Hubbry Logo
PelletizingPelletizingMain
Open search
Pelletizing
Community hub
Pelletizing
logo
7 pages, 0 posts
0 subscribers
Be the first to start a discussion here.
Be the first to start a discussion here.
Contribute something
Pelletizing
Pelletizing
Pelletizing
View on Wikipedia
from Wikipedia

Pelletizing is the process of compressing or molding a material into the shape of a pellet. A wide range of different materials are pelletized including chemicals, iron ore, animal compound feed, plastics (nurdles), waste materials, and more. The process is considered an excellent option for the storage and transport of said materials.[1] The technology is widely used in the powder metallurgy engineering and medicine industries.[2]

Iron ore

[edit]

Edward W Davis of the University of Minnesota is credited for devising the process of pelletizing iron ore.

Processed Taconite pellets as used in the steelmaking industry, with a US Quarter shown to scale.

Pelletizing iron ore is undertaken due to the excellent physical and metallurgical properties of iron ore pellets.[1] Iron ore pellets are spheres of typically 6–16 mm (0.24–0.63 in) to be used as raw material for blast furnaces. They typically contain 64–72% Fe and various additional material adjusting the chemical composition and the metallurgic properties of the pellets.[3] Typically limestone, dolomite and olivine is added and Bentonite is used as binder.

The process of pelletizing combines mixing of the raw material, forming the pellet and a thermal treatment baking the soft raw pellet to hard spheres. The raw material is rolled into a ball, then fired in a kiln or in travelling grate to sinter the particles into a hard sphere.[4]

The configuration of iron ore pellets as packed spheres in the blast furnace allows air to flow between the pellets, decreasing the resistance to the air that flows up through the layers of material during the smelting. The configuration of iron ore powder in a blast furnace is more tightly-packed and restricts the air flow. This is the reason that iron ore is preferred in the form of pellets rather than in the form of finer particles.[5] The quality of the iron ore pellets depends on different factors, which include feed particle size, amount of water used, disc rotating speed, inclination angle of the disc bottom, residence time in the disc as well as the quality and quantity of the binder(s) used.[1]

Preparation

[edit]

Additional materials are added to the iron ore (pellet feed) to meet the requirements of the final pellets. This is done by placing the mixture in the pelletizer, which can hold different types of ores and additives, and mixing to adjust the chemical composition and the metallurgic properties of the pellets. In general, the following stages are included in this period of processing: concentration / separation, homogenization of the substance ratios, milling, classification, increasing thickness, homogenization of the pulp and filtering.

Formation

[edit]
Disc Pelletizer

The formation of raw iron ore pellets, also known as pelletizing, has the objective of producing pellets in an appropriate band of sizes and with mechanical properties high usefulness during the stresses of transference, transport, and use. For example, waste materials are ground before being heated and introduced into a press for compression.[6] Both mechanical force and thermal processes are used to produce the correct pellet properties. From an equipment point of view there are two alternatives for industrial production of iron ore pellets: the drum and the pelletizing disk.

Thermal processing

[edit]

In order to confer to the pellets high resistance metallurgic mechanics and appropriate characteristics, the pellets are subjected to thermal processing, which involves stages of drying, preheating, firing, after-firing and cooling. The duration of each stage and the temperature that the pellets are subjected to have a strong influence on the final product quality.

Pharmaceutical industry

[edit]

In the field of medicine, pelletization is referred to as the agglomeration process that converts fine powders or granules into more or less spherical pellets.[7] The use of the technology increased because it allows for the controlled release of dosage form, which also lead to a uniform absorption with less mucosal irritation within the gastrointestinal tract.[7] There are different pelletization processes applied in the pharmaceutical industry and these typically vary according to the bonding forces.[8] Some examples of the processes include balling, compression, and spray congealing.[8] Balling is similar to the wet (or green) pelletization used in the iron ore industry.[9]

Animal feeds

[edit]
Animal feed pellets

Pelletizing of animal feeds can result in pellets from 1.2 mm (0.047 in) (shrimp feeds), through to 3–4 mm (0.12–0.16 in) (poultry feeds) up to 8–10 mm (0.31–0.39 in) (stock feeds). The pelletizing of stock feed is done with the pellet mill machinery, which is done in a feed mill.

Feed ingredients are normally first hammered to reduce the particle size of the ingredients. Ingredients are then batched, and then combined and mixed thoroughly by a feed mixer. Once the feed has been prepared to this stage the feed is ready to be pelletized.

Pelletizing is done in a pellet mill, where feed is normally conditioned and thermal-treated in the fitted conditioners of a pellet mill. The feed is then pushed through the holes and exit the pellet mill as pelleted feed.

Wood

[edit]
Wood pellets

Wood pellets made by compressing sawdust or other ground woody materials are used in a variety of energy and non-energy applications. In the energy sector, wood pellets are often used to replace coal with power plants such as Drax, in England, replacing most of their coal use with woody pellet. As sustainably harvested wood does not lead to a long-term increase in atmospheric carbon dioxide levels, wood fuels are considered to be a low-carbon form of energy.[10] Wood pellets are also used for domestic and commercial heating either in the form of automated boilers or pellet stoves. Compared to other fuels made from wood, pellets have the advantage of higher energy density, simpler handling as it flows similar to grain, and low moisture.

Concerns have been raised about the short-term carbon balance of wood pellet production, particularly if it is driving the harvesting of old or mature harvests that would otherwise not be logged.[11] Areas of concern include the inland rainforests of British Columbia These claims are contested by the pellet and forest industries.

After pelleting, the pellets are cooled with a cooler to bring the temperature of the feed down. Other post pelleting applications include post-pelleting conditioning, sorting via a screen, and maybe coating if required.

Plastics

[edit]
Plastic pellets

Plastic pellets, known as "nurdles", are used in the plastics industry.[12] They can pollute rivers and oceans when spilled, as birds and fish eat them mistaking them for eggs.[13]

See also

[edit]

References

[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

Pelletizing

View on Grokipedia
from Grokipedia

Pelletizing is an agglomeration process that converts fine particulate materials, such as powders, dusts, or fumes, into small, uniform spherical pellets to enhance handling, storage, transportation, and processing characteristics. The technique typically involves mixing the fines with a binder and moisture, followed by mechanical action in devices like disc pelletizers or rotary drums to form green pellets, which are then dried and indurated through heating to achieve strength. This method improves material , reduces dust loss, and ensures consistent size distribution for optimal performance in end-use applications. Widely applied in industries including , where it processes concentrates into pellets for efficient feed, pelletizing supports production by providing high-reducibility agglomerates that minimize and emissions compared to alternatives like . In plastics , it transforms molten polymers into uniform nurdles serving as standardized raw material for and molding. Additional sectors encompass production for improved digestibility and nutrient uniformity, pelletization from for dense energy carriers, and formulation for controlled-release properties. The process's versatility stems from its ability to handle diverse feedstocks while yielding pellets with tailored physical properties, such as and abrasion resistance, critical for industrial efficiency.

History

Origins and Early Developments

The process of pelletizing iron ore fines into spherical agglomerates originated with the patent granted to A. G. Andersson in Sweden in 1912 (Patent No. 35124), which described rolling moist fine ore in a rotating drum to form green balls, followed by drying and thermal firing to harden them. A similar patent was issued to C. A. Brackelsberg in Germany in 1913, focusing on analogous agglomeration techniques for powdered ores using binders like tar, which had been explored experimentally since the late 19th century. Early pilot-scale testing occurred in 1926 at Krupp's Rheinhausen Steel plant in , where a facility with a capacity of 120 tons per day demonstrated the feasibility of pelletizing followed by induration, though it was dismantled in 1937 due to limited demand for low-grade ore processing. , systematic research advanced in the 1940s at the University of Minnesota's Mines Experiment Station under Dr. E. W. Davis, targeting ores; initial experiments successfully fired experimental pellets in a shaft furnace by 1943, establishing key parameters for binder use and . Commercial adoption began in the early , with the first full-scale pellet plant operational in Babbitt, , in 1952, processing concentrates into feed. saw parallel commercialization starting in the using vertical-shaft kilns for induration, with initial plants producing 10,000 to 60,000 tons annually. By 1954, the Reserve Mining Company in commissioned an experimental pelletizing machine with 1,000 tons per day capacity, scaling to larger operations, while the Erie Mining Company's Hoyt Lakes plant, equipped with 24 vertical shaft furnaces, began production in 1957, marking a shift toward handling vast low-grade ore reserves depleted of high-grade natural ores.

Expansion and Industrial Adoption

The expansion of iron ore pelletizing gained momentum in the mid-20th century, driven by the depletion of high-grade natural ores and the post-World War II surge in global steel demand, which necessitated efficient processing of fine concentrates from low-grade deposits like taconite. In the United States, Minnesota's Iron Range pioneered large-scale adoption to sustain the domestic iron mining industry; the Reserve Mining Company's plant in Silver Bay commenced commercial taconite pellet production in 1955, marking a pivotal shift toward beneficiation and agglomeration of previously uneconomic ores. This was followed by Erie Mining Company's facility in Hoyt Lakes starting operations in 1957, enabling the utilization of vast taconite reserves estimated at billions of tons. Industrial adoption accelerated through the 1950s and 1960s as pelletizing addressed key limitations of fine ores, such as poor permeability in blast furnaces and handling difficulties, by producing uniform, high-strength agglomerates with iron contents typically exceeding 65%. U.S. pellet output rose from about 5 million short tons in 1955, representing roughly 5% of usable iron ore production, to approximately 17 million short tons by the late 1960s, accounting for over 23% of total input to steelmaking. Concurrently, Sweden scaled up commercial plants in the 1950s using vertical-shaft kilns with capacities of 10,000 to 60,000 tons per year, while innovations like the straight-grate and grate-kiln induration processes—first commercialized around 1960—facilitated larger facilities and higher throughputs, boosting efficiency and reducing energy use. By the , pelletizing had become integral to the industry worldwide, with adoption in , , and emerging producers like , as pellets offered superior reducibility and decreased coke consumption compared to sinter or lump ore. Global capacity expanded dramatically, from modest beginnings to supporting over 300 million tons annually by the , reflecting pelletizing's role in extending ore reserves and optimizing performance. Further growth in the late 20th and early 21st centuries, with world pelletizing capacity increasing from 350 million tons per year in 2000 to more than 600 million tons per year in 2020, was propelled by rising demands in and the shift toward direct reduction processes requiring high-quality feeds. This evolution underscored pelletizing's causal importance in sustaining ironmaking amid resource constraints, though early environmental concerns, such as disposal from processing, prompted regulatory adaptations without halting expansion.

Key Technological Milestones

The concept of pelletizing fines into spherical agglomerates was first ed in 1912 by A.G. Andersson in , who described a of rolling moist ore into balls followed by and firing. A similar was granted in 1913 to C.A. Brackelsberg in . These early inventions laid the groundwork for transforming fine concentrates into handleable forms suitable for blast furnaces, addressing issues with dust loss and inefficient charging. Industrial experimentation advanced in 1926 when constructed a pilot pellet plant at its Rheinhausen Steel works in , capable of producing 120 tons per day using shaft furnace induration; the facility operated until its dismantling in 1937. Significant progress for low-grade ores occurred in the United States during the 1940s, with E.W. Davis at the demonstrating viability in 1943 via an experimental shaft furnace. Commercialization accelerated in the 1950s in , where the first full-scale employed vertical shaft kilns for induration, achieving annual capacities of 10,000 to 60,000 tons. Key process innovations emerged in the mid-1950s, including the introduction of grate machines for preliminary drying and preheating. In 1956, Iron Company commissioned a grate-based operation at Eagle Mills, . The grate-kiln system, developed by , marked a major advancement by combining traveling grate preheating with firing for uniform induration; its first commercial plant started at Humboldt Mine, , in 1960, enabling higher throughput and better control over pellet quality. Parallel developments included multi-shaft furnace setups, such as the 1957 Erie Mining Company plant at Hoyt Lakes with 24 vertical shafts. These milestones shifted pelletizing from experimental to industrial scale, with straight-grate variants later optimizing for diverse ore feeds and larger capacities.

Fundamental Principles

Feedstock Preparation

Feedstock preparation in pelletizing encompasses the pretreatment of raw materials to achieve uniform (PSD), optimal content, and incorporation of binders or additives, ensuring effective agglomeration during subsequent stages. This step is critical for producing pellets with sufficient strength and uniformity, as inconsistencies can lead to poor pellet quality or process inefficiencies. Key objectives include reducing to enhance interparticle , controlling to promote plasticity without causing excessive or dusting, and blending additives to improve mechanical properties. Size reduction via crushing or grinding is typically the first subprocess, targeting a fine PSD—often with 80% of particles below 150 microns for mineral feedstocks like concentrates—to maximize surface area for binding while avoiding excessive fines that could hinder flowability. For or organic materials, grinding to 1-3 mm particles balances and mill operability, as overly fine particles increase demands and risk equipment jamming. Uniformity in PSD, achieved through screening or , is essential across feedstocks, though slight variance aids in forming robust pellets by facilitating interlocking during compression. Moisture adjustment follows, often via to 8-12% for cellulosic or pre-moistening dry powders, as levels outside the material-specific optimum (determined empirically) impair green pellet formation—excess moisture yields sticky masses, while deficiency causes . In mineral applications, water addition during mixing targets 9-10% to enable balling without disintegration. methods, such as rotary dryers, prevent mud-like behavior in wet feedstocks, while conditioning with softens lignins in for natural binding under and . Binders and additives are dosed and mixed homogeneously, typically at 0.5-1% by weight, to enhance adhesion; is standard for iron ores due to its swelling properties that confer green strength, though it introduces silica impurities, prompting exploration of organic alternatives like or for lower contamination. Mixing in pugmills or pin mixers ensures even distribution, preventing localized weaknesses. Impurities are removed via or screening, particularly in ores, to maintain chemical purity. These preparations are tailored by material—e.g., higher moisture tolerance in starch-rich feeds versus minerals—but universally prioritize empirical testing for PSD and moisture optima to optimize downstream pellet integrity.

Agglomeration Mechanisms

In wet pelletizing processes, agglomeration begins with , where fine particles are wetted by a binder, typically or a solution, forming initial small aggregates through the creation of pendular liquid bridges between particles; these bridges are stabilized primarily by forces arising from . As agitation continues in such as balling drums or discs, these nuclei grow via coalescence, in which colliding granules deform viscously or plastically upon impact, merging into larger entities if the overcomes inter-granule repulsion and insufficient liquid leads to successful bonding without rebound. Layering, or snowballing, represents another dominant growth mechanism, particularly in continuous operations, wherein moist fines adhere to the surface of existing pellets during tumbling, incrementally increasing size through successive deposition driven by capillary and mechanical interlocking. Concurrently, consolidation occurs as granules densify under compressive forces from agitation, expelling excess liquid and enhancing structural integrity via viscous flow and particle rearrangement. Opposing these growth processes are breakage and abrasion, where excessive fragments oversized pellets or erodes surfaces, redistributing material and influencing the final size distribution; optimal conditions balance growth and disruption to achieve uniform pellets typically 8-16 mm in . At the microscopic level, bonding transitions from pendular (isolated bridges with high negative ) to (interconnected filling voids, maximizing attractive forces) states as moisture content rises to 8-10% by weight, with viscous forces from binders like contributing to deformation resistance. In dry or compaction-based pelletizing, such as for or feeds, mechanisms shift toward solid-state via van der Waals forces, electrostatic interactions, and deformation under high pressure, without relying on phases. These mechanisms are modulated by factors including (finer particles favor ), binder (higher promotes coalescence over layering), and agitation intensity, with empirical models confirming predominance of layering and coalescence in industrial balling drums operating at 20-30 rpm.

Binding and Induration Processes

Binding processes in pelletizing primarily occur during the formation of green pellets, where fine particles are agglomerated using moisture and binders to achieve initial cohesion through capillary forces, viscous bonding, and adhesive interactions. Common binders include bentonite clay, added at approximately 0.5 wt%, which swells upon wetting to form viscous bonds and solid bridges upon drying, though it introduces silica and alumina impurities that can lower ore grade by 0.6 wt% per 1% bentonite. Organic polymers such as sodium lignosulfonate, starch, or sodium carboxymethyl cellulose provide alternative binding via hydrogen bonding, electrostatic adhesion to particle surfaces, and polymer chain entanglement, enhancing green pellet drop resistance (4–6 drops per pellet) without residual impurities after burnout. These binding mechanisms rely on interfacial forces like liquid bridges from controlled (typically 8–10 wt%) and molecular attractions such as van der Waals forces, ensuring pellets of 8–16 diameter withstand handling before induration. Combined binder systems, pairing organics with inorganic salts, further optimize wet, dry, and preheated strengths by promoting even dispersion and reducing sticking during thermal treatment. Induration follows to impart permanent strength, involving thermal processing that hardens pellets through , , and solid-state , converting temporary bonds into robust solid bridges. The process comprises drying up to 300°C to evaporate moisture, preheating to 1000–1100°C for initial oxidation, firing at 1200–1350°C to achieve metallurgical bonding, and cooling with ambient air for heat recovery, resulting in compressive strengths exceeding 2500 N per pellet. Straight-grate furnaces, accounting for about 60% of production, process pellets continuously across zones of drying, firing, and cooling, while grate-kiln systems separate preheating on a grate from firing, offering flexibility for varied feeds. Organic binders may lower bursting temperatures during induration due to gases but improve overall and reducibility when supplemented with additives like borates to form supportive phases. These steps ensure pellets suitable for blast furnaces or direct reduction, with principles adaptable to non-ore materials requiring enhanced durability.

Metallurgical Applications

Iron Ore Pelletizing

Iron ore pelletizing agglomerates fine iron ore concentrates, typically below 150 micrometers from beneficiation processes, into strong, uniform spheres of 8 to 16 millimeters in diameter for efficient metallurgical reduction. This method addresses the challenges posed by the high proportion of fines in modern low-grade ores, which would otherwise cause poor gas permeability and reduced productivity in blast furnaces if charged directly. Pellets typically contain 62 to 66 percent iron, with binders such as bentonite added at 0.5 to 1 percent to enhance green pellet strength during formation. The process begins with feedstock preparation, involving grinding to fine particles, often mixed with fluxes like for slag control and binders for adhesion. Green pellets are formed via tumbling in rotating drums or discs, where rolling motion and moisture (around 9 percent) promote spherical agglomeration through deformation and capillary forces. Induration follows, hardening the green pellets through thermal treatment: drying at 100 to 200°C removes moisture, preheating to 900 to 1100°C initiates oxidation for ores, and firing at 1200 to 1350°C in straight-grate or grate-kiln systems sinters the particles, achieving compressive strengths exceeding 200 kg per pellet. Straight-grate processes suit ores, enabling in-situ magnetization, while grate-kiln systems offer flexibility for various ore types and higher throughputs up to 10 million tons annually per plant. In operations, pellets enhance burden permeability due to their uniform (25 to 30 percent) and size consistency, facilitating better reducing gas distribution and faster iron reduction compared to sinter or lump . This results in higher furnace productivity, reduced coke consumption by 10 to 20 kilograms per ton of hot metal, and lower dust generation during handling and charging. Pellets also support production in shaft furnaces, where their mechanical strength withstands high temperatures without excessive degradation. Global pellet production reached approximately 400 million tons in 2023, with major capacity in , , and , driven by demand for high-quality inputs amid depleting lump reserves.

Other Ore and Mineral Pelletizing

Pelletizing of non-ferrous ores and other minerals involves agglomerating fine particles into uniform pellets to facilitate handling, reduce dust loss, and enhance metallurgical efficiency, similar to processes but adapted to specific mineralogies such as varying silica content or behavior. For , fines are mixed with binders like or organic alternatives, formed into green pellets via disc pelletization, and indurated through or pellet-sintering to achieve compressive strengths suitable for in submerged arc furnaces. This approach addresses the frail nature of chromite concentrates, enabling pre-oxidative that liberates iron from chromite at elevated temperatures, with pellet quality influenced by grind size and flux additions for control. Manganese ore fines, often containing high levels of , are pelletized using binders at 1-1.2 wt% addition and 15% moisture in disc pelletizers, followed by firing in grate-kiln systems to produce high-strength pellets for (EAF) feed in ferromanganese production. The process yields uniform pellets with stable compositions, outperforming in energy efficiency and productivity, though challenges include controlling cracking from during induration. For low-grade powdery ores, pelletizing precedes alkaline leaching, where green pellets are formed and sintered to improve zinc dissolution rates by reducing solidification time and enhancing reactivity. Phosphate rock fines, particularly low-grade powders, undergo pelletization to boost utilization in production, involving grinding to fine sizes, binder addition (e.g., or organics), and nodulation or pan pelletizing followed by to form durable pellets with controlled particle and release properties. This agglomeration eliminates dust issues and improves storage flowability, with processes like defluorination sometimes integrated post-pelletizing for ore upgrading. Nickel concentrates and copper-nickel have been granulated or pelletized similarly, using for to recover metals while forming stable aggregates for further hydrometallurgical treatment. Across these applications, pelletizing enhances dust control and transport economics compared to fines handling, but requires tailored induration—often at 1200-1400°C—to account for mineral-specific thermal behaviors, with binders selected to minimize introduction. Industry adoption remains less widespread than for due to ore variability and process economics, though advancements in organic binders aim to replace for purity in non-ferrous applications.

Agricultural and Feed Applications

Animal Feed Pelletizing

Animal feed pelletizing involves compressing ground feed ingredients, such as grains, proteins, and vitamins, into durable cylindrical pellets using mechanical pressure and heat, primarily to enhance nutritional delivery and handling efficiency in livestock, poultry, and aquaculture operations. This process originated in the early 20th century with the development of pellet mills, including the Schüler press in the 1920s, which used interlocking rollers to form feed mash into pellets, marking a shift from loose foraging or mash feeds to structured rations. By the mid-20th century, pelleting became widespread in commercial feed production due to its ability to reduce ingredient segregation and improve bulk density for storage and transport. The core process begins with feedstock preparation, grinding ingredients to uniform (typically 0.5-2 mm) to ensure even mixing and , followed by blending with binders like or steam-conditioned . Conditioning involves adding steam at 70-90°C to gelatinize starches and soften fibers, increasing pellet durability; the conditioned mash then passes through a ring-die or flat-die pellet mill where two rollers force it against a perforated die, extruding pellets at pressures of 20-100 MPa and temperatures up to 90°C. Post-pelletization, pellets are cooled to ambient temperature in counterflow coolers to harden them and reduce moisture to 10-12%, followed by screening to remove fines and crumbling for smaller animals like chicks. Pelleted feeds offer empirical advantages over mash forms, including 5-10% improvements in feed conversion ratios (FCR) for broilers and due to enhanced digestibility from and reduced selective feeding, leading to more uniform nutrient intake. Studies confirm that high-quality pellets minimize dust and waste, lowering feed costs by up to 7% through better flowability and reduced spoilage, while promoting gut health via slower ingestion rates that stimulate gizzard development in birds. Globally, a significant portion of the 1.396 billion metric tons of compound feed produced in 2024 is pelleted, particularly for and pigs, where pelleting rates exceed 80% in intensive systems to optimize growth performance. Equipment advancements, such as variable-speed conditioners and dies with optimized hole patterns, have improved pellet quality metrics like the Pellet Durability Index (PDI), targeting >90% to prevent breakage during handling. For ruminants, larger pellets (8-12 mm) reduce sorting behavior, while uses floating or sinking variants tailored to species like , where pelleting enhances stability and minimizes leaching. Challenges include energy-intensive operations (up to 20-30 kWh/) and potential degradation from overheating, necessitating precise control to preserve vitamins and enzymes. Overall, pelleting's causal benefits stem from physical agglomeration that enforces consistent consumption, supported by decades of production data showing superior animal outcomes when PDI and conditioning are optimized.

Fertilizer and Soil Amendment Pellets

Pelletizing fertilizers and soil amendments entails the mechanical agglomeration of powdered or slurry-based feedstocks into compact, uniform granules or cylinders, typically 3-6 mm in diameter, to enhance manageability and agronomic efficacy. The process often employs extrusion for moist organic materials (up to 20% moisture content), where forced feeding through a die forms dense pellets, or rotary drum/disc methods for inorganic formulations, involving tumbling of reactive slurries that solidify into spherical shapes during chemical reactions. These techniques incorporate binders like water or biochar to optimize pellet durability, with production stages including crushing, mixing, pelleting, drying, and cooling to achieve densities exceeding 900 kg/m³ and abrasion resistance above 95%. Feedstocks commonly pelletized encompass organic sources such as animal manures, , and co-mixtures with or ash (SSA), yielding nutrient-rich products with controlled heavy metal levels below regulatory thresholds. Inorganic amendments, including lime-based fertilizers and , undergo disc pelletizing to form stable aggregates suitable for acid neutralization. Waste-derived materials, like wood pellet ash rich in and micronutrients or , are processed into conditioner pellets that repurpose byproducts while providing and mineral supplementation. Pelletization confers operational advantages by minimizing dust generation, enabling bulk storage without settling or , and facilitating precise application that reduces uneven distribution. Agronomically, pellets promote slow-release dynamics, particularly for , where processing parameters like compression and binder ratios extend soil residence time, curbing leaching losses by up to 30-50% compared to uncoated powders and boosting crop uptake efficiency. Soil amendments in pellet form enhance physical properties, including water-holding capacity, texture, and microbial , as evidenced by compost-biochar mixtures that increased bioavailability and suppressed in field trials. This technology supports waste recycling, converting manure or industrial residues into marketable fertilizers that maintain with lower environmental footprints than synthetic alternatives, including reduced runoff and from handling. However, pellet quality hinges on feedstock homogeneity and induration conditions, with suboptimal potentially leading to under field exposure.

Pharmaceutical Applications

Techniques for Drug Delivery Systems

Pelletization techniques in pharmaceutical systems produce multiparticulate , typically spherical units ranging from 0.5 to 2 mm in diameter, which enhance , enable controlled release, and reduce variability in gastrointestinal transit compared to single-unit forms. These methods facilitate site-specific delivery, such as enteric or colonic targeting, by allowing subsequent of uniform pellets, thereby minimizing risks like observed in matrix tablets. Pellet-based systems are particularly advantageous for drugs with narrow therapeutic indices, as their dispersion in the gut promotes more predictable absorption profiles. The predominant technique, extrusion-spheronization, involves preparing a wet mass of active pharmaceutical ingredient (API), excipients like , and a granulating , followed by through a die to form cylindrical rods that are cut into short segments and rounded in a spheronizer via . Developed in the early , this process yields high and , making it suitable for sustained-release formulations where pellet during and compression into capsules is critical. Key parameters include liquid-to-solid ratio (typically 0.3–0.5), screen size (0.5–1.5 mm), and spheronizer speed (500–2000 rpm), which influence pellet density and ; deviations can lead to irregular shapes or breakage, compromising release kinetics. This method accommodates both hydrophilic and lipophilic APIs but requires optimization to avoid overheating sensitive compounds. Layering techniques, including powder layering and solution/suspension layering, deposit onto starter cores such as nonpareil sugar spheres or beads in a centrifugal pan coater or apparatus. Powder layering sprays binder solutions alternately with -excipient powders, achieving high drug loads (up to 90% w/w) for potent APIs, while solution layering dissolves the drug for uniform deposition, ideal for poorly soluble compounds to enhance dissolution rates. These methods support multiparticulate systems for pulsatile release, with process controls like atomization pressure and bed ensuring layer and preventing agglomeration; for instance, layering has been used in formulations like enteric-coated omeprazole pellets to protect against . Drawbacks include potential core erosion during GI transit if not properly sealed, necessitating robust subcoating. Alternative approaches include hot-melt , where and polymers are melted and extruded into strands that are spheronized or pelletized post-cooling, enabling lipid-based matrices for gastroretentive floating systems. This technique, applied since the 1990s for sustained-release profiles, avoids solvents but demands thermal stability from the , with screw speed and (typically 80–150°C) dictating melt and pellet uniformity. Cryopelletization and spray congealing, involving freezing or rapid solidification of emulsions, produce porous pellets for immediate-release or taste-masked applications, though scalability remains limited compared to methods. Across techniques, pellet quality is assessed via parameters like (<1.2 for ), Hausner ratio (<1.25 for flowability), and dissolution matching pharmacokinetic targets, ensuring efficacy in delivery systems.

Biomass and Fuel Applications

Wood and Biomass Pellet Production

Wood and biomass pellets are produced by compressing lignocellulosic materials into dense, cylindrical forms typically 6-8 mm in diameter, primarily for use as renewable in heating, power generation, and co-firing applications. The process relies on the natural binding properties of , which softens under and during , eliminating the need for added binders in most cases. Raw materials consist mainly of wood residues such as , shavings, and chips from sawmills and mills, which account for the majority of production; non-wood includes agricultural residues like , rice husks, and energy crops such as switchgrass or . The production process begins with feedstock , involving debarking and chipping of logs or slabs to uniform sizes under 50 mm, followed by grinding in hammer mills to particles of 2-5 mm for optimal density and flow. Moisture content is then adjusted to 10-15% through , often using rotary drum or flash dryers fueled by waste, as higher moisture impedes pellet formation and leads to energy inefficiency. Pelletizing occurs in mills where conditioned is forced through a heated die under pressures of 30-100 MPa and temperatures of 80-100°C, forming soft strands that are cut to length; ring-die mills predominate in commercial operations for capacities exceeding 1 ton per hour, while flat-die types suit smaller scales. Post-extrusion, pellets are cooled to ambient temperature in counterflow coolers to solidify structure and reduce moisture below 10%, then screened for fines and packaged. Equipment demands significant energy, with pellet mills requiring 50-100 kW per metric ton of hourly output, and total plant efficiency influenced by integrated drying systems that recover heat from exhaust gases. Quality standards, such as ENplus established by the European Pellet Council in 2010, classify pellets into grades A1 (premium residential, ash <0.7%, nitrogen <0.3%) and A2 (higher ash tolerance), prohibiting chemically treated or demolition wood to ensure low emissions and consistent ; compliance involves third-party for from source to delivery. In the United States, the Pellet Fuels Institute (PFI) standards similarly emphasize mechanical durability above 96.5% and over 600 kg/m³. Global production reached approximately 48 million metric tons in 2024, with the European Union-27 as the leading region at over 20 million tons, driven by policy support for co-firing; the exported 10 million tons that year, primarily from southern pine residues. Growth averaged 8-10% annually pre-2023, stabilizing amid constraints, though demand for certified pellets persists due to their higher (17-19 MJ/kg) compared to loose .

Efficiency and Combustion Characteristics

Biomass pellets, particularly pellets, exhibit combustion efficiencies typically ranging from 70% to 83% in certified pellet stoves, surpassing traditional wood-burning stoves which often achieve only 50-70% due to inconsistent fuel size and higher content. Modern pellet boilers and stoves can reach up to 95% through automated air- mixing and controlled , minimizing heat loss compared to open-fire wood systems. This efficiency stems from the pellets' uniform density (approximately 40 lb/ft³ versus 10-25 lb/ft³ for raw ) and low content (under 10%), enabling consistent ignition and sustained burning. Combustion characteristics of biomass pellets include rapid ignition (often within seconds in optimized burners) and steady flame propagation due to their high volatile content (70-80%), which releases gases that burn more completely than in loose biomass. Pellet orientation and composition influence burn profiles; for instance, additives like rice husk can extend combustion duration by up to 16% while reducing peak temperatures. Torrefied pellets, processed at 225-300°C, demonstrate higher (up to 29.9 MJ/kg versus 18.9 MJ/kg for untreated wood) and more even , with slower ignition but lower burnout temperatures, contributing to reduced slagging. Emissions during pellet combustion are characterized by low particulate matter (often below EPA limits for certified appliances) and efficient conversion averaging 80-93% across various pellet types, though non-biomass baselines show biomass facilities emitting up to 2.8 times more CO₂ per unit energy due to lower inherent energy density. Higher torrefaction temperatures further mitigate CO, CO₂, and NOₓ outputs, but untreated pellets can produce elevated volatiles leading to incomplete combustion if moisture exceeds optimal levels. Ash content, typically 0.5-3% for quality wood pellets, fuses at higher temperatures than raw wood residues, reducing operational disruptions in automated systems.

Polymer and Materials Processing

Plastics and Polymer Pelletizing

Polymer pelletizing involves extruding molten thermoplastic polymers through a die to form continuous strands or directly cut shapes, followed by cooling and into uniform pellets typically 1-5 mm in diameter, serving as standardized feedstock for processes like injection molding and . This method enhances , metering accuracy, and uniformity in downstream , applicable to both virgin resins and recycled plastics. Pelletizing originated with strand-cutting techniques in the mid-20th century, evolving to systems invented in the 1950s by Automatik, which improved efficiency for heat-sensitive or sticky polymers by enabling immediate cooling and cutting in water. Key techniques include strand pelletizing, where extruded strands are cooled in water baths or air and then chopped into pellets, suitable for stable, non-sticky materials like ; underwater pelletizing, which cuts pellets directly in a for rapid , ideal for viscous or hydrolyzable polymers such as PVC or ; and die-face or hot-face pelletizing, involving cutting at the die exit followed by air or cooling, often used for with additives. Water-ring pelletizing, a variant, employs rotating blades against a die face submerged in a water ring for cooling, balancing cost and performance for standard thermoplastics. Selection depends on polymer properties, throughput rates—often exceeding 10 tons per hour in industrial systems—and desired pellet quality, with underwater methods reducing defects like fines or tails in challenging formulations. In recycling, pelletizing converts post-consumer or industrial plastic waste into reusable granules after sorting, shredding, washing, and melting, enabling closed-loop material flows and reducing reliance on virgin production. Life-cycle assessments indicate that pellets from recycled plastics emit 22.6% less carbon and 11-40% lower impacts in other categories compared to virgin equivalents, though process energy for melting and extrusion contributes to overall footprint. However, handling risks exist, as spills of pre-production pellets—known as nurdles—release an estimated 445,000 tonnes annually into global environments, exacerbating microplastic pollution despite regulatory efforts like the EU's 2023 measures to curb losses. Modern systems incorporate automation and filtration to minimize such losses, prioritizing safety and yield in operations processing biopolymers, adhesives, and engineering plastics.

Impacts and Controversies

Economic and Operational Benefits

Pelletizing enhances by increasing material , which reduces storage volume requirements and facilitates automated handling systems in industries such as and production. For instance, in processing, pellets exhibit superior resistance to degradation during and storage compared to fines, minimizing in and enabling consistent feeding into furnaces. In manufacturing, pelleted forms improve flowability through bins and reduce generation, lowering equipment maintenance needs and enhancing safety in processing facilities. Economically, pelletizing supports cost reductions in logistics and waste management by converting fines or by-products into value-added products, extending resource lifecycles. Iron ore pellet plants have demonstrated after-tax internal rates of return up to 25% and annual EBITDA of US$173 million at US$70/t pellet prices, driven by efficient utilization of low-grade ores otherwise unsuitable for direct reduction. Biomass pellet production from agricultural residues, such as corn straw, can cut heating fuel costs by approximately USD 254.26 per hectare while diverting waste from landfills, promoting circular economies. In polymer recycling, pelletizing recycled plastics yields uniform feedstocks that lower downstream processing expenses and reduce landfill fees associated with waste disposal. Operationally, the process improves downstream performance metrics, such as combustion uniformity in fuels and digestibility in feeds, leading to indirect economic gains through higher yields. Wood pellets achieve densities that halve fuel costs relative to fossil alternatives like or gas, with burning times comparable to despite lower dosage volumes. In feed applications, pelleting boosts animal growth rates and feed conversion ratios by up to 10-15% via reduced selective feeding and nutrient loss, optimizing farm-level productivity. These benefits collectively lower capital and operational expenditures, with pelletizing enabling scalable production from marginal feedstocks in and biofuels.

Environmental Effects and Criticisms

Biomass pellet production generates significant , including particulate matter (PM2.5), volatile organic compounds, nitrogen oxides, and hazardous pollutants such as polycyclic aromatic hydrocarbons (PAHs) and dioxins during grinding, , and pelletizing stages. These emissions have been linked to respiratory issues and cancer risks in communities near facilities, particularly in the U.S. , where production has expanded rapidly. Lifecycle analyses indicate that harvesting, processing, and transporting wood for pellets can result in net exceeding those of when accounting for carbon debt from forest regrowth delays, challenging claims of carbon neutrality. Critics, including environmental groups and scientists, argue that sustainability certifications like the Sustainable Biomass Program fail to ensure residue-only sourcing, often relying on whole trees and contributing to and . Iron ore pelletizing is energy-intensive, relying on fossil fuels for drying and induration, which drives 86% of fossil and 95% of depletion impacts in assessed plants. for pellet feedstock emits particulate matter that affects human health through , while and water use exacerbate local disruption. Although pellets improve efficiency and reduce coking coal needs in —potentially lowering CO2 emissions per ton of —unmitigated dust and emissions from pellet plants have prompted calls for stricter controls. Studies emphasize that without cleaner integration, such as hydrogen-based processes, pelletizing perpetuates high environmental footprints tied to global demand. Plastic pelletizing contributes to microplastic via nurdle spills during , , and handling, with an estimated 445,970 tonnes entering global environments annually. These pellets, often 2-5 mm in size, are ingested by , mimicking and carrying adsorbed toxins like PCBs and additives that bioaccumulate up food chains, threatening fisheries and . High-profile incidents, such as the 2021 spill off releasing 1,410 tonnes, demonstrated agglomeration, fragmentation, and chemical alteration under environmental exposure, amplifying ecological harm. Regulatory efforts, including IMO guidelines, highlight ongoing challenges in preventing leaks despite industry protocols. Fertilizer pelletizing aims to control release, potentially reducing leaching and compared to uncoated forms, but production emissions and overapplication still drive . Ammonia-based synthesis emits NOx and contributes to , while excess and from fields cause algal blooms depleting oxygen in waterways, as seen in U.S. dead zones. Pelletized variants show promise in enhancing efficiency and minimizing runoff, yet lifecycle assessments reveal persistent GHG emissions from energy use in . Criticisms focus on insufficient adoption of slow-release technologies to counter systemic overuse in intensive .

Recent Developments

Technological Innovations

In biomass pellet production, pretreatment has emerged as a key , enhancing pellet , hydrophobicity, and energy content by thermally treating raw at 200–300°C in low-oxygen conditions, reducing and volatiles while improving grindability for co-firing with . This process, scaled commercially since 2020, allows pellets to achieve higher calorific values comparable to fossil fuels, with pilot plants reporting up to 20–30% improvements in . Co-pelletization of diverse feedstocks, such as agricultural residues with , further optimizes resource use, yielding uniform pellets with stable mechanical properties through optimized binderless under high-pressure dies. For pelletizing, developments in organic binders derived from , including starch-based and lignosulfonate alternatives to , have reduced silica impurities and improved pellet strength by 15–25% in tests conducted from 2020 onward, minimizing energy requirements. via process control systems and AI-driven sensors now enables real-time adjustments to , binder dosage, and disc speed, cutting by up to 10% in industrial plants, as evidenced by advancements in grate-kiln induration technologies. Prereduction during pelletizing, integrating hydrogen-based reduction in pilot continuous processes, produces pellets with metallization degrees exceeding 90%, supporting lower-carbon pathways tested since 2021. In pelletizing for , underwater strand and die-face cut systems incorporating IoT monitoring have advanced since 2022, allowing precise control of cooling and cutting parameters to produce uniform nurdles from mixed post-consumer plastics, reducing defects by 20% and enabling higher throughput in advanced mechanical lines. These innovations facilitate depolymerization-compatible feedstocks, where pellets from sorted PET and HDPE achieve purity levels suitable for food-grade re-extrusion, with energy-efficient extruders minimizing degradation. Across sectors, Industry 4.0 integration, including via on vibration and temperature data, has boosted overall pelletizing reliability, with reported downtime reductions of 15–30% in and mineral operations by 2025. The global market for pelletized products, encompassing , , and plastics, continues to expand amid rising demand for efficient and energy alternatives. In the sector, which dominates applications, the market is projected to reach USD 10.17 billion in , growing to USD 16.27 billion by 2033 at a (CAGR) of 6.04%, fueled by policies promoting renewable heating and industrial co-firing in and . Wood pellets specifically are expected to see production in the rise to 20.5 million metric tons in , up from 19.9 million in 2024, though industrial consumption may recover only marginally due to economic pressures on energy prices. In metallurgy, iron ore pellet production supports high-grade steelmaking, with the market valued at USD 61.64 billion in 2025 and forecasted to reach USD 94.51 billion by 2032 at a CAGR of 6.3%, driven by global infrastructure demands and the shift toward direct reduced iron processes for lower emissions. Alternative estimates project growth to USD 67.5 billion in 2025, reflecting replenished stockpiles and production increases in major exporters like Brazil. However, oversupply concerns have prompted adjustments, such as Vale S.A. revising its 2025 pellet output forecast downward to 31-35 million metric tons from prior expectations. The plastics pelletizing segment, essential for processing, is anticipated to grow from USD 8.45 billion in 2024 to USD 12.68 billion by 2032 at a CAGR of 5.2%, propelled by lightweight material needs in and automotive industries despite environmental scrutiny over microplastic from nurdles. Equipment markets for pelletizing machines across sectors, valued at USD 2.9 billion in 2023, are set to expand at a 3.8% CAGR through 2032, indicating sustained in and upgrades. Overall, industry trends emphasize technological integration for higher throughput and compliance, though volatility in supplies and regulatory shifts pose risks to projected trajectories.

References

  1. https://feeco.com/what-is-pelletizing/
  2. https://www.marsmineral.com/why-pelletize.php
  3. https://feeco.com/iron-ore-pelletization/
  4. https://www.industrialbladesandknives.com/articles/what-is-pelletizing
  5. https://www.borregaard.com/markets/animal-feed/applications/pelleting-aids/more-on-pelleting/your-guide-to-pelleting
  6. https://www.sciencedirect.com/topics/chemical-engineering/pelletizing
  7. https://www.ispatguru.com/iron-ore-agglomeration-processes-and-their-historical-development/
  8. https://www.intechopen.com/chapters/58868
  9. https://nrri.umn.edu/news/davis-taconite
  10. https://www.environmentandsociety.org/arcadia/taconite-mining-silver-bay-tale-extraction-and-accumulation
  11. https://usitc.gov/publications/tea/pub96.pdf
  12. http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S2225-62532015000200010
  13. https://www.tandfonline.com/doi/abs/10.1111/j.1467-8306.1969.tb00688.x
  14. https://storage.blucher.com.br/ecommerce/leanwork_files/CONCEPTUAL_ASPECTS_CONCERNING_THE_PELLETIZING_OF_IRON_ORES_Version_2_1.pdf
  15. https://abmproceedings.com.br/en/article/evolution-and-growth-of-iron-ore-pelletizing
  16. https://www.sciencedirect.com/science/article/abs/pii/S0273230007001390
  17. https://feeco.com/material-pretreatment-requirements-for-pelletizing/
  18. https://feeco.com/how-to-pelletize-fine-powder/
  19. https://www.pmmer.com/technical-guide/preparation-prior-to-making-pellets-common-materials-for-pelletization.html
  20. https://www.sciencedirect.com/science/article/abs/pii/0032591073800129
  21. https://www.sciencedirect.com/science/article/abs/pii/S0032591002002711
  22. https://pmc.ncbi.nlm.nih.gov/articles/PMC3745079/
  23. https://www.lfatabletpresses.com/articles/the-mechanism-of-granulation-formation-and-methods
  24. https://www.sciencedirect.com/science/article/abs/pii/S003259101000046X
  25. https://pmc.ncbi.nlm.nih.gov/articles/PMC9698213/
  26. https://www.ispatguru.com/use-of-iron-ore-pellets-in-blast-furnace-burden/
  27. https://stacks.cdc.gov/view/cdc/10433/cdc_10433_DS1.pdf
  28. https://digitalcommons.mtu.edu/cgi/viewcontent.cgi?article=2601&context=etdr
  29. https://maxtonco.com/iron-ore-pellets-for-blast-furnace-a-technical-guide/
  30. https://pubs.usgs.gov/periodicals/mcs2024/mcs2024-iron-ore.pdf
  31. https://www.persistencemarketresearch.com/market-research/iron-ore-pellets-market.asp
  32. https://feeco.com/pelletizing-minerals-for-improved-handling-and-use/
  33. https://www.pyrometallurgy.co.za/InfaconVIII/184-Fangming.pdf
  34. https://www.researchgate.net/publication/248401260_Study_the_effect_of_chromite_ore_properties_on_pelletisation_process
  35. https://www.mdpi.com/2075-163X/14/12/1203
  36. https://onlinelibrary.wiley.com/doi/pdf/10.1002/9781118062081.ch29
  37. https://link.springer.com/content/pdf/10.1007/s11771-014-2326-4.pdf
  38. https://journal.hep.com.cn/jocsu/EN/10.1007/s11771-014-2326-4
  39. https://www.researchgate.net/publication/248402240_Pelletizing_and_alkaline_leaching_of_powdery_low_grade_zinc_oxide_ores
  40. https://www.zkcomp.com/solution/phosphate-ore-pelletization-production-line.html
  41. https://patents.google.com/patent/US3032408A/en
  42. https://feeco.com/upgrading-phosphate-ores-with-rotary-kilns/
  43. https://www.mdpi.com/2075-163X/12/2/129
  44. https://www.sciencedirect.com/science/article/abs/pii/S0032591024000044
  45. https://www.tandfonline.com/doi/abs/10.1080/08827508.2023.2298718
  46. https://www.sciencedirect.com/science/article/abs/pii/S0377840112003690
  47. https://phileo-lesaffre.com/en/the-history-and-future-of-feed-processing/
  48. https://img.feedstrategy.com/files/base/wattglobalmedia/all/image/static/feedstrategy/feed-pelleting-reference-guide/1-1_Pelleting_History.pdf
  49. https://www.feedandadditive.com/innovations-in-pelleting-technology-for-improved-quality-control-in-animal-feed/
  50. https://www.sciencedirect.com/science/article/pii/S0032579119457544
  51. https://pmc.ncbi.nlm.nih.gov/articles/PMC7998960/
  52. https://www.feedstrategy.com/animal-nutrition/poultry/article/15439498/pelleted-feeds-understanding-nutritional-benefits-issues
  53. https://www.ars.usda.gov/ARSUserFiles/30200525/399Feedpelletandcorndurability.pdf
  54. https://www.feedstrategy.com/animal-feed-manufacturing/news/15745955/global-feed-production-rises-in-2024-led-by-growth-in-poultry-and-dairy
  55. https://www.sciencedirect.com/science/article/pii/S2772801324000022
  56. https://amlan.com/us-en/blog/the-benefits-of-pelleting-feed-and-related-diet-considerations/
  57. https://researchrepository.wvu.edu/cgi/viewcontent.cgi?article=3798&context=etd
  58. https://www.allaboutfeed.net/animal-feed/feed-processing/animal-nutrition-with-high-quality-pellets/
  59. https://www.lameccanica.it/en/news/press-review-fertilizers/pelleting-process-fertilizer
  60. https://feeco.com/systems-for-granular-fertilizer-and-soil-amendment-production/
  61. https://www.mdpi.com/2071-1050/16/7/2868
  62. https://pmc.ncbi.nlm.nih.gov/articles/PMC11901632/
  63. https://ecologynorth.ca/wp-content/uploads/2020/02/Wood-Pellet-Ash-as-an-Agricultural-Soil-Amendment-in-the-NWT-FINAL-Aug-27-2014-Submitted_to_TFA.pdf
  64. https://www.sciencedirect.com/science/article/pii/S0961953425000388
  65. https://www.researchgate.net/publication/43339426_Effect_of_Pellet_Processing_of_Fertilizer_on_Slow-Release_Nitrogen_in_Soil
  66. https://www.sciencedirect.com/science/article/pii/S2352186423005011
  67. https://tammi.tamu.edu/files/2022/03/mp-series-pelleting.pdf
  68. https://agricotec.es/noticias/646/el-abono-en-pellet-como-herramienta-de-la-sostenibilidad-agricola/lang-EN
  69. https://pmc.ncbi.nlm.nih.gov/articles/PMC8873546/
  70. https://pubmed.ncbi.nlm.nih.gov/19418964/
  71. https://pubmed.ncbi.nlm.nih.gov/33475056/
  72. https://www.sciencedirect.com/science/article/pii/S1818087616300721
  73. https://ijppr.humanjournals.com/wp-content/uploads/2022/05/15.Raviteja-G-V-Panner-Selvam-R-Vineeth-Chandy.pdf
  74. https://pmc.ncbi.nlm.nih.gov/articles/PMC3011062/
  75. https://www.researchgate.net/publication/341000800_Pelletization_by_Extrusion-Spheronization_A_detailed_review
  76. https://pubmed.ncbi.nlm.nih.gov/17430098/
  77. https://pmc.ncbi.nlm.nih.gov/articles/PMC9227027/
  78. https://pmc.ncbi.nlm.nih.gov/articles/PMC4691578/
  79. https://pubmed.ncbi.nlm.nih.gov/19259877/
  80. https://extension.psu.edu/manufacturing-fuel-pellets-from-biomass/
  81. http://m.biofuelmachines.com/Raw-materials-for-pelletization.html
  82. https://www.sciencedirect.com/science/article/abs/pii/S0961953410003685
  83. https://www.gemco-energy.com/guide-to-start-wood-pellet-plant/biomass-wood-pellet-plant-process-pelletizing-technology.html
  84. https://utia.tennessee.edu/publications/wp-content/uploads/sites/269/2023/10/W214.pdf
  85. https://enplus-pellets.eu/wp-content/uploads/Documents/ENplus-ST-1001-ENplus-wood-pellets-Requirements-for-companies-5.pdf
  86. https://enplus-pellets.eu/
  87. https://bioenergyeurope.org/new-report-highlights-key-role-of-pellets-in-defossilising-heating-sector-in-europe/
  88. https://apps.fas.usda.gov/newgainapi/api/Report/DownloadReportByFileName?fileName=Wood%2520Pellets%2520Annual_The%2520Hague_European%2520Union_E42025-0004
  89. https://biomassmagazine.com/articles/usda-us-wood-pellet-exports-top-10-million-metric-tons-in-2024
  90. https://www.energy.gov/energysaver/wood-and-pellet-heating
  91. https://www.comfortbilt.net/blogs/stoves/pellet-stoves-vs-wood-stoves-which-is-better-for-my-home
  92. https://www.linkedin.com/pulse/energy-efficiency-wood-pellets-perfect-hnrzc
  93. https://www.pelletheat.org/what-are-pellets-
  94. https://pubs.acs.org/doi/10.1021/acs.iecr.2c03557
  95. https://www.sciencedirect.com/science/article/pii/S0960148124006931
  96. https://bioresources.cnr.ncsu.edu/resources/emissions-and-combustion-characteristics-of-torrefied-wood-pellets/
  97. https://www.eia.gov/biofuels/biomass/
  98. https://www.mdpi.com/1996-1073/16/4/1695
  99. https://www.sciencedirect.com/science/article/pii/S0960148123014519
  100. https://extension.psu.edu/characteristics-of-biomass-as-a-heating-fuel/
  101. https://www.specialchem.com/plastics/guide/solving-common-polymer-pelletizing-issue-appearance-of-fines
  102. https://maag.com/maag-products/pelletizing-systems/
  103. https://www.cowellextrusion.com/the-history-of-underwater-pelletizers-and-their-evolution-over-time/
  104. https://www.pureloop.com/en/blog/plastic-pelletizing--99/
  105. https://scrapmanagement.com/blog/what-is-plastic-pelletizing/
  106. http://nycoa.com/recent-news/2021/5/7/nycoa-topics-pelletization-technologies
  107. https://www.ptonline.com/articles/follow-these-guidelines-to-select-the-right-pelletizing-system
  108. https://www.plasticstoday.com/plastics-processing/pelletizing-established-solutions-and-challenging-trends
  109. https://accelpolymers.com/2021/02/02/what-is-plastic-pelletizing/
  110. https://www.sciencedirect.com/science/article/pii/S2352186423002857
  111. https://www.fauna-flora.org/wp-content/uploads/2024/04/INC4_fauna-flora-pellet-primer.pdf
  112. https://strategic-res.com/news/2024/strategic-resources-announces-robust-economic-results-from-its-iron-pellet-plant-study/
  113. https://www.mdpi.com/2077-0472/15/6/664
  114. https://www.kitechpm.com/cost-benefit-analysis-of-investing-in-pe-pp-film-pelletizing-machines/
  115. https://www.recyclingtoday.org/blogs/news/plastic-pelletizer-everything-you-need-to-know
  116. https://www.bestpelletplant.com/related-topics/make-wood-pellets-fuel-investment-benefits.html
  117. https://shalimarengineering.co.in/iron-ore-pelletizing-plants-sustainability/
  118. https://news.mongabay.com/2024/01/study-burning-wood-pellets-for-energy-endangers-local-communities-health/
  119. https://earthjustice.org/experts/allison-brouk/wood-pellet-manufacturing-in-the-south-harms-communities-and-the-environment
  120. https://www.eia.gov/energyexplained/biomass/biomass-and-the-environment.php
  121. https://news.mongabay.com/2025/08/sustainable-biomass-certification-scheme-is-flawed-degrades-forests-report-finds/
  122. https://www.sciencedirect.com/science/article/pii/S0048969725016262
  123. https://pubmed.ncbi.nlm.nih.gov/40618673/
  124. https://www.malvernpanalytical.com/en/learn/knowledge-center/insights/iron-ore-pellets-for-sustainable-steel
  125. https://www.nurdlehunt.org.uk/the-problem.html
  126. https://pmc.ncbi.nlm.nih.gov/articles/PMC10114858/
  127. https://www.imo.org/en/MediaCentre/HotTopics/Pages/FAQ-Plastic-pellets.aspx
  128. https://www.sciencedirect.com/science/article/abs/pii/S0269749121009945
  129. https://www.epa.gov/nutrientpollution/basic-information-nutrient-pollution
  130. https://www.nature.com/articles/s41598-025-20818-9
  131. https://biomassmagazine.com/issues/1953/print
  132. https://biomassmagazine.com/articles/riding-the-wave-of-innovation
  133. https://ui.adsabs.harvard.edu/abs/2021CCST....100005C/abstract
  134. https://pmc.ncbi.nlm.nih.gov/articles/PMC12526317/
  135. https://stacks.cdc.gov/view/cdc/225998/cdc_225998_DS1.pdf
  136. https://stacks.cdc.gov/view/cdc/206227/cdc_206227_DS1.pdf
  137. https://www.intelmarketresearch.com/under-water-strand-pelletizing-system-market-2916
  138. https://www.tomra.com/about-tomra/circular-economy/advanced-mechanical-recycling
  139. https://pelletmill.in/guide-to-biomass-pellet-production/exploring-cutting-edge-innovations-and-sustainable-practices-in-biomass-pellet-production
  140. https://straitsresearch.com/report/biomass-pellets-market
  141. https://biomassmagazine.com/articles/report-eu-wood-pellets-consumption-expected-to-expand-in-2025
  142. https://www.fortunebusinessinsights.com/iron-ore-pellets-market-113953
  143. https://marketmindsadvisory.com/iron-ore-pellet-market-trends/
  144. https://pubs.usgs.gov/periodicals/mcs2025/mcs2025-iron-ore.pdf
  145. https://finance.yahoo.com/news/vale-vale-cuts-2025-iron-044637624.html
  146. https://www.maximizemarketresearch.com/market-report/global-plastic-pellets-market/16572/
  147. https://www.gminsights.com/industry-analysis/pelletizing-machine-market
  148. https://www.archivemarketresearch.com/reports/pelletizing-machine-218311
Add your contribution
Related Hubs
Contribute something
User Avatar
No comments yet.