Wet Separation Research Articles

Creation of self-aligning multisatellite planetary gears

In this study, we aim to identify shortcomings in the operation of multisatellite planetary gearboxes and to justify improved designs of planetary self-aligning mechanisms, which allow torque to be transmitted through all installed satellites. To that end, we studied a domestic planetary three-satellite MPZ gearbox installed on a magnetic separator, designed for wet separation of strongly magnetic ores and materials into magnetic and non-magnetic products, and a planetary gearbox of a special structure. 3D models of the classical three-satellite and single-sliding self-aligning gearboxes were constructed in the 3D module of the T-Flex CAD software. The performance of the mechanisms was evaluated by structural analysis and Chebyshev’s mobility formula. The constructed 3D models were used to study the engagement process of the classical three-satellite and single-sliding self-aligning gearbox. The latter is distinguished by the presence of two levers, which are introduced additionally to three satellites. During the research, the lateral clearance between the pairs of satellite teeth and center wheels was accepted according to GOST 1643–81. The conducted analysis of contacts at rotation of the central driving wheel by 30°, 110°, 200°, and 310° established further designing of the applied planetary gears to be inexpedient due to impossibility of realization of power transfer simultaneously through all satellites. The main disadvantage of the operation of multisatellite gearboxes was found to be the requirement for the side clearance selection, which should ensure the operability of the transmission at the moment of motion transfer. When designing multi-satellite single-slide selfaligning planetary mechanisms, additional levers should be introduced into the structure, the number of which should be equal to the number of satellites. Hence, the use of self-aligning planetary gears makes it possible to reduce the dimensions due to the uniform distribution of the transmitted torque, since the calculated value of the torque can be reduced by the number of satellites. This allows the gears to be adapted to the working loading conditions, which significantly improves the performance of the entire machine or unit.

A Review on Methods of Cenosphere Separation from Fly Ash

Cenospheres are valuable material contained inside the fly ash. Its low weight, low density, and high strength made it very versatile and can be used in various fields. The way of separating the cenosphere from the fly ash consists of two categories, wet and dry separation. For wet separation, it involves submerging the fly ash inside a mixture made either by pure acetone, pure water, or a mixture of water and acetone with different mixing ratios before stirring the mixture. The cenospheres, floating on top of the mix due to low density, can be collected and dried. The dry separation technique involves putting the fly ash into a cyclone separator at a constant velocity. The fly ash will then move into the bottom of the cyclone. Particles can also be separated by diameter sizes by sieving. By manipulating various parameters, cenosphere yield may differ. This paper is written to help gain more understanding on cenosphere properties and its separation method.

WET SEPARATION OF PALM KERNEL AND SHELL MIXTURE USING LATERITE AND ANTHILL SLURRY.

Palm kernel, one of the end products of oil palm fruits processing is recovered by cracking of the palm nuts which is first dried to aid efficient kernel recovery. The possibility of separating oil palm kernel and shell mixture using media other than kaolin in wet separation was investigated in this study. The separation efficiency of laterite was compared with that of anthill. The effect of media type, pH, specific gravity, slurry viscosity on the efficiency of separation were investigated. The media/water percentages of 0, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75 and 80% w/v were prepared in bowls for each media at a time and used to separate the cracked nut (palm kernel and shell mixture). The soil particle size distribution showed that laterite contains 40.3% clay while anthill contains 20.3%. The laterite and anthill slurry shows that the specific gravity and the viscosity increases with increase in media percentage while the pH decreases. Optimum kernel recovery percentages (%Kr) of 99.3 and 99.6% was observed at 30 and 35% ratio respectively for laterite and %Kr of 98.9 and 98.4% at 45 and 50% ratio for the anthill slurry. Among the media used, laterite was found to be comparable to clay at a medium-to-water percentages of 30 and 35% giving optimum efficiency. Thus, it is recommended laterite can be used for wet separation when compared to anthill.

Material mechanics properties and critical analyses of fish farm netting and trusses

Fish farms face the risk of aquaculture failure due to prolonged operation and the excessive loads caused by typhoons. Aging tests conducted for this study using salt spray, humid heat, and xenon lamps confirm that netting performance significantly declines compared to that of unused nets. The seawater-exposed portion of the netting in the dry–wet separation area is especially susceptible to damage. After three years of natural aging, the netting retains 48% of its original strength, and its elongation at break decreases from 90% to 32%. Under a standard load of 20 N, the equivalent wire model's maximum wear length is 205 m. The fishing net is prone to wear because of sliding friction with the truss. The net opening may fracture when loaded with 1000 N, with a maximum stress of 36.40 MPa at the corners. The netting's fatigue life decreases sharply when the vibration force exceeds 60% of its maximum strength. Moreover, risk analysis shows that fish farms with single-point mooring can successfully withstand a tension of 1256.72 kN during super-typhoons. In redesigned models, buoyancy tanks decrease current resistance, and trapezoidal fishing nets with an increasing slope along the truss column effectively reduce wear.

Research on Hydrocyclone Separation of Palygorskite Clay

The separation methods of palygorskite can be divided into dry separation and wet separation. For wet separation, which is more efficient, the centrifuge is the commonly used method but is characterized as having a high cost. It remains a challenge to separate ultra-fine palygorskite with an economical method. This work tried to separate palygorskite using a hydrocyclone with two separation stages. Orthogonal experiments are designed to investigate the influence of feed concentration, feeding pressure, and underflow port diameter on separation performance. The element content, mineral composition, and particle size distribution of the separation products are analyzed, respectively, by XRD, XRF, and laser particle sizers. The apparent viscosity of palygorskite pulp is characterized by a rotational rheometer. The purity of the feed and palygorskite concentrate is measured using an internal standard method. The results show that the purity of palygorskite increased from 45.1% to 64.2%, with a recovery of 95.9%.

THE STUDY OF HETEROGENEOUS SYSTEMS AND METHODS FOR THEIR SEPARATION

The article shows the importance of methods for separating inhomogeneous systems, classified depending on the size of dispersed particles, the difference in densities of continuous and dispersed phases, as well as the viscosity of the continuous phase. The main methods of separation are considered: sedimentation, filtration, centrifugation, wet separation.

High gravity wet purification of fine particles and naphthalene in gas

Coke oven gas contains fine particles and naphthalene, these impurities are easily deposited in equipment and pipelines and cause blockage. Moreover, it is extremely harmful to the human health and environment. In this paper, a pilot-scale experimental system was built employing a cross-flow rotating packed bed to explore the purification ability of the high gravity wet separation technology for naphthalene and the mixture of fine particles and naphthalene. It was shown that under the operating conditions of inlet gas naphthalene content of 5 mg/m3, high gravity factor of 83.70, gas velocity of 1.43 m/s and liquid spray density of 7.19 m3/(m2·h), the high gravity wet purification efficiency of naphthalene was 89.53%. At the inlet dust concentration of 50 mg/m3, the naphthalene content of 5 mg/m3, the gas velocity of 1.43 m/s, the high gravity factor of 83.70 and the liquid spray density of 6.0 m3/(m2·h), the purification efficiency of fine particles was as high as 99.23%, and the purification efficiency of naphthalene was 82.87%. It can be seen that high gravity wet purification technology possess a great potential for industrial application with better removal of naphthalene-containing gas as well as gas containing fine particles and naphthalene.

Deep purification of low concentration fine particles in a cross flow rotating packed bed

BackgroundThe traditional wet dust removal technology is not effective in removing fine particles with low concentration, which is far from meeting the ultra-low emission and production requirements. However, national emission requirements for fine particles are becoming more stringent year by year. Therefore, it is vital to explore a purification technology for low concentration of fine particles. MethodsCoal-fired fly ash was used to simulate low concentration dust-containing gas and a pilot-scale experimental system was set up employing a cross-flow rotating packed bed (RPB) as the wet separation device to explore the purification capacity of high gravity wet dust removal technology for low concentration fine particles. Significant FindingsThe obtained results suggested that under the operating conditions of inlet dust concentration of 50 mg/m3, high gravity factor of 138.36, gas velocity of 1.71 m/s and liquid spray density of 4.8 m3/(m2·h), the dust removal efficiency was 99.46%. The cut-off particle size of RPB was 0.09 μm, and the fine particles removal efficiency with particle size above 0.2 μm was more than 95%. It can be seen that high gravity wet dust removal technology is a wonderful technology for deep purification of fine particles with strong industrial application potential.

An all-in-one strategy for municipal solid waste incineration fly ash full resource utilization by heat treatment with added kaolin

Resourcization has become a popular research topic for the final disposal of municipal solid waste incineration fly ash (MSWI FA). However, the current research is limited to building material preparation or valuable chloride recovery, which may cause resource waste and secondary pollution. A unique process, heat treatment with the addition of kaolin (KL), was presented to achieve complete resource utilization of MSWI FA. The physical properties of ceramsite could be improved by adding KL, and dioxin removal, heavy metals, and valuable chloride separation could be achieved via sintering at 1150 °C. The separation and purification of dust carried by the flue gas during thermal treatment (secondary fly ash) was achieved via wet separation. A building ceramsite with a compressive strength of 24.8 MPa was obtained, whereas dioxin and heavy metal toxicity were far below the standard limits. Heavy metal content was enriched by 12 times, approximately 59.6%, achieved after secondary fly ash separation and purification. A heavy metal product containing 39.5% Zn, 19.1% Pb, and chloride salt containing 41.8% KCl were obtained. This showed a high potential for the developed process to separate multiple valuable elements from ashes. This novel process will further promote the development and application of harmless and resourceful technologies for MSWI FA.

Nutrient content and physical characteristics linkage of palm kernel meal and coconut meal after wet separation using molecular weight approac

The use of palm kernel meal and coconut meal is restriction in broiler feed due to the high crude fiber content, caused by the mixture of shells. This study aims to analyze the nutrient content, i.e., crude protein and crude fiber of palm kernel meal and coconut meal before and after using wet separation and molecular weight approach. The wet separation process for palm kernel meal and coconut meal was carried out for 6 hours to obtain a precipitate. The palm kernel meal and coconut meal that have been separated is divided into 3 fractions, i.e., upper, middle and lower. Each fraction was analyzed for crude fiber and crude protein content for chemical characteristics, and bulk density (g l-1), compacted bulk density (g l-1), specific gravity (kg l-1), angle of purpose (o). Crude protein and crude fiber content of palm kernel meal before being separated by wet separation were 11.72% and 13.11%, for coconut meal were 12.65% and 8.67%. The fraction of palm kernel meal has the highest crude protein content of 22.21% with the lowest crude fiber content 9.68%. Coconut meal in the middle fraction had the highest crude protein content 18.92% and the lowest crude fiber content of 11.95% in the upper fraction. The physical characteristics of the upper fraction of palm kernel meal and coconut meal had the lowest values (P0.05) of specific gravity (kg l-1), bulk density (g l-1) and compacted bulk density (g l-1). It can be concluded that the wet separation process with the molecular weight approach is able to increase the nutrient content especially of each fraction and can minimize the mixture of shells in palm kernel meal and coconut meal

Dry Permanent Magnetic Separator: Present Status and Future Prospects

Dry permanent magnetic separators have been widely used in the mineral and coal processing industries due to their simple operation and high separation efficiency. These tools not only discard some amount of bulk gangue from the raw ore, thereby reducing the volume of the grinding operation and cutting energy consumption, but also do not require water in the sorting process, thereby expanding their applicability to arid and cold areas. With the depletion of global iron ore resources, a dry, low-cost processing or pre-sorting prior to the wet separation has received the attention of industrial practitioners as a potential alternative. The performance of dry magnetic separators plays a critical role in dry processing This paper reviews the dry magnetic separators available in the literature and describes their operating principles, separation performance, and applications. A detailed comparison of different separators is also conducted to evaluate the differences in their sorting performance and mechanisms and to provide a reference for the optimization of dry magnetic separators.

Potential of air-currents assisted particle separation (ACAPS) technology for hybrid fractionation of clean-label faba bean (Vicia faba L.) protein

Air-currents assisted particle separation (ACAPS) of faba beans prior to wet separation was evaluated for its impact on chemical composition, yield and recovery of protein, starch and dietary fibre, and protein secondary structural changes. The protein and dietary fibre contents of faba bean cultivars Snowbird and Athena were positively correlated (r = 0.9, P < 0.0001) with the increasing particle size, which was offset by starch contents. ACAPS treatment of faba bean dehulled bean flours resulted in both protein- and dietary fibre-rich coarse fractions (75–500 μm). Subjecting the ACAPS-treated protein-rich (Snowbird: 38.96 ± 0.33% and Athena: 37.54 ± 0.20%) coarse fractions (250–500 μm) to micellization resulted in protein isolates (Snowbird: 97.74 ± 0.18% and Athena: 94.30 ± 0.29%). This method also resulted in starch isolates (Snowbird: 94.05 ± 1.67% and Athena: 94.33 ± 0.53%) and dietary fibre concentrates (Snowbird: 54.41 ± 1.87% and Athena: 44.89 ± 1.40%) as co-products, which were “clean label” ingredients. FTIR data confirmed that hybrid fractionation had minimal impact on protein secondary structures with β-sheets as the major structures.

LIB 습식분리막 열손상에 따른 발화위험성에 관한 연구

LIB-related fires are continuously increasing due to the increase in personal transportation means and the commercialization of electric vehicles. Among the LIB components, the separation membrane is the most important key material for stability, and there is a problem in that it is lost at the scene of a fire and cannot confirm its shape. Accordingly, fire statistics and cases were analyzed, and the experimental outline was established through theoretical consideration of the wet separation membrane, which is the most used as a personal transportation means. As for the experimental method, we conducted a study on the shrinkage rate and tensile strength of the wet separator according to thermal damage for each temperature change with five experimental variables using the wet separator, which plays an important role in the stability of the battery components, as a sample. Through this, the change in shrinkage rate and mechanical properties of the wet separator were derived to understand the fire of lithium-ion batteries caused by damage to the wet separator and to contribute to the fire investigation analysis technique.

Carbonation Curing on Magnetically Separated Steel Slag for the Preparation of Artificial Reefs.

Magnetic separation is an effective method to recover iron from steel slag. However, the ultra-fine tailings generated from steel slag become a new issue for utilization. The dry separation processes generates steel slag powder, which has hydration activity and can be used as cement filler. However, wet separation processes produce steel slag mud, which has lost its hydration activity and is no longer suitable to be used as a cement filler. This study investigates the potential of magnetically separated steel slag for carbonation curing and the potential use of the carbonated products as an artificial reef. Steel slag powder and steel slag mud were moulded, carbonation-cured and seawater-cured. Various testing methods were used to characterize the macro and micro properties of the materials. The results obtained show that carbonation and hydration collaborated during the carbonation curing process of steel slag powder, while only carbonation happened during the carbonation curing process of steel slag mud. The seawater-curing process of carbonated steel slag powder compact had three stages: C-S-H gel formation, C-S-H gel decomposition and equilibrium, which were in correspondence to the compressive strength of compact increasing, decreasing and unchanged. However, the seawater-curing process of carbonated steel slag mud compact suffered three stages: C-S-H gel decomposition, calcite transfer to vaterite and equilibrium, which made the compressive strength of compact decreased, increased and unchanged. Carbonated steel slags tailings after magnetic separation underwent their lowest compressive strength when seawater-cured for 7 days. The amount of CaO in the carbonation active minerals in the steel slag determined the carbonation consolidation ability of steel slag and durability of the carbonated steel slag compacts. This paper provides a reference for preparation of artificial reefs and marine coagulation materials by the carbonation curing of steel slag.

Current Progress in the Extraction, Functional Properties, Interaction with Polyphenols, and Application of Legume Protein.

Legume protein can replace animal-derived protein because of its high protein content, low price, lack of cholesterol, complete amino acids, and requirements of vegetarianism. Legume protein has not only superior functional properties but also high biological activities. Therefore, it is widely used in the food industry. However, there are few studies on the comprehensive overview of legume protein. In this review, the extraction, functional properties, interaction with polyphenols, application of legume protein, and activities of their peptides were comprehensively reviewed. Legume proteins are mainly composed of globulin and albumin. The methods of protein extraction from legumes mainly include wet separation (alkali solution and acid precipitation, salt extraction, enzyme extraction, and ultrasonic-assisted extraction) and dry separation (electrostatic separation). Besides, various factors (heat, pH, and concentration) could significantly affect the functional properties of legume protein. Some potential modification technologies could further improve the functionality and quality of these proteins. Moreover, the application of legume protein and the effects of polyphenols on structural properties of legume-derived protein were concluded. Furthermore, the bioactivities of peptides from legume proteins were discussed. To improve the bioactivity, bioavailability, and commercial availability of legume-derived protein and peptides, future studies need to further explore new preparation methods and potential new activities of legume-derived proteins and active peptides. This review provides a real-time reference for further research on the application of legume protein in the food industry. In addition, this review provides a new reference for the development of legume-derived protein functional foods and potential therapeutic agents.

Study of a Waste Kaolin as Raw Material for Mullite Ceramics and Mullite Refractories by Reaction Sintering.

A deposit of raw kaolin, located in West Andalusia (Spain), was studied in this work using a representative sample. The methods of characterization were X-ray diffraction (XRD), X-ray fluorescence (XRF), particle size analysis by sieving and sedimentation, and thermal analysis. The ceramic properties were determined. A sample of commercial kaolin from Burela (Lugo, Spain), with applications in the ceramic industry, was used in some determinations for comparison purposes. The kaolin deposit has been produced by alteration of feldspar-rich rocks. This raw kaolin was applied as an additive in local manufactures of ceramics and refractories. However, there is not previous studies concerning its characteristics and firing properties. Thus, the meaning of this investigation was to conduct a scientific study on this subject and to evaluate the possibilities of application. The raw kaolin was washed for the beneficiation of the rock using water to increase the kaolinite content of the resultant material. The results indicated that the kaolinite content of the raw material was 20 wt % as determined by XRD, showing ~23 wt % of particles lower than 63 µm. The kaolinite content of the fraction lower than 63 µm was 50 wt %. Thus, an improvement of the kaolinite content of this raw kaolin was produced by wet separation. However, the kaolin was considered as a waste kaolin, with microcline, muscovite and quartz identified by XRD. Thermal analyses by Thermo-Dilatometry (TD), Differential Thermal Analysis (DTA) and Thermo-Gravimetry (TG) allowed observe kaolinite thermal decomposition, quartz phase transition and sintering effects. Pressed samples of this raw kaolin, the fraction lower than 63 µm obtained by water washing and the raw kaolin ground using a hammer mill were fired at several temperatures in the range 1000–1500 °C for 2 h. The ceramic properties of all these samples were determined and compared. The results showed the progressive linear firing shrinkage by sintering in these samples, with a maximum value of ~9% in the fraction lower than 63 µm. In general, water absorption capacity of the fired samples showed a decrease from ~18–20% at 1050 °C up to almost zero after firing at 1300 °C, followed by an increase of the experimental values. The open porosity was almost zero after firing at 1350 °C for 2 h and the bulk density reached a maximum value of 2.40 g/cm3 as observed in the ground raw kaolin sample. The XRD examination of fired samples indicated that they are composed by mullite, from kaolinite thermal decomposition, and quartz, present in the raw sample, as main crystalline phases besides a vitreous phase. Fully-densified or vitrified materials were obtained by firing at 1300–1350 °C for 2 h. In a second step of this research, it was examined the promising application of the previous study to increase the amount of mullite by incorporation of alumina (α-alumina) to this kaolin sample. Firing of mixtures, prepared using this kaolin and α-alumina under wet processing conditions, produced the increase of mullite in relative proportion by reaction sintering at temperatures higher than 1500 °C for 2 h. Consequently, a mullite refractory can be prepared using this kaolin. This processing of high-alumina refractories is favoured by a previous size separation, which increases the kaolinite content, or better a grinding treatment of the raw kaolin.

Diffusion of aerosol pollution in residential bathroom under different air distribution

In this study, based on the numerical simulation, we investigated aerosol pollution diffusion in residential bathroom with exhaust vents at different positions and different ventilation methods. The results show that setting an air outlet under the side wall next to the toilet can discharge aerosol pollutants in time, which not only shortens the diffusion path of aerosol pollutants, but also optimizes the air organization form. The dry and wet separation of the toilet area and the wash area separated by a physical partition adopts the principle of "screen", which effectively blocks the transmission path of aerosol pollutants.

Heavy metal recovery from the fine fraction of solid waste incineration bottom ash by wet density separation

This work is aimed at exploring the recovery of heavy metals from the fine fraction of solid waste incineration bottom ash. For this study, wet-discharged bottom ash fine-fraction samples from full-scale treatment plants in Germany and Sweden were analyzed. The potential for the recovery of heavy metal compounds was investigated through wet density-separation with a shaking table. The feed materials were processed without any pre-treatment and the optimum processing conditions were determined by means of design of experiments. Tilt angle and stroke frequency were identified as the most relevant parameters, and the optimum settings were − 7.5° and 266 rpm, respectively. The obtained balanced copper enrichments (and yields) were 4.4 (41%), 6.2 (28%) and 2.4 (23%). A maximum copper enrichment of 14.5 with 2% yield was achieved, providing a concentrate containing 35.9 wt.% relevant heavy metal elements. This included 26.3 wt.% iron, 4.3 wt.% zinc and 3.8 wt.% copper. In conclusion, density separation with shaking tables can recover heavy metals from bottom ash fine fractions. Medium levels of heavy metal enrichment (e.g., for Cu 2.7–4.4) and yield (Cu: 26–41%) can be reached simultaneously. However, the separation performance also depends on the individual bottom ash sample.

Investigation of Metal and Trace Elements of Cenospheres from Lignite High-Calcium Fly Ash (Thailand)

High-calcium fly ashes contain a large content of small particles including cenospheres of chemical constituents known to be similar to fly ash and the parent coal. Coal fly ash contains metal and trace elements that may leach out during disposal or utilization. This work aimed to understand an overview of cenosphere characteristics relating to fly ash and leaching study. To our knowledge, this is the first report on metal and trace element leaching of cenospheres separated from high-calcium (28.9 wt.%) class C fly ash produced from the Mae Moh coal-fired thermal power plant in Thailand. In this study, the cenospheres were separated from fly ash by a wet separation process (sink-float method) using water as medium. Physical properties, morphology, chemical composition, the mineral phases of cenospheres and fly ash have been characterized. Extraction was carried out by acid digestion; the selected metal and trace elements in this study are Mg, Al, Zn, Pb, Cd, Cr, and Cu; the obtained environmentally available concentrations of cenospheres were analyzed in comparison to those of fly ash. The concentrations of Cu, Cr, Pb, and Cd elements of interest in the leachates obtained from the toxicity characteristic leaching procedure (TCLP) showed the tendency to decrease in that order. All the elements were found below the permissible limit values regarding Thailand soil quality standards. Association of the heavy metal trace elements in cenospheres and fly ash was discussed in in terms of physico-chemical-geochemistry correlating with the leaching concentrations.

Pulse protein ingredient modification.

Increasing population and depletion of resources have paved the way to find sustainable and nutritious alternative protein sources. Pulses have been identified as a nutritious and inexpensive alternative source of protein that can meet this market demand. Pulses can be converted into protein concentrates and isolates through dry and wet separation techniques. Wet extraction results in relatively pure protein isolates but less sustainable due to higher energy requirements and high waste generation. Dry separation focuses on ingredient functionality rather than molecular level purity. These extracted pulse protein ingredients can be incorporated into different food systems to increase the nutritional value and to achieve the desired functionality. But many plant-based alternative proteins including pulses, face several formulation challenges especially in nutritional, sensory, and functional aspects. Native pulse protein ingredients can contain antinutrients, beany flavor, and undesirable functionality. Modification by biological (enzymatic, fermentation), chemical (acylation, deamidation, glycosylation, phosphorylation), and physical (cold plasma, extrusion, heat, high pressure, ultrasound) methods or a combination of these can improve pulse protein ingredients at the macro and micro level for their desired use. These modification processes will thermodynamically change the structural and conformational characteristics of proteins and expect to improve the quality. © 2021 Society of Chemical Industry.