scholarly journals Modified Collector: New Approaches

2020 ◽  
Author(s):  
Ainur Aitkazynovna Mukhanova
Keyword(s):  
Particle Size ◽  
Diesel Fuel ◽  
Raw Materials ◽  
Structural Characteristics ◽  
Processing Methods ◽  
Flotation Process ◽  
Standard Methods ◽  
Testing Technology ◽  
Molybdenum Concentrate ◽  
Selection Of

The process of complex raw materials is currently characterized by the fine-dispersed mineralogical structure and difficult structural characteristics complicating the flotation process. In this study, the processing methods for flotation of Aktogay deposits of copper-molybdenum ore were performed by using basic and modified agents. The properties of modified collector based on Kumkol deposit and diesel fuel were studied using the standard methods. The testing technology included the grinding of initial ore to a particle size of 65% of the class -0.074 mm, collective flotation to produce coarse copper-molybdenum concentrate, desorption, regrinding of the collective copper-molybdenum concentrate to 95% of the class -0.074 mm, selection of the collective concentrate. It was established that this application increased the extraction of copper/molybdenum concentrate by 3.8 % without loss of concentrate quality. This technology is applicable to mining and beneficiation enterprises processing molybdenum ores. Keywords: copper, molybdenum concentrate, modified agent

scholarly journals Study of the prospects for expanding the range of collectors in the flotation of fluorite from technogenic raw materials

2020 ◽  
Vol 192 ◽  
pp. 02019
Author(s):  
Olga Voronova ◽  
Lidia Kiyenko
Keyword(s):  
Fatty Acids ◽  
Raw Materials ◽  
Careful Selection ◽  
Tall Oil ◽  
Mining Company ◽  
Flotation Process ◽  
Fine Grinding ◽  
Fundamental Possibility ◽  
Technogenic Raw Materials ◽  
Selection Of

The results of studies on the development of a technology for the extraction of fluorite concentrates from finely disseminated refractory technogenic raw materials from Primorsky deposits were presented. The account of the technological features of the stale tailings of the concentration plant of Yaroslavkaya Mining Company has been given. The necessity of fine grinding of the material and careful selection of reagent compositions providing the required flotation selectivity has been substantiated. The fundamental possibility of obtaining fluorite concentrates containing CaF2 up to 94% and more using several samples of collectors from the group of fatty acids has been established. Fatty acids of tall oil produced by Ust-Ilimsk timber processing complex and a mixture of fatty acids produced in India, branded MASOIL 1880, provide a sufficient level of flotation selectivity. The recovery of fluorite in an open enrichment cycle according to the scheme with seven cleanings of the foam product can be 61.85-63.84%. The use of collectors compositions promotes an increase in the selectivity of the adsorption of reagents, which is accompanied by an increase in the selectivity of their action in comparison with the results obtained with the dosage of certain brands of the tested reagents into the flotation process. The extraction of fluorite into a concentrate obtained using a combination of tall oil and MASOIL-S fatty acids in a 1:1 ratio was 59.55-66.27% with a content of 95.6-94.23% CaF2 in it, respectively.

Cure Characteristics and Mechanical Properties of Rubber Compound Reinforced with Activated Carbon from Coconut Husks as Alternative to Carbon Black

2021 ◽  
Vol 1041 ◽  
pp. 17-22
Author(s):  
Mitch Irene Kate Oyales ◽  
Miguel Lorenzo H. Yorro ◽  
Marietta M. Valdez-Liu ◽  
Ivy Ann C. Razonado ◽  
Leslie Joy L. Diaz
Keyword(s):  
Particle Size ◽  
Tensile Strength ◽  
Activated Carbon ◽  
Carbon Black ◽  
Complex Modulus ◽  
Raw Materials ◽  
Bet Surface Area ◽  
Complete Replacement ◽  
Hardness Values ◽  
Selection Of

Selection of raw materials for rubber products is an important aspect of rubber engineering. One of the components often investigated is the filler material, wherein among the considerations include reinforcing capability, cost, and environmental impact. In this study, a greener alternative to carbon black (CB) was explored using activated carbon (AC) from coconut husk. Results showed that AC has lower fixed carbon content (33.64 wt%C) than CB (96.92 wt%C) due to the retained volatile organic components. AC also has a larger particle size distribution (< 150μm) in terms of 80% passing than CB (which is 28-36 nm for technically specified particle size of commercial N330). However, AC exhibits larger BET surface area (423.66 m2/g) due to natural porosity of activated carbon materials as compared to CB (58.109 m2/g). Moreover, AC was found to be basic while CB has a neutral pH. Consequently, the tensile strength and complex modulus G* of the AC-compound (4.3 MPa and 75.36 kPa, respectively) are inferior to CB-compound (20.3 MPa and 87.41 kPa, respectively). This is thought to be mainly due to the larger particle size and porous structure of the activated carbon. Yet, the % elongation and hardness values are comparable. Processability may also be a concern in using activated carbon as a filler due to higher Mooney viscosity (45.8 M). Nonetheless, the scorch time and cure index of the two compounds were found to be comparable. Hence, the potential of complete replacement of carbon black with activated carbon is viable for rubber products with low tensile strength requirements, such as protective matting.

Microstructural characterization of laser-melted/roller-quenched dicalcium silicate

1988 ◽  
Vol 46 ◽  
pp. 582-583
Author(s):  
C. J. Chan ◽  
K. R. Venkatachari ◽  
W. M. Kriven ◽  
J. F. Young
Keyword(s):  
Particle Size ◽  
Raw Materials ◽  
Shape Change ◽  
Microstructural Characterization ◽  
Particle Size Effect ◽  
Dicalcium Silicate ◽  
Laser Melting ◽  
Uniform Size ◽  
Cell Shape Change ◽  
Wide Range

Dicalcium silicate (Ca2SiO4) is a major component of Portland cement. It has also been investigated as a potential transformation toughener alternative to zirconia. It has five polymorphs: α, α'H, α'L, β and γ. Of interest is the β-to-γ transformation on cooling at about 490°C. This transformation, accompanied by a 12% volume increase and a 4.6° unit cell shape change, is analogous to the tetragonal-to-monoclinic transformation in zirconia. Due to the processing methods used, previous studies into the particle size effect were limited by a wide range of particle size distribution. In an attempt to obtain a more uniform size, a fast quench rate involving a laser-melting/roller-quenching technique was investigated.The laser-melting/roller-quenching experiment used precompacted bars of stoichiometric γ-Ca2SiO4 powder, which were synthesized from AR grade CaCO3 and SiO2xH2O. The raw materials were mixed by conventional ceramic processing techniques, and sintered at 1450°C. The dusted γ-Ca2SiO4 powder was uniaxially pressed into 0.4 cm x 0.4 cm x 4 cm bars under 34 MPa and cold isostatically pressed under 172 MPa. The γ-Ca2SiO4 bars were melted by a 10 KW-CO2 laser.

BÖHLER W403 VMR

Alloy Digest ◽  
2013 ◽  
Vol 62 (9) ◽  
Keyword(s):  
Heat Treatment ◽  
Chemical Composition ◽  
Physical Properties ◽  
Tool Steel ◽  
Raw Materials ◽  
Heat Treating ◽  
Diffusion Annealing ◽  
Selection Of

Abstract Böhler (or Boehler) W403 VMR is a tool steel with outstanding properties, based not only on a modified chemical composition, but on the selection of highly clean raw materials for melting, remelting under vacuum (VMF), optimized diffusion annealing, and a special heat treatment. This datasheet provides information on composition, physical properties, and elasticity. It also includes information on forming and heat treating. Filing Code: TS-721. Producer or source: Böhler Edelstahl GmbH.

scholarly journals Leaching Behaviour of Construction and Demolition Wastes and Recycled Aggregates: Statistical Analysis Applied to the Release of Contaminants

2021 ◽  
Vol 11 (14) ◽  
pp. 6265
Author(s):  
Alessandra Diotti ◽  
Giovanni Plizzari ◽  
Sabrina Sorlini
Keyword(s):  
Particle Size ◽  
Statistical Analysis ◽  
Raw Materials ◽  
Primary Source ◽  
Recycled Aggregates ◽  
Critical Parameters ◽  
Material Particle ◽  
Analysis Methodology ◽  
Construction And Demolition Wastes ◽  
Leaching Behaviour

Construction and demolition wastes represent a primary source of new alternative materials which, if properly recovered, can be used to replace virgin raw materials partially or totally. The distrust of end-users in the use of recycled aggregates is mainly due to the environmental performance of these materials. In particular, the release of pollutants into the surrounding environment appears to be the aspect of greatest concern. This is because these materials are characterized by a strong heterogeneity which can sometimes lead to contaminant releases above the legal limits for recovery. In this context, an analysis of the leaching behaviour of both CDWs and RAs was conducted by applying a statistical analysis methodology. Subsequently, to evaluate the influence of the particle size and the volumetric reduction of the material on the release of contaminants, several experimental leaching tests were carried out according to the UNI EN 12457-2 and UNI EN 12457-4 standards. The results obtained show that chromium, mercury, and COD are the most critical parameters for both CDWs and RAs. Moreover, the material particle size generally affects the release of contaminants (i.e., finer particles showed higher releases), while the crushing process does not always involve higher releases than the sieving process.

scholarly journals Mining Wastes of an Albite Deposit as Raw Materials for Vitrified Mullite Ceramics

Minerals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 232
Author(s):  
Pedro J. Sánchez-Soto ◽  
Eduardo Garzón ◽  
Luis Pérez-Villarejo ◽  
George N. Angelopoulos ◽  
Dolores Eliche-Quesada
Keyword(s):  
Particle Size ◽  
Raw Materials ◽  
Phase Evolution ◽  
Particle Size Analysis ◽  
Size Analysis ◽  
Mining Wastes ◽  
X Ray Diffraction ◽  
X Ray ◽  
Maximum Value

In this work, an examination of mining wastes of an albite deposit in south Spain was carried out using X-ray Fluorescence (XRF), X-ray diffraction (XRD), particle size analysis, thermo-dilatometry and Differential Thermal Analysis (DTA) and Thermogravimetric (TG) analysis, followed by the determination of the main ceramic properties. The albite content in two selected samples was high (65–40 wt. %), accompanied by quartz (25–40 wt. %) and other minor minerals identified by XRD, mainly kaolinite, in agreement with the high content of silica and alumina determined by XRF. The content of Na2O was in the range 5.44–3.09 wt. %, being associated with albite. The iron content was very low (<0.75 wt. %). The kaolinite content in the waste was estimated from ~8 to 32 wt. %. The particle size analysis indicated values of 11–31 wt. % of particles <63 µm. The ceramic properties of fired samples (1000–1350 °C) showed progressive shrinkage by the thermal effect, with water absorption and open porosity almost at zero at 1200–1250 °C. At 1200 °C, the bulk density reached a maximum value of 2.38 g/cm3. An abrupt change in the phase evolution by XRD was found from 1150 to 1200 °C, with the disappearance of albite by melting in accordance with the predictions of the phase diagram SiO2-Al2O3-Na2O and the system albite-quartz. These fired materials contained as main crystalline phases quartz and mullite. Quartz was present in the raw samples and mullite was formed by decomposition of kaolinite. The observation of mullite forming needle-shape crystals was revealed by Scanning Electron Microscopy (SEM). The formation of fully densified and vitrified mullite materials by firing treatments was demonstrated.

scholarly journals A Multiple and Multi-Level Substructure Method for the Dynamics of Complex Structures

2021 ◽  
Vol 11 (12) ◽  
pp. 5570
Author(s):  
Binbin Wang ◽  
Jingze Liu ◽  
Zhifu Cao ◽  
Dahai Zhang ◽  
Dong Jiang
Keyword(s):  
Structural Characteristics ◽  
Complex Structure ◽  
Complex Structures ◽  
System Matrix ◽  
Substructure Method ◽  
Residual Structure ◽  
The Matrix ◽  
Multi Level ◽  
Fixed Interface ◽  
Selection Of

Based on the fixed interface component mode synthesis, a multiple and multi-level substructure method for the modeling of complex structures is proposed in this paper. Firstly, the residual structure is selected according to the structural characteristics of the assembled complex structure. Secondly, according to the assembly relationship, the parts assembled with the residual structure are divided into a group of substructures, which are named the first-level substructure, the parts assembled with the first-level substructure are divided into a second-level substructure, and consequently the multi-level substructure model is established. Next, the substructures are dynamically condensed and assembled on the boundary of the residual structure. Finally, the substructure system matrix, which is replicated from the matrix of repeated physical geometry, is obtained by preserving the main modes and the constrained modes and the system matrix of the last level of the substructure is assembled to the upper level of the substructure, one level up, until it is assembled in the residual structure. In this paper, an assembly structure with three panels and a gear box is adopted to verify the method by simulation and a rotor is used to experimentally verify the method. The results show that the proposed multiple and multi-level substructure modeling method is not unique to the selection of residual structures, and different classification methods do not affect the calculation accuracy. The selection of 50% external nodes can further improve the analysis efficiency while ensuring the calculation accuracy.

scholarly journals Development of nitazoxanide-loaded colon-targeted formulation for intestinal parasitic infections: centre composite design-based optimization and characterization

2020 ◽  
Vol 6 (1) ◽  
Author(s):  
Charu Bharti ◽  
Upendra Nagaich ◽  
Jaya Pandey ◽  
Suman Jain ◽  
Neha Jain
Keyword(s):  
Particle Size ◽  
Desirability Function ◽  
In Vitro Release ◽  
Entrapment Efficiency ◽  
In Vitro Drug Release ◽  
Release Studies ◽  
Percentage Yield ◽  
Vitro Release ◽  
Selection Of

Abstract Background The current investigation is focused on the development and characterization of Eudragit S100 coated nitazoxanide-loaded microbeads as colon-targeted system utilizing central composite design (CCD) and desirability function. The study initiated with the selection of a BCS class II drug nitazoxanide and its preformulation screening with excipients, selection of polymer and identification of concentration for CCD, selection of optimized formulation based on desirability function, and in vitro release studies in simulated gastric and colonic media and stability studies. A two-factor, three-level CCD was employed with two independent variables, i.e. X1 (chitosan % w/v) and X2 (sodium tripolyphosphate % w/v), and three dependent variables, i.e. Y1 (particle size in micrometres), Y2 (percentage yield) and Y3 (percent entrapment efficiency), were chosen. Additionally, surface morphology, mucoadhesion and in vitro drug release studies were also conducted. Result Chitosan concentration showing maximum entrapment and optimum particle size was selected to formulate chitosan beads. The polynomial equation and model graphs obtained from the Design-Expert were utilized to examine the effect of independent variables on responses. The effect of formulation composition was found to be significant (p ˂ 0.05). Based on the desirability function, the optimized formulation was found to have 910.14 μm ± 1.03 particle size, 91.84% ± 0.64 percentage yield and 84.75% ± 0.38 entrapment efficiency with a desirability of 0.961. Furthermore, the formulations were characterized for in vitro drug release in simulated colonic media (2% rat caecal content) and have shown a sustained release of ∼ 92% up to 24 h as compared to in vitro release in simulated gastric fluid. Conclusion The possibility of formulation in enhancing percentage yield and entrapment efficiency of nitazoxanide and the utilization of CCD helps to effectively integrate nitazoxanide microbeads into a potential pharmaceutical dosage form for sustained release.

scholarly journals Sol-Gel Synthesis of the Double Perovskite Sr2FeMoO6 by Microwave Technique

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 3876
Author(s):  
Jesús Valdés ◽  
Daniel Reséndiz ◽  
Ángeles Cuán ◽  
Rufino Nava ◽  
Bertha Aguilar ◽  
...  
Keyword(s):  
Particle Size ◽  
Hydrothermal Synthesis ◽  
Microwave Radiation ◽  
Structural Characteristics ◽  
Sol Gel ◽  
Synthesis Method ◽  
Double Perovskite ◽  
Synthesis Methods ◽  
X Ray ◽  
Sol Gel Synthesis

The effect of microwave radiation on the hydrothermal synthesis of the double perovskite Sr2FeMoO6 has been studied based on a comparison of the particle size and structural characteristics of products from both methods. A temperature, pressure, and pH condition screening was performed, and the most representative results of these are herein presented and discussed. Radiation of microwaves in the hydrothermal synthesis method led to a decrease in crystallite size, which is an effect from the reaction temperature. The particle size ranged from 378 to 318 nm when pH was 4.5 and pressure was kept under 40 bars. According to X-ray diffraction (XRD) results coupled with the size-strain plot method, the product obtained by both synthesis methods (with and without microwave radiation) have similar crystal purity. The Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS) techniques showed that the morphology and the distribution of metal ions are uniform. The Curie temperature obtained by thermogravimetric analysis indicates that, in the presence of microwaves, the value was higher with respect to traditional synthesis from 335 K to 342.5 K. Consequently, microwave radiation enhances the diffusion and nucleation process of ionic precursors during the synthesis, which promotes a uniform heating in the reaction mixture leading to a reduction in the particle size, but keeping good crystallinity of the double perovskite. Precursor phases and the final purity of the Sr2FeMoO6 powder can be controlled via hydrothermal microwave heating on the first stages of the Sol-Gel method.

New uses for brick-making clay materials from the Bailén area (southern Spain)

Clay Minerals ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 453-465 ◽  
Author(s):  
I. Gonzalez ◽  
E. Galan ◽  
A. Miras ◽  
P. Aparicio
Keyword(s):  
Particle Size ◽  
Iron Oxides ◽  
Raw Materials ◽  
The Other ◽  
Southern Spain ◽  
Other Hand ◽  
Floor Tiles ◽  
Potential Applications ◽  
Clay Materials

AbstractAn attempt has been made to assess new potential applications for the Bailén clays, traditionally used for manufacturing bricks, based on mineralogical, chemical, particle size, plasticity and firing results. Raw materials and mixtures used by the local factory were selected and tested with the addition of some diatomite, feldspar or kaolin. Based on their properties, clay materials from Bailén might be suitable for making porous red wall tiles, clinker, vitrified red floor tiles and porous light-coloured wall tiles by pressing; the first could be manufactured from the raw materials and mixtures currently used by the local manufactures. On the other hand, stoneware shaped by extrusion, such as perforated bricks, facing bricks and roofing tiles, can be also manufactured from the mixtures used at the factory if they contain 20-25% carbonate and small amounts of iron oxides; lightweight bricks require black and yellow clays with diatomite.

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