Fine Generation Research Articles

Nanoparticle deagglomeration driven by a high shear mixer and intensification of low-speed stirring in a viscous system

High shear mixers (HSMs), with their unique advantages of high shear forces and a wide operational range, are commonly used in nanoparticle deagglomeration. This study explores a novel approach to intensifying nanoparticle deagglomeration in a 100 mPa‧s viscous system using HSMs combined with low-speed stirring. The effects of main operating and structural parameters were experimentally investigated. The results show that the teethed HSM outperforms the blade-screen HSM, achieving a smaller attainable size (114 nm vs. 210 nm) and a higher fine particle generation fraction (46.08% vs. 18.77%). Increasing HSM size directly affects the energy input (from 6.478 MJ/kg to 31.879 MJ/kg), which influences the deagglomeration mechanism and kinetics but does not affect the smallest attainable size (117 nm). Higher solid contents improve energy efficiency, while low-speed stirring, though not altering the deagglomeration mechanism, enhances its kinetics. The process intensification factor (S) and energy efficiency factor (εm) were defined to evaluate the intensification of low-speed stirring. Increasing the impeller speed enhances this effect. The PBT impeller with a diameter ratio of 0.35 is identified as the ideal structure in this study, improving deagglomeration performance by 8.26% while reducing energy consumption by 8.3%. These results provide guidance for optimizing processes and improving deagglomeration performance through the combination of low-speed stirring in viscous systems for process industries.

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.

Enhancing Fracturing Proppant Performance: Methods and Assessment

AbstractThe use of fracturing proppants is a key element of hydraulic fracturing operations in the oil and gas industry. The selection of proppants with superior performance is critical to ensure efficient and effective hydraulic fracturing. Proppant technologies are developing rapidly. Therefore, standardization of proppant evaluation is necessary to ensure accurate proppant evaluation during proppant production. Although the API and ISO have released a number of recommended practices for this purpose, there are still significant gaps in them. This is because several hypotheses regarding proppant performance, including proppant embedment and diagenesis, and their influence on proppant conductivity, are still not fully clear. Numerous proppants have been produced within the petroleum industry, featuring diverse compositions, sizes, shapes, and intended uses. While many proppants consist of silica or ceramics, there is growing interest in advanced types such as ultra-lightweight proppants. These innovations aim to minimize settling and enable transport using low-viscosity fluids. Moreover, to reduce expenditures, it is common practice in hybrid completions to mix proppant of different sizes according to stimulation design objectives and assumptions. Proppant can be equally mixed, separated by tail-in, or mixed with dominating concentrations of a specific size, depending on the type of fluids, viscosity, and anticipated settlement velocity. Surface modification involves altering the surface properties of the proppant to improve its adhesion to the fracture face and to reduce embedment and fines generation. Surface modification techniques include silane treatment, plasma treatment, and chemical treatment. The method can maintain oil flow channels after the hydraulic fracturing operation for a very long time. Proppant flowback, fines generation, and gel degradation are the key factors that contribute to a proppant pack losing permeability. Proppant pack conductivity can be increased, and well cleanup can be hastened, with the aid of a surface modification. This review paper aims to provide a comprehensive overview of proppant and its types, proppant performance assessment, and methods to enhance proppant performance. We discuss various techniques to evaluate proppant performance, including crush resistance, conductivity, embedment, and closure stress. Additionally, we highlight the importance of selecting the most appropriate proppant type for a particular well based on the formation properties and proppant characteristics. Furthermore, we explore recent advancements in proppant enhancement methods, such as coating, sintering, altering proppant surface, and consolidation, and their effectiveness in improving proppant performance. The comprehensive review provides insight into current industry practices and highlights potential areas for future research to improve fracturing proppant performance.

Spray characteristics of steam-assisted oil atomization in Y-jet nozzles

Twin-fluid atomizers, valued for handling viscous fluids and high operating loads, are extensively used in combustion processes and oil refineries. In the latter scenario, internal mixing nozzles are employed in fluid catalytic cracking units for oil dispersion using steam as the dispersing medium. While steam-assisted atomization studies often focus on flue gas analysis, the associated steam/oil internal mixing process and the spray droplet dynamics lack proper investigation. Accordingly, this work explores the Y-jet nozzle performance for oil atomization using steam, aiming to determine favorable conditions for obtaining a stable spray with fine droplet distribution. This analysis is accomplished by characterizing the mixing chamber pressure, investigating the spray boundary instabilities using high-speed images, and exploring the spray droplet size using the shadowgraphy technique. Work relevance relies on performing experiments at industrially representative conditions, characterized by the similarity of important dimensionless numbers. Additionally, the nozzle design is optimized by varying key geometric parameters. The nozzle geometry and the operating condition impacts on the steam-assisted atomization performance and spray behavior constitute the main findings of this work. The outcomes highlight the relevance of the fluid dynamics investigation for optimized nozzle performance, involving a balance between spray stability and fine droplet distribution generation.

MSRR-T2I: Multi-Scale Reverse Residual for Text-to-Image

Abstract Text-generated image is a very challenging task in the artificial intelligence and machine learning. To address the problems of low quality and no-diversity in images generated by conventional text-generated approaches, a multi-scale reverse residual text-generated image network (MSRR-T2I) is proposed in this paper. Firstly, the multi-scale residuals inverse structure is embedded into the fine image generation module to resolve the issue of loss of feature information when original residuals are reduced. Then, the information content of the feature map is extended, and the features of different resolutions are captured by multi-scale convolution. Finally, channel transformation technology is introduced to achieve cross-group information fusion and enhance image diversity. The test results of common CUB and COCO data sets indicate that compared with the original model ATTNGAN, the IS of MSRR-T2I increases by 8.7% and 8.4%, and the FID increases by 24.8% and 17.0%, respectively. Therefore, the proposed method is confirmed to be effective.

Demonstration of a novel jaw crusher design at a lab scale

ABSTRACT A novel jaw crusher was designed, constructed and tested at a lab scale. Differences from a conventional jaw crusher include a swing plate that is supported at the outlet, rather than the inlet, wear plates with a corrugation pattern that are designed to break the ore in bending rather than compression, and a trapezoidal wear plate shape to allow for swelling of broken ore. The crusher was tested using an ore sample that was mainly composed of feldspar. The performance of the crusher was evaluated by measuring changes in the size distribution of the ore and the corresponding electrical energy consumed, as a function of ore feed rate. The results indicated that the crusher product size distribution was narrower than that of the feed and independent of ore feed rate, with relatively little generation of fines, demonstrating that the crusher performed as designed in terms of ore breakage mechanism. Though calculated breakage efficiencies suggest that the crusher may be more energy efficient than a conventional jaw crusher, the use of an undersized crusher motor and possible deficiencies in the design of the transmission mechanism, prevent any concrete conclusions from being drawn.

Factors influencing physical and mechanical properties of direct reduced iron ore pellets

Direct Reduction processes for iron ore employing natural gas or hydrogen are becoming more important. Correspondingly, properties of outgoing products are of importance. Degradation of Direct Reduced Iron (DRI) feedstock greatly influences storage, handling, risk of reoxidation, and following melting operations. The focus of this work has been on the physical properties of DRI, and their effect on mechanical properties. Four types of industrially produced DRI having varying metallization, carbon content, structure and apparent porosity have been studied. Three of the selected DRI types have been reduced using natural gas, and one DRI type has been reduced using pure hydrogen. Cold compression strength and tumbling tests are performed. Qualitative analysis of samples before and after mechanical testing is made using SEM and LOM. Results show that total carbon content has a significant influence on overall mechanical strength of DRI. Degradation of samples in tumbling tests is least significant for the hydrogen-reduced – and hence carbon-free – DRI type. The DRI type containing the most carbon (3 wt%) exhibits the most fines generation and lowest compression strength. Furthermore, apparent porosity and fractures formed during reduction have a small though not as significant impact as carbon content on mechanical properties.

Modelling breakage of steelmaking materials for simulation of mechanical degradation during handling

Mechanical degradation of steelmaking materials can have significant economic and environmental implications. Such degradation typically occurs as result of impacts during transportation and handling from their production site to the steelmaking furnace, in operations that include transfers in chutes, ship loading, stockpiling, reclaiming, wagon loading and discharging, etc. Predicting the extent of such degradation and attempting to prevent it, is worthwhile. Fortunately, mechanical degradation during such operations can now be predicted using different approaches, but a proper breakage model is required. The work presents results from single-particle breakage tests of iron ore lump, sinter, briquette, and pellet samples, besides coke, followed by fitting parameters of the Tavares UFRJ Breakage Model. These are then used to simulate degradation in a hypothetical handling circuit. Predictions demonstrate the high susceptibility of iron ore lump and briquette to fines generation, when compared to the other materials, and the occurrence of conditioning for briquettes and sinter, which is the increase in strength of particles surviving handling. Iron ore pellets and coke remained comparatively unaffected by the handling operations simulated, which is explained by their greater resistance to either body or surface breakage.

The comparsion of different fabrication processes on the microstructure and mechanical properties of Cu-11Al-3Ni alloy

In this paper, two different fabrication processes, mainly including Hopkinson bar (HB) + cold rolling (CR) method (process Ⅰ) or CR + CR method (process Ⅱ), were carried out to fabricate the Cu-11Al-3Ni alloy sheet. The role of the HB method on the microstructure and mechanical properties of the Cu-11Al-3Ni alloy was investigated in detail. Due to the vast discrepancy in strain rates between the HB (102 - 103 s−1) and CR (10−2 - 10−3 s−1) processes, the fraction of twins in the HB + CR sample was attached 14.7 %, much higher than the 1.68 % of the CR + CR sample, accompanied by the increase in the frequency of recrystallised grains and the enhancement of BRASS texture component. In addition, due to the generation of fine and numerous twins and the resulting twin strengthening (σtwin), the performance of tensile strengths (including yield strength and ultimate tensile strength) in the HB + CR sample were 868 and 1051 MPa, respectively, much higher than those of the CR + CR sample (734 and 940 MPa). Consequently, the HB method was considered to be as a potential approach to obtaining ultrahigh-strength Cu alloys.

Inhibiting the Accretion in the Coal-Fired Rotary Kiln of High-Silica Iron Ore Pellets Application by Reducing Fines Generation and Liquid Phase Formation

Inhibiting the Accretion in the Coal-Fired Rotary Kiln of High-Silica Iron Ore Pellets Application by Reducing Fines Generation and Liquid Phase Formation

A Strategy for Partial Replacement of Lime by Limestone and Its Impact on Basic Oxygen Furnace Steelmaking

Production of steel in a sustainable manner is gaining importance day by day. Optimizing fluxes in basic oxygen furnace (BOF) steelmaking, such as partial replacement of lime with limestone, can be a step toward this. The heat available in BOF can decompose the limestone which partially avoids the need for calcination in lime kiln. However, the size, quantity, and time of limestone addition in BOF are important parameters as they influence the decomposition behavior of limestone. The associated problems of slopping, presence of uncalcined limestone, fines generation, etc. are also influenced by these parameters. In the present study, laboratory experiments are conducted by changing the size, temperature, and time of exposure which help in understanding high‐temperature behavior of limestone. With these inputs, along with theoretical calculations, a trial is conducted in a 160 t BOF by limestone addition and replacing equivalent amount of lime. The study focusses on the benefits of limestone addition in BOF along with other aspects, that is, impact on blow profiles, slag condition, lining wear, etc. Characterization of slags help in explaining the improvement observed during this trial. The article presents the findings of laboratory studies and limestone addition trials and uniquely highlights its overall impact on BOF steelmaking.

A quantitative study between HPGR and cone crusher aided ball mill grinding: mathematical modeling by evaluating the possible microfracture effect produced by HPGR technology and cone crusher

High Pressure Grinding Rolls (HPGR) have been used in the mining industry for decades. However, there are limited quantifications of the particle properties after comminution. Furthermore, the influence of microcracks in grinding provided by this technology has not been extensively quantified. In the recent work, there were two comminution paths tested: 1 (Jaw crusher + cone crusher + ball mill) and 2 (Jaw crusher + HPGR + ball mill). The possible weakening effect aiding ball mill grinding due to microcracks of HPGR path was shown via specific energy, fines generation and breakage rate measurements. To achieve a quantification about the impact of microcracks and the high rate of reduction rate of HPGR technology, first the product was reconstructed using Rosin Rammler's Weibull double formula and the similar particle size distribution was obtained by a conventional cone crusher. By this way the feed size distribution to the grinding stage remained constant regardless of the type of crushing process (HPGR or cone crusher). The results showed that the microfractures generated by the HPGR technology influence the specific energy consumption, fines generation and breakage rates. Ball mill after HPGR consumed 12.46 kWh/t of specific energy, however ball mill after cone crusher consumed 14.36 kWh/t of specific energy. The experimental methodology proposed in this paper maintains a consistent feed size range (-1500 to +41.31 µm) to show that the size reduction observed in the sample undergoing HPGR grinding is not the primary factor contributing to reduced energy consumption and increased fines generation. Instead, it is predominantly associated with the microfractures generated through the compression in HPGR technology; the energy reduction (optimization) of a grinding path is shown in the study.

Rock fragmentation size distribution control in blasting: a case study of blasting mining in Changjiu Shenshan limestone mine

Deep-hole bench blasting is the primary method for aggregate extraction in mines. However, factors such as complex geological conditions and suboptimal blasting parameters often result in uneven rock fragmentation and high fines content. This not only increases the cost and energy consumption of subsequent aggregate processing but also has adverse environmental implications. In this study, based on the Changjiu Shenshan limestone aggregate mining project in China, large-scale blasting experiments were conducted to investigate the influence of rock properties and blasting parameters on the size distribution of post-blast fragments and fines content. The results of the blasting experiments indicate that by controlling the size of the crushing zone and adjusting explosive performance, it is possible to significantly reduce fines content while improving mining efficiency. Recommended values for drilling and blasting parameters have been proposed based on geological conditions to more effectively control the generation of fines. The results highlight the importance of optimizing blasting parameters and charge structure for large-scale mining operations to achieve uniform rock fragmentation and low fines content. By adopting explosive performance adjustment methods based on reasonable control of the crushing zone, improving explosive performance can improve the economic benefits of mining operations, reduce energy consumption, and contribute to environmental protection.

Effect on Fine Particles Output Characteristics of Ceramic Ball Grinding

Steel balls as traditional grinding media are prone to excessive fines generation and high energy consumption. Therefore, in light of this problem, the authors investigated another media—ceramic balls based on the output characteristics of fine particles. This study discusses the effect of ceramic balls on the change of the particle size distribution, zero-order output characteristics, micro-strain, and collision energy in ground products. The results showed that for −10 μm particle size, ceramic balls have a smaller production rate than steel balls. In addition, when the filling rate of ceramic balls is 40%, the yield of −10 μm is reduced compared to steel balls. Therefore, ceramic balls greatly reduced the overgeneration of fines. Additionally, the micro-strain rate of ceramic ball grinding with time is 67% lower than that of steel ball grinding. Furthermore, ceramic balls cannot only mitigate excessive fines generation but also effectively reduce energy consumption.

Fines migration poses challenge for reservoir-wide chemical stimulation of geothermal carbonate reservoirs

Fines material, which can compromise the permeability of geothermal reservoirs, is often only considered with regard to existing fines like clay particles that are mobilized. However, fines are also generated due to dissolution. This is a significant risk coming from chemical stimulation techniques in geothermal reservoirs, that try to increase the range of stimulation with retarded acid systems. Deeper in the reservoir, fines cannot be extracted as is done in the near wellbore region after stimulation and the generation of fines has to be prevented. This work investigates the dependence of fines generation on the reaction conditions. Flow-through experiments with citric acid on dolostone were conducted, creating dissolution regimes with a range of different Damköhler numbers. During the stimulation experiments, the creation of wormholes and the widening of existing flow paths could be differentiated by the shape of the differential pressure curves measured across the samples. Fines were always generated and could greatly reduce the permeability of the rock samples. But for very high Damköhler numbers, where the dissolution created large pathways, the fines were transported out of the major pathways as well as dissolved therein, thus not interfering with the increase of permeability due to dissolution.

Ceramic Grinding Kinetics of Fine Magnetite Ores in the Batch Ball Mill

Aiming to reveal the kinetic characteristics of ceramic ball grinding of fine magnetite comprehensively, two types of ceramic balls ground with the same filling rate and total weight as steel balls were researched. The results show that the breakage rate of ceramic ball grinding is only half of that of steel ball grinding with the same media filling rate. With the same total media weight and a feed size less than 0.212 mm, the breakage rate of the ceramic ball grinding approaches the steel ball grinding and is 17.14% higher than that of the steel ball grinding. The main crushing form of magnetite changed from impact to abrasion in ceramic ball grinding compared with steel ball grinding, which significantly affected the value of the zero-order output constant a. The shift indirectly led to a very different character of the variation ing the parameter β, related to the fines generation rate in the cumulative distribution function of the ceramic ball grinding compared to the steel ball grinding. Therefore, ceramic grinding with a high ball-filling rate can greatly save on energy consumption under the premise of meeting normal production.

ESTIMATING SEDIMENT GENERATION FROM ROCK CONSTRUCTION WORKS

The dispersal of fine sediments into receiving waters from dredging and disposal associated with major port developments, and the modelling of these, is often a major focus of the environmental approval process for the construction of these works. An aspect that is often overlooked in the environmental assessment of these works is the generation of sediment sourced directly from the construction materials used for breakwater and revetment construction. While fine sediment generation from dredging and offshore sediment disposal is often well documented, there is little guidance or research that has been undertaken in quantifying the direct generation of sediment from the placement of rock armour. This paper demonstrates a method applied to a construction project at Eastland Port NZ to quantify the generation and dispersal of construction-generated fine sediments.

Experimental Investigation on the Impact of Coal Fines Migration on Pores and Permeability of Cataclastic Coal.

During the production process of coalbed methane, the generation and migration of coal fines can obstruct fractures in coal reservoirs and reduce their permeability. In order to investigate the effects of coal fines migration on the porosity and permeability of coal reservoirs, we conducted core water flooding experiments, low-field nuclear magnetic resonance (NMR), and low-temperature N2 adsorption experiments to study the variations in porosity and permeability of cataclastic coal during coal fines migration and the impact of coal fines migration on porosity and permeability. The experimental results reveal that the initial porosity ratio of cataclastic coal exhibits the characteristics of micropore > macropore > transitional pore > mesopore, with the pore types being predominantly fissured. The porosity of pores larger than 1000 nm and those larger than 10,000 nm exhibit consistent trends before and after water flooding, indicating that the blockage or unblocking of pores with radius larger than 10,000 nm by coal fines can also cause blockage or unblocking of some interconnected macropore. The early stage of flooding is the main period for coal fines migration and production in cataclastic coal, during which the mass concentration of coal fines production is higher and some macropores and fractures become blocked, resulting in a larger decrease in porosity. The higher the initial permeability of cataclastic coal samples with a larger end-face fracture density, the more similar the variations in porosity and permeability of pores larger than 10,000 nm during the flooding experiment, indicating that coal fines mainly block interconnected pores and fractures with radius larger than 10,000 nm through migration, thereby reducing permeability. This study provides a theoretical basis for the efficient production of coalbed methane.

An Experimental Study on the Impact of the Particle Size and Proportion of Composite Proppant on the Conductivity of Propped Fractures in Coalbed Methane Reservoirs following Pulverized Coal Fines Infiltration

Coalbed methane reservoirs exhibit a low strength and high heterogeneity, rendering them susceptible to coal fines generation during hydraulic fracturing operations. The detrimental impact of coal fines on the conductivity of the propped fracture has been overlooked, leading to a substantial negative effect on the later-stage recovery of coalbed methane reservoirs. Moreover, the particle size distribution of the composite proppant also affects the conductivity of the propped fracture. To mitigate the damage caused by coal fines to the conductivity of the proppant pack in CBM reservoirs, this study conducted conductivity tests on actual coal rock fractures. The aim was to assess the effect of various particle size ratios in composite proppant blends on the conductivity of complex fractures in CBM reservoirs. The ultimate goal was to identify an optimized proppant blending approach that is suitable for hydraulic fracturing in coal seams. The results indicated that, in terms of the short-term conductivity of coalbed methane reservoirs, the conductivity of composite proppants is primarily influenced by the proportion of large or small particles. A higher proportion of large particles corresponds to a stronger conductivity (e.g., the conductivity is highest at a particle ratio of 5:1:1 for large, medium, and small particles). On the other hand, a higher proportion of small particles leads to a poorer conductivity (the conductivity is lowest when the particle ratio is 1:1:5). In the long-term conductivity of coalbed methane reservoirs, the fluid flushing of the fracture surfaces generates coal fines, and small particles can fill the gaps between larger particles, hindering the infiltration of coal fines. Therefore, it is important to control the particle size ratio of composite proppants, with a predominant proportion of larger particles. This approach can maintain long-term conductivity and prevent the excessive infiltration of coal fines, thereby avoiding fracture blockage (e.g., the conductivity is highest at a particle ratio of 5:1:5, followed by a ratio of 3:1:3). Furthermore, considering the influence of proppant placement methods and the support effect on near-wellbore opening fractures and far-end sliding fractures, segmented placement is utilized to fully fill the fractures for short-term conductivity, whereas mixed placement is employed for long-term conductivity to achieve a balance in particle gaps and hinder the infiltration of coal fines. The findings of this study contribute to the understanding of proppant selection and placement strategies for efficient hydraulic fracturing in coalbed methane reservoirs.

A transformers-based approach for fine and coarse-grained classification and generation of MIDI songs and soundtracks.

Music is an extremely subjective art form whose commodification via the recording industry in the 20th century has led to an increasingly subdivided set of genre labels that attempt to organize musical styles into definite categories. Music psychology has been studying the processes through which music is perceived, created, responded to, and incorporated into everyday life, and, modern artificial intelligence technology can be exploited in such a direction. Music classification and generation are emerging fields that gained much attention recently, especially with the latest discoveries within deep learning technologies. Self attention networks have in fact brought huge benefits for several tasks of classification and generation in different domains where data of different types were used (text, images, videos, sounds). In this article, we want to analyze the effectiveness of Transformers for both classification and generation tasks and study the performances of classification at different granularity and of generation using different human and automatic metrics. The input data consist of MIDI sounds that we have considered from different datasets: sounds from 397 Nintendo Entertainment System video games, classical pieces, and rock songs from different composers and bands. We have performed classification tasks within each dataset to identify the types or composers of each sample (fine-grained) and classification at a higher level. In the latter, we combined the three datasets together with the goal of identifying for each sample just NES, rock, or classical (coarse-grained) pieces. The proposed transformers-based approach outperformed competitors based on deep learning and machine learning approaches. Finally, the generation task has been carried out on each dataset and the resulting samples have been evaluated using human and automatic metrics (the local alignment).