Green Pellets Research Articles

Improving the roller screen efficiency to classify green iron pellets using DEM simulation, novel roll design and implementing banana configuration

Roller screens play a decisive character in the efficiency of pelletizing circuits and induration furnaces. Unlike vibrating screens, there have been no studies on roller screens to determine their capacity and dimensions. Most studies have utilized the discrete element method (DEM) simulation to assess roller screen performance by employing a spherical shape and the Hertz-Mindlin elastic model. However, this approach is unsuitable due to green pellets’ non-spherical shape and elastic–plastic properties. This study introduces the incorporation of the actual shape of green pellets and a hysteretic spring elastoplastic contact model. In this research work, a novel design of rolls with a grooved surface was recommended for the first time, resulting in a Total Screening Efficiency (TSE) of 96.4% compared to 87.1% for rolls with a smooth surface. Additionally, while exploring the impact of the decks number on the roller screen, a new design, known as the banana roller screen, was introduced. Under similar conditions, the TSE increased by 1.22% compared to the general roller screen type. It was also found that the roller screen’s capacity is directly related to the diameter, speed of rotation, and the number of rolls, while it has a reverse relationship with TSE and deck angle.

MAKING QUALITY AGGLOMERATES USING LEAN IRON ORES FOR SUSTAINABLE IRON-MAKING

For sustainable iron making and hassle-free operation of large blast furnaces (BF) and direct reduced iron (DRI) units, a more prepared burden in the form of good quality agglomerates is required. However, the situation is becoming more and more challenging owing to the faster depletion of high-grade iron ore, increased fines generation due to mechanized mining, wide variations in chemistry & mineral characteristics, high content of gangue minerals, and poor liberation characteristics. The growing demand for steel vis-à-vis iron ores has necessitated the utilizationof low-grade iron ores for steel production. The challenges lie in the economic extraction of lean ores and their conversion into quality agglomerates for use in iron making. The utilization of low-grade iron ores has assumed greater significance for the optimal utilization of natural resources and the sustainability of the steel industry. Thebeneficiated concentrate of BHQ iron ore from the Sandur Schist belt is used for the pellets. Green green pellets with 1.21 kg/pellet GCS and drop strength of 12 drop number were producedat an optimum binder of 1.2% and moisture of 9.5%. Induration of green pellets at a firing temperature of 1300 °C has resulted in adequate pellet properties of 237 kg/pellet of CCS, 91.87% TI, 7.41% RDI, and 22.56% porosity. An attempt is made to produce pellets suitable for iron making by optimizing various raw materials and operating parameters.This will reduce dependency on high-grade ores and effectively utilize low-grade iron ore to produce good-qualityiron-making pellets.

Experimental study on parameters optimisation of adding vanadium-titanium magnetite to iron ore pellet

Vanadium-titanium magnetite has coarse particle size, small specific surface area, poor surface hydrophilicity and low strength when being made into pellets. However, vanadium-titanium magnetite pellet also has a certain application requirement due to its large reserves and high comprehensive utilisation value. Therefore, this article investigated the effects of water ratio, bentonite ratio, vanadium-titanium magnetite ratio, CaO ratio and roasting temperature on the strength of pellets. The results showed that better parameters of green pellets were obtained as follows: the water ratio was 9%, the bentonite ratio was 2.5% and the vanadium-titanium magnetite ratio was 25%. There was no obvious relationship between the CaO ratio and green pellet strength. Better preparation parameters of roasted pellets were as follows: water ratio was 9%, bentonite ratio 2%, vanadium-titanium magnetite ratio 25%, CaO ratio 1% and roasting temperature 1300°C. This provides guidance for the effective use of vanadium-titanium magnetite.

High efficiency filtration and optimization of pelletizing performance of fine hematite concentrate using sulfuric acid filter aid: Behavior and mechanism

Following the application of anionic reverse flotation to fine low-grade hematite ore, a significant challenge emerges with elevated slurry viscosity and heightened moisture content in the resulting filter cakes. To address the challenge of dewatering during the filtration process of fine hematite concentrate, the impact of sulfuric acid filter aid dosage and filtration temperature on the filtration performance of hematite concentrate was systematically investigated in this study. In addition, the effect of sulfuric acid filter aid on the preparation of hematite pellets was also studied. The results revealed a significant decrease from 1.10 × 1010 1/m2 to 5.7 × 109 1/m2 in the specific resistance of the hematite filter cake when the sulfuric acid dosage was 1.2 g/kg and the filtration temperature was 20 °C. The mechanism underlying the enhancement of filtration performance of fine hematite concentrate by sulfuric acid was summarized. Sulfuric acid compressed the double electric layer on the surface of hematite concentrate particles, reducing the surface zeta potential and causing the aggregation of fine particles into larger ones. This led to an increase in filter cake porosity and compression of the hydration film thickness on particle surfaces, facilitating easier removal of filtrate from the filter cake. The appropriate dosage of bentonite for pelletizing was not significantly affected by sulfuric acid filter aid. Sulfuric acid improved the porosity, drying rate, and burst temperature of hematite green pellets. While the compressive strength of preheated pellets from sulfuric acid-assisted filtration of hematite concentrate showed a slight decrease, the compressive strength of roasted pellets was significantly increased.

Tribological and high-water jet erosion characteristics of Si3N4 + SiO2 based wave transparent ceramics prepared via green pellet compression molding

Si3N4 + SiO2 based wave-transparent ceramics are popular due to their excellent hardness, good flexural strength, and superior dielectric properties. A recent study explored the use of compression molding to produce green pellets, followed by sintering. However, further investigation into the friction, wear, and water erosion characteristics should be explored to provide the final shape on the green and sintered pellets. Therefore, this study investigates the friction, wear, and water erosion behaviour of Si3N4 + SiO2 ceramic green compact GP1 and GP2 (compression molded at 305 MPa and 1912 MPa, respectively) and their sintered pellets SP1 and SP2 (sintered at 1500 °C). The wear and friction behaviour of the green pellets were studied under various loads (5 N and 10 N), while the sintered samples were tested at 5, 10, and 20 N, using ball-on-disk tribology in dry sliding conditions. The results show that the wear rate rises with an increase in the applied load. GP1 showed a high wear rate (165.0 ×10−4 mm3/N m), coefficient of friction (COF) of 0.36, and lower Hertzian contact stress (2.49 ×107 N/mm2) under 10 N load. Additionally, GP1 exhibited a higher erosion rate (143.61 mm3/min) with continuous erosion traces. In contrast, the sintered ceramics SP2 had an insignificant wear rate (4.55 ×10−4 mm3/N m) and erosion rate (15.83 mm3/min) with discontinuous erosion traces due to having higher hardness. Fractographic analysis showed that the primary wear mechanisms were abrasive wear, grain pull-out, crack propagation, debris formation, and surface fatigue. Additionally, the wear debris size decreased from green to sintered ceramics. HRTEM results confirmed the non-stoichiometric composition of mixed phases (Si3N4, SiO2, SiC, and Si2N2O) in the wear debris of both samples SP1 and SP2. In water jet erosion, the primary wear mechanisms identified were crack propagation, particle pull-out, striations, delamination, brittle fracture, and crater formation.

Investigating effects of sintering mean residence time on engineering properties of coal ash‐based lightweight aggregate

AbstractThis study examines the effect of sintering mean residence time (MRT) on the engineering properties and morphological structure of lightweight aggregates (LWA) manufactured from waste coal combustion ash (W‐CCA). A thermodynamics‐based framework was used to tune LWA manufacturing processes. A minimum 35% liquid phase (by mass) and a lower bound viscosity of 100 Pa·s of molten material were found necessary to successfully produce LWA. Using W‐CCA's chemical composition and FactSage thermodynamic modeling, the sintering temperature for LWA was set to 1075°C. Green spherical pellets made using a pelletizer were sintered at MRT of 5.1, 14.8, and 25.9 min to test LWA physical‐mechanical properties including, unit weight, specific gravity, water absorption, and compressive strength. Results indicated that unit weight ranged from 752 to 800 kg/m3, providing desirable lightweight properties. Oven dry specific gravity ranged from 1.24 to 1.43, complying with ENI13055 specification for LWA. Water absorption capacity decreased as MRT extended from 5.1 to 14.8 min and then increased as MRT proceeded from 14.8 to 25.9 min, achieving an average absorption capacity of 26% ± 1.5%. The inverse effect was noticed for compressive strength as LWA sintered with an MRT of 14.8 min demonstrated the highest compressive strength of 14.7 ± 1.8 MPa. The initial decrease in water absorption and increase in compressive strength are attributed to the efficient sintering of the LWA's internal structure. The inverse effect observed as MRT proceeded from 14.8 to 25.9 min was believed to be a result of thermal cracking due to extensive heat exposure. MRT of 14.8 min is recommended for LWA production using the coal ash utilized in this study for its buoyancy characteristics, sufficient absorption capability, and higher compressive strength.

Intercalation based synthesis of Chevrel phase superconductors

This work focuses on the superconducting and magnetic properties of Chevrel phase (CP) compounds (Cu2Mo6S8 and Ni2Mo6S8) processed via a novel self-propagating high-temperature synthesis (SHS) method involving ternary cation intercalation in MoS2 high-temperature polymorphs. Green pellets of the precursor materials sealed under vacuum and exposed to 1050 °C or 1200 °C rapidly transformed from a powder mixture into submicron CPs within minutes. X-ray diffraction analysis confirmed the presence of Cu2Mo6S8 CP (67%), and Ni2Mo6S8 (93%). This group has illustrated the first time CP were formed at low energy cost and full stoichiometry. Magnetization versus temperature data obtained for the samples under different field conditions confirmed the superconducting behavior of the Cu–CP at a critical temperature of 8.3 K. The Ni–CP behaved as a superparamagnetic at low temperature (4.2 K). The results of this work suggest that the novel SHS process offers a viable scalable synthesis route for the Chevrel family of compounds and that it is worth exploring the functional applications of the new compounds of this material system.

Development of red mud based sintered artificial aggregates with various industrial wastes

Red mud (RM) has drawn a lot of attention in the search for potential uses in the production of sintered artificial aggregate from industrial waste products. The main objective of the study is to produce an RM-based sintered artificial aggregate (SAA), with several blends (binary, ternary, and quaternary) using various industrial wastes. This study includes assessing the mechanical and physical properties of SAA as well as the sintering parameters in order to determine the appropriate material mix ratio. To achieve these objectives, a comprehensive experimental approach was adopted. A total of 35 different mixtures were formulated by incorporating various industrial wastes as binders and sintering additives. The green pellets were preheated at 105 °C for 24 h, and consecutively sintered at different temperatures, namely 700 °C, 900 °C, 1100 °C, and 1150 °C with a duration of 30 min. A compressive strength test was performed in order to find the mechanical property of SAA similarly water absorption and bulk density tests were conducted to find the physical properties of SAA. To characterize the SAA, scanning electron microscope analysis (SEM), X-ray diffraction (XRD) and energy dispersive x-ray analysis were conducted, and also data analysis was performed using Artificial Neural Network (ANN) tools, yielding accurate predictions. Successfully best compressive strength low water absorption SAA was produced. The best material weight mix ratio for the production of SAA was identified as (A18) RM: Fly Ash: Waste Glass Powder; 78:10:12. Out of all blends the ternary blend (A18) SAA exhibited impressive properties after 30 min of sintering at 1150 °C: high compressive strength of 22.92 MPa, water absorption of 4.26%, and bulk density of 1296.12 kg m−13. This was made possible by the high amount of Al2O3, SiO2, in the combination of fly ash, and waste glass powder with RM. SEM and XRD analysis also confirmed that the (A18) SAA achieved the best compressive strength, and low water absorption due to turning the surface and core area into a solid, reduced internal pores and formed quartz, and hematite phases. The findings of this study serve as a foundation for future work and pave the way for the development of sustainable construction materials.

Enhancing Sintered Wave Transparent Ceramics (Si3N4 + SiO2) for Radome Application through Green Pellet Compression Molding

Enhancing Sintered Wave Transparent Ceramics (Si3N4 + SiO2) for Radome Application through Green Pellet Compression Molding

Optimisation of thermal regime and consolidation properties of high-silica magnesium-containing pellets

An in-depth study on the preparation process of high-silica magnetite magnesium pellets based on a grate-rotary kiln process is of great significance for promoting the utilisation of low-grade magnetite resources. When the magnetic hematite ratio is 30% and the proportion of magnesia is 1.5%, the performance of green pellets is the best. The preparation of high-silica magnesium pellets requires two stages of grate preheating for additional heating, and the appropriate preheating system is 1150°C for 15 min. The suitable magnetic hematite mixture ratio of pellets should not exceed 30%, and the reasonable magnesia ratio should not exceed 1.5%. Otherwise, the preheating temperature should be further increased, or the preheating time should be extended. The suitable roasting temperature is low, only 1225°C for 15 min, and the pellet strength can reach more than 2365N. Magnetic hematite and added magnesium flux inhibited the continuous crystallisation consolidation property in the pellet. The high SiO2 content in the gangue of high-silica magnetite impedes the recrystallisation consolidation of Fe2O3 particles in the pellet. At the same time, the primary Fe2O3 in the magnetic hematite mixed ore is less reactive than the new Fe2O3 in the magnetite oxidation. With the roasting process, the magnesium ferrite content in the pellet increases, and the recrystallisation consolidation is inhibited, so the grate-rotary kiln process to produce high-silica magnesium-containing pellets is suitable to use a higher preheating temperature to meet the requirements of grate-rotary kiln pellet strength.

Microstructure, dielectric, ferroelectric and piezoelectric properties of K0.45Na0.45Li0.1NbO3 lead-free ceramics prepared via cold sintering with post-annealing

Via the method of cold sintering with post-annealing, the lead-free ceramics [Formula: see text][Formula: see text][Formula: see text]NbO3 were prepared. The cold sintered pellet without post-annealing shows a relative density ([Formula: see text] of 77.9%, which is larger than [Formula: see text] of the green pellet via the conventional solid-state sintering (SSS) method ([Formula: see text]). The cold sintered pellets were post-annealed at temperatures between [Formula: see text]C and [Formula: see text]C. The effect of post-annealing temperatures on microstructure, dielectric, ferroelectric and piezoelectric properties of the ceramics was studied in detail. After being post-annealed, the relative densities and grain sizes of the ceramics were increased. The ceramics post-annealed at [Formula: see text]C show excellent dielectric, ferroelectric and piezoelectric properties. Compared to the conventional SSS method, the method of cold sintering with post-annealing is successful in preparing dense [Formula: see text][Formula: see text][Formula: see text]NbO3 lead-free ceramics in a wide temperature range and at relatively low temperatures.

Energy consumption optimization model and system for the pellet drying process of straight grate

The drying process is a crucial stage in the thermal treatment of iron ore pellets in a straight grate, as it has a direct impact on pellet quality and energy consumption. Consequently, this paper develops a simulation model for the pellet bed drying process, which is validated through industrial data and enables the visualization of temperature and moisture distribution within the pellet bed. Based on the simulation model, an optimization model for the drying process is developed to minimize the specific energy consumption per tonne of green pellets. The constraints of the drying process are the moisture content requirements and burst temperature. A genetic algorithm is employed to optimize the parameters such as trolley speed, pellet bed thickness, air temperature, and air pressure. The results show that, with an absolute error criterion of 10 °C, the temperature calculation accuracy of the simulation model exceeds 86%, effectively describing the drying process in a straight grate sintering machine. Under yield limitations, the optimal cumulative energy consumption per tonne of green pellet is reduced by 1.50% during the drying process. Finally, a simulation and optimization system for the drying process in the straight grate is implemented in C++. This system not only generates essential data for designing the drying section in a straight grate but also lays a theoretical foundation for system optimization and optimal control.

Implementation of DEM to calibrate contact parameters, as a novel simulation of the elastoplastic behavior of green iron pellet classified by roller screen

As green iron ore pellets exhibit elastoplastic behaviors, it is crucial to select an appropriate DEM model that accounts for these behaviors to simulate their classification in a roller screen. The most important DEM models include the Hertz-Mindlin and the hysteretic spring. In this study, for the first time, green pellet behaviors were modeled based on their actual shape (multi-spheres) under various conditions of moisture content, bentonite dosage, and iron concentrate type, using the image analysis. All parameters required to simulate the behavior of green pellets were measured through experimental tests. These properties include shape (sphericity), physical (angle of repose), and mechanical characteristics (shear modulus, yield stress, coefficient of restitution as well as static and rolling friction coefficients). Thus, the total contact parameters were adjusted based on these properties. Additionally, a comprehensive comparison was made between the Hertz-Mindlin and hysteretic spring models to accurately simulate the characteristics of the green pellets and assess the efficiency of the roller screen. Finally, it was found that the use of a realistic shape and hysteretic spring model provides a more accurate simulation of pellet classification when applying a roller screen and shows a stronger correlation with the laboratory results.

Waste to shield: Tailoring cordierite/mullite/zircon composites for radiation protection through controlled sintering and Y2O3 addition

In this study, investment casting shell waste successfully utilized to produce cordierite/mullite/zircon composites. Green pellets, consisting of investment casting shell waste, alumina, and magnesia, were prepared and sintered at temperatures between 1250 and 1350 °C. The influence of the sintering temperature on the crystalline phase composition, densification behavior, flexural strength, microstructure, and radiation shielding properties of the cordierite/mullite/zircon composites is investigated. Phase analysis showed that characteristic cordierite peaks appear at 1250 °C, but the complete conversation of silica from investment casting shell waste into cordierite requires a sintering temperature of at least 1300 °C. Notably, the cordierite/mullite/zircon composite sintered at 1350 °C exhibited a sixfold increase in flexural strength compared to the ceramic composite directly fabricated from investment casting shell waste at the same sintering temperature. Furthermore, the effect of Y2O3 addition on composites' radiation shielding properties is investigated. The results show that the Y2O3 addition improves densification behavior, enhancing the shielding capabilities of the composites against fast neutron and gamma radiation. Our findings suggest that the developed ceramic composites show significant potential for gamma-ray and neutron shielding applications.

Comparing the growth and survival of tautog (Tautoga onitis) fed a diet of green crab (Carcinusmaenas) or commercial pellets in a recirculating aquaculture system

Tautog, a coastal marine wrasse, is a highly sought food fish in southern New England and the Mid-Atlantic region of the United States due to its firm white fillet. Tautog has been identified as a candidate species for marine aquaculture in the region. Unfortunately, previous grow out studies have documented slow growth, which is detrimental for aquaculture. However, these studies contrast with data from wild populations which indicate rapid growth in the first few years of life. It is theorized that these differences in growth could be due to available diets. In the wild, tautog primarily prey on mollusks and crustacean prey, while laboratory studies rely on commercial fishmeal-based diets. This study compared the growth and survival of juvenile tautog fed with chopped green crabs, commercial fish pellets and a hybrid diet consisting of both green crabs and pellets. Wild juvenile tautog were collected from local waters and cultivated in a recirculating aquaculture system for 250 days. Tautog fed the commercial pellet diet had a growth rate of 0.31 ± 0.11 mm/day, consistent with previous grow out studies. The average growth rate of tautog fed the green crab diet was 0.52 ± 0.13 mm/day, with a peak growth rate of 0.66 ± 0.07 mm/day. The hybrid diet was intermediate to the other treatments at an average growth rate of 0.46 ± 0.1 mm/day. Statistically significant differences were observed across treatment groups (P < 0.05). Survival was high in the green crab and hybrid treatments (96.7% ± 1.2% and 96.0% ± 2.0%, respectively), and lower in the pellet treatment (85.3% ± 9.5 %). Data from this study indicate that the growth potential of tautog is higher than previously documented in aquaculture studies. This study highlights the need for additional research to develop feed formulations for non-piscivorous marine carnivores.

Analysis of the Luminescent Emission during Flash Sintering of 8YSZ and 20SDC Ceramics

Light-emission data were collected before, during, and after the occurrence of the flash event in pressureless electric-field-assisted (flash) sintering experiments on ZrO2: 8 mol% Y2O3 (8YSZ) and CeO2: 20 mol% Sm2O3 (20SDC) ceramic green pellets to analyze the luminescent emission from the samples. The experiments were performed at 800 °C with an applied electric field of 100 V·cm−1 at 1 kHz, limiting the electric current to 1 A. Luminescence data were obtained in the 200–1200 nm (ultraviolet–visible–near-infrared) range. The deconvolution of the optical spectra allowed for the identification of emission bands in the visible range due exclusively to the samples. The wavelength maxima of the emission bands in 8YSZ were found to be different from those in 20SDC. It is suggested that these bands might originate from the interaction of the electric current, resulting from the application of the electric field, with the depleted species located at the space-charge region at the grain boundaries of these ceramics. The main results represent a contribution to help to clarify the mechanisms responsible for the fast densification with inhibition of grain growth in electroceramics.

Mechanical Activation of CaSO4 Enriched Petroleum Coke Fly Ash for Development of Green Pellets

Mechanical Activation of calcium sulphate enriched petroleum coke fly ash (PCFA) generated from circulation fluidized bed combustion (CFBC) boiler was investigated to improve the surface reactivity of PCFA. The physico- chemical, mineralogical (XRD), morphological (SEM) characteristics of PCFA, activated PCFA and developed green pellets were studied in detail. It was found that the milling time of 45 minutes is efficient for the activation of PCFA and results in fragmentation of coarse particle into fine porous particles. Mechanical activation results in enhancing physical properties and reactivity of PCFA without any further chemical treatment. The mean particle size of activated PCFA with 45 min milling time was 12.51-12.60µm and the porous morphology were seen through SEM. The hydration phases like ettringite, portlandite and calcium silicate hydrate mainly contribute to the development of mechanical strength in activated PCFA pellets which were also confirmed through morphology of needle-shaped crystallites. The study recommends that mechanically activated PCFA could be used as an adsorbent material for heavy metals removal from waste waters.

Effects of Magnesium Mineral on the Reduction and Expansion Performances of Baiyun Ebo Iron Pellets

Pellet ore is an important raw material for blast furnace ironmaking, and its reduction and expansion performance directly affects the smooth operation and smelting indicators of the blast furnace. This paper quantitatively studied the effects of magnesium minerals such as dolomite and serpentinite on the pellet-forming performance, the microstructure after roasting, compressive strength, and the reduction expansion performance of Baiyun Ebo iron concentrate. The optimal ratio of dolomite and serpentinite to add was determined when preparing pellets using Baiyun Ebo iron concentrate powder. The results showed that the drop strength and compressive strength of the green pellet after adding serpentine were relatively higher than those after adding dolomite, indicating that controlling the MgO content in the green pellet at 2.5% using serpentine was beneficial for improving the drop strength and compressive strength. Under the condition of adding dolomite, when the MgO content was 2.5%, the compressive strength of the roasted pellet was the highest, which was 2192.6 N, and the volume expansion rate was 12.32%. Under the condition of adding serpentine, when the MgO content was 2.5%, the compressive strength of the roasted pellet was 2622.2 N, and the volume expansion rate was 9.71%. Compared with dolomite as a magnesium additive, when the reduction expansion rate of Baiyun Ebo iron concentrate was controlled within 20%, serpentine only needed to have a MgO content of about 1.5% in the pellets, while dolomite needed to have a MgO content of about 2.5%. Therefore, under the condition that the MgO contents of dolomite and serpentine were equivalent, the amount of serpentine used was lower.

Hydroxyapatite and pore former effects on the microstructure and mechanical strength of porous pellets loaded with Lactobacillus

Porous hydroxyapatite (HAP) pellets were prepared by extrusion/spheronization/sintering and loaded with Lactobacillus (La-5). Micronized (PFm) or coarse size (PFc) microcrystalline cellulose were the pore formers, while HAP grades from Budenheim (Tri-cafos®) and Sigma-Aldrich with different specific surface (Sw) were the substrates. Green pellets were heated to sublime microcrystalline cellulose, followed by sintering to form porous pellets. These were characterized by electron/optical microscopy/image analysis, porosimetry, nitrogen sorption and mechanically. Stronger pellets resulted from the high Sw HAP and PFm, and larger pores from the low Sw HAP and PFc. HAP origin impacted on pellet strength. Two loading methods were applied: (i) immersion of pellets in La-5 suspension and (ii) injection of suspension into pellets under vacuum. The latter gave 3-x higher loading, which was maximum for the Tri-cafos® 250 HAP/PFc pellets with larger pores that allowed entrance of bacteria, but adequate strength to resist disintegration during loading. La-5 viability in 250 HAP/PFc pellets was 1.2 × 108 CFU/g.

Investigation of cigarette effect and elastic-plastic behavior of green iron pellets on the roller screen efficiency

The green iron pellet demonstrates elastic–plastic deformation behavior during classification on a roller screen, which has a significant effect on its inefficiency due to the occurrence of phenomena such as the cigarette effect. This phenomenon causes the quantity and quality of produced pellets to drop by transferring the on-size pellets to the fine grain section and especially the oversized pellets to the product section. In this research, the effective factors in creating this phenomenon and the solutions to reduce it are investigated. It is observed that the optimum plastic behavior of the pellet and consequently the efficiency of the roller screen would be achieved when the green pellet is made from magnetite concentrate with 8 % moisture and 1 % bentonite, and roller screen operational parameters include feed rate of 1.5 t/h, the deck inclination angle of 13 degrees and the roll rotation speed of 150 rpm. The results obtained for the optimum fine removal efficiency, product screening efficiency, loss of production to undersize, on-size contamination, and oversize removal efficiency are 92.1 %, 93.7 %, 5.36 %, 5.23 %, and 73.2 %, respectively. The total screening efficiency of the roller screen is also estimated as 86.29 % and the cigarette effect is decreased to the most optimal state.