Pellet Plant Research Articles

An integrated life-cycle greenhouse gas protocol accounting on oil palm trunk and empty fruit bunch biofuel production

Improper discard of oil palm trunk and empty fruit bunch renders massive greenhouse gases. Turning these palm wastes into solid biofuels could aid in carbon reduction. The embodied environmental impacts of the solid biofuel densification process are neglected in carbon emission quantification studies applying Greenhouse Gas Protocol while the significance of classifying the system's direct and indirect carbon emissions were overlooked in those utilising life cycle assessment. Despite the prospect of both methodologies to complement their limitations for carbon emissions quantification, no study integrates both methodologies to investigate direct and indirect emissions systematically from a life cycle perspective. An integrated framework of life cycle assessment and Greenhouse Gas Protocol is developed to quantify the direct and indirect carbon emissions of oil palm trunk and empty fruit bunch densification from cradle-to-gate for three pellet plants in Indonesia and Malaysia. The emissions are categorised into three emission scopes: Scope 1, Scope 2, and Scope 3 according to the Greenhouse Gas Protocol, integrated with avoided emissions which are quantified via life cycle assessment. The pellet plants generate 534.7–732.3 kg CO2-eq/tonnepellet per hour, in which Scope 1 (i.e., direct emissions) is the major emission scope due to high emissions from wastewater production and drying fuel combustion. Washing equipment (169.2–439.0 kg CO2-eq/tonnepellet per hour) and burners (87.1–214.5 kg CO2-eq/tonnepellet per hour) are the hotspots found in the pellet plants. Producing empty fruit bunch pellets could reduce 62.0–74.1 % of emissions than landfilling the empty fruit bunch. Empty fruit bunch pellet and oil palm trunk pellet are recommended to co-fire with coal to phase down coal usage in achieving COP26 pledge. This study provides data-driven insights for quantifying carbon emissions through the integrated framework and could be a reference in future life cycle carbon footprint studies of the biomass densification process.

A Real-World Industrial Application of Particle Swarm Optimization: Baghouse Designing

Due to the high ability and flexibility of meta-heuristic algorithms (MAs), they can widely be used in many applications to solve different problems. Recently, real-world engineering applications of these optimization algorithms have attracted researchers’ attention. This paper applies particle swarm optimization (PSO) as an effective population-based MAs to design the baghouse (BH). BH filters are among the most commonly used devices in air pollution control systems in mining and food manufacturers and power plants. Designing the BH depends on several parameters such as its capacity or airflow (Nm3/h), air-to-cloth ratio ([Formula: see text]), cam velocity, and installation limitations. Generally, industrial designers select the number and length of bags and their arrangement based on the experimental observations to meet the parameters mentioned above. The minimum cost or total weight of equipment is utilized for proposing a competitive price for suppliers. In this paper, a PSO algorithm is used to minimize the total cost by finding the best possible design (the number, length, and arrangement of bags). In addition, a real example of installed BH in a pelletizing plant is given and compared with PSO results to investigate the efficiency of the proposed algorithm. The results suggest that PSO can find a better design with minimum total cost than an installed BH filter, and therefore, PSO is applicable to industrial designers.

Evaluation of Source Emissions Dispersion Potential Near a Coastal Village of Maharashtra, India

Industrial emissions are a serious environmental problem worldwide due to particulates and toxic gases. This study aims to generate an activity-specific emission inventory and estimate emissions dispersion extent in the vicinity of the coastal industrial village by simulating the existing coke oven and pellet plant emissions using the steady-state plume model. Continuous air quality monitoring results were compared with the predicted consequential emissions for the year 2018-19. The maximum ground-level concentrations of particulate and gases within the modeling simulation domain were observed at 9005 m away from the center. They were predicted to be 116.39 μg.m-3, 79.14 μg.m-3, 52.97 μg.m-3, and 211.86 μg.m-3. Data analysis showed that air mass transport from the project to the receptor sites resulted in ambient air concentrations higher than those observed in the other sites. Overall predicted results obtained from AERMOD Cloud simulations were shown to have less bias than the measured results. They recommended considering it as appropriate for the prediction of annual average concentration.

Optimization of Pellet Plant Straight Grate Induration Furnace Firing Cycle for High Alumina and High LOI Iron Ore Pellet

Optimization of Pellet Plant Straight Grate Induration Furnace Firing Cycle for High Alumina and High LOI Iron Ore Pellet

Analysis of modern wood processing techniques in timber terminals

Abstract The transportation of forestry products is performed over long distances and is quite expensive, which limits the development of biofuel plants in Russia and around the world. The use of timber terminals contributes to transportation cost reduction and mitigates negative environmental impacts. This work aims to analyze various technological solutions for optimization of forestry products processing at temporary terminals and cost reduction of transportation, shipping, and wood treatment. The work presents a discussion on the technological and economic possibilities of the mobile pellet plant, the mobile essential oil production plant, and an enhanced autonomous electric generator system. It is shown that the use of mobile plants for obtaining pellets and essential oils allows processing wood residues at the terminal, which reduces the cost of transportation and shipment of raw materials and improves the quality of the finished products. The current study also examines some of the modern scanning technologies used to detect log defects and obtain complete biometric information in real time while assessing the productivity of wood processing operations. The results of the study can be used to develop efficient movable timber terminals.

Simultaneous effect of temperature, shrinkage, and self-weight creep on RC beams: A case study

This study presents the results of long-term field measurement of two RC beams under the simultaneous effect of medium to high temperature, shrinkage, and self-weight creep. In industrial complexes such as steel making plants, these members may, in addition to creep and shrinkage, be exposed to high temperature. However, less attention has been paid to the simultaneous effect of creep, shrinkage, and temperature in a case study framework. In this regard, two RC beams with the same geometric properties in a pelletizing plant located in Kerman, Iran, were studied. In addition, in order to establish a powerful numerical method for these effects, numerical results were compared with the field measurement data. The results showed that an average increase by 50% in temperature would increase the maximum deflection of RC beam by 37%. In the case of the environment temperature, grate machine temperature increased the maximum deflection of RC beam by 61%. Moreover, field measurements showed that for self-weight creep level, shrinkage, temperature, and cracking strains covered more than 80% of the total strain. Similarly, such as this case study, simultaneous effects of these triple factors can change the long-term serviceability of structural elements exposed to harsh environmental conditions.

The Efficiency of Railways Specialized in Transporting Iron Ore and Pellets

ABSTRACT Objective: the objective is to compare the relative efficiency of the railways specialized in transporting iron ore (MFe) and pellets (PLMFe), which are part of the assets of mining companies and pellet plants considering the 2016 scenario. Methods: the methods used were the data envelopment analysis (DEA) technique, with the application of the output-oriented constant returns scale (CRS) model; the initial combinatorial multicriteria method for choosing the input variables; and Tobit regression as a validation strategy for the DEA model. Results: of the twelve railways evaluated, three railways were identified as efficient: Estrada de Ferro Carajás, Fortescue, and Mount Newman. Conclusions: the applied model was considered a good method to evaluate the efficiency of railways specialized in transporting MFe and PLMFe, as it determined the efficiency of each railway, suggesting the necessary increase in the output variable or adjustments in the input variables so that the railways reach the efficiency frontier. With that, companies can use the results of this study to guide future improvements to make their railways more efficient or maintain them on the frontier of efficiency.

The Efficiency of Railways Specialized in Transporting Iron Ore and Pellets

ABSTRACT Objective: the objective is to compare the relative efficiency of the railways specialized in transporting iron ore (MFe) and pellets (PLMFe), which are part of the assets of mining companies and pellet plants considering the 2016 scenario. Methods: the methods used were the data envelopment analysis (DEA) technique, with the application of the output-oriented constant returns scale (CRS) model; the initial combinatorial multicriteria method for choosing the input variables; and Tobit regression as a validation strategy for the DEA model. Results: of the twelve railways evaluated, three railways were identified as efficient: Estrada de Ferro Carajás, Fortescue, and Mount Newman. Conclusions: the applied model was considered a good method to evaluate the efficiency of railways specialized in transporting MFe and PLMFe, as it determined the efficiency of each railway, suggesting the necessary increase in the output variable or adjustments in the input variables so that the railways reach the efficiency frontier. With that, companies can use the results of this study to guide future improvements to make their railways more efficient or maintain them on the frontier of efficiency.

Development of process for reduction in fines generation at direct reduced iron plant by coating of magnetite iron ore fines on hematite iron ore pellets

Iron ore pellet fines generation at direct reduced iron (DRI) plant is ranging from 10 to 12% during handling of the pellets from pellet plant to DRI plant. The generation of fines during handling depends on the quality of the produced pellets, mainly due to the abrasion index (AI) of the pellet. To reduce the generation of pellet fines, detailed laboratory studies have been carried out by coating the hematite iron ore pellet surface with magnetite fines generated from reduction roasting plant, and mixed magnetite fines with limestone fines. The coated green pellets were fired in a rising hearth furnace. The magnetite fines were varied from 0 to 2.5% as coating agent, and limestone fines was varied from 0 to 0.6% as coating agent mixed with magnetite fines. At optimum 1.5% magnetite fines as coating agent achieved better pellet properties and reduced the fines generation from 6.8 to 3.2% due to formation of secondary hematite phases at the pellet shell. With mixed 0.2% limestone and 1.5% magnetite fines reduced pellet fines generation from 6.8 to 4.2%. Reduction in fines generation with mixed fines was due to formation of secondary hematite and Ca-ferrite at the pellet surface. Secondary hematite and Ca ferrite phases having higher micro-hardness compared to other phases of iron ore pellet. The sequence of micro-hardness of the pellet phases is secondary hematite > Ca-ferrite > primary hematite > magnetite. The secondary hematite and Ca-ferrite formed at the pellet surface due to coating of magnetite as well as magnetite with limestone fines improved the overall pellet quality and reduced the generation of fines at DRI plant. Coating of magnetite fines alone showed better pellet properties with lesser fines generation compared to coating of mixed limestone and magnetite fines.

Modeling breakage by impact of fragments of fired iron ore pellets

As soon as fired iron ore pellets suffer their first breakage event, fragments are created. During handling from the pelletizing plant to the steelmaker furnace, several stages of handling occur, so that if a well-formed and nearly spherical pellet breaks early in the handling chain, its fragments may also end up undergoing breakage. This is particularly important if one wishes to predict breakage during all handling stages. Unfortunately, no study in the past analyzed breakage of fragments of fired iron ore pellets, which will likely differ in comparison to the nearly spherical pellets owing to the irregular shapes of fragments. This work investigates breakage of fragments of iron ore pellets by impact using a pneumatic gun device, investigating the effect of fragment history and impact velocity on the breakage probability, the generation of fines by surface breakage as well as the fragment size distribution from body breakage. Results show that fragments are more amenable to surface breakage than well-formed pellets and also that their strength increases as fragment sizes reduce.

Comparative analysis of straight grate machines and combined facilities grate-tubetype kiln-cooler for selection technologies of pellets production

At present, mainly straight grate machines (SGM) and combined facilities grate-tube-type kiln-cooler (GKC) are used for heat-strengthening induration of iron ore pellets. Their total share in the produced iron ore pellets in the world accounts for 93%, of which SGM takes 60% and GKC – 33%, which speaks about high efficiency of both methods of induration. At the same time, when making decision on construction a pelletizing plant, a question of selection of most effective technology of iron ore pellets production by SGM and GKC often arises. Results of comparative analysis of efficiency of technologies of iron ore pellets production by SGM and GKC presented. Features of various ore types pellets induration considered as well as possibilities of ensuring the required quality of finished pellets at application for induration SGM and GKC. Data on maximum productivity of the considered induration facilities, amount of dust, fines formation, emissions of harmful substances into environment and electric energy consumption presented. Importance of a possibility of accounting of fuel type selection, of heat expenses for heat treatment, of expenses for maintenance, capital and operation costs were noted. It was shown that choice of a particular variant of technology should be done at the stage of elaboration feasibility study accounting existing experience of facilities running, availability of fuel types, cost of energy resources, climate zone and assembling solutions.

Workers’ Health Risk Factors in the Production of Iron Ore Pellets

Introduction. The labor of workers of the main occupations in the mining industry is characterized by a combined effect of occupational risk factors, which can be further aggravated by adverse environmental conditions. Objective: to study working conditions of employees in the mining industry. Materials and methods. We conducted a hygienic assessment of the technological process of manufacturing oxidized fluxed and non-fluxed pellets during the extraction of iron ore by surface mining and its further processing into high-quality raw materials for ferrous metallurgy, and a study of harmful physical and chemical factors of the working environment. Results. We established that a sinter machine operator (Class 3.3 hazard working conditions in the summer time), an operator of the agglomeration and firing furnace (Сlass 3.4), and a bunker operator in the shop for fired pellets (Сlass 3.3) work in hot occupational environment. The average value of the intensity of thermal radiation over the irradiation period (1.35 hours) for agglomeration and firing furnace operators was 356.2 W/m2 or 2–2.5 times higher than the maximum permissible level. Increased noise levels (Class 3.2) were measured at the workplaces of conveyor, sinter and furnace operators (14.8 % and 9.25 %). At individual workplaces of sintering machine operators, we registered elevated dust concentrations (Class 3.1), noise levels (Classes 3.1 and 3.2), sulfur dioxide concentrations (Class 3.1), and the sum of irritant chemicals (Classes 3.1 and 3.2 by excess of the maximum permissible concentration (MPC)) were recorded. At workplaces and in the service area of the furnaces at agglomeration and roasting, the maximum permissible level was exceeded for dust (Class 3.1), noise (Classes 3.1 and 3.2), sulfur dioxide (Class 3.1), and the sum of irritant chemicals (Classes 3.1 and 3.2). Conclusions: The hygienic analysis of the technological process of manufacturing iron ore pellets at the pelletizing plant indicates the presence of sources and conditions forming adverse occupational factors posing health risks for workers. In order to address occupational health and safety issues, it is necessary to introduce comprehensive measures to prevent health disorders in the working population.

Evaluating the Economic Viability of Agricultural Pellets to Supplement the Current Global Wood Pellets Supply for Bioenergy Production

In this study, an inter-continental agricultural pellet supply chain is modeled, and the production cost and price of agricultural pellets are estimated and compared against the recent cost and price of wood pellets in the global marketplace. The inter-continental supply chain is verified and validated using an integration of an interactive mapping application and a simulation platform. The integrated model is applied to a case study in which agricultural pellets are produced in six locations in Canada and shipped and discharged at the three major ports in Western Europe. The cost of agricultural pellets in the six locations is estimated to be in the range of EUR 92–95/tonne (CAD 138–142/tonne), which is comparable with the recent cost of wood pellets produced in small-scale pellet plants (EUR 99–109/tonne). The average agricultural pellet price shipped from the six plants to the three ports in Western Europe is estimated to be in a range of EUR 183–204 (CAD 274–305/tonne), 29–42% more expensive that the average recent price of wood pellets (EUR 143/tonne) at the same ports. There are several potential areas in the agricultural pellet supply chains that can reduce the pellet production and distribution costs in the mid and long terms, making them affordable supplement to the existing wood pellet markets. Potential economic activities generated by the production of pellets in farm communities can be significant. The generated annual revenue in the biomass logistics system in all six locations is estimated to be about CAD 21.80 million. In addition, the logistics equipment fleet needs 176 local operators with a potential annual income of CAD 2.18 million.

Design modification of iron ore bearing transfer chute using discrete element method

Purpose The dryer feed chute of the pellet plant plays an important role in the pelletizing process. The chute discharges sticky and moist iron ore fines (<1 mm) to the inline rotary dryer for further processing. Since the inception of the installation of the dryer feed chute, the poor flowability of the feed materials has caused severe problems such as blockages and excessive wear of chute liners. This leads to high maintenance costs and reduced lifetime of the liner materials. Constant housekeeping is needed for maintaining the chute and reliable operation. The purpose of this study is to redesign the dryer feed chute to overcome the above challenges. Design/methodology/approach The discrete element method (DEM) has been used to model the flow of cohesive materials through the transfer chute. Physical experiments have been performed to understand the most severe flow conditions. A DEM material model is also developed for replicating the worst-case material condition. After identifying the key problem areas, concept designs were proposed and simulated to assess the design improvements to increase the reliability of chute operation. Findings Flow simulations correlated well with the existing flow behavior of the iron ore fines inside the chute. The location of the problematic areas has been validated with that of the previously installed chute. Subsequently, design modifications have been proposed. This includes modification of deflector plate and change in slope and cross-section of the chute. DEM simulations and analysis were conducted after incorporating these design changes. A comparison in the average velocity of particle and force on chute wall shows a significant improvement using the proposed design. Originality/value Method to calibrate DEM material model was found to provide accurate prediction and modeling of the flow behavior of bulk material through the real transfer chute. DEM provided greater insight into the performance of the chute especially modeling cohesive materials. DEM is a valuable design tool to assist chute designers troubleshoot and verify chute designs. DEM provides a greater ability to model and assess chute wear. This technique can help in achieving a scientific understanding of the flow properties of bulk solids through transfer chute, hence eliminate challenges, ensuring reliable, uninterrupted and profitable plant operation. This paper strongly advocates the use of calibrated DEM methodology in designing bulk material handling equipment.

Study of Frequent Failures of the Pressure Roller at Sinter Plant

Pressure rollers are used for gripping pellet cars as they travel through the track. Of 776 pressure rollers, four were found broken after three years of service in a pellet plant of an integrated steel plant. Fatigue cracks had initiated from heavy dent marks at outer surface in all the failed roller. Microstructural analysis revealed dents with some foreign particles embedded on them. EDS analysis of particles showed the presence of iron, calcium and oxide and sulfide elements, indicating presence of FeO with CaS, which are components of sinter particles. No grain deformation was observed around the dents as these were created by sinter particles which are softer than rollers (i.e., a hardness of ~ 450–600 HV against 770 HV for the rollers). After creating these “soft” dents, the sinter particles got embedded in them. Subsequent crevice corrosion caused pits to form, a result of the difference in oxygen potential between the sinter particles and the roller. Sinter fines were probably deposited on the sprocket teeth at either the discharge or the feed ends. The surface roughness (Ra) of used and failed rollers were measured, post which it has been recommended that rollers that develop a surface roughness, Ra higher than 4.5 should be replaced to avoid a failure. This maintenance practice has been implemented in plant with an elimination of such failures.

Comparative Study on Induration of Wet Iron Ore Pellets in Different Straight Grate Furnaces in Iran Using Mathematical Models

The current study presents mathematical modelling of the pellet induration process in several straight-grate pelletizing plants in Iran. The change in the essential parameters includes gas and pellet temperature, moisture, and oxidation rate for pellets in three drying, sintering, and cooling stages in the pelletizing plants of Gohar Zamin, Gol Gohar Sangan, Mobarakeh steel and Khuzestan steel. This article is validated by a semi-industrial study conducted by Mobarakeh Steel Company. By using this model, the oxidation of magnetite is followed by sintering of the oxidized magnetite. The results show that the magnetite oxidation for the lower layers of the pellet about 11% is less than the upper layers. This model can enhance induration productivity, optimise fuel costs, reduce power consumption, control gas temperature and pressure, and as an operator training simulator. This simulation also helps the control room monitor the conversion percentage of magnetite to hematite in pellets and extract the best for the oxidation rate.

Effect of multi-layer feeding of sized green pelletson bed permeability, structure and properties of fired pellets in straight grate induration furnace

Green pellets while indurating in a straight grate induration furnace, pass through different thermal treatments, namely drying, preheating, heating and cooling. The firing of the pellet bed is downdraft using Corex gas and cooling is updraft using ambient air. Coke breeze is used as solid fuel to supplies the necessary heat for uniform heating of the pellet. The physicochemical conditions prevailing in the indurating furnace, i.e., feeding rate, bed height, pellet size, position of the pellets in the bed, temperature, partial pressure of oxygen, amount of fuel, etc. have bearings on the phases and structures of the fired pellets across the core to the shell. The time difference between the reduction and oxidation of the pellet depends on the size of the pellet as well as position of the pellet in the bed. The pellet size as well as the position of the pellet in the furnace has a marked effect on the formation of different phases and microstructure. Usually, mixed pellets of different sizes varying from 8 to 16 mm pellets are fired in duration furnace. The study was aimed at to optimize the pellet bed with different size range of pellets put in layers to make uniform firing and cooling of the pellets throughout the bed to achieve desired micro-structure and properties. The green pellets were divided into three sizes as A − coarse (–16 + 12.5 mm), B − medium (–12.5+10 mm) and C − small (–10 + 8 mm). The bed permeability of pellet plant induration furnace was 91.7JPU (Japanese Permeability Unit). Except permeability of pellet bed with single layer of smaller size pellets (C-C-C), the bed permeability with three layers, two layers & single layer of different size pellets was similar or greater than the bed permeability of pellet plant. From the results of basket trials conducted at pellet plant, it was found that the layer wise pellets like B-A-C, CA-B, AB-C and B-B-B resulted in higher Tumbler Index (TI) and Cold Crushing Strength (CCS) compared to other different size pellets as layer due to better slag bonding and lower pellet porosity. These pellets were exposed to optimum firing temperature as well as the cooling process with the presence of sufficient oxygen for the conversion of magnetite to hematite.

Dealing with pest infested wood in the pelleting process

The performance of a pellet plant depends highly on the feedstock quality and the pretreatment. The usual difficulties in operation increase when the wooden raw material is infested with pests and varmints. For the past years, we have been experiencing an increase in infections on a larger and broader scale. This means, more and more forests are experiencing dramatic losses. Infested wood is useless to the timber industry and needs to be removed from the woods to prevent further damage.

Pellet Production from Miscanthus: Energy and Environmental Assessment

The production of wood pellets has grown considerably in the last decades. Besides woody biomass, other feedstocks can be used for pellet production. Among these, miscanthus presents some advantages because, even if specifically cultivated, it requires low inputs such as fertilisers and pesticides and shows high biomass yield (up to 28 tons of dry matter ha−1 in Europe). Even if in the last years some studies evaluated the environmental impact of woody pellet production, there is no information about the environmental performances of miscanthus pellet production. In this study, the environmental impact of miscanthus pellet was evaluated using the Life Cycle Assessment approach with a cradle-to plant gate perspective. Primary data were collected in a small-medium size pelletizing plant located in Northern Italy where miscanthus is cultivated to be directly processed. The results highlight how the miscanthus pellet shows lower environmental impact compared to woody pellet, mainly due to the lower energy consumption during pelletizing. The possibility to pelletize the miscanthus biomass without any drying offsets the environmental impact related to the miscanthus cultivation for all the evaluated impact categories (except for Marine eutrophication). In detail, for global warming potential, 1 ton of miscanthus pellet shows an impact of 121.6 kg CO2 eq. (about 8% lower respect to woody pellet) while for the other evaluated impact categories the impact reduction ranges from 4 to 59%. Harvesting, which unlike the other field operations is carried out every year, is by far the main contributor to the impacts of the cultivation phase while electricity is the main contributor to the pelletizing phase.

Analysis of the factors affecting the iron ore pellet FEO index using data mining technique

One of the most critical factors affecting iron pellet quality is the reduction in FeO (Iron Oxide) index in the final product. This study aims to predict factors affecting the FeO (Iron Oxide) of iron pellets and find out the contribution of each factor to reduce the pellets FeO (the ideal amount is between 0.4 to 0.6) using data mining tech­niques. When the FeO index's value is in the optimal range, the quality and price of pellets are higher. The data used in this study was collected from the pelletizing plant of Gol-E-Gohar in Sirjan, Iran, and the decision tree and regression algorithms are used in this analysis. Forty-five factors that can affect the FeO (Iron Oxide) index of the final product were studied, showing that the Magnesium Oxide and Airflow of the inlet fan of the indurating machine had the greatest impact on the FeO (Iron Oxide) of iron pellets.