scholarly journals Optimization of the active component grinding process and hydrophobization of the obtained powder fire extinguisher

2021 ◽  
Vol 75 (2) ◽  
pp. 65-75
Author(s):  
Slavica Mihajlovic ◽  
Natasa Djordjevic ◽  
Marina Jovanovic ◽  
Milica Vlahovic ◽  
Ljubinko Savic ◽  
...  
Keyword(s):  
Particle Size ◽  
Grain Size ◽  
Ball Mill ◽  
Active Component ◽  
Grinding Process ◽  
Two Stage ◽  
Ceramic Ball ◽  
Fire Extinguishing ◽  
Stage Process ◽  
Grinding Time

This work presents a grinding process of monoammonium phosphate (MAP) as an active component in a powder fire extinguisher (PFE). The aim was to determine the grinding time for reaching the optimal particle size of MAP necessary for permanent fire extinguishing. MAP grinding was performed by using a laboratory ceramic ball mill and a vibrating cup mill. The grinding process was controlled by sieving using a 100 ?m sieve at precisely defined time intervals. The efficiency of a PFE depends on the share of the -100 ?m fraction of the active component, which has to exceed 60 %. The optimal grain size with 64 % of fraction of particle size -100 ?m was obtained after 33 min of grinding of ?3000 ?m mm grain size MAP by using a ball mill (single-stage grinding). In two-stage process, by grinding the same initial MAP sample (?3000 ?m) in the vibro mill for 10 min, powder with the upper limit grain size of 300 ?m and the mean grain diameter of 120 ?m was obtained. This sample with a reduced size was further ground in the ceramic ball mill yielding 67.5 % of the fraction of particle size -100 ?m after 19 min. The total time of the two-stage grinding process was 29 min. By analyzing the grinding time of MAP required to get the lowest required share of the fraction of particle size -100 ?m that provides the effectiveness of formed PFE it can be concluded that 64 % of this fraction was obtained after 33 min of single-stage grinding, while only after 26 min in the two-stage process. Thus, the grinding time was reduced by 7 min indicating certain energy savings. Stability and hydrophobicity of the obtained PFE were achieved by coating with magnesium stearate (MgSt) at the content of 2 % in a ball mill for 15 min. The coating was confirmed by the standardized procedure for verification of PFE hydrophobic properties in contact with water drops. To obtained PFE had component mass ratios of MAP:AS:CC:QS:MgSt=55:20:18:5:2 (AS-ammonium sulfate; CC-calcium carbonate, QS-quartz sand) and was further characterized by chemical and granulometric analyses. The fire extinguishing efficiency of the PFE was tested in controlled conditions, whereby fires were initiated by burning solid materials and flammable liquids. In both cases, immediate elimination of flames was achieved, thus proving the efficiency of the PFE obtained in this work for practical applications.

A Study on Grinding Rate of Mica Particles

2012 ◽  
Vol 508 ◽  
pp. 192-195
Author(s):  
Hong Yong Xie ◽  
Hao Yuan ◽  
Jie Guan
Keyword(s):  
Particle Size ◽  
Ball Mill ◽  
Mass Fraction ◽  
Distribution Parameter ◽  
Grinding Process ◽  
Kutta Method ◽  
Runge Kutta Method ◽  
Comparison Results ◽  
Breakage Rate ◽  
Grinding Time

Grinding rate of mica particles by a planetary ball mill was studied by the measurement of specific breakage rate and breakage distribution parameter for different size ranges. The relationships between specific breakage rate and breakage distribution parameter with particle size were obtained from the measured results. The results show that grinding rate decreases fast as particle size decreases. Using integraldifferential equation for the mass fraction in grinding process with experimental obtained relationships of specific breakage rate and breakage distribution parameter with particle size, grinding process of mica particles are simulated by the 4thRunge-Kutta method, and particle size distribution between simulated and measured has been compared. The comparison results show that the specific breakage rate of mica particles was proportional to grinding time.

Effects of Wet Grinding Process on the Properties of the Ground Diatomite Particles

2010 ◽  
Vol 178 ◽  
pp. 124-128
Author(s):  
Xu Ming Wang ◽  
Yan Xi Deng ◽  
Yan Feng Li
Keyword(s):  
Methylene Blue ◽  
Particle Size ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Grinding Process ◽  
X Ray Diffraction ◽  
X Ray ◽  
Wet Grinding ◽  
Grinding Time

Wet grinding of diatomite was carried out in a stirred mill. The changes in particle size, specific surface area and structure or the particle shape in the wet grinding process were investigated. The adsorption of methylene blue from aqueous solution by the ground diatomite was also studied. X-ray diffraction (XRD), scanning electron microscopy (SEM) and IR spectra were employed to characterize the ground diatomite. The median particle size decreased and the specific surface area increased with the grinding time, an agglomeration phenomenon was not observed during the experimental grinding time. The X-ray diffraction patterns versus grinding time showed that a peak intensity reduction of opal. The results of adsorption of methylene blue onto diatomite indicated the adsorption capacity increases with the increase of grinding time until eventually reaches a constant value.

scholarly journals Research on the Grinding Energy Density in a Jet Mill

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2008
Author(s):  
Dariusz Urbaniak ◽  
Henryk Otwinowski ◽  
Tomasz Wyleciał ◽  
Vladimir Pavlovich Zhukov ◽  
Aleksei Yevgenyevich Barochkin ◽  
...  
Keyword(s):  
Particle Size ◽  
Grain Size ◽  
Energy Consumption ◽  
Raw Materials ◽  
Thermodynamic Theory ◽  
Raw Material ◽  
Grinding Process ◽  
Volumetric Density ◽  
Comminution Process ◽  
New Material

Raw materials are used in many industrial technologies. The raw material frequently has to be prepared as an intermediate with an appropriate particle size distribution, which requires the use of grinding. In grinding processes, energy consumption is a very important profitability criterion for the applied particular size reduction technology. The paper describes the comminution process that takes place in the jet mill using a modified form of the thermodynamic theory of grinding. In this theory, new material characteristics have been added: the surface and volumetric density of grinding energy. The thermodynamic theory is a combination of the classical Kick’s theory and the modified form of Rittinger’s theory. The tested physical magnitudes are a measure of the energy consumption of the grinding process. They describe the energy that must be provided in the grinding process to overcome interactions between particles related to the volume and surface of the material. Knowledge of these magnitudes is necessary to model thermomechanical phenomena in the solid state. The paper presents the results of research on comminution in a jet mill, on the basis of which the values of the tested material magnitudes were determined. It is graphically shown how the values of the tested magnitudes depend on the grain size of the ground samples.

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.

scholarly journals Characterization and leaching of mechanically activated zinc residue

2021 ◽  
Author(s):  
M. Deniz Turan
Keyword(s):  
Grain Size ◽  
Ball Mill ◽  
Xrd Analysis ◽  
Original Sample ◽  
Zinc Extraction ◽  
Peak Intensity ◽  
Mineral Phases ◽  
Solid Liquid ◽  
Grinding Time ◽  
Sem Analyses

AbstractZinc extraction from zinc-containing residual (ZCR) was examined with the leach of sulfuric acid of original materials and the materials milled in two different mill systems. For this purpose, vibrating ball mill (VBM) and ring mill (RM) were used. In chemical analysis of ZCR, it was determined that it contains a significant amount of zinc, lead, iron and silver and consisted of mostly CaSO4.2H2O, PbO, SiO2, Fe2O3, ZnFe2O4, Al2FeO4 and PbSO4 mineral phases. It was determined in XRD analysis of samples milled at both mills that peak intensity dramatically decreased when compared to original sample.According to comparative characterization analyses of the milled samples, it was determined that through the increasing grinding time, the particles became agglomerated and an increase in grain size occurred. This situation was also supported by N2-BET and SEM analyses.While zinc extraction value of the sample milled for 1 min, which was obtained at 0.5 M H2SO4 at leach temperature of 25 °C, at the solid–liquid rate of 100:1 and during the leach time of 30 min, was 90% and 60% for, respectively, VBM and RM, zinc of 54% was determined to be extracted in the leach of the original sample, under the same conditions.

scholarly journals Influence of Particle Morphology of Ground Fly Ash on the Fluidity and Strength of Cement Paste

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 283
Author(s):  
Juntao Ma ◽  
Daguang Wang ◽  
Shunbo Zhao ◽  
Ping Duan ◽  
Shangtong Yang
Keyword(s):  
Particle Size ◽  
Fly Ash ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Cement Paste ◽  
Ball Mill ◽  
Particle Morphology ◽  
Spherical Particles ◽  
Grinding Process ◽  
And Performance

The grinding process has become widely used to improve the fineness and performance of fly ash. However, most studies focus on the particle size distribution of ground fly ash, while the particle morphology is also an important factor to affect the performance of cement paste. This article aims at three different kinds of ground fly ash from the ball mill and vertical mill, and the particle morphology is observed by scanning electron microscopy (SEM) to calculate the spherical destruction (the ratio of spherical particles broken into irregular particles in the grinding process of fly ash), which provides a quantification of the morphology change in the grinding process. The fluidity of cement paste and the strength of cement mortar are tested to study the relation of spherical destruction and fluidity and strength. The results show that the spherical destruction of ground fly ash in a ball mill is more than 80% and that in a vertical mill with a separation system is only 11.9%. Spherical destruction shows a significant relation with the fluidity. To different addition of ground fly ash, the fluidity of cement paste decreases with the increase of spherical destruction. To the strength of cement paste, particle size distribution and spherical destruction are both the key factors. Therefore, spherical destruction is an important measurement index to evaluate the grinding effect of the fly ash mill.

scholarly journals Two-Stage Biodiesel Synthesis from Used Cooking Oil with a High Acid Value via an Ultrasound-Assisted Method

Energies ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3703
Author(s):  
Ming-Chien Hsiao ◽  
Wei-Ting Lin ◽  
Wei-Cheng Chiu ◽  
Shuhn-Shyurng Hou
Keyword(s):  
Acid Value ◽  
Molar Ratio ◽  
Optimal Conditions ◽  
Two Stage ◽  
Cooking Oil ◽  
High Acid ◽  
Used Cooking Oil ◽  
Biodiesel Synthesis ◽  
Stage Process ◽  
Ultrasound Assisted

In this study, ultrasound was used to accelerate two-stage (esterification–transesterification) catalytic synthesis of biodiesel from used cooking oil, which originally had a high acid value (4.35 mg KOH/g). In the first stage, acid-catalyzed esterification reaction conditions were developed with a 9:1 methanol/oil molar ratio, sulfuric acid dosage at 2 wt %, and a reaction temperature of 60 °C. Under ultrasound irradiation for 40 min, the acid value was effectively decreased from 4.35 to 1.67 mg KOH/g, which was decreased to a sufficient level (<2 mg KOH/g) to avoid the saponification problem for the subsequent transesterification reaction. In the following stage, base-catalyzed transesterification reactions were carried out with a 12:1 methanol/oil molar ratio, a sodium hydroxide dosage of 1 wt %, and a reaction temperature of 65 °C. Under ultrasound-assisted transesterification for 40 min, the conversion rate of biodiesel reached 97.05%, which met the requirement of EN 14214 standard, i.e., 96.5% minimum. In order to evaluate and explore the improvement of the ultrasound-assisted two-stage (esterification–transesterification) process in shortening the reaction time, additional two-stage biodiesel synthesis experiments using the traditional mechanical stirring method under the optimal conditions were further carried out in this study. It was found that, under the same optimal conditions, using the ultrasound-assisted two-stage process, the total reaction time was significantly reduced to only 80 min, which was much shorter than the total time required by the conventional method of 140 min. It is worth noting that compared with the traditional method without ultrasound, the intensification of the ultrasound-assisted two-stage process significantly shortened the total time from 140 min to 80 min, which is a reduction of 42.9%. It was concluded that the ultrasound-assisted two-stage (esterification–transesterification) catalytic process is an effective and time-saving method for synthesizing biodiesel from used cooking oil with a high acid value.

scholarly journals Wheat Grinding Process with Low Moisture Content: A New Approach for Wholemeal Flour Production

Processes ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 32
Author(s):  
Waleed H. Hassoon ◽  
Dariusz Dziki ◽  
Antoni Miś ◽  
Beata Biernacka
Keyword(s):  
Particle Size ◽  
Moisture Content ◽  
Average Particle Size ◽  
Average Particle ◽  
Grinding Process ◽  
Mixing Properties ◽  
New Approach ◽  
Grain Moisture ◽  
Flour Production ◽  
And Storage

The objective of this study was to determine the grinding characteristics of wheat with a low moisture content. Two kinds of wheat—soft spelt wheat and hard Khorasan wheat—were dried at 45 °C to reduce the moisture content from 12% to 5% (wet basis). Air drying at 45 °C and storage in a climatic chamber (45 °C, 10% relative humidity) were the methods used for grain dehydration. The grinding process was carried out using a knife mill. After grinding, the particle size distribution, average particle size and grinding energy indices were determined. In addition, the dough mixing properties of wholemeal flour dough were studied using a farinograph. It was observed that decreasing the moisture content in wheat grains from 12% to 5% made the grinding process more effective. As a result, the average particle size of the ground material was decreased. This effect was found in both soft and hard wheat. Importantly, lowering the grain moisture led to about a twofold decrease in the required grinding energy. Moreover, the flour obtained from the dried grains showed higher water absorption and higher dough stability during mixing. However, the method of grain dehydration had little or no effect on the results of the grinding process or dough properties.

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