scholarly journals Experimental Study on Factors Influencing the Strength Distribution of In Situ Cemented Tailings Backfill

Metals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 2059
Author(s):  
Xiaopeng Peng ◽  
Lijie Guo ◽  
Guangsheng Liu ◽  
Xiaocong Yang ◽  
Xinzheng Chen
Keyword(s):  
Particle Size ◽  
Fine Particles ◽  
Cement Content ◽  
Flow Direction ◽  
Strength Distribution ◽  
Median Particle Size ◽  
Distribution Law ◽  
Minimum Value ◽  
Median Particle

Previous studies have found that the strength of in situ cemented tailings backfill usually presents an S-shaped distribution, which decreases first, then increases, and decreases thereafter along the direction of slurry flow. In this study, to explore the factors determining the distribution, a similar model test of cemented tailings backfill was carried out. The distribution law of grain size composition and the cement content of backfill materials along the flow direction were experimentally studied, and the comprehensive factor influencing the strength distribution was analyzed. The results show that, firstly, near the feeding point, there are more coarse particles, whereas the content of fine particles is higher farther away. The measured maximum median particle size can be more than three times the minimum value. Secondly, the cement content increases gradually along the flow direction and reaches the peak at the end of the model, which can be more than twice the minimum value, indicating that the degree of segregation is significant. Thirdly, the strength distribution of cemented backfills is comprehensively determined by both the particle size distribution (PSD) and the cement content. The maximum value appears neither at the point with peak median particle size, nor at the point with the highest cement content. Lastly, there is a strong linear correlation between the strength of cemented backfills and the strength factor (SF), which is defined as the product of the uniformity coefficient and cement content of filling materials, indicating that the SF can be used to quantitatively reflect the comprehensive effects of PSD and cement content on the strength. As SF is a comprehensive quantitative index reflecting the distribution of strength, it will be further studied in later research to acquire more experimental results of the relationship between sample strength and SF, which will be meaningful for the quality evaluation of in situ cemented backfills, and the optimization of backfill system.

Influence of Powder Particle Size of Slurries on Mechanical Properties of Porous Hydroxyapatite Ceramics

2005 ◽  
Vol 284-286 ◽  
pp. 365-368 ◽  
Author(s):  
Yin Zhang ◽  
Yoshiyuki Yokogawa ◽  
Tetsuya Kameyama
Keyword(s):  
Particle Size ◽  
Flexural Strength ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Particle Sizes ◽  
Wet Milling ◽  
Median Particle Size ◽  
Powder Characteristics ◽  
Median Particle

The effect of different particle sizes on the flexural strength and microstructure of three different types of hydroxyapatite (HAp) powders was studied. The powder characteristics of laboratory synthesized HAp powder (Lab1 and Lab2) were obtained through a wet milling method, and the median particle size and the specific surface area of powders are different with the dryness period. The median particle sizes of Lab1 and Lab2 are 0.34 µm and 0.74 µm, and the specific surface areas of Lab1 and Lab2 are 38.01 m2/g and 19.77 m2/g. The commercial HAp had median particle size of 1.13 µm and specific surface area of 11.62m2/g. The different powder characteristics affected the slip characteristics, and the flexural strength and microstructure of the sintered porous HAp bodies are also different. The optimum value for the minimum viscosity in these present HAp slip with respect to its solid loading and the optimum amount of the deflocculant were investigated. The flexural strengths of the porous HAp ceramics prepared by heating at 1200°C for 3 hrs in air were 17.59 MPa for Lab1 with a porosity of 60.48％, 10.51 MPa for Lab2 with a porosity of 57.75％, and 3.92 MPa for commercial HAp with a porosity of 79.37％.

Obtaining and research of pharmaceutical properties of antiemetics in a form of powder for inhalation

2021 ◽  
Author(s):  
Igor M. Ivanov ◽  
Tatiana B. Pechurina ◽  
Nikolai G. Vengerovich ◽  
Mikhail A. Yudin ◽  
Aleksandr S. Nikiforov ◽  
...  
Keyword(s):  
Particle Size ◽  
Dosage Form ◽  
Production Method ◽  
Particle Fraction ◽  
Median Particle Size ◽  
Antiemetic Drugs ◽  
Median Particle ◽  
Pharmaceutical Properties ◽  
Mass Median ◽  
Respirable Particle

Samples of antiemetic drugs (ondansetronum, palonosetronum, metoclopramidum) in the form of powder for inhalation have been developed by the method of spray drying. The granulometric composition, hygroscopicity and aerodynamic distribution of aerosol particles of the drugs have been investigated. The dosage form of the powder for inhalation of antiemetics (ondansetronum and palonosetronum) in terms of its particle size distribution, hygroscopicity and content of the agent corresponds to those for inhalation using dry powder inhalers. In the study of the phase-dispersed composition of aerosol, ondansetronum and palonosetronum in the dosage form of powder for inhalation as part of the HandiHaler inhaler (at a flow rate of 60 l / min) showed high rates of the released dose up to 72-76%, respirable particle fraction (up to 5 m) up to 54 -56% and a mass median particle size of about 3 microns. Obtaining the inhaled form of metoclopramide requires optimization of the production method for receiving the product with acceptable pharmaceutical properties.

scholarly journals Extraction of single serve coffee capsules: linking properties of ground coffee to extraction dynamics and cup quality

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
André Eiermann ◽  
Samo Smrke ◽  
Loïc-Marco Guélat ◽  
Marco Wellinger ◽  
Anja Rahn ◽  
...  
Keyword(s):  
Particle Size ◽  
Product Development ◽  
Total Dissolved Solids ◽  
Fine Tuning ◽  
Median Particle Size ◽  
Flow Restriction ◽  
General Rules ◽  
Median Particle ◽  
Ground Coffee ◽  
Cup Quality

Abstract The objective of this paper is to elucidate the variables that govern coffee extraction from single serve coffee capsules. The study was conducted on 43 Nespresso and Nespresso-compatible capsules of the same geometry, from all of which the coffee was extracted on the same machine. This allowed the link between a range of coffee and capsule (input) parameters with coffee brew (output) variables to be studied. It was demonstrated that the most efficient way to increase total dissolved solids in the brew is to use more coffee for extraction, and/or to grind the coffee more finely. However, grinding too finely can lead to excessive flow restriction. The most significant new insight from this study is the importance of the proportion of fines (particles smaller than 100 µm) regarding the capsule extraction dynamics. Capsules with a higher share of fines, for similar median particle size of the ground coffee, led to longer extraction times. General rules applicable for capsule coffee product development were established, although fine-tuning of parameters for successful capsule coffee extraction remains specific to production line and type of coffee.

scholarly journals Preparation of Curcumin Nanosuspension with Gum Arabic as a Natural Stabilizer: Process Optimization and Product Characterization

Processes ◽  
2020 ◽  
Vol 8 (8) ◽  
pp. 970 ◽  
Author(s):  
Bao Hoang Duong ◽  
Hoai Nam Truong ◽  
Quynh Anh Phan Nguyen ◽  
Thuong Nhan Nguyen Phu ◽  
Le Thi Hong Nhan
Keyword(s):  
Particle Size ◽  
High Speed ◽  
Gum Arabic ◽  
Spherical Shape ◽  
Aqueous Solubility ◽  
Polymeric Surfactant ◽  
Median Particle Size ◽  
Curcumin Nanoparticles ◽  
Homogenization Time ◽  
Median Particle

Low aqueous solubility and poor bioavailability of curcumin have limited its application in various fields. One approach to address this issue is to formulate a nanosuspension that incorporates curcumin, which has been previously shown to exhibit remarkably improved solubility in comparison with that of a bare compound. In this study, the preparation process of curcumin nanosuspension was optimized with a median particle size as the outcome. Gum arabic was used as a natural polymeric surfactant and the suspension was formulated using high speed homogenization. Optimization results, realized via a response surface methodology, showed that a minimum median particle size (8.524 µm) could be attained under the following conditions: curcumin:gum arabic ratio of 1:6 g/g; homogenization speed of 8300 rpm and homogenization time of 40 min. Under these conditions, the particle size of obtained suspension was shown to be consistent for around seven days without major aggregation. The homogenization process could be scaled up to five times in terms of suspension volume. TEM also showed that curcumin nanoparticles had a nearly spherical shape and homogeneous structure with a size range of 40–80 nm.

scholarly journals Implementing Feedback Granule Size Control in a Continuous Dry Granulation Line Using Controlled Impeller Speed of the Granulation Unit, Compaction Force and Gap Width

2020 ◽  
Author(s):  
Annika Wilms ◽  
Andreas Teske ◽  
Robin Meier ◽  
Raphael Wiedey ◽  
Peter Kleinebudde
Keyword(s):  
Particle Size ◽  
Process Parameters ◽  
Control Strategies ◽  
Granule Size ◽  
Oral Dosage ◽  
Impeller Speed ◽  
Median Particle Size ◽  
Dry Granulation ◽  
Median Particle ◽  
Roll Compaction

Abstract Purpose In continuous manufacturing of pharmaceuticals, dry granulation is of interest because of its large throughput capacity and energy efficiency. In order to manufacture solid oral dosage forms continuously, valid control strategies for critical quality attributes should be established. To this date, there are no published control strategies for granule size distribution in continuous dry granulation. Methods In-line laser diffraction was used to determine the size of granules in a continuous roll compaction/dry granulation line (QbCon® dry). Different process parameters were evaluated regarding their influences on granule size. The identified critical process parameters were then incorporated into control strategies. The uncontrolled and the controlled processes were compared based on the resulting granule size. In both processes, a process parameter was changed to induce a shift in median particle size and the controller had to counteract this shift. Results In principle, all process parameters that affect the median particle size could also be used to control the particle size in a dry granulation process. The sieve impeller speed was found to be well suited to control the median particle size as it reacts fast and can be controlled independently of the throughput or material. Conclusion The median particle size in continuous roll compaction can be controlled by adjusting process parameters depending on real-time granule size measurements. The method has to be validated and explored further to identify critical requirements to the material and environmental conditions.

Electroacoustic determination of size and zeta potential of casein micelles in skim milk

1996 ◽  
Vol 63 (3) ◽  
pp. 387-404 ◽  
Author(s):  
Theresa Wade ◽  
James K. Beattie ◽  
William N. Rowlands ◽  
Mary-Ann Augustin
Keyword(s):  
Particle Size ◽  
Zeta Potential ◽  
Skim Milk ◽  
Median Particle Size ◽  
Casein Micelles ◽  
Median Particle ◽  
Decreasing Ph ◽  
Good Agreement

SummaryMeasurements of the zeta potential and particle size of casein micelles in skim milk suspensions at natural and lower pH have been made using the technique of electroacoustics. This technique requires no dilution or change of environment of the casein micelles. The zeta potential obtained at natural pH for a commercial skim milk suspension was −18 mV; it became less negative with decreasing pH. The median particle size observed at natural pH for a commercial skim milk suspension was 0·2 εm, in good agreement with previously reported values. The particle size increased as the pH was decreased.

Vacuum Inert Gas Atomisation of Cr-Mn-Ni Austenitic Steel Alloys

2014 ◽  
Vol 875-877 ◽  
pp. 1265-1269 ◽  
Author(s):  
Tobias Dubberstein ◽  
Hans Peter Heller
Keyword(s):  
Surface Tension ◽  
Particle Size ◽  
Austenitic Steel ◽  
Matrix Composite ◽  
Liquid Steel ◽  
Inert Gas ◽  
Median Particle Size ◽  
Steel Alloys ◽  
Median Particle ◽  
Mass Median

The Cr-Mn-Ni austenitic steel cast alloys containing 16 wt.-% chromium, 7 wt.-% manganese and 3 to 9 wt.-% nickel are used as matrix material to manufacture TRIP-Matrix-Composite containing MgO partially stabilised ZrO2ceramics. In the present work, these steel master alloys were atomised via a vacuum inert gas atomisation to provide fine grain sized metal powders for the assembling of TRIP-Matrix-Composite. The atomised steel powders where characterised according to their chemical composition and the d50mass median particle size determined by a laser diffraction analyses. The surface tension of the liquid steel alloys was experimentally investigated using the maximum bubble pressure (MBP) method. The reference austenitic steel alloy (AISI 304) has the highest surface tension and the highest mass median particle size compared to the Cr-Mn-Ni steel alloys, where d50values are lower due to lower surface tension values. Finally, it is concluded from the present investigation, that the d50size of the atomised steel powders decreases by a decrease of surface tension values for the liquid steel alloys.

Near-infrared mass median particle size determination of lactose monohydrate, evaluating several chemometric approaches

The Analyst ◽  
1998 ◽  
Vol 123 (10) ◽  
pp. 2043-2046 ◽  
Author(s):  
P. Frake ◽  
C. N. Luscombe ◽  
D. R. Rudd ◽  
I. Gill ◽  
J. Waterhouse ◽  
...  
Keyword(s):  
Particle Size ◽  
Near Infrared ◽  
Size Determination ◽  
Median Particle Size ◽  
Lactose Monohydrate ◽  
Particle Size Determination ◽  
Median Particle ◽  
Mass Median

The effects of process variables for GCC pre-flocculation on floc and handsheet properties

2012 ◽  
Vol 27 (2) ◽  
pp. 382-387 ◽  
Author(s):  
Dongil Seo ◽  
Wan Hee Im ◽  
Hye Jung Youn ◽  
Hak Lae Lee
Keyword(s):  
Mechanical Properties ◽  
Particle Size ◽  
Critical Factor ◽  
Process Variables ◽  
Median Particle Size ◽  
High Concentration ◽  
Floc Size ◽  
Turbulent Environments ◽  
Median Particle ◽  
Ground Calcium Carbonate

Abstract Pre-flocculation is a technique that aggregates filler particles by means of polyelectrolytes. The size of the filler flocs is a critical factor affecting the properties of the paper. Process variables including the concentration of the flocculants, the stirring speed, and the dilution of the suspension change the size of the flocculated fillers. Ground calcium carbonate and cationic polyacrylamide were used to investigate the influence of these variables on flocculation. The median particle size and size distribution were examined and the tensile and optical properties influenced by the floc size and ash levels were evaluated. The addition of high concentration C-PAM increased the median particle size. Stirring speeds in the range of 1000 ~ 3000 rpm were used to simulate various turbulent environments, and it was shown that high stirring speeds drastically decreased the floc size. Diluting and low speed stirring the flocculated GCC suspension was effective in keeping the particle size intact without disruption before sheet forming. Larger GCC flocs in the handsheets resulted in better mechanical properties.

scholarly journals Microspheres as potential fillers in composite polymeric materials

2019 ◽  
Vol 108 ◽  
pp. 02009
Author(s):  
Anna Magiera ◽  
Monika Kuźnia ◽  
Wojciech Jerzak ◽  
Magdalena Ziąbka ◽  
Radosław Lach ◽  
...  
Keyword(s):  
Particle Size ◽  
Polymer Matrix ◽  
Cellular Structure ◽  
Microscopic Analysis ◽  
Polymeric Materials ◽  
Foam Sample ◽  
Median Particle Size ◽  
Cross Sectional ◽  
Median Particle ◽  
Sectional Surface

Microspheres used in our work were acquired from one of Kazakhstan coal-fueled power plant. The size of the microspheres varied between 45 and 400 μm, the median particle size (D50) was 158 μm. Microscopic analysis revealed that the material consisted mainly of cenospheres. The results of elemental and oxide analysis showed that microspheres were composed of aluminosilicates. Identified crystalline phases were mullite (approx. 12 %) and trace amount of quartz (silica). Microscopic observations of the cross-sectional surface of both unmodified PUR foam and foams modified with microspheres showed a well formed, cellular structure of all materials. The observed cells are polyhedron in shape, most of them are closed, microspheres were uniformly distributed within polymer matrix and placed between cells. The apparent densities calculations of the samples showed that when microspheres were added to the polymer matrix, apparent density of the resulting composite materials increased. The results of elemental analysis pointed out the highest content of all three elements in unmodified PUR foam sample. The addition of the microspheres to the system resulted in decrease of the concentration of all three elements.

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