Metal Filters Research Articles

Effects of Tin Mining on Water Sources in Mwerasandu Tin Mine, Ntungamo District, Uganda

Tin mining is a widespread economic activity across various regions worldwide. Understanding the consequences of such operations is crucial for sustainable water management and environmental conservation. The current study aimed at determining the concentrations tin, lead and mercury in the water sources of Nyakahiimbura Stream in Mwerasandu, and assessed the physico-chemical properties including pH, turbidity, and chemical oxygen demand (COD) of the water from the Nyamuhimbura stream, Ntungamo district. Water samples from three locations, that is; the upstream, impact area and downstream of the Nyakahiimbura water stream were collected during the dry and wet seasons of the year 2024. The samples collected were analyzed for the physico-chemical properties in the laboratory while the Inductively Coupled Plasma-Optical Emission Spectrometry (ICP – OES) was used to determine the concentration of heavy metals in the water samples. The pH, COD values obtained were within the acceptable effluent standards while the turbidity values at the upstream and downstream of the dry season and downstream during the wet season were above the acceptable effluent Standards. The tin concentration was high in the dry season (0.09mg/L) as compared to concentration (0.118mg/L) in the wet season. Lead concentration was the same (0.015mg/L) in both seasons. The concentrations of the heavy metals showed some variations in both dry and wet seasons in the upstream, impacted area and the downstream of the study area as compared to the values of the effluent standards. The study recommends that alternative sources of water for domestic use should be sought of. Also, the government officials especially from the Ministry of Health should carry out awareness campaigns to members of the community about the health risks associated with the uptake of the contaminated waters for domestic purposes. Constructed wetlands should be in place around the mining sites to act as filters for the dangerous metals before the water enters the surrounding environment.

Design and application of exhaust gas purification device for diesel vehicles based on Copper-Manganese catalyst

A series of Cu-Mn oxide catalysts were synthesized and the catalytic combustion effects of these catalysts on soot in both NO-containing and NO-free atmospheres were tested. Utilizing a copper-manganese catalyst as the core, in conjunction with a folded metal filter, an exhaust gas purification device was developed. Bench experiments demonstrate this device effectively enhances carbon smoke conversion and reduces CO and NOx concentrations in tailpipe emissions. Two kinds of explosion-proof diesel vehicles were further modified in Liangshuijing Coal mine and the changes in exhaust gas were analyzed. The results demonstrate that the installation of the purification device leads to an average CO removal efficiency exceeding 60.0%, NOx removal efficiency surpassing 50.4%, and soot removal efficiency reaching over 84.6%. This research presents an efficient solution for purifying exhaust gases emitted by explosion-proof diesel vehicles.

Numerical analysis of the mechanics of foreign particle entry on automotive turbocharger compressor blades

Automotive turbochargers, essential for enhancing intake air pressure and boosting torque in internal combustion engines, operate at exceptionally high rotational speeds of approximately 100,000 to 300,000 rpm. Despite the implementation of dual or triple air filtration systems to filter contaminants, neglected maintenance can lead to clogged filters, resulting in the ingestion of metallic filter mesh, and other small-sized objects from filter indicators, washers, and plastic components into the turbocharger assembly. The current study explores the impact of foreign particles on the mechanics of turbocompressor impeller blades in automotive turbochargers through a computational approach. A finite element model of the turbocompressor wheel was developed with suitable boundary conditions for the turbocompressor and the foreign particle. A Design of Experiments (DoE) approach was employed using a Taguchi L12 orthogonal array to optimize the multiple parameters during the foreign particle impact. The study considered two geometric shapes of the foreign particle (conical with unit aspect ratio and hemispherical), two sizes, and two rotational speeds ranging from 150,000 to 250,000 rpm. ANSYS Explicit Dynamics® software was utilized for the numerical simulations to simulate the mechanics of foreign particle entry and the resulting damage on compressor blades.

Designing Metallic Neutral Density Filters with Constant Optical Density Versus Wavelength

Observations in space and on earth can be subject to wide dynamic ranges of light levels which may need to be controlled by neutral density filters. The optical density (OD) of neutral density (ND) filters made with single metal layers is often not very neutral or constant in OD versus wavelength over the wavelength band of interest. Photographers are the major users of quantities of ND filters, but there are many other applications for smaller numbers of ND filters. There are a limited number of publications on how to design metallic ND filters. It is shown here that designs of metal-dielectric-metal (MDM) can be designed to have more constant OD over a wavelength band. Designs are shown employing software which accommodates the fact that the indices of thin metal films usually vary with film thickness

Preparation of β-SiAlON/SiC composite ceramic foam filters and their oxidation resistance

In this study, ceramic foam filters with high porosity, strength, and oxidation resistance are produced at low temperatures by preparing porous β-SiAlON/SiC composite ceramic foams using the foam impregnation method with Si, Si, α-Al2O3, AlN, and SiC as the raw materials. The presence of SiC inhibits the growth of β-SiAlON grains, which reduces the amount of β-SiAlON produced. As the proportion of β-SiAlON increases, the porosity of the β-SiAlON/SiC composite ceramic foam decreases, whereas the bulk density and compressive strength increase. Non-isothermal oxidation experiments show that β-SiAlON/SiC composite ceramic foams exhibit high oxidation resistance and their macroscopic morphology does not change significantly after oxidation. As the proportion of β-SiAlON increases, the smooth SiO2 oxide layer on the surface of the ceramic foam gradually changes to acicular and columnar mullite crystals, and the oxidation resistance increases. Therefore, β-SiAlON acts as a high-temperature binder when it is added to SiC. Hence, the prepared β-SiAlON/SiC composite ceramic foams can be used as ceramic filters in the field of molten metal filtration.

MECHANICAL PROPERTIES OF POROUS SILICON CARBIDE CERAMICS: A REVIEW

Porous silicon carbide (SiC)-based ceramics exhibit exceptional structural and functional properties, such as excellent mechanical, chemical, and thermal stability, and controlled electrical resistivity. Owing to their superior properties, porous SiC ceramics are suitable for various industrial applications, including heatable filters, heating elements, thermoelectric energy converters, fusion reactors, thermal insulators, water purifiers, molten metal and hot gas filters, diesel particulate filters, membrane supports, and catalyst supports. A deeper understanding of the mechanical properties of porous SiC ceramics, coupled with the development of new strategies for tuning these properties, will enable the realization of numerous new applications. In this review, important factors known to determine the mechanical strength of porous SiC ceramics, such as microstructures (necking area) and pore characteristics (porosity, pore size), have been analyzed. With increasing porosity and pore size of porous SiC ceramics, the flexural strength tends to decrease. The flexural strength increases with decreasing pore size at a constant porosity, whereas the flexural strength decreases with increasing porosity at a constant pore size. In addition, the flexural strength of porous SiC ceramics is primarily influenced by the developed necking area between SiC grains, which can be obtained through the doping of soluble atoms into the SiC lattice. Based on these critical factors affecting the mechanical properties, a novel strategy for tuning the flexural strength of porous SiC ceramics is proposed.

Preparation of novel reticulated porous ceramics with textured structures enabled by in situ generated interlocking Al2O3 platelets

Al2O3 reticulated porous ceramics (ARPCs) are extensively employed in high-temperature catalytic support, molten metal filtration, and porous media combustion because of their high specific surface area and heat resistance. The high specific surface area is usually maintained by high apparent porosity, but unfortunately, the accompanying poor mechanical properties severely compromise the durability of ARPCs. To synergistically improve the mechanical properties and apparent porosity, a new strategy was proposed to prepare ARPCs with textured structures of in situ interlocking Al2O3 platelet integration using vacuum impregnation Na3AlF6–SiC–Al2O3 slurry technique. The obtained textural structure had a significant strengthening effect on ARPCs, attributed to the increased contact area among non-equiaxed grains, and the compact growth of Al2O3 platelets with high aspect ratios provided the high apparent porosity and specific surface area of ARPCs, resulting in compressive strength as high as 3.93 MPa at an apparent porosity of 85.31 %, as well as the degradation of Congo red up to 75.35 % due to the Al2O3 platelets facilitating the loading of TiO2.

Fast kV-switching and dual-layer flat-panel detector enabled cone-beam CT joint spectral imaging

Purpose. Fast kV-switching (FKS) and dual-layer flat-panel detector (DL-FPD) technologies have been actively studied as promising dual-energy spectral imaging solutions for FPD-based cone-beam computed tomography (CT). However, cone-beam CT (CBCT) spectral imaging is known to face challenges in obtaining accurate and robust material discrimination performance. That is because the energy separation by either FKS or DL-FPD, alone, is still limited, along with apparently unpaired signal levels in the effective low- and high-energy projections in real applications, not to mention the x-ray scatter in cone-beam scan which will make the material decomposition almost impossible if no correction is applied. To further improve CBCT spectral imaging capability, this work aims to promote a source-detector joint multi-energy spectral imaging solution which takes advantages of both FKS and DL-FPD, and to conduct a feasibility study on the first tabletop CBCT system with the joint spectral imaging capability developed. Methods. For CBCT, development of multi-energy spectral imaging can be jointly realized by using an x-ray source with a generator whose kilo-voltages can alternate in tens of Hertz (i.e. FKS), and a DL-FPD whose top- and bottom-layer projections corresponds to different effective energy levels. Thanks to the complimentary characteristics inherent in FKS and DL-FPD, the overall energy separation will be significantly better when compared with FKS or DL-FPD alone, and the x-ray photon detection efficiency will be also improved when compared with FKS alone. In this work, a noise performance analysis using the Cramér–Rao lower bound (CRLB) method is conducted. The CRLB for basis material after a projection-domain material decomposition is derived, followed by a set of numerical calculations of CRLBs, for the FKS, the DL-FPD and the joint solution, respectively. To compensate for the slightly angular mismatch between low- and high- projections in FKS, a dual-domain projection completion scheme is implemented. Afterwards material decomposition from the complete projection data is carried out by using the maximum-likelihood method, followed by reconstruction of basis material and virtual monochromatic images (VMI). In this work, the first FKS and DL-FPD jointly enabled multi-energy tabletop CBCT system, to the best of our knowledge, has been developed in our laboratory. To evaluate its spectral imaging performance, a set of physics experiments are conducted, where the multi-energy and head phantoms are scanned using the 80/105/130 kVp switching pairs and projection data are collected using a prototype DL-FPD, whose both top and bottom layer of panels are composed of 550 μm of cesium iodine (CsI) scintillators with no intermediate metal filter in-between. Results. The numerical simulations show that the joint spectral imaging solution can lead to a significant improvement in energy separation and lower noise levels in most of material decomposition cases. The physics experiments confirmed the feasibility and superiority of the joint spectral imaging, whose CNRs in the selected regions of interest of the multi-energy phantom were boosted by an average improvement of 21.9%, 20.4% for water basis images and 32.8%, 62.8% for iodine images when compared with that of the FKS and DL-FPD, respectively. For the head phantom case, the joint spectral imaging can effectively reduce the streaking artifacts as well, and the standard deviation in the selected regions of interest are reduced by an average decrement of 19.5% and 8.1% for VMI when compared with that of the FKS and DL-FPD, respectively. Conclusions. A feasibility study of the joint spectral imaging solution for CBCT by utilizing both the FKS and DL-FPD was conducted, with the first tabletop CBCT system having such a capability being developed, which exhibits improved CNR and is more effective in avoiding streaking artifacts as expected.

Durable Nano-Flower Structured Foam Coupled with Electrically-Driven in Situ Aeration Enable High-Flux Oil/Water Emulsion Separation with Dynamic Antifouling Ability.

The conventional membranes used for separating oil/water emulsions are typically limited by the properties of the membrane materials and the impact of membrane fouling, making continuous long-term usage unachievable. In this study, a filtering electrode with synchronous self-cleaning functionality is devised, exhibiting notable antifouling ability and an extended operational lifespan, suitable for the continuous separation of oil/water emulsions. Compared with the original Ti foam, the in situ growth of NiTi-LDH (Layered double hydroxide) nano-flowers endows the modified Ti foam (NiTi-LDH/TF) with exceptional superhydrophilicity and underwater superoleophobicity. Driven by gravity, a rejection rate of over 99% is achieved for various emulsions containing oil content ranging from 1% to 50%, as well as oil/seawater emulsions. The flux recovery rate exceeds 90% after one hundred cycles and a 4-h filtration period. The enhanced separation performance is realized through the "gas bridge" effect during in situ aeration and electrochemical anodic oxidation. The internal aeration within the membrane pores contributes to the removal of oil foulants. This study underscores the potential of coupling foam metal filtration materials with electrochemical technology, providing a paradigm for the exploration of novel oil/water separation membranes.

THE POTENTIAL OF BRYOPHYTES IN PHYTOFILTRATION OF HEAVY METAL CONTAMINATED WATER

Bryophytes are a group of plants vital to many ecosystems and biogeochemical cycles and are well known bioindicators and biomonitoring tools. However, they have been deemed industrially less important than vascular plants and their potential for applications other than as biomonitoring tools has been overlooked. In recent years, however, bryophytes, and in particular mosses, are starting to gain attention as viable phytoremediation agents. Studies indicate that some moss species have the ability to uptake heavy metals such as Pb, Cd, Zn, Cu, As, and Cr from contaminated water. Tested mosses could both adsorb and absorb significant amounts of specific heavy metals without adverse effects on the plant. Results suggest that moss biomass, either dry or wet, could be used as a bio-sorbent in filtration of heavy metals. The review of available literature shows a promising prospect of moss to be used in phytofiltration of heavy metals. Existing knowledge on this topic could be the basis for further research which isneeded. KEYWORDS:moss; heavy metal; phytofiltration; bio-sorbent

Effects of water and other filters on fracture resolution in industrial micro-CT scanning

Filtering is known to improve image quality of CT scans. Water immersion is one type of filtering that has been used for CT scanning dry (skeletonized) bones, and it has been suggested that this approach can increase measurement accuracy and improve fracture resolution. These tests have previously involved clinical CT scanners. Here we use an industrial micro-CT scanner and test whether water immersion and other x-ray filtering options increases fracture resolution in reconstructed scans of dry bones.Eleven dry non-human bones were CT scanned using the same acquisition parameters, while varying filter options. Bones were scanned (1) in an unfiltered “dry” air environment, (2) using metal filters at the x-ray source, and (3) with the bones immersed in water. A small subset of bones (N = 3) was also scanned using the same parameters except increasing the number of projections acquired from 500 to 1500. Reconstructed scans were evaluated by the authors, in part using a Likert scale comparing filtered with unfiltered scans, to assess fracture resolution (overall appearance and extent).Results showed that increasing the projections resulted in the greatest improvement in fracture resolution, followed by filtering at the x-ray source. Water immersion performed poorly overall, possibly due to movement artifacts that result from this type of scanning, in which the specimen rotates on a stage during the scan. When using this type of CT scanner, if increased fracture resolution is desired, water immersion is not recommended; increasing the number of projections or filtering at the x-ray source is suggested instead.

Wettability and Mechanical Properties of Red Mud-Al2O3 Composites.

In 2023, the global production of new red mud is expected to reach nearly 200 million tons, but less than 10% of it is currently being utilized in an environmentally friendly manner. To reduce the sintering temperature of alumina ceramics, a sintering aid method is used, as high-purity alumina ceramics require a solid-phase sintering temperature of over 1700 °C. The metal oxides present in red mud are necessary components for high-performance composite alumina ceramics. Composites were obtained by mixing and sintering red mud and Al2O3. This study focused on the mechanical properties and wettability of these composites. The results indicated that the 10% red mud-Al2O3 composite exhibited the highest hardness (20.12 GPa) and flexural strength (346 MPa). This is attributed to the formation of a mineral phase dominated by CaAl12O19, generated by the red mud during the sintering process, which filled the pores and reduced porosity. The surface energy of the red mud-Al2O3 composite was the highest at room temperature and high temperature, reaching 49.60 mJ·m-2 and 1164.7 mJ·m-2, respectively, indicating that it has better stability at both room and high temperatures. This study provides an important fundamental basis for the application of red mud-alumina composites to replace alumina-based composites in the field of construction materials, molten metal filters, ceramic cleavers, etc.

60 Years of Open‐Celled Ceramics Based on Replica Technique: Applications, Obstacles, and Opportunities

Open‐celled ceramics look back on a remarkable history of development and innovation spanning around 60 years. Starting with the first patents to produce ceramic foams in the 1960s, the Schwartzwalder process became established industrially for manufacturing molten metal filters. Since then, a wide range of potential applications for these specific structured materials has been identified and discussed in the literature, such as porous burners, direct heaters, structured catalyst supports, filters, bone substitute materials, energy absorbers, preforms, and lightweight or acoustic construction components. For such high‐performance applications, ceramic foams require high quality in terms of purity, mechanical strength, high temperature, and chemical resistance or structural design. On this account, production technologies and material variety of ceramic foams have developed rapidly over the past few decades, and there are numerous applications in the industrial sector. This article gives an overview of the current state of development of open‐celled ceramic foams for various applications. Based on selected examples, it is demonstrated for which applications an industrial implementation is successfully realized and why some applications will never get beyond the proof‐of‐concept stage in research.

Functional characteristics of bivalves of the genus Unio as indicators of the ecological state of populations and water quality

The levels of accumulation of heavy metals (HM) in mollusks of the genus Unio from different zones of Lake Kenon, the cooling reservoir of the Chita Thermal Power Plant, were studied. The priority role of mollusk gills in the process of water filtration and bioaccumulation of heavy metals (HM) in tissues has been revealed. The calculated values of IB, an indicator of the bioaccumulation of heavy metals, make it possible to assess the ecological state of mollusks, water quality and technogenic load on the reservoir in the current growing season. It has been shown that the increase in the accumulation of heavy metals in the shell, which integrates this long-term process corresponding to the age of the mollusk, has a reliable connection with the increase in the content of heavy metals in the aquatic environment.

A novel measurement system for unattended, in situ characterization of carbonaceous aerosols

Abstract. Carbonaceous aerosol is a relevant constituent of the atmosphere in terms of climate and health impacts. Nevertheless, measuring this component poses many challenges. There is currently no simple and sensitive commercial technique that can reliably capture its totality in an unattended manner, with minimal user intervention, for extended periods of time. To address this issue we have developed the fast thermal carbon totalizator (FATCAT). Our system captures an aerosol sample on a rigid metallic filter and subsequently analyses it by rapidly heating the filter directly, through induction, to a temperature around 800 ∘C. The carbon in the filter is oxidized and quantified as CO2 in order to establish the total carbon (TC) content of the sample. The metallic filter is robust, which solves filter displacement or leakage problems, and does not require a frequent replacement like other measurement techniques. The limit of detection of our system using the 3σ criterion is TC =0.19 µg-C (micrograms of carbon). This translates to an average ambient concentration of TC =0.32 µg-C m−3 and TC =0.16 µg-C m−3 for sampling interval of 1 or 2 h respectively using a sampling flow rate of 10 L min−1. We present a series of measurements using a controlled, well-defined propane flame aerosol as well as wood-burning emissions using two different wood-burning stoves. Furthermore, we complement these measurements by coating the particles with secondary organic matter by means of an oxidation flow reactor. Our device shows a good correlation (correlation coefficient, R2>0.99) with well-established techniques, like mass measurements by means of a tapered element oscillating microbalance and TC measurements by means of thermal–optical transmittance analysis. Furthermore, the homogeneous fast-heating of the filter produces fast thermograms. This is a new feature that, to our knowledge, is exclusive of our system. The fast thermograms contain information regarding the volatility and refractoriness of the sample without imposing an artificial fraction separation like other measurement methods. Different aerosol components, like wood-burning emissions, soot from the propane flame and secondary organic matter, create diverse identifiable patterns.

The impact of a metallic partial-flow particulate filter on diesel engine combustion and emission characteristics using palm oil biodiesel blends

The impact of a metallic partial-flow particulate filter on diesel engine combustion and emission characteristics using palm oil biodiesel blends

Effect of a retrofitted metallic microfiber partial flow diesel particulate filter on a light duty diesel vehicle particle emission characteristics

This study was conducted two distinct experiments, using a light-duty diesel vehicle at various engine speeds and loads as well as the new European driving cycle (NEDC) comparing commercial diesel fuel (B7) and pure biodiesel (B100). The NEDC involves a combination of urban and extra urban driving conditions. It aims to study a diesel vehicle's thermal efficiency as well as its gaseous and particulate matter (PM) emissions. This involves comparing results with and with no diesel oxidative catalyst (DOC) and a partial flow diesel particulate filter (PDPF) system. The surface morphology, micro- and nanostructure of a diesel vehicle's PM were also examined using scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and thermogravimetric analysis (TGA) to determine nanostructural and dimensional changes after mounting a DOC-PDPF system. Comparison of B7 and B100 combustion showed that B100 had around 1 % increase in brake thermal efficiency (BTE) at 1500 and 2000 rpm compared to B7 since B100 is a more oxygenated biofuel. At 2500 rpm, similar BTE values were observed. Introduction of a DOC-PDPF system resulted in an approximately 1 % BTE reduction for both fuels. This was due to greater friction losses caused by backpressure from the DOC-PDPF system. Increased exhaust backpressure was progressive, ranging from 1 kPa at idle speed to 6 kPa at high engine speeds for both tested fuels. The DOC-PDPF system respectively minimized PM emissions and particle numbers (PNs) by more than 50 % and 35 % for B7 and 71 % and 31 % for B100. These results are average values under the various phases of NEDC testing. A 30 % decrease in PM and a 44 % reduction in PNs under the overall test cycle were found when B100 was tested compared to B7. The soot primary particle size was reduced from 34.69 to 29.08 nm and the carbon fringe length diminished from 1.25 to 0.949 nm at different pre- and post-DOC-PDPF locations. This was due to partial oxidation on the surfaces of the PDPF metallic microstructure. PM undergoes simultaneous partial oxidation after passing through the DOC-PDPF system, as confirmed by TGA analysis.

Measurements of Thermophysical Characteristics of Thin Film Metal Filters for Extreme Ultraviolet Radiation

Knowledge of the emissivity and thermal conductivity of thin metal films used in conjunction with multilayer mirrors for spectral selection of radiation in the extreme ultraviolet and soft X-ray wavelength ranges is necessary in order to correctly calculate the heating of film elements at high heat loads. Heating is associated with the absorption in the film of a significant fraction of the incident intensity, and the concept of a high heat load is somewhat arbitrary, since even at an absorbed intensity level of the order of 1 W/cm2 a freestanding film can be heated in vacuum by several hundred degrees. In the first approximation, to estimate the thermal conductivity coefficient, one could use tabular values for massive samples of the corresponding metals or use the well-known Wiedemann–Franz law which links the thermal conductivity and the electrical resistivity of the sample – the latter is easier to be measured. However, an analysis of the literature data indicates significant errors that are possible when using any of these approaches. Therefore, in this work, we have measured the thermal conductivity directly by processing the temperature distribution obtained by IR pyrometry over a film sample mounted on a heated frame or heated by a flowing electric current. Thermophysical characteristics (thermal conductivity and emissivity) were determined for samples of film absorption filters based on Mo, Al, and Be of submicron thickness (from 100 nm), as well as for films of copper – a metal whose bulk samples have high thermal and electrical conductivity. As expected, significant differences were found between the thermal and electrical properties of the film materials and the properties of the same metals in monolithic samples.

Superhydrophobic Coatings Based on Montanic Acid

uperhydrophobic coatings with a thickness of 0.7–1.3 μm based on montanic acid (MA) are formed by dynamic spin-coating on substrates made of single-crystal silicon and steel of the 12Kh17 brand. The contact angle (CA) for water is 154.2° in the case of MA coatings on silicon and 155.8° in the case of those on steel. The values of the CA of these coatings for hexadecane are less than 5.0°, which makes it possible to use MA for hydrophobization of the surface of metal filters for the purpose of separating emulsions of the water-in-oil type.

Experimental validation of energy dependences of YALO3:Mn TL detectors: irradiation to ISO radiation qualities.

The effect of application of filters, made of different materials and various thickness, is studied by Monte Carlo calculations using MCNP6.2 code. The calculated data were validated by experimental studies (benchmark tests). Experimental results obtained for YAlO3:Mn high-Z TL detectors irradiated to different standard ISO radiation qualities (X-ray series N-40, N-60, N-80, N-100, N-120, N-150 and N-200 as well as isotopic series S-Cs) modified by various metal (copper and aluminum) filters of thickness of 0.5, 0.8 and 1mm. The experimental results are compared with results of Monte Carlo simulations done for the same 'radiation-attenuator-detector' combinations and geometry. Obtained results show good consistence between the experimental and calculated data that testifies adequacy of the used calculations and their applicability to modeling of modification of an output from the high-Z detectors exposed to photons of various energies.