scholarly journals Processing of Superfine and Ultrafine Phosphate of a Phosphomud (Part Two)

2019 ◽  
Vol 9 (2) ◽  
pp. 102
Author(s):  
Suzan S. Ibrahim ◽  
Khaled E. Yassin ◽  
Tawfik R. Boulos
Keyword(s):  
Ultrafine Particles ◽  
Feeding Rate ◽  
Separation Efficiency ◽  
Water Pressure ◽  
Rotation Frequency ◽  
Variable Frequency Drive ◽  
Phosphate Industry ◽  
Irreversible Effect ◽  
Mineral Industries ◽  
Central Composite

Mineral industries in common generate a lot of rejects in the form of fines and slimes, which ultimately create environmental and social problems besides causing losses of mineral values. In view of the recent stringent policy imposed on the environment, there is an urgent need to attempt possible simple and cheap solutions to such problems. These slimes have long been considered in the industry to be unrecoverable. It has been standard practice over many years in the phosphate industry to separate and discard the fines and ultrafine particles. In this respect, the present study shed light on the recovery of super and ultrafine phosphate of a phosphomud produced after the processing of an East Mediterranean phosphate ore. Falcon Concentrator model SB40-VFD (semi-continuous with variable frequency drive) was used in this study to recover the -32 micron phosphate fines of D50=11 micron. The effect of the main variables of the semi-continuous Falcon concentrator model SB40-VFD, including the bowl rotation frequency Hz, the fluidizing water pressure psi, and feeding rate g/min on the separation efficiency were followed up. In addition, two feeding modes based on a particle size-by-size were tried in this study: The sample was fed as a global -32 micron sample or as two fractions, -32+11 micron, and -11 micron samples. Central Composite Rotatable Design (CCRD) was applied on the Falcon separation of the -11 micron fraction with D50 < 3 micron alone to model and optimize the separation process for the two responses: the recovered phosphate grade and recovery. Results showed that the phosphate fines containing 14.73% P2O5, 15.03% acid insoluble, and 19.07% loss in ignition was recovered with grade and P2O5 recovery reaching 28.29%, and 95.97% in case of separating the overall -32 micron sample as one feed. In case of the fractionated feeding samples, the total grade and recovery reached 29.21%, and 88.42%, respectively. The application of the CCRD results showed that the bowl rotation frequency showed to have the main irreversible effect on the product grade, where the fluidizing water pressure had the main reversible effect on the recovery. On the other hand, feeding rate showed some effect on the product grade with almost no effect on its P2O5 recovery%.

scholarly journals Optimization of VFD Operations for Transporting Equipment of Packages

2021 ◽  
Vol 27 (1) ◽  
pp. 4-11
Author(s):  
Lione Urmoniene ◽  
Jelena Dikun ◽  
Jolanta Januteniene
Keyword(s):  
Electricity Consumption ◽  
Experimental System ◽  
Rotation Frequency ◽  
Total Efficiency ◽  
System Efficiency ◽  
Periodic Mode ◽  
Servo Drive ◽  
Variable Frequency Drive ◽  
Linear Speed ◽  
Drive Motor

This study is focused on the efficiency of automated transferring system of packages equipped by variable-frequency drive (VFD) and servo drive motor. It was found that rotation frequency of induction motors and linear speed of servo drive decisively affected the unit efficiency that operates in the periodic mode. The system duty cycle was divided in two separate parts taking into account time spans needed to complete the specific tasks by each separate equipment of the system. In order to reduce the power usage of the system, the duration of each part of cycle was extended. Lowered electricity consumption leads to the extension of each cycle’s stage operating times. Frequencies of motors and linear speed of servo drive motors were optimized depending on cycle stages duration. Optimized frequency and linear speed values were calculated and loaded into motors controllers, and the efficiency of each separate equipment was measured, as well as total efficiency of the system. Experimental system debugging using optimized parameters proved that system efficiency increases up to 60 %, and that is closely matched with calculated values.

Quantitative Investigation of Flocs Flotation Removal and Hydrocyclonic Separation for the Washing Water Treatment

2013 ◽  
Vol 333-335 ◽  
pp. 1857-1861
Author(s):  
Yi Yong Yang ◽  
Xiao Jing Ren ◽  
Si Chen Li ◽  
Li Min Zhu ◽  
Shang Yun Tian
Keyword(s):  
High Efficiency ◽  
Separation Efficiency ◽  
Water Pressure ◽  
Particle Separation ◽  
Wash Water ◽  
Gas Generator ◽  
Split Ratio ◽  
Inlet Flow Rate ◽  
Dimensional Parameters ◽  
Washing Water

A new hydrocyclone and gas-flotation device was designed and tested for the treatment of the wash water containing the flocs. The device separates particles and removes flocs simultaneously. The gas-generator equipment can produce a large number of micro-bubbles, and the bubbles adhere to the impure flocs particles. This makes the density of the bubble-floc less than that of water, and their buoyancy enables particle separation and removal of suspended flocs. To achieve a high efficiency of flocs removal and particle separation, some of the factors that influence the separation efficiency (such as the gas-liquid pressure difference, gas-liquid ratio, underflow split ratio, water pressure, inlet flow rate, and the contact time of the gas and particles, bubble size, and number of bubbles) were investigated. The results showed that there is an optimum combination of multi-dimensional parameters; good particle separation and a high efficiency of flocs removal were achieved.

The Effects of RPM and Recycle on Separation Efficiency in a Clinical Blood Cell Centrifuge

1987 ◽  
Vol 109 (4) ◽  
pp. 324-329
Author(s):  
P. D. Drumheller ◽  
B. J. Van Wie ◽  
J. N. Petersen ◽  
R. J. Oxford ◽  
G. W. Schneider
Keyword(s):  
Experimental Design ◽  
Blood Cell ◽  
Red Blood Cells ◽  
Whole Blood ◽  
Blood Cells ◽  
Separation Efficiency ◽  
Factorial Experimental Design ◽  
Centrifuge Model ◽  
Computer Controlled ◽  
Central Composite

A COBE blood cell centrifuge, model 2997 with a single stage channel, was modified to allow computer controlled sampling, and to allow recycle of red blood cells (RBCs) and plasma streams using bovine whole blood. The effects of recycle of the packed RBC and plasma product streams, and of the centrifuge RPM on platelet and white blood cell (WBC) separation efficiencies were quantified using a central composite factorial experimental design. These data were then fit using second order models. Both the model for the WBC separation efficiency and the model for the platelet separation efficiency predict that RPM has the greatest effect on separation efficiency and that RBC and plasma recycle have detrimental effects at moderate to low RPM, but have negligible impact on separation efficiency at high RPM.

Lab Scale Vibrating Screen Study on Operational Variables that Affect the Separation Efficiency

2017 ◽  
Vol 899 ◽  
pp. 124-129 ◽  
Author(s):  
Fernando Guerreiro ◽  
Vinícius Barbosa ◽  
Rubens Gedraite ◽  
Carlos Henrique Ataíde
Keyword(s):  
Feed Rate ◽  
Size Range ◽  
Separation Efficiency ◽  
Full Description ◽  
Coarse Particles ◽  
Particle Size Range ◽  
Several Variables ◽  
Operational Variables ◽  
Main Effects ◽  
Central Composite

Vibrating screening is an equipment of simple design and execution, but its full description may be difficult to predict, considering that several variables can influence it. This work evaluates the effects of the independent variables: proportion of particles larger than the screen aperture size, average feed rate and g-force on the separation efficiency of coarse particles in a lab scale vibrating screening, where the material to be screened was phosphate rock, with density of 3.25 g/cm3 and particle size range of 0.6–600 μm. For this, a central composite design (CCD) was applied to quantify the main effects of the variables. As a result, the average feed rate was not relevant and the proportion of coarse particles and the g-force contributed positively to the increase of the efficiency. The point where the variables have their highest values, the maximum experimental efficiency was observed (94.93%).

Fractionation of ultrafine particles: Evaluation of separation efficiency by UV–vis spectroscopy

2020 ◽  
Vol 213 ◽  
pp. 115374 ◽  
Author(s):  
Marvin Winkler ◽  
Heiko Sonner ◽  
Marco Gleiss ◽  
Hermann Nirschl
Keyword(s):  
Ultrafine Particles ◽  
Separation Efficiency ◽  
Vis Spectroscopy

The growth of mica polytypes as studied by conventional and high-resolution TEM

1983 ◽  
Vol 41 ◽  
pp. 174-177
Author(s):  
A. Baronnet ◽  
M. Amouric
Keyword(s):  
Water Pressure ◽  
Point Of View ◽  
Temperature Fields ◽  
Natural Occurrence ◽  
Growth Mechanisms ◽  
Long Period ◽  
High Resolution Tem ◽  
Layer Stacking ◽  
Experimental Works ◽  
Potential Use

The origin of mica polytypes has long been a challenging problem for crystal- lographers, mineralogists and petrologists. From the petrological point of view, interest in this field arose from the potential use of layer stacking data to furnish further informations about equilibrium and/or kinetic conditions prevailing during the crystallization of the widespread mica-bearing rocks. From the compilation of previous experimental works dealing with the occurrence domains of the various mica "polymorphs" (1Mr, 1M, 2M1, 2M2 and 3T) within water-pressure vs temperature fields, it became clear that most of these modifications should be considered as metastable for a fixed mica species. Furthermore, the natural occurrence of long-period (or complex) polytypes could not be accounted for by phase considerations. This highlighted the need of a more detailed kinetic approach of the problem and, in particular, of the role growth mechanisms of basal faces could play in this crystallographic phenomenon.

Studies of copper selenide ultrafine particles by newly developed gas evaporation method

1990 ◽  
Vol 48 (4) ◽  
pp. 306-307
Author(s):  
Chihiro Kaito ◽  
Yoshio Saito
Keyword(s):  
Crystal Structure ◽  
Ultrafine Particles ◽  
Fine Particles ◽  
Production Method ◽  
Atmospheric Temperature ◽  
Copper Selenide ◽  
Quartz Boat ◽  
Selenium Vapor ◽  
Ar Gas ◽  
Ultra Fine Particles

The direct evaporation of metallic oxides or sulfides does not always given the same compounds with starting material, i.e. decomposition took place. Since the controll of the sulfur or selenium vapors was difficult, a similar production method for oxide particles could not be used for preparation of such compounds in spite of increasing interest in the fields of material science, astrophysics and mineralogy. In the present paper, copper metal was evaporated from a molybdenum silicide heater which was proposed by us to produce the ultra-fine particles in reactive gas as shown schematically in Figure 1. Typical smoke by this method in Ar gas at a pressure of 13 kPa is shown in Figure 2. Since the temperature at a location of a few mm below the heater, maintained at 1400° C , were a few hundred degrees centigrade, the selenium powder in a quartz boat was evaporated at atmospheric temperature just below the heater. The copper vapor that evaporated from the heater was mixed with the stream of selenium vapor,and selenide was formed near the boat. If then condensed by rapid cooling due to the collision with inert gas, thus forming smoke similar to that from the metallic sulfide formation. Particles were collected and studied by a Hitachi H-800 electron microscope.Figure 3 shows typical EM images of the produced copper selenide particles. The morphology was different by the crystal structure, i.e. round shaped plate (CuSe;hexagona1 a=0.39,C=l.723 nm) ,definite shaped p1 ate(Cu5Se4;Orthorhombic;a=0.8227 , b=1.1982 , c=0.641 nm) and a tetrahedron(Cu1.8Se; cubic a=0.5739 nm). In the case of compound ultrafine particles there have been no observation for the particles of the tetrahedron shape. Since the crystal structure of Cu1.8Se is the anti-f1uorite structure, there has no polarity.

Crystal structure-size relationship in ultrafine metallic particles

1989 ◽  
Vol 47 ◽  
pp. 266-267
Author(s):  
Jun Liu ◽  
Mehmet Sarikaya ◽  
Ilhan A. Aksay
Keyword(s):  
Ultrafine Particles ◽  
Carbon Film ◽  
Lattice Defects ◽  
Careful Examination ◽  
Seeded Growth ◽  
Gold Particles ◽  
Metallic Particles ◽  
Interfacial Structures ◽  
Typical Particle ◽  
Many Particles

Ultrafine particles usually have unique physical properties. This study illustrates how the lattice defects and interfacial structures between particles are related to the size of ultrafine crystalline gold particles.Colloidal gold particles were produced by reducing gold chloride with sodium citrate at 100°C. In this process, particle size can be controlled by changing the concentration of the reactant. TEM samples are prepared by transferring a small amount of solution onto a thin (5 nm) carbon film which is suspended on a copper grid. In this work, all experiments were performed with Philips 430T at 300 kV.With controlled seeded growth, particles of different sizes are produced, as shown in Figure 1. By a careful examination, it can be resolved that very small particles have lattice defects with complex interfaces. Some typical particle structures include multiple twins, resulting in a five-fold symmetry bicrystals, and highly disordered regions. Many particles are too complex to be described by simple models.

Development and Evaluation of a Compact Facility for Exposing Humans to Concentrated Ambient Ultrafine Particles

2004 ◽  
Vol 38 (1) ◽  
pp. 27-35 ◽  
Author(s):  
Chandan Misra ◽  
Philip M. Fine ◽  
Manisha Singh ◽  
Constantinos Sioutas
Keyword(s):  
Ultrafine Particles
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