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Buckwheat husks are a valuable source of carbon and show the potential to be used as an energy source. However, due to low bulk density and low susceptibility to compaction, it is beneficial to use them in the form of co-pellets. The study presents comprehensive research detailing buckwheat husks' potential for co-pelletization with oily (peanut husks) and dusty (senna leaves) agri-food wastes, whereas the effect of material parameters such as the amount of additive (10, 15, 20%) and the process parameters as the die rotational speed (170, 220, 270 rpm) on pellets' quality (kinetic durability, bulk and particle density, degree of compaction) and the energy consumption of the pelletization process were examined. Ten percent of potato pulp as a binder was added to each pelletized mixture. It was found that an increase in the senna leaf content affects positively the kinetic durability of pellets. The fatty peanut husks have a negative effect on the pellets' quality (measured by the kinetic durability and bulk density); however, both additions of senna leaves and peanut husks are lowering the energy consumption of the pelletizer. The highest quality pellets and the addition of 10% peanut husks to buckwheat husks (kinetic durability of 96%) and 20% of senna leaves to buckwheat husks (kinetic durability of 92%) obtained at 170 rpm were subjected to combustion in a fixed-bed unit, and the content of CO, CO2, NO, SO2, HCl, and O2 in the fuel gases was measured. The emission factors were higher than the Ecodesign limitations (CO > 500 mg·Nm−3, NO > 200 mg·Nm−3). The obtained results indicate that buckwheat husks can be successfully co-pelletized with other waste biomass; however, the pellets to be combusted require a boiler with improved air-supplying construction. [ABSTRACT FROM AUTHOR]

The demand for pellets in blast furnaces has recently increased because of their uniform shape and size, controlled chemistry, iron-enriched feed, high strength, and quality consistency. To meet this demand, low- and medium-grade iron ore fines with alumina (> 3.5 wt%) must be used for pelletization because of the limited availability of high-grade ore. The alumina present in the ore has an adverse effect on the pellet properties because of its refractory nature. Therefore, a study was conducted to optimize the firing temperature and chemistry of the feed blend to produce pellets with good pellet properties. Firing temperature (1280 °C, 1300 °C, and 1320 °C), carbon (1 and 1.2%) in the form of coke fines, and MgO (0.60 and 0.80%) in the form of dolomite were used to optimize the pellet-making process for high-alumina iron ore fines. The best result was obtained for feed blend with 1.2% carbon and 0.80% MgO fired at 1300 °C to produce pellets of cold compressive strength more than 300 kg/pellet, reduction degradation index (− 6.33 mm) near 7%, and porosity near 20%. [ABSTRACT FROM AUTHOR]

Hydrogen peroxide (H2O2) is an environmentally friendly oxidant, producing only water as a by-product upon decomposition. Given the energy-intensive nature of the conventional anthraquinone process for commercial H2O2 production, photocatalytic production of H2O2 using graphitic carbon nitride (g-C3N4) emerges as a viable alternative. Among the other alternatives for improving the efficiency of g-C3N4, potassium ion doping in g-C3N4 is one of the efficient methods that can further increases the yield of H2O2 production, as the K+ doping enhances the photogenerated charge carriers' separation, intensity and range of visible light absorption, etc. However, traditional methods of catalyst dispersion are inefficient due to the challenges of retrieving the catalyst. Immobilization, while addressing the retrieval issues, adversely affects mass transfer and lowers photocatalyst efficiency. Hence, in this study, we explore an innovative approach to catalyst recycling by forming the catalyst into pellets that avoid immobilization, centrifugation, or any other tedious energy intensive separation process. Pellets of undoped g-C3N4 and 10 wt% K-doped g-C3N4 are tested for the photocatalytic production of H2O2 under direct sunlight and recycled for three times. These materials, i.e., undoped g-C3N4 and 10 wt% K-doped g-C3N4 pellets are able to produce ~ 407 µM g−1 h−1 and ~ 853 µM g−1 h−1 of H2O2, respectively, after three recycles. Such a novel approach of recycling the catalysts in the form of pellets can be extended for the large-scale production of H2O2 by loading the pellets to fixed bed column and operating it in continuous flow manner. [ABSTRACT FROM AUTHOR]

Application of sewage sludge as fertilizer can be beneficial for sustainable agriculture as it could largely account for nitrogen and phosphorus demand for crops and has lower costs compared to other disposal routes, e.g., incineration, and sanitary landfills. This study evaluates the feasibility of pilot-scale pelletization of sewage sludge for non-food crops (e.g., ornamental plants). The co-pelletization method was designed by mixing sewage sludge and binder (tapioca starch) at a 9:1 sludge-to-starch weight ratio. The amount of nitrogen (N), phosphorus (P), and potassium (K) of the resultant pellets were determined at 5.7%, 4.9%, and 0.2%, respectively. Following Malaysian and US Standards, non-essential elements and pathogenicity of the pelletized sewage sludge were measured below the predetermined limits and hence safe for agricultural application. The planting trial using 50% inorganic fertilizer + 50% sewage sludge pellets exhibited a promising result on the growth of the flowering plant Celosia plumosa, with having better dimension and color, 20% higher in height, 4% more chlorophyll content, 54% more leaf, 43% greater stem growth, and 27% more flowers compared to control. Likewise, the planting trial on Tagetes erecta resulted in 10.5% wider leaf, 10.6% heavier leaf dry weight, and 12.5% more chlorophyll content compared to control with full usage of inorganic fertilizer. By considering liquidities to operate the production facility, the economic analysis estimated that the production cost per ton of pelletized sewage sludge produced was USD 0.98. [ABSTRACT FROM AUTHOR]

At the Chelyabinsk Zinc Plant of the Ural Mining and Metallurgical Company, oxidized zinc and lead-containing raw materials are processed in Waelz kilns. Waelz oxides, containing chlorine and fluorine, are calcined in tubular rotary kilns. The results of studies on the halide removal are provided – in the calcination process, chlorine is removed mainly in the form of zinc and lead chlorides, while in calcined oxide, chlorine remains in multicomponent difficult-to-digest substances; – at an increase in the specific volume of exhaust gases from 300 to 820 m3/kg of chlorine, charged into the kiln, the residual chlorine content in the calcined Waelz oxide decreases from 5.2 to 0.05%; – at the pilot kiln (length of 1.9 m, diameter of 0.2 m), tests were carried out to determine the specific volumes of exhaust gases and the gas flow velocity. The following results were established – within 1 h from the beginning of the experiment, the reaction proceeds in the diffusion-kinetic mode; – when the velocity of gases at the outlet of the kiln decreases to 3 m/s, the sublimation occurs in the forced diffusion mode. This correlates with the data on the velocity of gases in a real industrial kiln; – the capacity of the industrial kiln (L = 41 m, D = 2.5 m) is 8.0 t/h of waelz oxide using the calcined product (chlorine content of 0.05%) with a volume of kiln exhaust gases of 12–18 thous. Nm3/h at a temperature of 500–550 °C and the size of the charged waelz oxide pellets of 6–10 mm. When the pellet size is reduced to 2–4 mm, the kiln capacity increases from 8 to 10 t/h, while the chlorine content decreases from 0.05 to 0.04%. On the basis of pilot tests, a cyclone cooler, capable of cooling 18,000–19,000 Nm3/h of gases with a temperature of 600 °C, was developed for the kiln. [ABSTRACT FROM AUTHOR]

Owing to a severe shortage of natural aggregates in terms of quantity and quality, alternative aggregate resources must be utilized in civil engineering construction to meet significant increase in aggregate demand. This study focuses on manufacturing artificial aggregates for pavement applications using two waste materials- mine overburden waste from the coal mining industry and fly ash from thermal power plants. Liquid alkali activator, a mixture of sodium silicate and sodium hydroxide, is used as a binder. The centrifugal forces generated due to a rotating disc pelletizer enables mixing the said components resulting in formation of spherical-shaped pellets. The nucleated pellets are oven cured at 70°C for 7 days. Based on extensive laboratory test trials, the optimal features to produce competent aggregates in terms of angle and revolution speed of the disc pelletizer, dosage of the liquid alkali activator and the concentration of the NaOH are proposed. Finally, the manufactured aggregates are tested for properties relevant to flexible pavement applications. The aggregate impact and Los Angeles abrasion values are found to be 17% and 21.6%, indicating satisfactory resistance to impact and abrasion of aggregate particles under traffic loads. The basic material properties of these aggregates are found to conform to the Indian Roads Congress (IRC) and American Association of State Highway and Transportation Officials (AASHTO) standards for base and subbase layers. Moreover, base/subbase layers prepared with artificial aggregates and mine waste showed high California bearing ratio (CBR) of 54.3% and 80.5% for 2.5 mm and 5.0 mm penetration of the plunger, respectively, indicating high load-bearing capacity of pavement layers. [ABSTRACT FROM AUTHOR]

The excessive use of natural aggregates raises mining activity. Further, it leads to environmental damage, which can be reduced using artificial aggregates produced from waste powdered materials. This study discussed the production process of alkali-activated artificial coarse aggregates and how their use affects the behavior of concrete. The different concrete mixtures were designed by replacing natural aggregates with artificial ones at different percentages. Various tests were conducted to determine concrete's fresh, hardened, permeability, and microstructural characteristics. The result showed that concrete incorporated with artificial aggregates can achieve higher workability and lower density than natural aggregate concrete. The mechanical strengths were slightly decreased as the percentage addition of artificial aggregates in a mix increased. However, adding up to 50% showed comparable results to natural aggregate concrete. The water permeability and chloride ion penetration were within the standard limits for all the mixes. The scanning electron micrographs showed a solid and compact ITZ between the phases. XRD pattern revealed that the addition of artificial aggregates had not changed the mineralogical composition of the concrete; the formation of hydrated products helps concrete obtain strength. The study concluded that artificial aggregates could effectively replace natural coarse aggregate in producing structural concrete with many advantages. [ABSTRACT FROM AUTHOR]

The utilization of waste rubber as aggregates shows both environmentally friendly features and high cost-efficiency in construction, but may cause poor workability such as rubber flotation and agglomeration. To address the above issues, the pelletization method was adopted to produce rubberized artificial geopolymer aggregates (R-GPA), and the effects of different rubber modification methods and rubber contents were investigated through pelletization technologies, mechanical tests, X-ray computed tomography (XCT) and backscattered electron with energy-dispersive spectroscopy (BSE-EDS). Results showed that the combined modification with NaOH solution and silane coupling agent presented the most effective surface modification efficiency. According to microscopic analysis, rubber modification could effectively enhance the rubber-matrix interface. The produced R-GPA could thus possess an oven-dried particle density within 1500–1800 kg/m³, a water absorption of 7%–10.5%, and a pelletization efficiency over 98%, which provided a new insight into the value-added utilization of waste rubber and the promotion of artificial aggregate technologies.

Calcium looping (CaL) process, as an effective way to achieve CO2 mitigation from high-temperature flue gas streams, is one of the most promising alternatives to amine scrubbing (a well-established technology for industrial post-combustion CO2 capture). CaO sorbent is considered to be an ideal CO2 adsorption material. Moreover, the development of granulation/pelletization techniques along with the mass preparation of the CaO-based sorbent is imperative for realistic large-scale applications. This work proposes two practicable moulding-crushing techniques for the scale-up granulation of CaO-based sorbents, in which the kilogram-scale produced Al-promoted CaO-based sorbent powders were first moulded and subsequently crushed into the granules of target sizes. Three types of organic acids–acetic acid, citric acid and malonic acid were employed as peptizing agents to optimize the granulation process. As a result, the anti-attrition properties and compressive strength of the synthetic sorbents were elevated owing to the introduction of an appropriate amount of acetic or malonic acid, for it expedited the disintegration of the pseudo-boehmite (served as binder agent) particles into sol particles, which allowed for tighter bonding of sorbent particles. In addition, corncob powder acted as a pore-forming agent, enhancing the porous structure of the sorbent particles due to the gases released from the thermal decomposition of organic groups during calcination. Nevertheless, the results revealed that the porous and loose structure adversely affected the mechanical strength of the granules.

This study addresses the effects of densification at varied pelletization temperatures on the novel Malaysian Khaya senegalensis wood-derived pellets biomass fuel characteristics. The lack of comprehensive understanding regarding the biomass fuel characteristics of this species prompted the research. By addressing this knowledge gap, this study explores the impact of temperature variations on key fuel properties, contributing to the optimization of sustainable biomass fuel production in manufacturing and materials processing. Khaya senegalensis wood, grown and harvested in Malaysia, was pelletized at different temperatures to analyze the calorific value, volatile matter content, ash content, fixed carbon, bulk density, and moisture contents of the pellets. The experimental data revealed a significant relationship between temperature and these fuel properties. Pelletizing at 75 °C produced the highest calorific value of 19.47 MJ/kg and the maximum fixed carbon content of 10.04%. A low ash level of 4.26% was achieved via pelletizing at 75 °C. According to the results, 75 °C produced the best thermophysical properties. These findings provide valuable understanding of how pelletization temperature influences fuel pellet thermophysical properties, a critical aspect in optimizing fuel pellet production, storage, advancing renewable energy resource utilization, and, finally, promoting a cleaner and more sustainable energy future. [ABSTRACT FROM AUTHOR]

The depletion of fossil fuels has fueled an increased interest in biomass resources usage for heat and electricity generation. As an important biomass resource, Chinese medicine residues have great potential in substituting fossil fuels. However, that is basically limited by its poor properties, including low bulk density, high moisture content, and inhomogeneous structure. Herein, a safe and sustainable strategy was reported to prepare a high-quality densified pellet derived from Chinese medicine residues to address these worries. In this process, mixed and simple size materials were densified under various moisture content and pressure using a laboratory electronic tablet press machine equipped a single pellet mold. Results showed that higher pressure, ideal moisture content (∼6.5 %), and mixed particle size could densify better quality pellets. These findings pave the way for the safely and efficient resource utilization of Chinese medicine residues, as well as providing theoretical guidance and technical support for the household heating.

Lignocellulosic biomass has demonstrated great potential as feedstock for pellet production, notwithstanding the fact that the industrial production of pellets is faced with some economic challenges. This study presents a technoeconomic analysis of six scenarios to develop a process model for pellet production from sawdust and oat straw that employs torrefaction and steam explosion pretreatment prior to pelletization. SuperPro Designer was used to carry out this evaluation. The pellet plants were designed to have a capacity of 9.09 t/h of sawdust and oat straw each. The pellet yield ranged from 59 kt to 72 kt/year. The scenarios analyzed included variations of steam explosion and torrefaction. In some scenarios, materials were lost in the form of liquid and gas due to the pretreatment process. The breakdown of equipment purchase cost showed that the torrefaction reactor is the most expensive unit with approximately 51% of the purchase cost. Facility-dependent and feedstock costs were the major significant contributors to the pellet production cost. The minimum selling prices of the pellets obtained from Scenarios 1–6 were $113.4/t, $118.7/t, $283.4/t, $298.7/t, $200.5/t, and $208.4/t, respectively. The profitability of pellet production as determined by the net present value (NPV), internal rate of return (IRR), and payback period was found to be sensitive to variations in feedstock cost. [ABSTRACT FROM AUTHOR]

Abstract The oral route of delivery is the most preferred route for administering most of the drugs. Pellets have gained importance since they offer numerous advantages like decreased dose dumping, improved patient compliance since dosing frequency is reduced, and ease of administering multiple chemically incompatible drugs immediately without the possibility of them interacting with each other. The critical variables related to process and equipment are identified and what impact they have on the quality of pellets formed is discussed. The position of the spray nozzle also affects the pellets and their yield. A complete guideline has been drawn which makes the process of pelletization using the Wurster method easier. The process variables affecting the pelletization process include inlet and product temperature, relative humidity, batch size; spray rate, and atomization air pressure and the equipment variables include column height, air distribution plate, a type of filter, and shaking interval. All these variables have a low, medium, or high impact on the process and they all together contribute to the quality of pellets formed. This review article focuses on critical process and equipment variables affecting the process of pelletization and the quality of pellets formed when using the Wurster equipment. The main objective is to review critical variables affecting the layering method of palletization and to sketch some basic problems encountered during pelletization and their troubleshooting.

Y-type zeolites are widely used in the carbon dioxide (CO2) adsorption applications due to their exceptional ion exchange performance and high stability. However, the pelletization of Y powder by adding binders such as kaolin often results in performance drops, which has limited its industrial application. This study employs a zeolite-kaolin blend to produce cylindrical pelletized Y zeolite, in which the kaolin is then transformed to zeolites via hydrothermal crystallization, resulting in binder-free Y pellets. The Design-Expert software and the response surface method (RSM) are employed to optimize the hydrothermal crystallization conditions for binder transformation, with the objective of attaining a maximized capacity for CO2 adsorption. Results demonstrate that optimized synthesis conditions yield cylindrical Y zeolite with a notable CO2 adsorption capacity of 5.52 mmol/g at 298 K and 1 bar, surpassing that of the initial Y powder. The average crushing strength is 110 N per particle (Diameter × Height = 3 mm × 3 mm). The IAST selectivity of CO2/N2 (15/85) is 824 at 298 K and 1 bar. The reaction mechanisms of the binder transformation are also investigated via experiments and DFT simulation. This study presents a simple and reliable method for manufacturing binder free Y zeolite, which is promising for carbon capture applications.

• Cl distribution and speciation were determined during MSW pellets pyrolysis. • Chlorine mainly distributed in char (42.36–65.29 %) and gas (26.66–35.03 %). • Inorganic-Cl was the main form of chlorine in char. • Organic-Cl was converted into inorganic-Cl during MSW thermal decomposition. • Chlorine release was inhibited by the unprosperous pores in char. The migration process of chlorine during municipal solid waste (MSW) pellets pyrolysis was studied in a fixed bed reactor. Distribution and speciation changes of chlorine at different pyrolysis temperatures were determined by ion chromatography (IC) and X-ray photoelectron spectroscopy (XPS) analyses. Results showed that chlorine was mainly distributed in pyrolysis char (42.36–65.29 %) and gas (26.66–35.03 %) after MSW pellets pyrolysis. With the temperature increasing, chlorine in char and tar was enriched due to the increase of chlorine release and the decrease of product yields, with chlorine concentration increasing to 3498 ppm and 1415 ppm at 800 °C, respectively. Results of chlorine forms analysis indicated that most of the organic-Cl in MSW was released into the volatiles during pyrolysis due to the dissociation of C Cl. Inorganic-Cl became the dominant form of chlorine in char after pyrolysis, with the proportion increasing from 46.69 % (raw) to 61.22 % (500 °C), which also suggested that part of organic-Cl was converted into the inorganic-Cl. Notably, the proportions of inorganic-Cl decreased at >600 °C due to the migration of inorganic. In addition, the pyrolysis release behavior of chlorine was affected by the pore structure of char, which could be inhibited by the unprosperous pores in char, especially at low temperatures (<600 °C). These findings provided a reference for the chlorine regulation of MSW pyrolytic products. [ABSTRACT FROM AUTHOR]

This study was carried out to investigate the combined effects of torrefaction and binders on the quality of pellets produced from oat straw. Torrefaction pretreatment was performed with the aid of a lab-scale microwave oven at temperatures in the range of 200–300 °C and a retention time of 5–9 min in an inert environment to ascertain the effect of these two process variables on the physiochemical, thermal, and mechanical properties of the torrefied biomass. Torrefaction liquid (TL) and sawdust were introduced during pelletization as binding agents in the pellet formulation. From the results in this study, the physiochemical and thermal properties of the oat straw pellet improved after torrefaction except for the tensile strength. The higher heating value (HHV), particle density, and bulk density of the torrefied oat straw improved from 16.84 to 24.23 MJ/kg, 882.23 to 1374.87 kg/m3, and 127.87 to 80.23 kg/m3, respectively. The tensile strength of the pellet after torrefaction ranged between 0.35 and 1.02 MPa. The introduction of the binder during pelletization improved the pellet tensile strength to about 1.32–2.28 MPa. Although ash content increased after torrefaction from 5.32 to 10.22%, there was no significant increase in the ash content after the addition of binders as the value ranged between 8.88 and 9.00% for the torrefied pellet sample used. The addition of binder further improved the HHV, pellet density, dimensional stability, and moisture uptake rate from approximately 21 to 24 MJ/kg, 1032 to 1393 kg/m3, 2.23 to 1.02%, and 16 to 9%, respectively for the torrefied pellet sample used. The energy efficiency of this system was improved by the addition of the substance lost during torrefaction as a heat source. [ABSTRACT FROM AUTHOR]

Bentonite is the traditionally used binder in iron ore pelletization. However, it consists of up to 85% silica and alumina which are undesired acidic gangue in iron-making. In this study, carboxymethyl cellulose, sodium lignosulfonate and cornstarch were used as acidic gangue-free organic alternatives to bentonite in synthesizing iron pellets. Iron ore, water and the corresponding binder were mixed and rolled in a pelletizing disk to form green pellets. The green pellets were dried and subsequently indurated in a furnace at 1200 °C to form indurated pellets. To evaluate the effectiveness of the organic binders, the pellets produced were tested on various pellet properties. Known industrial pellet property standards and the bentonite binder were used as references. Carboxymethyl cellulose, sodium lignosulfonate and corn starch produced green pellets with average drop numbers of 7.20 ± 0.84, 5.60 ± 0.89 and 6.00 ± 1.00 respectively, compared to bentonite's 5.00 ± 0.71. Dry pellets of average compressive strength 5.93 ± 0.09, 5.86 ± 0.03 and 11.52 ± 0.18 kg/pellet were produced by carboxymethyl cellulose, sodium lignosulfonate and corn starch respectively while bentonite's averaged 5.60 ± 0.08 kg/pellet. For indurated pellets, carboxymethyl cellulose (210.2 ± 1.88 kg/pellet) and sodium lignosulfonate (198.1 ± 2.49 kg/pellet) pellets were weaker than those of bentonite (250.4 ± 2.06 kg/pellet) but satisfied the industrial requirement of 181.4 kg/pellet. A boron oxide additive (0.1 wt. %) was used to boost the strength of carboxymethyl cellulose indurated pellets to 252.6 ± 1.32 kg/pellet, rendering them superior to those of bentonite. [ABSTRACT FROM AUTHOR]

The employment of metal-organic frameworks in powder form is undesirable from an industrial perspective due to process and safety issues. This work is devoted to evaluating the impact of compression on the textural and structural properties of CPO-27(Ni). For this purpose, CPO-27(Ni) was synthesized under hydrosolvothermal conditions and characterized. Then, the resulting powder was compressed into binderless pellets using variable compression forces ranging from 5–90 kN (37–678 MPa) and characterized by means of nitrogen adsorption/desorption, thermogravimetric analysis and powder X-ray diffraction to evaluate textural, thermal and structural changes. Both textural and structural properties decreased with increasing compression force. Thermal stability was impacted in pellets compressed at forces over 70 kN. CPO-27(Ni) pelletized at 5, 8 and 10 kN, and retained more than 94% of its initial textural properties, while a loss of about one-third of the textural property was observed for the two most compressed samples (70 and 90 kN) compared to the starting powder. [ABSTRACT FROM AUTHOR]

Torrefied biomass is characterized as a high-quality renewable energy commodity that can substitute fossil fuels. Combined torrefaction and pelletization are used to increase the value of biomass by improving its handling and fuel properties. The aim of this study is to present the influence of pelletization process on torrefaction in a pilot-scale unit. Above that, two process modes were assessed, and the properties of the torrefied and pelletized biomass and vice versa were studied. Mode I involved torrefaction prior pelletization. In mode II, on the contrary, the waste biomass was first pelletized and then torrefied. Analysis of mechanical parameters and chemical composition was therefore used to determine which of the modes was more advantageous. The results showed that within both modes it is evident that a higher torrefaction temperature caused wettability index decrease with a simultaneous higher heating value increase. Pellets produced in mode I showed better calorific values, however worse mechanical properties particularly durability. [ABSTRACT FROM AUTHOR]

The oral route of delivery is the most preferred route for administering most of the drugs. Pellets have gained importance since they offer numerous advantages like decreased dose dumping, improved patient compliance since dosing frequency is reduced, and ease of administering multiple chemically incompatible drugs immediately without the possibility of them interacting with each other. The critical variables related to process and equipment are identified and what impact they have on the quality of pellets formed is discussed. The position of the spray nozzle also affects the pellets and their yield. A complete guideline has been drawn which makes the process of pelletization using the Wurster method easier. The process variables affecting the pelletization process include inlet and product temperature, relative humidity, batch size; spray rate, and atomization air pressure and the equipment variables include column height, air distribution plate, a type of filter, and shaking interval. All these variables have a low, medium, or high impact on the process and they all together contribute to the quality of pellets formed. This review article focuses on critical process and equipment variables affecting the process of pelletization and the quality of pellets formed when using the Wurster equipment. The main objective is to review critical variables affecting the layering method of palletization and to sketch some basic problems encountered during pelletization and their troubleshooting. [ABSTRACT FROM AUTHOR]

Radioactive substances released as nuclear power plant accident can contaminate soil in a wide area. Soil washing is used as decontamination technique for Cs-contaminated soil, which exhibits short processing time and maximization of Cs removal rate by applying flocculating agents. However, soil washing generates secondary waste in the form of sludge/slurry. In this context, proposed a method of pelletization and solidification of powdered waste to facilitate treatment/disposal of the Cs-contaminated fine soil (secondary waste). In addition, by characterizing the prepared waste form, it was examined whether waste form satisfies Waste Acceptance Criteria for disposal facilities in South Korea. [ABSTRACT FROM AUTHOR]

Gasification reaction characteristics of pinewood block char (PW char) and pinewood pellet char (PWP char) were studied by analyzing CO (a component of syngas) generating rate at different temperatures (900, 1000, 1100 °C), respectively. The results demonstrated that the char with smaller size (15 mm) showed higher reactivity index than bigger size (30 mm). Increase in temperature (900 − 1100 °C) improved reaction rate and likely compensated for the diffusion resistance for larger particle. The reaction rate of PW char could be considered a constant varying from 10 to 90% carbon conversion when temperature was less than 1000 °C, and the nucleation and growth model with two close nucleation speed stages confirmed it. The parameter with great influence on PW char and PWP char gasification was porosity, followed by pore structure. Similar porosity between PW char and PWP char resulted in similar carbon conversion time, while more smaller pores (2–13.5 nm) of PW char led to high specific surface area (SSA) then increased higher gasification reactivity. These results are useful for gasification materials selection. Specifically of interest is adjustment of gasifier and bed layer movement to better match properties of materials. [ABSTRACT FROM AUTHOR]

Infrastructure development and urbanization have created a demand for the prime construction material—"Concrete." The manufacture of concrete has pressurized the aggregate supply chain for over-exploitation of natural resources leading to eco-detrimental impacts besides environmental regulations. The auxiliary sectors of the construction industry are creating a vast quantum of by-products and waste, causing environmental degradation, which concerns governing bodies. Developing aggregates artificially using these by-products and waste materials would be an eco-friendly and economical solution. This article provides an overview of the ingredients, production methods, and factors influencing the characteristics of such sustainable building materials, which can substitute conventional aggregates in the near future. [ABSTRACT FROM AUTHOR]

Manufacturing artificial aggregate by utilizing waste materials has gained great importance as the aggregate occupies a high volume in concrete (60-70%). In this paper, ground-granulated blast-furnace slag (GGBFS) is utilized in aggregate manufacturing. Cold bonding and sintering methods were used as production processes. The pellets were put through a series of tests such as dry density, specific gravity, water absorption, and crushing strength. The results indicated that the density of pellets increased by increasing the GGBFS dosage while the water absorption capacity was reduced. Furthermore, the highest crushed strength was recorded at 50% addition of GGBFS. [ABSTRACT FROM AUTHOR]

Abstract The Hayabusa2 spacecraft succeeded in sampling and returning materials from the C-type, near-Earth asteroid (162173) Ryugu. As part of the Hayabusa2 Initial Analyses, chemical and isotopic compositions of volatile species were measured. The samples analyzed were grains of about 1 mm in diameter and were individually treated without exposure to Earth’s atmosphere throughout the entire analytical/experimental processes to minimize alteration and contamination effects by adsorption of Earth’s atmosphere or chemical reactions with reactive species such as oxygen and water in Earth’s atmosphere. In order to perform spectroscopic and electron-microscopic observations in advance of a series of the isotopic measurements, the sample surface needed to be smoothed. We employed a pelletization method to obtain the required flatness for the returned samples because pelletization is a less sample-consuming method compared to mechanical polishing, microtomy, or ion milling. In order to perform the subsequent analyses, the samples must undergo minimal contamination during the pelletization procedure and be easy to remove from the pelletization tools. Therefore, embedding with resins or low-melting-point metals was not employed. Under these constraints, tools and methods for sample pelletization, handling, and transportation were developed. The tools developed for pelletization and housing also contributed to easier handling of small (less than about 1 mm in diameter) samples. Here we describe the methods and the tools that enable treatment of pristine asteroidal samples under non-atmospheric exposure conditions throughout transportation, weighing, pelletization, and installation into the instruments for chemical and isotopic measurements. The methods and tools we developed can be applied to other small samples including meteorites, cosmic dust, and future returned samples. Graphical Abstract

This study was aimed at utilizing a mixture of these by combination of torrefaction and co-pelletization process. The Box–Behnken design (BBD) response surface method (RSM) statistical experimental design technique was applied to achieve optimization of some of the significant torrefaction parameters. Torrefaction temperature, biomass mix composition, and particle size were selected as the experimental parameters. Calorific value and charcoal yield of torrefied mixed pellets were examined as the experimental responses. Based on the analysis of variance, all selected parameters were found significant study parameters, which affected both calorific value and charcoal yield. The interaction effects of the selected parameters well fitted with the second-order quadratic model equation. Model predictions were in good agreement with experimental data with 99.35% and 99.27% variability. The optimum values of the influencing parameters were found to be particle size between 100 and 125 μm, mix composition of 33%, and torrefaction temperature of 300 °C for maximum calorific value of 23.955 MJ/kg and charcoal yield of 40.841%. The physicochemical and thermal properties of the mixed torrefied pellet prepared at the optimum parameters were compared with raw coffee husk and cotton stalk. Accordingly, the mixed torrefied pellet demonstrated good characteristics in terms of charcoal yield and calorific value. [ABSTRACT FROM AUTHOR]

This work aimed to produce porous poly‐hydroxybutyrate (PHB) pellets in order to evaluate the pellets as a support for immobilization of the metagenomic lipase, LipG9. Four types of pelletized PHB particles with different morphological characteristics were obtained using the double emulsion and solvent evaporation technique (DESE). The micropores of these PHB pellets had similar average diameters (about 3 nm), but the pellets had different specific surface areas: 11.7 m2 g−1 for the PHB powder, 8.4 m2 g−1 for the control pellets (Ø < 0.5 mm, produced without the pore forming agent), 10.0 m2 g−1 for the small pellets (Ø < 0.5 mm), 9.5 m2 g−1 for the medium pellets (0.5 < Ø < 0.8 mm) and 8.4 m2 g−1 for the large pellets (Ø > 1.4 mm). Purified LipG9 was immobilized by adsorption on these pellets, and the results were compared with those obtained with PHB powder. The highest immobilization yield (83%) was obtained for the medium PHB pellets, followed by large (76%) and small (55%) PHB pellets. The activity of LipG9 immobilized on the pellets, for the synthesis of ethyl oleate in n‐hexane, was highest for the medium pellets (22 U g−1). The immobilization yield was high for PHB powder (99%) but the esterification activity was slightly lower (20 U g−1). These results show that pelletized PHB beads can be used for the immobilization of lipases, with the advantage that pelletized PHB will perform better than PHB powder in large‐scale enzyme bioreactors. [ABSTRACT FROM AUTHOR]

This study aimed to determine the best fungi to form the algal‐bacterial‐fungal symbionts and identify the optimal conditions for the synchronous processing of biogas slurry and biogas. Chlorella vulgaris (C. vulgaris) and endophytic bacteria (S395‐2) isolated from it, and four different fungi (Ganoderma lucidum, Pleurotus ostreatus, Pleurotus geesteranus, and Pleurotus corucopiae) were used to form different symbiotic systems. Four different concentrations of GR24 were added to systems to examine the growth characteristics, the content of chlorophyll a (CHL‐a), the activity of carbonic anhydrase (CA), the photosynthetic performance, the removal of nutrients, and the biogas purification performance. The results suggested that the growth rate, CA, CHL‐a content, and photosynthetic performance of the C. vulgaris‐endophytic bacteria‐Ganoderma lucidum symbionts were higher than the other three symbiotic systems when 10−9 M GR24 was added. The highest nutrients/CO2 removal efficiency 78.36 ± 6.98% for chemical oxygen demand (COD), 81.63 ± 7.35% for total nitrogen (TN), 84.05 ± 7.16% for total phosphorus (TP), and 65.18 ± 6.12% for CO2 was obtained under the above optimal conditions. This approach will provide a theoretical basis for the selection and optimization of the algal‐bacterial‐fungal symbionts for biogas slurry and biogas purification. Practitioner Points: Algae‐bacteria/fungal symbiont presents superior nutrients and CO2 removal capacities.The maximum CO2 removal efficiency was 65.18 ± 6.12%.The removal performance was affected by fungi type. [ABSTRACT FROM AUTHOR]

This work presents a thermochemical evaluation of fique bagasse waste resulting from industrial processes. Pelletization was implemented in order to mitigate the difficulty of dosing the raw waste with conventional feeding systems. The energy value of the fique bagasse used as fuel was evaluated separately through combustion and gasification. Combustion tests found the process to be thermally stable, and compatible with autothermal operation, with a thermal efficiency greater than 90% and a potential of use as energy close to 80% in the combustion gasses. Gasification produced the best quality of synthesis gas at an ER of 0.23, with a conversion greater than 96% and an HHV of greater than 5.0 MJ/Nm3, qualifying this gas as a potential heat source or as a fuel for power generation in internal combustion engines and micro-turbines. [ABSTRACT FROM AUTHOR]

Biomass pellets are one of the most crucial feedstocks for bioenergy production on a global scale due to their numerous advantages over raw biomass resources. Pellets provide improved energy density, bulk density, moisture content, and homogeneity thereby reducing storage, handling, and transportation costs. To produce high-quality solid fuel, it is necessary to comprehend the properties of wood fuel. This study explored the potential of Khaya senegalensis (khaya) as a dedicated energy crop (DEC) for the production of green energy. It thrives in less-than-ideal conditions and grows rapidly. The low durability of energy pellets raises the risk of dust and fire during handling and storage. In addition, the potential for fines and dust formation is strongly correlated with the mechanical strength of materials. Due to this necessity, the current study examines the effects of pelletization factors, including temperature and pressure, on pellet properties, particularly on its mechanical properties. The durability and compressive strength of pellets were determined using a sieve shaker and a universal testing machine, respectively. The highest mechanical durability was observed at 3 tons of pressure and 75 degrees Celsius, each with a value of 99.6%. The maximum axial compressive strength was measured at 57.53 MPa under 5 tons of pressure. When pelletized at 125 °C, the axial compressive strength increased by 13.8037% to 66.06 MPa compared to the strength obtained at 5 tons of pressure. Pelletizing Khaya feedstocks at 4 tons of pressure, on the other hand, produced a slightly lower diametral compressive strength of 7.08 MPa compared to 7.59 MPa at 125 °C. The experimental results revealed that the aforementioned factors significantly affect the mechanical properties of pellets. The elucidation of wood biomass, solid fuel qualities and pelletization parameters of this potential energy crop may facilitate the production of high-quality pellets from Khaya senegalensis wood to meet the increasing local and worldwide energy demands. [ABSTRACT FROM AUTHOR]

A comprehensive understanding of the mechanisms associated with the pelletization of an anaerobic digestate is necessary to optimize the pellet production process and achieve better and more sustainable management of the digestate. This work evaluated the digestate behavior during cyclic loading and unloading in a closed matrix. The results presented here are a continuation of those observed in previous work that evaluated the effect of moisture content on the behavior of the digestate under cyclic loading/unloading conditions in a closed matrix. The effect of moisture content on the distribution of permanent and elastic strain energy demonstrated in the previous study was verified in the present work under different loading conditions. A Zwick universal machine was used for the experiments. The samples were loaded with amplitudes of 8, 11, 14, 17, and 20 kN for 10 cycles. Two distinct moisture levels of the digestate—10% and 22%—were analyzed. The results of the present study confirmed that the elastic energy dissipated was independent of the moisture content of the digestate and remained relatively constant for a wide range of the applied loads. Higher values of elastic strain energy were observed for the digestate with higher moisture content only when higher loads were applied. In the range of the studied loads, characteristic differences were noted in loading/unloading curves regardless of the load magnitude. The increase in the applied load led to an increase in pellet strength, but only when the moisture content of the digestate was 10%. The results of the pellet strength reflect well the results of irreversible energy and the conclusions about the area enclosed between loading and unloading curves. [ABSTRACT FROM AUTHOR]

An agro-waste composite with a pelletized form was prepared and characterized via IR and 13C solids NMR spectroscopy. Thermal gravimetry analysis (TGA) was used to study the weight loss profiles, while SEM images provided insight on the biocomposite morphology, along with characterization of the sulfate adsorption properties under equilibrium and dynamic conditions. The sulfate monolayer adsorption capacity (qe = 23 mg/g) of the prepared agro-waste pellets was estimated from the adsorption isotherm results by employing the Langmuir model, and comparable fitting results were obtained by the Freundlich model. The dynamic adsorption properties were investigated via adsorption studies with a fixed bed column at pH 5.2. The effects of various parameters, including flow rate, bed height and initial concentrations of sulfate, were evaluated to estimate the optimal conditions for the separation of sulfate. The experimental data of the breakthrough curves were analyzed using the Thomas and Yoon–Nelson models, which provided satisfactory best-fits for the fixed bed kinetic adsorption results. The predicted adsorption capacities for all samples according to the Thomas model concur with the experimental values. The optimum conditions reported herein afford the highest dynamic adsorption capacity (30 mg/g) as follows: 1100 mg/L initial sulfate concentration, 30 cm bed height and 5 mL/min flow rate. The breakthrough time was measured to be 550 min. This study contributes to a strategy for controlled separation of sulfate using a sustainable biocomposite material that is suitable for fixed-bed column point-of-use water treatment systems. [ABSTRACT FROM AUTHOR]

This study addresses the effects of densification at varied pelletization temperatures on the novel Malaysian Khaya senegalensis wood-derived pellets biomass fuel characteristics. The lack of comprehensive understanding regarding the biomass fuel characteristics of this species prompted the research. By addressing this knowledge gap, this study explores the impact of temperature variations on key fuel properties, contributing to the optimization of sustainable biomass fuel production in manufacturing and materials processing. Khaya senegalensis wood, grown and harvested in Malaysia, was pelletized at different temperatures to analyze the calorific value, volatile matter content, ash content, fixed carbon, bulk density, and moisture contents of the pellets. The experimental data revealed a significant relationship between temperature and these fuel properties. Pelletizing at 75 °C produced the highest calorific value of 19.47 MJ/kg and the maximum fixed carbon content of 10.04%. A low ash level of 4.26% was achieved via pelletizing at 75 °C. According to the results, 75 °C produced the best thermophysical properties. These findings provide valuable understanding of how pelletization temperature influences fuel pellet thermophysical properties, a critical aspect in optimizing fuel pellet production, storage, advancing renewable energy resource utilization, and, finally, promoting a cleaner and more sustainable energy future.

The study investigates the use of artificial aggregates (AAs), specifically manufactured from ground granulated blast furnace slag (GGBFS) and ordinary Portland cement (OPC), to mitigate environmental harm caused by illegal quarrying due to the scarcity of natural aggregates (NAs). A cold-bonded pelletization technique was employed to produce five types of AAs with varying proportions of GGBFS & OPC as 82.5:17.5, 85:15, 87.5:12.5, 90:10, 95:5. The AAs with maximum OPC content exhibited a density of 1298 kg m ^−3 , water absorption of 4.8%, and crushing and impact values of 28.6% and 26.3%, respectively. The impact of these AAs on concrete properties was assessed, revealing that AAs facilitated the production of workable concrete with low-density ranges between 1700–2337 kg m ^−3 . Despite a decrease in concrete strength with higher AAs content, structural requirements were met, demonstrating AAs’ potential to effectively substitute natural coarse aggregates (NCAs). The concrete microstructure confirmed the formation of a strong interfacial transition zone (ITZ) and strength-developing cement-hydrated products. This research underscores the scientific contribution of AAs to address aggregate scarcity sustainably and recommends its application in structural elements by experimental validation.

This part reviews the goals of introducing organic binders into iron ore pelletization. Organic binders present a relatively small number of unique binding options but provide an extraordinary amount of flexibility in how to apply them. The key factors that lead into an effective organic binder are good dispersion into the iron ore, the ability to maintain the dispersion of the iron ore during the binding process, and limited water retention. The factors leading into a useful organic binder are more complex, depending on the availability of the material locally and the downsides it may introduce in the form of impurities (e.g. in some cases sulfur, phosphorous) or from poor quality control, especially for waste materials. Organic binders are primarily important because they do not typically introduce silica into the pellet, they are effective at lower overall weight dosages, and are more readily available in some locations than high-quality bentonite binders. A significant amount of emphasis is placed on the impact of organic binders on pellet strength, as the typically low dosages and the combustion of organic binders during firing means that most other pellet properties that would be negatively impacted by the presence of a binder are non-issues. Controlling dustiness among pellets formed with organic binders is also a major concern with several novel methods explored in recent years. [ABSTRACT FROM AUTHOR]

Pyrolysis of dry kitchen waste (KW) has been investigated using TGA/DTG, DSC, and lab-scale fixed-bed pyrolyser. Thermal characterization of the dry kitchen waste (KW) was carried out using standard protocols. The pyrolysis has been carried out at three different heating rates of 15, 20, and 40 °C/min from room temperature to 1000 °C. Kinetic analysis of the pyrolysis process using TGA data has been carried using iso-conversional model-free methods of Flynn-Wall-Ozawa (FWO), Kissinger–Akahira–Sunose (KAS), Tang, and Starink methods as well as model fitting method of Coats–Redfern. The pyrolysis for liquid yield (bio-oil) of pelletized KW was also performed at 400, 450, 500, 550, and 600 °C at a single heating rate of 15 °C/min in an inert atmosphere using a lab-scale fixed-bed pyrolyser. The maximum bio-oil yield (29.52%) was obtained at 500 °C. The FTIR results indicated the presence of alcoholic, phenolic, ester, and oxygenated group containing compounds, and GCMS results also indicated the presence of varying amounts of several organic molecules. The calorific value of the bio-oil was found to be 24 MJ/kg. [ABSTRACT FROM AUTHOR]

Tensile and impact test samples of ultra‐high molecular weight polyethylene (UHMWPE), high‐density polyethylene (HDPE), and their blends at various UHMWPE/HDPE weight ratios were prepared via compression molding and injection molding for thermal, rheological, and mechanical characterization. A twin‐screw extruder with either a tapered die with air‐cooling or a regular die was used to compound and extrude the materials prior to pelletization and molding. To the best of our knowledge, there has been no publication on pelletizing neat UHMWPE using a regular extruder. The differential scanning calorimetry analysis suggested the occurrence of re‐crystallization and co‐crystallization for all the blends. The rheology test confirmed that all the blends exhibited a solid‐like behavior and the degree of compatibility increased with increasing HDPE content in the blends. A strong synergistic effect was observed the blends possessed a higher tensile and impact strength than their neat UHMWPE and HDPE counterparts. The compression molded (95/5) UHMWPE/HDPE samples extruded using the tapered die yielded the highest tensile strength (50.1 MPa), which was about 40% higher than that of the neat UHMWPE samples. The best composition of these blends for compression and injection molded parts is 10% HD and 50% HD, respectively. [ABSTRACT FROM AUTHOR]

The demand for bioenergy is increasing due to the diminishing popularity of fossil fuels and rising greenhouse gas emissions. However, according to recent reports, renewable energy sources account for only 14% of the total primary energy supply, of which bioenergy accounts for 67%. Densification of biomass offers a sustainable pathway to generate solid fuels, which can replace coal while liberating bioenergy, reducing carbon emissions and valorizing organic wastes. Because of the rising demand for fuel pellets, there has been an increased interest in utilizing a wider range of biomass resources. Density, mechanical stability, hydrophobicity and energy content are the major properties controlling the quality of fuel pellets. These properties are influenced by biomass type, pretreatments, formulations such as binders, additives and lubricants, densification methods and conditions including temperature, pressure and relaxation time. Here we review biomass densification, mechanisms, factors affecting the pelletization process and pellet quality, and characterization techniques to access the fuel quality of pellets. Furthermore, we present additives, binders and lubricants used for the pelletization of a wide variety of biomass. This review also identifies the major applications for fuel pellets. [ABSTRACT FROM AUTHOR]

Hydrothermal carbonization is highly applicable to high moisture biomass upgrading due to fact that moisture involved can be directly used as reaction media under subcritical-water region. With this, value-added utilization of hydrochar as solid fuel with high carbon and energy density is one of the important pathways for biomass conversion. In this review, the dewatering properties of hydrochar after the hydrothermal carbonization of biowaste, coalification degree with elemental composition and evolution, pelletization of hydrochar to enhance the mechanical properties and density, coupled with the combustion properties of hydrochar biofuel were discussed with various biomass and carbonization parameters. Potential applications for the co-combustion with coal, cleaner properties and energy balance for biowaste hydrothermal carbonization were presented as well as the challenges. [ABSTRACT FROM AUTHOR]

Experimental research was carried out to produce pellets from bauxite residue for the further extraction of iron and alumina. Bauxite residue and limestone with three different mixture compositions were pelletized experimentally via agglomeration followed by drying and sintering at elevated temperatures. X-Ray diffraction (XRD) and scanning electron microscopy (SEM) were used for the phase and microstructural analysis, respectively. Tumble, abrasion, and breaking load tests were applied to determine the strength of the pellets. For measurement of porosity and surface area, mercury porosimetry and BET surface area methods were applied. It was found that at 1100 °C sintering temperature, all the three sintered pellet compositions have a moderate porosity and low strength, but the reverse result was found when 1200 °C sintering temperature was applied. Moreover, for the pellets sintered at 1150 °C high strength and proper porosities were obtained. In the sintered pellets, iron present in form of brownmillerite (Ca2Fe1.63Al0.36O5), srebrodolskite (Ca2Fe2O5), and fayalite (Fe2SiO4), while alumina present mostly in gehlenite (Ca2Al2SiO7) and little fraction in mayenite (Ca12Al14O33) and brownmillerite phases. The identified phases are the same for of the three pellets, however, with variations in their quantities. Porosity and mechanical properties of pellets are inversely related with both varying sintering temperature and composition. It was found that with more CaCO3 use in pelletizing, higher porosity is obtained. However, with increasing sintering temperature the strength of the pellets increases due to clustering of particles, while porosity decreases. [ABSTRACT FROM AUTHOR]

Pelletizing mixed plastic wastes (MPW) has gained interest as an upcycling technology and an alternative to conventional recycling. To investigate its potential, we conducted a cost analysis and life-cycle assessment (LCA) for a conceptual pelletization facility designed to produce 1 kg of pellets per batch of MPW (comprising polyethylene—PE and polypropylene—PP). This work has the following merits: (i) evaluating environmental impact (EI), cost analysis, and mechanical strength based on actual experimental data and its comparison with local and international manufacturers; (ii) enabling the evaluation of LCA impacts of MPW pellets; and (iii) emphasizing the significance of waste management in reducing EIs. The following ten EIs were assessed: climate change (CC), net energy, particulate matter formation, natural land transformation, metal depletion, marine ecotoxicity, ionising radiation, freshwater ecotoxicity, freshwater eutrophication, and terrestrial ecotoxicity. The CC of the as-synthesized pellets is 1.26 kg CO 2 eq., significantly lower than the data obtained from the Gulf Petrochemicals and Chemicals Association (GPCA) and an actual plant in Gulf Cooperation Council (GCC) countries. Additionally, the net energy required for the production of 1 kg of pellets is 54.1 MJ, while the cost is around 0.55 USD. The tensile strength of MPW pellets (24.63 MPa) falls between that of PE virgin pellets (21.12 MPa) and PP virgin pellets (28.12 MPa). This suggests that the MPW pellets exhibit competitive strength characteristics, warranting its consideration for applications where moderate strength is required. Overall, the competitive cost, coupled with the reduced EIs, demonstrates the potential of pelletization as a sustainable and economically viable waste management solution. [Display omitted] • MPW pelletization upcycles PE & PP, cutting environmental impact & costs. • Pelletizing MPW creates reusable material, reducing landfill waste. • LCA shows pelletization lowers GWP over traditional recycling. • Pellets cost ≈ 0.545 USD/kg, with strength near virgin plastics. • GCC countries can benefit from pelletization for sustainability. [ABSTRACT FROM AUTHOR]