scholarly journals Fine Comminution of Pine Bark: How Does Mechanical Loading Influence Particles Properties and Milling Efficiency?

2019 ◽  
Vol 6 (4) ◽  
pp. 102 ◽  
Author(s):  
Karine Rajaonarivony ◽  
Xavier Rouau ◽  
Komlanvi Lampoh ◽  
Jean-Yves Delenne ◽  
Claire Mayer-Laigle
Keyword(s):  
Particle Size ◽  
Energy Consumption ◽  
Ultrafine Particles ◽  
Plant Biomass ◽  
Pine Bark ◽  
Coarse Particles ◽  
Attrition Mill ◽  
Attrition Milling ◽  
Process Energy ◽  
Fine Milling

The use of lignocellulosic plant biomass as an alternative to fossil feedstocks for chemistry, energy and materials often involves an intense dry comminution step, for which the energy consumed can vary significantly according to the process parameters, the particle size targeted, and the properties of the biomass. Here we studied the fine milling of maritime pine bark in an impact-mill configuration and in an attrition-mill configuration. The properties of the resulting powders (particle size distribution, particle shape, specific surface area, agglomeration level) obtained in each configuration were compared in relation to process energy consumption. Results evidenced that the agglomeration phenomena drive milling efficiency and limit the possibilities for reaching ultrafine particles. Interestingly, impact loading proved more effective at breaking down coarse particles but tended to generate high agglomeration levels, whereas attrition milling led to less agglomeration and thus to finer particles.

scholarly journals Influence of Copper Ore Comminution in HPGR on Downstream Minerallurgical Processes

2017 ◽  
Vol 62 (3) ◽  
pp. 1689-1694 ◽  
Author(s):  
D. Saramak ◽  
S. Wasilewski ◽  
A. Saramak
Keyword(s):  
Particle Size ◽  
Energy Consumption ◽  
Ball Mill ◽  
Research Programme ◽  
Size Reduction ◽  
Grinding Process ◽  
Operating Pressure ◽  
Qualitative Properties ◽  
Copper Ore ◽  
Process Energy

AbstractCrushing processes taking place in high-pressure grinding rolls devices (HPGR) are currently one of the most efficient methods of hard ore size reduction in terms of the energy consumption. The HPGR products are characterized by a fine particle size and the micro-cracks formation in individual particles, which appears in downstream grinding processes, decreasing their energy consumption. The purpose of the paper was to analyze the effectiveness of a ball mill grinding process and flotation operations depending on the changeable conditions of run of the HPGR crushing process. The research programme carried out included crushing tests in the laboratory scale HPGR device at various settings of the operating pressure volume and selected qualitative properties of the feed material (i.e. particle size distribution). On the basis of obtained results the models, defining the grinding process effectiveness as a function of changeable conditions of HPGR process run, were determined. Based on these models the optimal grinding time in a ball mill was specified which is, in turn, the basis for optimization of operation the technological comminution circuits for a given material type. The obtained results proved that the application of HPGR devices in given copper ore comminution circuit may improve the effectiveness of downstream grinding process what leads to improvement of the entire circuit work efficiency through decreasing the process energy consumption and enhancing the product size reduction.

Determination of grinding parameters of fenugreek seed

1970 ◽  
Vol 26 (1) ◽  
pp. 16 ◽  
Author(s):  
S Balasubramanian ◽  
Rajkumar Rajkumar ◽  
K K Singh
Keyword(s):  
Particle Size ◽  
Energy Consumption ◽  
Moisture Content ◽  
Specific Energy ◽  
Feed Rate ◽  
Average Particle Size ◽  
Specific Energy Consumption ◽  
Average Particle ◽  
Fenugreek Seeds ◽  
Fenugreek Seed

Experiment to identify ambient grinding conditions and energy consumed was conducted for fenugreek. Fenugreek seeds at three moisture content (5.1%, 11.5% and 17.3%, d.b.) were ground using a micro pulverizer hammer mill with different grinding screen openings (0.5, 1.0 and 1.5 mm) and feed rate (8, 16 and 24 kg h-1) at 3000 rpm. Physical properties of fenugreek seeds were also determined. Specific energy consumptions were found to decrease from 204.67 to 23.09 kJ kg-1 for increasing levels of feed rate and grinder screen openings. On the other hand specific energy consumption increased with increasing moisture content. The highest specific energy consumption was recorded for 17.3% moisture content and 8 kg h-1 feed rate with 0.5 mm screen opening. Average particle size decreased from 1.06 to 0.39 mm with increase of moisture content and grinder screen opening. It has been observed that the average particle size was minimum at 0.5 mm screen opening and 8 kg h-1 feed rate at lower moisture content. Bond’s work index and Kick’s constant were found to increase from 8.97 to 950.92 kWh kg-1 and 0.932 to 78.851 kWh kg-1 with the increase of moisture content, feed rate and grinder screen opening, respectively. Size reduction ratio and grinding effectiveness of fenugreek seed were found to decrease from 4.11 to 1.61 and 0.0118 to 0.0018 with the increase of moisture content, feed rate and grinder screen opening, respectively. The loose and compact bulk densities varied from 219.2 to 719.4 kg m-3 and 137.3 to 736.2 kg m-3, respectively.  

scholarly journals Contribution of Fine Particles to Air Emission at Different Phases of Biomass Burning

Atmosphere ◽  
2019 ◽  
Vol 10 (5) ◽  
pp. 278 ◽  
Author(s):  
Niloofar Ordou ◽  
Igor E. Agranovski
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Fine Particles ◽  
Combustion Process ◽  
Coarse Particles ◽  
Biomass Smoke ◽  
Smoke Particles ◽  
Air Emission ◽  
Entire Duration ◽  
Diffusion Properties

Particle size distribution in biomass smoke was observed for different burning phases, including flaming and smouldering, during the combustion of nine common Australian vegetation representatives. Smoke particles generated during the smouldering phase of combustions were found to be coarser as compared to flaming aerosols for all hard species. In contrast, for leafy species, this trend was inversed. In addition, the combustion process was investigated over the entire duration of burning by acquiring data with one second time resolution for all nine species. Particles were separately characterised in two categories: fine particles with dominating diffusion properties measurable with diffusion-based instruments (Dp < 200 nm), and coarse particles with dominating inertia (Dp > 200 nm). It was found that fine particles contribute to more than 90 percent of the total fresh smoke particles for all investigated species.

Intermetallic Effects on the Ductility of Sintered Aluminium

2008 ◽  
Vol 587-588 ◽  
pp. 380-384
Author(s):  
Jesus Cintas ◽  
José A. Rodríguez ◽  
Francicso Gomez Cuevas ◽  
José M. Gallardo
Keyword(s):  
Heat Treatment ◽  
Particle Size ◽  
Intermetallic Particle ◽  
Quantitative Metallography ◽  
Mechanically Alloyed ◽  
Aluminium Powder ◽  
Attrition Milling ◽  
Different Temperatures ◽  
Alloyed Aluminium ◽  
Milled Powders

Mechanically alloyed aluminium powder was prepared by attrition-milling for 10 hours in the presence of a wax. Milled powders were annealed in vacuum at different temperatures (500, 575, 600, 625 and 650°C). Compacts were consolidated starting from unannealed and from 600°Cannealed powders. Studies by SEM microfractography and quantitative metallography, to investigate the influence of Fe-Al intermetallics on compacts fracture, have been carried out. It is concluded that fracture takes place at regions where the area occupied by the intermetallics is high and intermetallics particles are big. Intermetallic particle size can be controlled by an appropriated heat treatment.

Ultrafine particles in the cabin of a waiting commercial airliner at Tianjin International Airport, China

2017 ◽  
Vol 27 (9) ◽  
pp. 1247-1258 ◽  
Author(s):  
Jianlin Ren ◽  
Junjie Liu ◽  
Xiaodong Cao ◽  
Fei Li ◽  
Jianmin Li
Keyword(s):  
Particle Size ◽  
Ultrafine Particles ◽  
Size Range ◽  
Environmental Control ◽  
Particle Dynamic ◽  
Ground Vehicles ◽  
Flight Delays ◽  
Penetration Factor ◽  
International Airport ◽  
Outdoor Concentration

Passengers and crew on board of commercial airliners often spend extra time in the cabin waiting for departure due to flight delays. During the waiting period, a large amount of ambient ultrafine particles (UFPs) may penetrate into the aircraft cabin through the environmental control system (ECS) and ground air-conditioning cart (GAC). However, limited data are available for human exposure, in waiting commercial airliners, to freshly emitted UFPs from the exhaust of ground vehicles and airliners. To address this issue, we measured the ambient and in-cabin particle number concentrations and particle size distributions (PSDs) simultaneously in an MD-82 airliner parked at Tianjin International Airport, China. When air was supplied to the cabin by GAC, particle counts variation outdoors caused in-cabin variation with a 1–2 min delay. The in-cabin and ambient PSDs ranged from 15 to 600 nm were bimodal, with peaks at 30–40 and 70–90 nm. The GAC and ECS removed 1–73% particles in the size range of 15–100 nm and 30–47% in the size range of 100–600 nm. The relationship between the penetration factor and particle size was an inverted U-curve. An improved particle dynamic model from this study was used to calculate the time-dependent in-cabin UFPs concentrations with dramatic changes in outdoor concentration.

Reduction Effects of Suspended Particulate Matters in Air by Thermal Moisture Swing Method

2011 ◽  
Author(s):  
Nagisa Onoda ◽  
Shota Ishiguchi ◽  
Osamu Nakabeppu
Keyword(s):  
Particle Size ◽  
Energy Consumption ◽  
Simple Model ◽  
Experimental Result ◽  
Particulate Matters ◽  
Removal Mechanism ◽  
Air Cleaning ◽  
Suspended Particulate ◽  
Suction Flow ◽  
Suspended Particulate Matters

We are studying the effects of thermal moisture swing air-cleaning method on removal of suspended particulate matter, SPM. This method continuously humidifies sample air with heating and dehumidifies it by cooling, in a channel. It was experimentally demonstrated that the thermal moisture swing method reduces SPM suspended in sample air. The experimental result showed reduction of SPM above 10 nm in particle size, and the removal ratio increased with intensifying the thermal moisture swing. The SPM removal mechanism of this method was theoretically estimated. The estimation suggests that the reasons for the SPM reduction are suction flow accompanying condensation and thermophoresis. These phenomena would transport SPM to cooling wall of the dehumidifier. Also, diffusional deposition and gravitational sedimentation would transport SPM to the wall of the channel. And, the transported particles are separated from the air with adhering on the wall. We estimated the effects of these phenomena on SPM removal using simple model and energy consumption. The estimation qualitatively agreed with the experimental result.

scholarly journals Preserving the Cellular Tissue Structure of Maize Pith Though Dry Fractionation Processes: A Key Point to Use as Insulating Agro-Materials

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5350
Author(s):  
Claire Mayer-Laigle ◽  
Laia Haurie Ibarra ◽  
Amélie Breysse ◽  
Marina Palumbo ◽  
Frédéric Mabille ◽  
...  
Keyword(s):  
Particle Size ◽  
Composite Materials ◽  
Plant Biomass ◽  
Cellular Tissue ◽  
Added Value ◽  
Vascular Bundles ◽  
Dry Fractionation ◽  
Promising Alternative ◽  
Structural Support ◽  
Electrostatic Separator

Plant biomass has various compositions and structures at different scales (from the component organs to their constitutive tissues) to support its functional properties. Recovering each part of the plant without damaging its structure poses a challenge to preserving its original properties for differential dedicated end uses, and considerably increases its added value. In this work, an original combination of grinding based on shearing stress and separation based on particle size and density was successfully used to sort rind (65% w/w) and pith (35% w/w) from maize stem internodes. More than 97% of the rind was isolated. The pith alveolar structure was well preserved in coarse particles, making them suitable for insulation bio-based composite materials, a promising alternative to conventional nonbiodegradable insulation panels. Boards produced from the dry fractionated pith exhibited thermal conductivities like those produced from hand dissected pith, with values equal to 0.037 W·mK−1 and 0.039 W·mK−1, respectively. In the finest fraction (particle size <1 mm), the pith vascular bundles (around 300–400 µm in diameter) were dissociated from parenchyma cells and successfully isolated using a cutting-edge electrostatic separator. Their structures, which provide the plant structural support, make them potentially valuable for reinforcement in composite materials.

A Study of Airborne Wear Particles Generated From a Sliding Contact

2009 ◽  
Vol 131 (4) ◽  
Author(s):  
Ulf Olofsson ◽  
Lars Olander ◽  
Anders Jansson
Keyword(s):  
Ultrafine Particles ◽  
Fine Particles ◽  
Urban Environments ◽  
Airborne Particles ◽  
Wear Particles ◽  
Coarse Particles ◽  
Sliding Velocity ◽  
Airborne Particle ◽  
Particle Generation ◽  
Pin On Disk

Recently, much attention has been paid to the influence of airborne particles in the atmosphere on human health. Sliding contacts are a significant source of airborne particles in urban environments. In this study airborne particles generated from a sliding steel-on-steel combination are studied using a pin-on-disk tribometer equipped with airborne-particle counting instrumentation. The instrumentation measured particles in size intervals from 0.01μm to 32μm. The result shows three particle size regimes with distinct number peaks: ultrafine particles with a size distribution peak around 0.08μm, fine particles with a peak around 0.35μm, and coarse particles with a peak around 2 or 4μm. Both the particle generation rate and the wear rate increase with increasing sliding velocity and contact pressure.

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