag after reduction was SiO2 and the ZnO concentration was below 1 wt%, indicating a purity greater than 99 %. This method can realize the separation, recovery, and reuse of zinc-bearing dust to maximize the value-added utilization of this resource.

Long-term multiwavelength monitoring and reverberation mapping of NGC 2617 during a changing-look event

ABSTRACT We present the results of photometric and spectroscopic monitoring campaigns of the changing look AGN NGC 2617 carried out from 2016 until 2022 and covering the wavelength range from the X-ray to the near-IR. The facilities included the telescopes of the SAI MSU, MASTER Global Robotic Net, the 2.3-m WIRO telescope, Swift, and others. We found significant variability at all wavelengths and, specifically, in the intensities and profiles of the broad Balmer lines. We measured time delays of ∼6 d (∼8 d) in the responses of the Hβ (Hα) line to continuum variations. We found the X-ray variations to correlate well with the UV and optical (with a small time delay of a few days for longer wavelengths). The K-band lagged the B band by 14 ± 4 d during the last three seasons, which is significantly shorter than the delays reported previously by the 2016 and 2017–2019 campaigns. Near-IR variability arises from two different emission regions: the outer part of the accretion disc and a more distant dust component. The HK-band variability is governed primarily by dust. The Balmer decrement of the broad-line components is inversely correlated with the UV flux. The change of the object’s type from Sy1 to Sy1.8 was recorded over a period of ∼8 yr. We interpret these changes as a combination of two factors: changes in the accretion rate and dust recovery along the line of sight.

Mineral Phase Reconstruction and Separation Behavior of Zinc and Iron from Zinc-Containing Dust.

Zinc-containing dust can be found in ironmaking and steelmaking, and it is an important secondary resource of zinc. Zinc-containing dust from an electric furnace was used as a raw material to study the phase transformation behavior of the dust using a calcification roasting process and the zinc-iron separation behavior by using ammonia leaching. The zinc-bearing dust was mixed with CaO and roasted to transform the zinc ferrite into zinc oxide. The results showed that increasing the calcium oxide to dust ratio could promote the conversion of zinc ferrite to zinc oxide. When the calcium oxide ratio reached 60%, the peak of zinc ferrite in the calcined-roasted product in the zinc-containing dust basically disappeared. As the temperature increased, the zinc oxide grains increased but were still smaller than 10 µm. The calcined-roasted product was crushed and ground, and the zinc was leached by ammonia. A zinc-iron recovery rate of 86.12% was achieved by the ammonia leaching. The leachate could be used for zinc extraction by electrolysis. The leaching residue was mainly calcium ferrate, which could be used in sintering production. The proposed process may achieve on-site recovery of zinc-containing dust in steel-making plants.

Designing Novel Cement Kiln Dust Recovery Process for Nox, Sox, and Co2 Utilization

Designing Novel Cement Kiln Dust Recovery Process for Nox, Sox, and Co2 Utilization

The Study of Carbon Recovery from Electrolysis Aluminum Carbon Dust by Froth Flotation

A large amount of carbon dust is generated in the process of aluminum smelting by molten salt electrolysis. The carbon dust is solid hazardous waste but contains a large quantity of recyclable components such as carbon and fluoride. How to recycle carbon dust more effectively is a challenge in the aluminum electrolysis field. In this study, X-ray diffraction, scanning electron microscope, and other methods were used to analyze the phase composition of electrolytic aluminum carbon dust. The effects of particle size distribution of carbon dust, impeller speed, reagent addition, mixing time, and flotation time on the flotation recovery of carbon dust were studied. The optimal flotation conditions were obtained and the flotation products were analyzed. The results show that the optimal particle size distribution is 70% of particles below 200 mesh, corresponding to a grinding time of 11 min. The optimum speed of the flotation machine was to be between 1600 and 1800 r/min with the best slurry concentration of 20–30% and 5 min mixing time, and the collector kerosene was suitable for adding in batches. Under the above conditions, the recovered carbon powder with a carbon content of 75.6% was obtained, and the carbon recovery rate was 86.9%.

A thermogravimetric analysis application to determine coal, carbonate, and non-carbonate minerals mass fractions in respirable mine dust

Occupational lung diseases such as coal worker’s pneumoconiosis, often called black lung, are caused by exposures to respirable coal mine dust. Dust composition is increasingly understood as an important disease factor, and it can vary significantly depending on dust source materials and generation processes. For regulatory compliance purposes, the mass concentration and quartz percentage of respirable dust are monitored in U.S. coal mines, but the whole composition is not typically determined. Previous work has indicated that thermogravimetric analysis (TGA) can be used to apportion the respirable dust mass to three important component fractions (i.e., coal, non-carbonate minerals, and carbonate), which should generally correlate with three different dust sources (i.e., coal strata, rock strata, and limestone rock dusting products being applied in the mine). However, a primary shortcoming of that previous work was use of fibrous sampling filters, which limited dust recovery and thus analytical accuracy. Here, an improved TGA application is presented using smooth polycarbonate filters. Based on experiments with laboratory-generated dust samples (masses ranging between 95–1,319 µg), the TGA-derived mass fractions (reported as percentage values) for all three components were found to generally be within ±10% of expected values.

Development of the Metallurgical Waste Recovery Process

We have developed the process that enables receiving pellets from zinc-containing dust and recovering them in a Waelz kiln with practically total zinc distillation and its capture in bag filters. As this takes place, metallic iron, still present in the pellets, can be used in metallurgical treatment. We have elaborated the process instructions to obtain pellets from zinc-containing dust with an addition of solid fuel, magnesite, and bentonite. To simulate recovery of the carbon-containing pellets in production, bench tests have been performed. These allowed us to determine principal operating conditions of the technological procedure of metallurgical zinc-containing dust recovery and validate the unit for recovery of this dust. The data obtained from the production tests prove feasibility of implementation of this process and allow assessing economic efficiency of zinc-containing dust recovery.

Filter forensics: microbiota recovery from residential HVAC filters

BackgroundEstablishing reliable methods for assessing the microbiome within the built environment is critical for understanding the impact of biological exposures on human health. High-throughput DNA sequencing of dust samples provides valuable insights into the microbiome present in human-occupied spaces. However, the effect that different sampling methods have on the microbial community recovered from dust samples is not well understood across sample types. Heating, ventilation, and air conditioning (HVAC) filters hold promise as long-term, spatially integrated, high volume samplers to characterize the airborne microbiome in homes and other climate-controlled spaces. In this study, the effect that dust recovery method (i.e., cut and elution, swabbing, or vacuuming) has on the microbial community structure, membership, and repeatability inferred by Illumina sequencing was evaluated.ResultsThe results indicate that vacuum samples captured higher quantities of total, bacterial, and fungal DNA than swab or cut samples. Repeated swab and vacuum samples collected from the same filter were less variable than cut samples with respect to both quantitative DNA recovery and bacterial community structure. Vacuum samples captured substantially greater bacterial diversity than the other methods, whereas fungal diversity was similar across all three methods. Vacuum and swab samples of HVAC filter dust were repeatable and generally superior to cut samples. Nevertheless, the contribution of environmental and human sources to the bacterial and fungal communities recovered via each sampling method was generally consistent across the methods investigated.ConclusionsDust recovery methodologies have been shown to affect the recovery, repeatability, structure, and membership of microbial communities recovered from dust samples in the built environment. The results of this study are directly applicable to indoor microbiota studies utilizing the filter forensics approach. More broadly, this study provides a better understanding of the microbial community variability attributable to sampling methodology and helps inform interpretation of data collected from other types of dust samples collected from indoor environments.

The postmortem study of used refractory brick in EAF dust recovery kiln

The aim of this study is to investigate the postmortem analysis of the used andalusite bricks in EAF dust recovery kiln. The bricks have been damaged by erosion and thermal spalling. Different samples are collected from reaction zone in the furnace and characterized by chemical (X-ray fluorescence, X-ray diffraction), physical (porosity, strength), and microstructural analyses (SEM equipped with EDS). It has been found that chloride, oxide, and sulfate phases in EAFD caused refractory erosion. Oxide phases are detected at the hot side of the bricks while chloride phases have detrimental effects on the cold side of the brick.

Influence of SiC addition on the properties of andalusite brick used in EAF dust recovery kiln

The aim of this study is to determine the properties of fired andalusite brick with silicon carbide addition. Brick samples were prepared by mixing, shaping, drying, and sintering at 1300 °C in a commercial tunnel kiln. The bulk density, apparent porosity, gas permeability, and cold crushing strength of fired brick samples were determined. Slag penetration test was investigated by static cup test with electric-arc furnace (EAF) dust recovery blend. The effects of SiC additions on the penetration properties of the samples have been investigated. The addition of SiC significantly affects the reduction behavior of metallic ingredients in EAF dust recovery on the brick surface. SiC shows the self-glazing properties in the brick and behaves as an antibarrier for zinc vapor.

The Development and Applications of the Dust and Rhenium Recovery Integrated Device of Calcination Exhaust of Molybdenum Concentrate which Contain Rhenium

A device, was used to recover dust and rhenium from molybdenum concentrate roasting exhaust gas, was developed. The device combine the self-swash dust catcher and spherical tray tower technology: the self-swash dust catcher was used to recover dust and rhenium; spherical tray tower was used to further dust and rhenium recovery and its application to engineering in practice. This was the first successful such devices used to recover dust and rhenium integration from calcination exhaust of molybdenum concentrate which contain rhenium in production practice. Through production practice, proved that the device is feasible, with high efficiency. And it has the advantages of simple structure, convenient operation, low cost and low energy consumption etc.. In addition, the dust removing system can also be used to the wet dust collector in the filed of metallurgical , mining, chemical and building.

Dry Sizing and Shaping Technique for Ceramic Tiles

This paper presents a dry processing technique for saving energy and reducing cost and the approach is based on dust collecting system with the conventional grinding edge technique. Dust collecting system is based on external filtration style. The ceramic tiles could be packed and stored immediately after processing without further drying. Experiment of dry processing system is investigated to evaluate the efficiency of saving energy. In the case of dust recovery and reutilization, ceramic factories have developed some new kinds of process to create new products by directly reusing the dusts.

Development of a Laser Ablation System Kit (LASK) for Tokamak in vessel tritium and dust inventory control

During Tokamak operation, Plasma Facing Components (PFCs) are subjected to severe interaction with plasma. As a consequence and independently of the PFCs composition, materials eroded and then re-deposited in the form of layers on the surfaces, can flake and produce dusts. These fragile structures are able to trap part of the hydrogenated species (tritium for example) in vessel inventory. For safety reasons, it is mandatory to measure and to control vessel dust and tritium inventory. Up to now, laser techniques are a part of the most promising methods able to solve these ITER open issues. Of special interest are laser systems loaded on a miniature tool that can be attached to a Multi Purpose Deployer (MPD) and used for laser treatments (détritiation and other), for PFCs chemical analysis as well as for micro particles recovery of dust produced during laser ablation. Such a system (Laser Ablation System Kit: LASK) is currently under development at IRFM and the following presentation will describe the current achievements of this project and the perspectives. In this paper, we will present an innovative compact system, which, loaded on a Multi Purpose Deployer, could allow operation in a harsh environment (pressure range from atmospheric to Ultra High Vacuum and temperature up to 120 °C). According to the process conditions, different treatments can be performed: at low laser fluence, PFCs thermal treatment will be expected, while at high laser fluence material will be ablated allowing Dust (and T) recovery as well as chemical analysis of material. This “in-line” chemical analysis based on Laser Induced Breakdown Spectroscopy (LIBS) enables the ablation process to be controlled and preserves the substrate integrity. The paper will be focussed on the methodology followed during the LASK development and the method used to determine a laser process window able to remove co-deposited film without damaging the bulk material and taking into account external parameter variation (Multi Purpose Deployer vibrations for example). The first design of the system is proposed that complies with the process requirements and the external constraints. Special emphasis will be given on limitations, and alternatives to these limitations will be proposed.

Resource recovery of cupola dust: Study on sorptive property and mechanism for hydrogen sulfide

Properties and mechanism for sorption of hydrogen sulfide (H2S) by cupola dust, which is formed by the solidification of gas exhausted from cupola furnaces, have been investigated through the characterizations, aiming at recycling as the desulfurization. From the results, the sorptive property was found to be induced by spinel-type crystals such as (MnxZn1−x)(MnyFe1−y)2O4 solid solutions in spherical matrixes comprising of amorphous SiO2 at room temperature in existence of water vapor. The further examination on the spinel-type crystals extracted by NaOH treatments revealed that H2S was dissolved in water adsorbed on the surface of the spinel-type crystals, and reacted with metal ions released from them. In addition, the H2S sorptive property was indicated to depend on amounts of Mn and Zn in the spinel-type crystals.

Comparative study of pretreatment methods for the determination of metals in atmospheric aerosol by electrothermal atomic absorption spectrometry

A comparative study of pretreatment methods for the determination of 10 elements (As, Cd, Pb, V, Ni, Mn, Cr, Cu, Fe, Al) in atmospheric aerosols by electrothermal atomic absorption spectrometry (ETAAS) was conducted. For the digestion of the particulates collected in filters, six methods were compared using a mixture of HNO 3 and HF with or without the addition of various oxidative agents (HClO 4 or H 2O 2) or acids (HCl). The comparative study was performed using loaded cellulose filter samples, which were digested in Parr bombs and heated in a conventional oven at 170 °C for 5 h. The extraction efficiency and blanks were compared and it was proved that the digestion method using only HNO 3–HF extracted most of the metals and gave the lowest blanks. The HNO 3–HF mixture was selected for the development of an improved microwave digestion method specific for aerosol-loaded filters. The operating parameters were optimized, so that quantitative recovery of the reference materials NIST 1649a urban dust and NIST 1648 urban particulate matter was achieved. The blank of cellulose and teflon filters were also determined and compared. Teflon filters present the lowest blanks for all the elements. The obtained limits of detection for each type of filters were adequate for environmental monitoring purposes. ETAAS instrumental operation was also optimized for the compensation and the elimination of interferences. The temperature optimization was performed for each metal in every type of filter and optimized parameters are proposed for 10 elements.

Integrated Technology for Processing Rhenium-containing Molybdenite Concentrates to Recover Molybdenum and Rhenium into Commercial Products

The paper reports on processing of molybdenite concentrate to recover molybdenum and rhenium products. The process involves roasting of molybdenite in a fluid bed. The fluid bed exhaust is passed through a cyclone, a electrostatic separator and finally subjected to wet gas scrubbing. The scrub is sent to solid ion exchange resin to produce ammonium perrhenate. The cinder from fluid bed roaster is processed to calcium molybdate and the dust from dust recovery is processed to ammonium paramolybdate.

The dewatering of a mining sludge containing hexavalent chromium using a tubular filter press - a South African development

A chromium smelting process can result, under oxidising conditions, in the production of a dust which when slurried and pumped to a waste dump heap is likely to pollute the environment. South Africa is a large producer of chromium metal and the problem of the release of hexavalent chromium (Cr6+) to the environment is a serious concern. The department of Water Affairs and Forestry in South Africa monitors all environmental discharges and regulate the levels of toxic chemicals and pollutants. The ‘Tubular Filter Press’ a South African developed sludge dewatering system was proposed for the recovery of dust in this effluent. The filter press was operated for the dewatering of waterworks sludges and promises to be successful for this application. A single tube pilot study shows that chromium discharge to the environment can be eliminated. Feed solids concentrations of between 40 and 50 g/l were fed to the tubular filter resulting in cake solids concentrations in excess of 50%. The operating pressure of the system was between 200 and 300 kPa and the flux reduced to 200 L/m2.h during the filtration cycle. The filtration was modelled using a variable pressure, internal cylindrical compressible cake filtration model and operating parameters for a full scale plant were proposed.