Strength Of Pellets Research Articles

The densification of cocoa bean shells for bioenergy purposes

The densification of cocoa bean shells into pellets was investigated to evaluate their potential as an alternative bioenergy source. The effect of shell particle size, compaction stress, compaction speed and binder addition was studied to ascertain the optimum processing conditions to produce the highest quality pellet. Compressive and tensile strength testing was employed to evaluate the mechanical integrity of the pellets, alongside their resistance to abrasion, impact and water. The results indicated that particle size reduction (to < 1 mm) and the addition of a binder were required to achieve acceptable pellet quality. Water, magnesium stearate and bentonite clay were selected as binding agents based on their industrial viability, accessibility and low cost. It was found that the addition of water or magnesium stearate was detrimental to pellet strength, whereas bentonite clay was found to enhance the strength. Pellets with added bentonite clay were subjected to combustion analysis to ascertain pellet moisture, ash content, elemental composition and calorific value. Promisingly, all pellets with added bentonite clay exceeded the 14.5 MJ kg−1 calorific value requirement set by ISO 17225-6 standards for Grade A ‘non-woody’ pellets.

Elution of rifampin and vancomycin from a weight-bearing silorane-based bone cement.

AimsPoly(methyl methacrylate) (PMMA)-based bone cements are the industry standard in orthopaedics. PMMA cement has inherent disadvantages, which has led to the development and evaluation of a novel silorane-based biomaterial (SBB) for use as an orthopaedic cement. In this study we test both elution and mechanical properties of both PMMA and SBB, with and without antibiotic loading.MethodsFor each cement (PMMA or SBB), three formulations were prepared (rifampin-added, vancomycin-added, and control) and made into pellets (6 mm × 12 mm) for testing. Antibiotic elution into phosphate-buffered saline was measured over 14 days. Compressive strength and modulus of all cement pellets were tested over 14 days.ResultsThe SBB cement was able to deliver rifampin over 14 days, while PMMA was unable to do so. SBB released more vancomycin overall than did PMMA. The mechanical properties of PMMA were significantly reduced upon rifampin incorporation, while there was no effect to the SBB cement. Vancomycin incorporation had no effect on the strength of either cement.ConclusionSBB was found to be superior in terms of rifampin and vancomycin elution. Additionally, the incorporation of these antibiotics into SBB did not reduce the strength of the resultant SBB cement composite whereas rifampin substantially attenuates the strength of PMMA. Thus, SBB emerges as a potential weight-bearing alternative to PMMA for the local delivery of antibiotics.Cite this article: Bone Joint Res 2021;10(4):277–284.

Enhanced Oil Palm Waste Properties through Torrefaction and Pelletization

Torrefaction is a thermal pre-treatment process to treat biomass at temperature range of 200-300°C under an inert atmosphere. It was known that torrefaction process strongly depended on the decomposition of the lignocellulosic constituents in oil palm waste namely hemicellulose, cellulose and lignin. The objective of this research is to study the effect of torrefaction on the characteristics of pellet formed from palm mesocarp fiber (PMF), oil palm frond (OPF) and palm kernel shell (PKS) as a solid fuel. The samples were torrefied at 270°C for 30 minutes. The torrefied samples were then densified into pellets through hot press machine at different temperatures (110 °C, 130 °C, 150 °C) and different pressure (10 MPa, 12 MPa, 14 MPa) for 20 minutes to find the optimum pelletization condition. The pellets were analyzed through mass yield, high heating value, fourier-transform infrared spectroscopy (FTIR) analysis, moisture absorption and compression test. Compression test is to study the strength of pellet by identifying the force required to break the pellet. The result shows that the mass yield of PKS was higher than PMF and OPF. The high heating value of torrefied oil palm waste improved as compared to the raw oil palm waste. Through FTIR, the changes of chemical bonds in oil palm waste after torrefaction have been identified. From the analysis of the pellet, the optimum conditions for pelletization were obtained, which are 130 °C and 12 MPa. The moisture absorption rate of torrefied pellet was lesser than raw pellets. Lastly, the torrefaction and pelletization process produced better quality pellets in term of high heating value, durability and more hydrophobic compared to raw pellets which can used as biofuel to replace the coal.

Preparation, Sintering Behavior and Consolidation Mechanism of Vanadium-Titanium Magnetite Pellets

High-quality oxidized pellets are the basis to achieve high-efficiency utilization of vanadium–titanium magnetite (VTM) ores. Bentonite was used as a binder of VTM. The main phase composition of VTM is titanomagnetite and ilmenite. When the amount of bentonite is 1%, the compressive strength and dropping strength of VTM pellets can meet the requirements. To improve metallurgical properties, the pellets need to be roasted. The best conditions for roasting are as follows: calcination temperature of 1523 K and a calcination time of 20 min. The consolidation mechanism, phase transformation, and crystal structure transformation of VTM in the process of oxidation roasting are also explained.

Effect of Incremental Utilization of Unground Sea Sand Ore on the Consolidation and Reduction Behavior of Vanadia–Titania Magnetite Pellets

In the iron and steel industry, improving the usage amount of New Zealand sea sand ore as a raw material for ironmaking can reduce the production costs of iron and steel enterprises to a certain extent. In this paper, New Zealand sea sand ore without any grinding pretreatment was used as a raw material, oxidized pellets were prepared by using a disc pelletizer, and the effect of sea sand ore on the performance of green pellets and the metallurgical properties of oxidized pellets was investigated. The effects of sea sand ore on the compressive strength, falling strength, compressive strength of oxidized pellets, and reduction performance were mainly investigated. X-Ray Diffraction (XRD) patterns and Scanning Electron Microscope (SEM) analysis methods were used to discuss the influence of sea sand ore on the microstructure of the pellets’ oxidation and reduction process. As the amount of sea sand ore used increased, the compressive strength of green pellets was gradually decreased, and the falling strength of green pellets and the compressive strength of oxidized pellets were gradually increased. When the amount of sea sand ore used was 40%, the reduction swelling index of pellets was 16.31%. The increase of sea sand ore used made the reduction of pellets suppressed and the reduction rate decreased. When the amount of sea sand ore used increased to 40%, the reduction degree of sea sand ore pellets was only 60.06%. The experimental results in this paper provide specific experimental data for the large-scale application of New Zealand sea sand ore in the blast furnace ironmaking process.

Effects of High Proportion Unground Sea Sand Ore on the Preparation Process and Reduction Performance of Oxidized Pellets

The New Zealand sea sand ore is a kind of vanadia–titania magnetite formed by erosion in the coastal zone. Because of its coarse particle size, smooth spherical particles, complex chemical composition, it has been added to sinter as an auxiliary material. Based on the principle of optimizing ore blending to strengthen advantages and weaken disadvantages, this paper used New Zealand sea sand raw ore that has not undergone any pretreatment as the main material and prepared it into oxidized pellets using a disc pelletizer and explored the influence of high-proportion unground sea sand ore on the preparation process and reduction performance of oxidized pellets. The influence of unground sea sand ore on the falling strength, compressive strength, reduction swelling index, and reduction degree of pellets was analyzed by the ICPAES, XRF, XRD, SEM-EDS, and other detection methods, and the change laws and influencing factors of oxidized pellets were analyzed. With the increase of the amount of unground sea sand ore used, the falling strength and compressive strength of the green pellets first decreased and then gradually increased, while the compressive strength of the oxidized pellets first increased and then decreased. At the same time, as the amount of sea sand ore used increased, the reduction process of pellets was restricted. The reduction swelling index and the reduction degree index generally show a downward trend. However, the compressive strength of the pellets gradually increased after reduction. Through the research on the pellet-forming performance and reduction properties of unground sea sand ore, it is shown that when the amount of unground sea sand ore used was 40%, it can still be used as raw material for blast furnace ironmaking. Thus, this research provided specific data support for iron and steel enterprises to improve the ratio of unground sea sand ore and reduce production cost.

Characterization and quality analysis of wood pellets: effect of pelletization and torrefaction process variables on quality of pellets

A lab-scale single-channel press was employed for producing pellets and the effect of pressure, die temperature, moisture content (MC), particle size, and binding agent on pellet quality was investigated. Meanwhile, torrefaction subsequent to pelletization was performed and the quality of pellets was evaluated under different torrefaction conditions. From the analysis of variance (at p < 0.05), temperature (70–200 °C), pressure (70–160 MPa), and MC (5.5–28%) were found most significant factors for density, strength, and compression energy of pellets. Particle density and strength of raw wood pellets were significantly affected by temperature and pressure. The highest particle density and strength (1.307 g/cm3, 11.8 N/mm2) for particles of 0.25–0.5 mm and (1.300 g/cm3 and 10.7 N/mm2) for particles of 0.5–1.41 mm were found at a temperature of 200 °C (pressure ≥ 100 MPa and MC 5.5%), indicating that pelletization at a temperature of 200 °C was beneficial. The relaxed density of pellets remained the same as of particle initial density after storage time of 2 weeks. The expansion ratio of the pellet was found lower. Use of synthetic resin as a binder in the proportion of 1:9 was found optimum, the particle density increased from 1.19 to 1.24 g/cm3 (0.25–0.5 mm) and from 1.17 to 1.22 g/cm3 (0.5–1.41 mm) and energy consumption reduced by 9.39% (0.25–0.5 mm) and 8.7% (0.5–1.41 mm). Pellets made at a temperature of 200 °C were found water-resistive as compared to those made at other temperatures. The highest lower heating value, i.e., 26.76 MJ/kg of torrefied pellets (TOPs) was achieved at 300 °C and 120 min. Torrefaction process parameters adversely affected the particle density, volumetric energy density, strength, and durability of TOPs. The highest true density (1.85 g/cm3) and porosity (65 v %) for TOPs were achieved at 300 °C and 120 min, much higher than those of raw pellets. Moisture uptake of TOPs at 300 °C was 2.0–2.8 wt.%, showing strong water-resistant ability. From the results of FTIR, O–H bond was destroyed after torrefaction.

Синтез и исследование физико-химических свойств и прочностных характеристик носителей на основе алюмосиликатных нанотрубок галлуазита для катализаторов гидропроцессов

Supports based on aluminosilicate halloysite nanotubes and alumina of different contents for hydroprocessing catalysts were synthesized and their textural characteristics and acidic properties were investigated. It was shown that the mechanical strength of the support pellets based on aluminosilicate nanotubes and alumina are comparable or superior to those for industrial analogs.

An advanced ash fusion study on the melting behaviour of coal, oil shale and blends under gasification conditions using picture analysis and graphing method

• Ash fusion behaviour was investigated via an image-based characterisation method. • Oil shale ash is an effective refractory additive to delay ash fusion of coal. • Low melting aluminosilicates reduces sintering temperature of ash samples. • Sinter strength of ash pellet increases with dilatometric shrinkage. • Oil shale improves ash chemistry without adversely affecting reaction quality. This study investigates the potential of solid fuel blending as an effective approach to manipulate ash melting behaviour to alleviate ash-related problems during gasification, thus improving design, operability and safety. The ash fusion characteristics of Qinghai bituminous coal together with Fushun, Xinghua and Laoheishan oil shales (and their respective blends) were quantified using a novel picture analysis and graphing method, which incorporates conventional ash fusion study, dilatometry and sintering strength test, in a CO/CO 2 atmosphere. This image-based characterisation method was used to monitor and quantify the complete melting behaviour of ash samples from room temperature to 1520 °C. The impacts of blending on compositional changes during heating were determined experimentally via X-ray diffraction and validated computationally using FactSage. Results showed that the melting point of Qinghai coal ash to be the lowest at 1116 °C, but would increase up to 1208 °C, 1161 °C and 1160 °C with the addition of 30%–50% of Laoheishan, Fushun, and Xinghua oil shales, respectively. The formation of high-melting anorthite and mullite structures inhibits the formation of low-melting hercynite. However, the sintering point of Qinghai coal ash was seen to decrease from 1005 °C to 855 °C, 834 °C, and 819 °C in the same blends due to the formation of low-melting aluminosilicate. Results also showed that blending directly influences the sintering strength during the various stages of melting. The key finding from this study is that it is possible to mitigate against the severe ash slagging and fouling issue arising from high calcium and iron coals by co-gasification with a high silica-alumina oil shale. Moreover, blending coals with oil shales can also modify the ash melting behaviour of fuels to create the optimal ash chemistry that meets the design specification of the gasifier, without adversely affecting thermal performance.

Sustainable utilization of a converter slagging agent prepared by converter precipitator dust and oxide scale

AbstractA converter slagging agent was prepared using converter precipitator dust and oxide scale as raw materials and bentonite, calcium oxide, and soluble glass as binders. The influence of different binders on the strength of the converter slagging agent was studied. The optimum ratio of bentonite, calcium oxide, and sodium silicate was determined by orthogonal experiments. The chemical composition, strength, moisture content, alkalinity, and other indicators of the prepared converter slagging agent met the requirements for converter smelting. The drop intensity of the green pellet was 3.7 times, and the compressive strength of the dry pellet could reach 988.72 N/m2. Therefore, the sustainable utilization of converter precipitator dust and oxide scale could be realized by the preparation of a converter slagging agent.

Induration aspects of low-grade ilmenite pellets: Optimization of oxidation parameters and characterization for direct reduction application

Induration of ilmenite pellets by oxidation is an essential step in the pelletization process since it decides the physical and metallurgical properties of the pellets. In this regard, the induration parameters such as temperature and roasting time have been optimized to obtain good quality ilmenite pellets made of concentrates obtained from low-grade ilmenite ores of Odisha, India. The oxidation temperature of 900 °C at a short roasting time of 15 min has been found suitable to achieve recommended requirements of various pellet properties such as cold compressive strength, porosity, metallization, tumble, and abrasion indices. X-ray diffraction and microstructural analysis indicate that the recrystallization of hematite in the oxidation process improves the mechanical strength of the pellets. In contrast, the formation of ferric pseudobrookite phase at 1000 °C and 1100 °C oxidation temperatures impairs the pellet strength.

Study of bentonite clay influence on indicators of pellet quality

Laboratory tests have been conducted to determine the suitability of bentonite clays of different mineralogical composition and exchange ion complex for the production of pellets. To assess the metallurgical characteristics of the obtained pellets, the moisture content of the pellets, the compressive strength of the raw and dry pellets, the number of drops without breaking the raw pellets and the temperature of the «shock» have been determined. Tests of the clays of Layers IV and Layer II composite mixtures and Layer II and Layer III composite mixtures were carried out, which showed that the quality of the raw pellets with Cherkassky bentonite is slightly worse than the pellets with Sarygyuhsky bentonite, but the absolute values of all the indicators satisfy the requirements imposed by the industry. Comparative tests of pelletizing different humidity charges, with the addition of 0,5% alkaline bentonite and the clays of Layers IV and Layer II composite mixtures of the Cherkassky deposit have been carried out. It has been shown that with increasing humidity in pellets with both types of binder additives, the dynamic strength, porosity and temperature of the «shock» of the pellets increases, the difference in the absolute values of indicators with different binders being minimum. It has been shown that the impact strength and compressive strength of raw pellets with a slightly increased specific consumption of bentonite of Cherkassky alkaline earth bentonite are not inferior to the same properties of pellets with alkaline Sarygyuhsky bentonite used as a binder. It has been shown that the clays of the Layer IV which are a natural mixture of alkaline earth bentonite of Layer II and palygorskite (Layer III), are preferable, to ensure good quality of the raw pellets, of the Cherkassky deposit clays

Effect of Sintering and Porosity Development on Direct Reduction of Manganese Ore Pellets

High manganese steels with > 10% Mn offer a combination of high tensile strength and good ductility, two critical properties for automotive steels. Conventional routes to produce the Mn units used for steelmaking are energy- and capital-intensive. Therefore, a novel methane-based solid-state reduction process for manganese ore pellets is under investigation. It was found in preliminary tests that the reduction of ore pellets by methane was limited by gas transport to the pellet interior. To enhance the reducibility of Mn ore pellets, this study aimed at improving pellet porosity through adjustment of Mn ore powder particle size and the addition of limestone, which thermally decomposes to CaO and CO2. The change in compressive strength with an increase in pellet porosity was also studied. It was found that the increase in porosity as a result of limestone addition improves the reducibility of pellets and decreases the pellet strength. The effect of particle size on pellet reducibility was, however, more complicated because of the simultaneous change in the total surface area and sintering behavior of the particles.

Durability Assessment of Wooden Pellets in Relation with Vibrations Occurring in a Logistic Process of the Final Product

Vibrations occurring during road transport can vary in a wide spectrum and they can lead to losses in quality of transported materials. However, the vibrations are definitely different than the loads experienced by pellet samples in the tester used for durability tests according to the standard ISO 17831-1. pThe aim of the study was to evaluate the durability of wood biomass pellets available for sale in large-area stores, in terms of loads occurring in transport. The durability of the ellets was tested by subjecting them to vertical and horizontal vibrations similar to those occurring during local transport of this type of fuel for the needs of households. Durability tests were also carried out in accordance with ISO 17831-1. The results were analyzed statistically. Among other, it was found that the vibration time impact on the tested pellet durability was significantly lower in case of horizontal vibrations than in vertical. Moreover, pellets with a diameter of 8 mm showed lower durability than pellets with a diameter of 6 mm. Durability tests carried out in accordance with ISO 17831-1 showed lower pellet strength results compared to the test methods based on lateral and vertical vibrations.

The effect of sodium alginate, lignosulfonate and bentonite binders on agglomeration performance and mechanical strength of micro-fine agricultural lime pellets

Agricultural lime (crushed limestone) is often applied to acidic soils as the release of carbonate ions neutralize acid forming compounds, such as those added during fertilizer addition. Agglomerated micro-fine limestone is an attractive alternative to powdered limestone, mitigating product losses as a result of windy conditions during application. This article examines the production of agglomerates using sodium alginate, lignosulfonate and bentonite binders for micro-fine CaCO3 powder. Central composite design was used to determine the optimal (i) amount of liquid, (ii) concentration of binder added to maximize the yield of agglomerates of 2–5.6 mm in diameter. Thereafter, four mechanical strength tests were carried out on the agglomerates, where strength was compared dependent on the binder and concentration thereof. The results show that lignosulfonate agglomerates performed the worst of the three binders, whereas agglomerates of >3 g/kg sodium alginate and 70 g/kg bentonite were acceptable in strength. While sodium alginate is a more expensive binder per gram, its high strength at relatively low levels may recommend its use industrially, contingent on economic modeling. This article successfully demonstrated the varying mechanical strengths of various limestone binders, which may assist with the development of novel soil amendment products.

An Analytical Way to Comparing the Affective Parameters on Iranian Pellet Strength

Iron ore pellets are the raw materials for direct reduction process of iron ore to sponge iron pellets and is an important step in the iron and steel production chain. Many of the defects in direct reduction and steel making processes could be identify in the iron ore processing stage. Therefore, the purpose of this study was to select the correct suppliers of iron ore pellets for direct reduction units based on criteria affecting the strength of cooked pellets, which played a key role in optimizing the production criteria of sponge iron and ultimately increasing production efficiency in the steelmaking stage which can be very effective. For this purpose, using the hierarchical analysis model, the parameters affecting the strength of pellets have been identified and studied by experts of several iron and steel production units, and finally, for example, several iron ore pellet production plants have been compared and ranked. According to AHP decision criteria, particle size is the most important parameter affecting the strength of cooked pellets.

Correlations between the compressive strength of the hydrochar pellets and the chemical components: Evolution and densification mechanism

Hydrochars of cotton stalk (CS) at the hydrothermal temperature of 180−280 °C and the retention time of 0−120 min were used for the purpose of developing fuel pellets. Subsequently, the physical properties and combustion characteristics of the hydrochar pellets were evaluated to assess the solid biofuel production potential. Then, the hydrochar samples were analyzed by FTIR, TGA, XRD, and SEM, aiming to investigate the evolution mechanism of the chemical compositions (hemicellulose, cellulose, and lignin) with the increasing hydrothermal temperatures and their effects on the compressive strength of the hydrochar pellets. The results indicated that the hydrochar pellets exhibited higher fixed carbon contents, elevated heating values, enhanced physical properties, and more stable combustion characteristics than the raw biomass pellets. Moreover, the skeleton structure of the crystalline cellulose was the critical factor affecting the compressive strength of the hydrochar pellets. In parallel, lignin was observed to be beneficial for fabricating solid bridges and also exhibited a substantial influence on the bonding performance. However, the crystalline cellulose completely decomposed into amorphous carbon, and the high carbonization degree of the lignin caused it to lose its bonding capacity, which led to a sharp decrease in the compressive strength of the hydrochar pellets pretreated at 280 °C to 2.9 MPa, lower than the CS pellets (4.2 MPa). Finally, the pictorial depiction of the chemical components’ structural characteristics exhibited in the hydrothermal carbonization process was displayed along with their influences on the hydrochar densification process.

Characterization of Colemanite and Its Effect on Cold Compressive Strength and Swelling Index of Iron Ore Pellets

In this study, the effect of colemanite and calcined colemanite (CC) addition on the properties of iron ore pellets is studied. The pellets are prepared in a lab without and with 0.2% colemanite and varying amounts of CC from 0 to 1.0 wt% in steps of 0.2%. A reference pellet is prepared under typical plant conditions, and the properties of the reference pellet are considered as the base value for improving the cold compressive strength (CCS) while maintaining the other parameters at an acceptable limit without altering the pellet. The study also aims to provide a detailed characterization of colemanite and calcined colemanite to better understand their behaviour during firing. The lab-scale results show that the CCS of pellets made with 0.2% colemanite was reduced by 222 points (60%) as compared to the reference pellets due to crack formation during firing. The results show an improvement in the CCS of the indurated pellets with CC dosage up to 0.4%, and decreasing strength is noted thereafter. It is observed that the swelling index increases with the increase in calcined colemanite dosage. To simulate plant conditions, reference pellets and pellets with optimized CC dosage were fired in a plant furnace.

Influence of Fraction Particle Size of Pure Straw and Blends of Straw with Calcium Carbonate or Cassava Starch on Pelletising Process and Pellet.

The aim of this study was to investigate the pressure agglomeration process of wheat straw (WS) and the blends of WS with calcium carbonate (CC) or cassava straw (CS) with a ratio of 6% wt./wt. from seven separate fractions with sizes in the range of 0.21–2.81 mm. The agglomeration was performed at a moisture of 30% wb and a material temperature of 78 °C, with a dose of 0.1 g, in a die of diameter 8 mm and height 80 mm. The effects of the process were evaluated based on the compaction parameters and the pellets’ density, tensile strength, and water absorption. The incorporation of additives into the WS improved the pellet process and quality. Refined results were achieved after adding CC, as compared to those achieved after adding CS, and the preferred particle size was in the range of 1.00–1.94 mm. This was because, under the given conditions, the back pressure in the die chamber significantly increased, allowing the achievement of a single pellet density of 800 kg·m−3. The pellets were resistant to compressive loads and cracked only at tensile strength of 6 MPa and a specific compression work of 6.5 mJ·mm−2. The addition of CC to the WS improved the strength of the adhesive and the cohesive bonds between the particles. The water absorption for the uncrushed pellets was considerably less than that for crushed pellets, which results in the safer storage of uncrushed pellets and excellent moisture absorption of crushed pellets. The addition of CC to the WS offers benefits in the form of pellet strength with a high water absorption capability. Notably, a study of crushed pellet litter under broiler rearing conditions and an analysis of the operational costs of using WS additives are required for implementing this study.

Influencing factors and evaluation system for Carbon–Calcium pellet performance in a pyrolysis furnace

In the new process of CaC2 production, C–Ca pellets need to be pyrolysed in a prepyrolysis furnace before being placed in a CaC2 furnace. In this paper, the factors influencing the performance of composite pellets in a pyrolysis furnace are studied experimentally. A comprehensive performance-evaluation system is established to calculate and evaluate composite pellets comprising five raw materials. The pyrolytic rate, compressive strength, and dust concentration of the composite pellets are tested through thermogravimetry, universal pressure tester and dust concentration detector, respectively. The effects of C/Ca ratio, temperature, time and raw material composition on these properties are explored. Results show that during the pyrolysis of the composite pellets, the C-containing raw materials have a significant effect on various performance indicators. With increased C/Ca ratio, the pellet pyrolysis rate and compressive strength show a downward trend; with increased pyrolysis temperature and time, the pellet pyrolysis rate, compressive strength and activity show an upward trend; with a change in raw material composition, the pellet activity and dust concentration change significantly. The comprehensive properties of CaO + coke and CaO + anthracite are superior to those of other raw materials in all aspects, and this finding is in line with the industrial-production practice.