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Pellets can be produced not only from forest dendromass but also from agricultural dendromass derived from short rotation coppice (SRC) plantations, as well as surplus straw from cereal and oilseed crops. This study aimed to determine the thermophysical properties and elemental composition of 16 types of pellets produced from four types of forest biomass (Scots pine I, alder, beech, and Scots pine II), four types of agricultural biomass (SRC willow, SRC poplar, wheat straw, and rapeseed straw), and eight types of pellets from mixtures of wood biomass and straw. Another aim of the study was to demonstrate which pellet types met the parameters specified in three standards, categorizing pellets into thirteen different classes. As expected, pellets produced from pure Scots pine sawdust exhibited the best quality. The quality of the pellets obtained from mixtures of dendromass and straw deteriorated with an increase in the proportion of cereal straw or rapeseed straw in relation to pure Scots pine sawdust and SRC dendromass. The bulk density of the pellets ranged from 607.9 to 797.5 kg m−3, indicating that all 16 pellet types met the requirements of all six classes of the ISO standard. However, it was determined that four types of pellets (rapeseed, wheat, and two others from biomass mixtures) did not meet the necessary requirements of the Premium and Grade 1 classes. The ash content ranged from 0.44% DM in pellets from pure Scots pine sawdust to 5.00% DM in rapeseed straw pellets. Regarding ash content, only the pellets made from pure Scots pine sawdust met the stringent requirements of the highest classes, A1, Premium, and Grade 1. In contrast, all 16 types of pellets fulfilled the criteria for the lower classes, i.e., Utility and Grade 4. Concerning the nitrogen (N) content, seven types of pellets met the strict standards of classes A1 and Grade 1, while all the pellets satisfied the less rigorous requirements of classes B and Grade 4.

High-chromium vanadium–titanium magnetite (HVTM) is a crucial polymetallic-associated resource to be developed. The all-pellet operation is a blast furnace trend that aims to reduce carbon dioxide emissions in the future. By referencing the production data of vanadium-titanium magnetite blast furnaces, this study explored the softening-melting behavior of high-chromium vanadium–titanium magnetite and obtained the optimal integrated burden based on flux pellets. The results show that the burden with a composition of 70wt% flux pellets and 30wt% acid pellets exhibits the best softening-melting properties. In comparison to that of the single burden, the softening-melting characteristic temperature of this burden composition was higher. The melting interval first increased from 307 to 362°C and then decreased to 282°C. The maximum pressure drop (Δ P max ) decreased from 26.76 to 19.01 kPa. The permeability index ( S ) dropped from 4643.5 to 2446.8 kPa·°C. The softening–melting properties of the integrated burden were apparently improved. The acid pellets played a role in withstanding load during the softening process. The flux pellets in the integrated burden exhibited a higher slag melting point, which increased the melting temperature during the melting process. The slag homogeneity and the TiC produced by over-reduction led to the gas permeability deterioration of the single burden. The segregation of the flux and acid pellets in the HVTM proportion and basicity mainly led to the better softening-melting properties of the integrated burden.

Bentonite pellets are recognized as good buffer/backfill materials for sealing technological voids in high-level radioactive waste (HLW) repository. Compared to that of a traditional compacted bentonite block, one of the most important particularities of this material is the initially discrete pellets and the inevitable heterogeneous porosity formed, leading to a distinctive water retention behaviour. In this paper, water retention and mercury intrusion porosimetry (MIP) tests were conducted on pellet mixture (constant volume), single pellet (free swelling) and compacted block (constant volume) of GMZ bentonite, water retention properties and pore structure evolutions of the specimens were comparatively investigated. Results show that the water retention properties of the three specimens are almost similar to each other in the high suction range (> 10 MPa), while the water retention capacity of pellet mixture is lower than those of the compacted block and single pellet in the low suction range (< 10 MPa). Based on the capillary water retention theory (the Young–Laplace equation), a new concept ‘saturated void ratio’ that was positively related to water content and dependent on pore size distribution of the specimen was defined. Then, according to the product of saturated void ratio and water density in saturated void, differences of water retention properties for the three specimens at low suctions were explained. Meanwhile, MIP tests indicate that as suction decreases, the micro- and macrovoid ratios of pellet mixture and compacted block decrease as the mesovoid ratio increases, while all the void ratios of single pellets increase. This could be explained that upon wetting, water is successively adsorbed into the inter-layer, inter-particle and inter-pellet voids, leading to the subdivision of particles and swelling of aggregates and pellets. Under constant volume condition, aggregates and pellets tend to swell and fill into the inter-aggregates or inter-pellets voids. While under free swelling condition, the particles and aggregates in a single pellet tend to swell outward rather than squeezing into the inter-aggregate voids, leading to the expansion of the pores and even formation of cracks. Results including the effects of initial conditions (initial dry density and fabric) and constraint conditions (constant volume or free swelling) on the water retention capacity and pore structure evolution reached in this work are of great importance in designing of engineering barrier systems for the HLW repository.

The study aimed to effect of speed and die holes diameter in the machine on feed pellets quality. In this study was measured pellet direct measurement (%), pellet lengths (%), pellet durability (%) and pellet water absorption (%). Three die speeds 280, 300, and 320 rpm, three diameters of die holes in the machine 3, 4, and 5 mm, have been used. The results showed that increasing the pellet die speeds from 280 to 300 then to 320 rpm led to a significant decrease in direct measurement, pellet durability, and pellet water absorption was increased, whereas it did not significantly affect the pellet lengths. Increasing the die holes diameter from 3 to 4 then to 5 mm led to a significant decrease in the pellet direct measurement, pellet lengths, pellet durability, and increased pellet water absorption. Pellet die speeds of 280 rpm and the die holes diameter of 3 mm recorded the highest direct measurement 95.61%, pellet lengths 86.30%, pellet durability 93.45%, and less pellet water absorption 15.74%. The minimum die speed and die holes diameter gave the highest pellet direct measurement, pellet lengths, pellet durability and lowest pellet water absorption with all the considered indicators.

This study evaluates the quality of 30 biomass pellets sold for residential use in Poland. It provides data on their physical, chemical, and petrographic properties and compares them to existing standards and the information provided by the fuel producers. The results reveal considerable variations in the quality of the pellets and show that some of the purchased samples are not within the DINplus and/or ENplus certification thresholds. Among all 30 purchased samples, only one passes the quality thresholds set by the PL-US BIO, a newly established quality certification in Poland that combines quality assessment following DINplus with optical microscopy analysis. The primary issues causing a decrease in pellet quality include elevated ash and fines content, compromised mechanical durability, too low ash melting temperature, and additions of undesired additions like bark, inorganic matter, and petroleum products. Our research highlights the need for improved fuel quality control measures, and transparent and accurate product labeling, as well as the need for a comprehensive and publicly available national database of solid biomass fuel producers and fuels sold. These are essential steps toward increasing customers’ awareness and trust, encouraging them to embrace biomass fuels as reliable and sustainable sources of energy.

The booster pellet is the key component of a certain-shaped charge-cutting device. The booster pellet at the initiation point is excited by the electric detonator, and the booster pellet at the booster point is excited by the cutting cord. The initiation reliability of the booster pellet determines the reliability of the shaped charge-cutting device, so it is necessary to study the shock sensitivity of the booster pellet. In this paper, the critical initiation pressure of the JO-11C booster explosive is investigated by using numerical simulation. The results show that the critical gap thickness range for JO-11C booster explosive is 50-50.5 mm, and the critical initiation pressure range is 2.05-2.11 GPa.

With sustainable energy being the key to reaching climate neutrality, the utilization of non-wooden biomass is a necessity. This article compares the emissions and efficiency of combusting a number of types of agrobiomass and wood pellets. A comparison was made on a moving grate pellet burner mounted in a boiler, where flue gas had a vertical flow via two pass heat exchangers with turbulization elements. Tests were conducted on wood pellets (ENPlus), miscanthus straw pellets, sunflower husk pellets, and corn stover pellets. During combustion, both wood and miscanthus pellets met the PN-EN 303-5:2012 emission and efficiency requirements. Corn stover pellets met the requirement on the nominal capacity. Sunflower husk pellets are characterized by excessive CO and particulate matter emissions. Sunflower husk pellets were the most problematic fuel from the point of view of the results of this research. During combustion of the miscanthus straw pellets there was a need to decrease the nominal heating capacity due to ash sintering.

Pellets for energy purposes are produced from various sources, such as residues from sawmills, carpentry, and other waste materials. As industry demands are always increasing, it is necessary to find new sources of biomass suitable for pelletization according to international standards, so that the present research aimed to characterize pellets from 17 sources of woody and agricultural biomass. Physical, mechanical, and energetic characterization was realized, evaluating length, diameter, density, moisture content, ashes, fixed carbon, gross calorific value, durability, and compressive resistance for pellet biofuels from agricultural and forestry sources. Pellets from all sources had moisture content less than 10%. The ash content in forestry residues was lower than 1% (except for laeta oak sawdust), in agricultural residues the values range from 2.12 to 10.54% (except for oil palm fiber). The gross calorific values were higher than 16.5 MJ kg−1. The durability showed the range 73.61–99.15%, and compressive resistance, the range 322–1,729 N mm−1, with oil palm fiber residues registering the lowest value, and laeta oak sawdust the highest. According to these results, pellets from forestry and agricultural sources had good characteristics for industrial and residential uses.

Wood pellets play an important role among biomass materials used as fuel. At the same time, today’s economic, environmental, political and social realities, as well as other circumstances related to fuels used for heat generation, mean that there is demand for increasingly efficient and environmentally friendly combustion sources. As is well known, each combustion source has a different efficiency due to its intended use, design, principle of operation and the type and composition of the fuel burned. The amount of pollutants emitted into the environment during combustion also largely depends on these factors. The aim of this study was to compare the flue gas emissions and efficiency of two pellet burners of different design, burning certified A1 wood pellets from different suppliers. The emission requirements were met during the combustion of wood pellets in a boiler with the two burners tested (one with a moving grate and an overfed burner). The analyses and studies carried out aim to improve the capability of managing the efficiency and environmental performance of the heat source (i.e., a boiler or a burner) and the fuel (type of wood pellets). This is done in the context of demonstrating a better combustion source when selecting the right burner and fuel in terms of efficiency and emissions. In this paper, comparisons of flue gas emissions are presented along with characteristics in the form of graphs, as well as thermal and combustion efficiencies for the corresponding solid fuel used in the form of wood pellets. After comparing the emissions, it was found that the statistical averages of CO, NOx, dust and VOCs were similar for combustion at full power using the burners tested. Taking into account the pollution levels at combustion, it can be said that the difference in CO emissions at full and minimum combustion is lower for the experimental burner compared with the moving grate burner (reference burner). In summary, it can be concluded that the experimental overfed burner under consideration can be successfully used as a solid fuel boiler to burn wood pellets.