Mechanical activation of raw materials in the synthesis of Fe2O3–ZrSiO4 inclusion pigment

2012 ◽  
Vol 32 (3) ◽  
pp. 643-647 ◽  
Author(s):  
M. Cannio ◽  
F. Bondioli
Keyword(s):  
Mechanical Activation ◽  
Raw Materials ◽  
Inclusion Pigment

Reactive Milling and Mechanical Alloying in Electroceramics

2010 ◽  
Vol 63 ◽  
pp. 420-424
Author(s):  
Riva Rivas-Marquez ◽  
Carlos Gomez-Yanez ◽  
Ivan Velasco-Davalos ◽  
Jesus Cruz-Rivera
Keyword(s):  
Grain Size ◽  
Mechanical Activation ◽  
Raw Materials ◽  
Planetary Mill ◽  
Fabrication Technique ◽  
Nonlinearity Coefficient ◽  
Grain Sizes ◽  
Zno Varistor ◽  
Reactive Milling ◽  
Good Homogeneity

Using Mechanical Activation it is possible to obtain small grain size and good homogeneity in a ceramic piece. For ZnO varistor devices Mechanical Activation appears to be a good fabrication technique, since good homogeneity and small grain sizes are advantageous microstructural features. The typical formulation is composed by ZnO, Bi2O3, Sb2O3, CoO, MnO2 and Cr2O3 as raw materials, and during sintering, several dissolutions and reactions to form pyrochlore and spinel phases occur. When Mechanical Activation is applied to the entire formulation, it is difficult to know what processes are being mechanically activated due to the complexity of the system. The aim of the present work was to clarify how the mechanical activation is taking place in a typical ZnO varistor formulation. The methodology consisted in the formation of all possible combinations of two out of the five oxides above mentioned and to apply mechanical activation on the mixture of each pair of powders. The results showed that systems containing Bi2O3 are prone to react during mechanical activation. Also, reduction reactions were observed in MnO2. In addition, the powder mixture corresponding to the whole formulation was milled in a planetary mill, pressed and sintered, and varistor devices were fabricated. Improvement in the nonlinearity coefficient and breakdown voltage was observed.

Effect of mechanically activated raw materials on β-sialon formation by combustion synthesis

2007 ◽  
Vol 22 (10) ◽  
pp. 2863-2867 ◽  
Author(s):  
Ramasamy Sivakumar ◽  
Kazuhiko Aoyagi ◽  
Tomohiro Akiyama
Keyword(s):  
Mechanical Activation ◽  
Combustion Synthesis ◽  
Milling Time ◽  
Raw Materials ◽  
Raw Material ◽  
First Time

The influence of different raw material mixtures on β-sialon (Si6−zAlzOzN8−z, 1 ⩽ z ⩽ 4) formation through mechanical activation coupled combustion synthesis (MA-CS) was investigated in low nitriding atmosphere of 1 MPa without diluent inclusions. The MA-CS performed for the first time on sialon raw materials with milling time of 18 min obtained sialons more than three times as pure as those obtained by CS of mixtures ball milled to 1 h (z = 3). The starting materials containing silicon, aluminum, and alumina (z = 4) after MA-CS had an increment of sialon amounts up to 88 mass%.

scholarly journals ESTIMATION OF THE EFFICIENCY OF MECHANICAL ACTIVATION OF SILICA-CONTAINING ROCKS

2021 ◽  
Vol 6 (5) ◽  
pp. 19-27
Author(s):  
A. Shamanina ◽  
Arkadiy Ayzenshtadt ◽  
V. Kononova ◽  
V. Danilov
Keyword(s):  
Mechanical Activation ◽  
Surface Activity ◽  
Raw Materials ◽  
Functional Dependence ◽  
Construction Materials ◽  
Mineralogical Composition ◽  
Optimal Time ◽  
Energy Potential ◽  
Mineral Components ◽  
Time Parameters

Rocks of various chemical and mineralogical composition are widely used as raw materials in the construction materials industry. At the same time, preliminary mechanical activation of mineral raw materials to a finely dispersed state contributes to a change in the energy potential of the system and affects the tendency of the surface of a finely dispersed system to transformations. Studies of the physicochemical activity of mechanically activated rocks allow to determine the rational areas of use of mineral components. The paper presents the results of evaluating the efficiency of mechanical activation of silica-containing raw materials by the values of surface activity (ks), defined as the ratio of the value of the free surface energy to the specific mass energy of atomization. Fine powders are obtained by grinding in a planetary ball mill to a different specific surface area of quartz sand (1200 – 3000 m2/kg) and polymineral sand (700 – 1335 m2/kg). The presence of a functional dependence of the surface activity on the time parameters of mechanical activation of the studied rocks is shown. The mechanical activation of the feedstock at the optimal time of its grinding makes it possible to achieve a given value of the surface activity. It is recommended to use the ks parameter as a criterion for assessing the efficiency of the process of mechanical activation of silica-containing rocks

USE OF MECHANICAL ACTIVATION OF POLYVINYL CHLORIDE IN THE PRODUCTION OF TENT MATERIALS

2019 ◽  
Keyword(s):  
Mathematical Model ◽  
Mechanical Activation ◽  
Polyvinyl Chloride ◽  
Raw Materials ◽  
Viscosity Change ◽  
Number Of Factors ◽  
Conformational Transformations ◽  
Minimum Number ◽  
Number Of Treatment

Physical and mechanical characteristics of tent materials depend on the quality of raw materials, which varies depending on its mechanical processing. A mathematical model of the process of dispersed materials activation is proposed, which describes the kinetics of change both during processing and dur-ing the further storage of the product of one or a number of factors characterizing physicochemical prop-erties of the material. The process of mechanical activation and verification of the adequacy of mathe-matical model proposed was carried out on emulsion polyvinyl chloride in a disintegrator unit. When processing PVC-E in a disintegrator, physicochemical processes take place, leading both to an increase and to a decrease in the viscosity of PVC-E solutions. The processes of dehydrochlorination breaking molecules, lead to a decrease in viscosity, and the formation of organic acids and copolymers - to in-crease. And these processes are irreversible. Conformational transformations of macromolecules con-tribute to the growth of viscosity of PVC-E solutions and are reversible. The adequacy of the proposed mathematical model describing the process of mechanical activation of dispersed materials is shown on the example of viscosity change of PVC-E solutions. Calculations show that increasing the loading speed, it is possible to maximize viscosity of PVC-E solutions in the minimum number of treatment cycles. If the number of processing cycles is more than one, then the rate of each subsequent loading should increase. The use of PVC-E, treated once in a disintegrator at a speed of 140 m / s, allows increasing physical and mechanical parameters of tent materials.

scholarly journals Risk assessment of negative effects on population health from the process of mechanical processing of secondary polymers

2021 ◽  
Vol 25 (1) ◽  
pp. 152-156
Author(s):  
O. S. Malyshevska
Keyword(s):  
Risk Assessment ◽  
Air Pollution ◽  
Mechanical Activation ◽  
Raw Materials ◽  
Statistical Processing ◽  
Polymer Processing ◽  
Mechanical Processing ◽  
Mechanical Recycling ◽  
Mean Values ◽  
The Impact

Annotation. The most hygienically safe process of recycling polymers is mechanical recycling, which does not cause the destruction of polymers, which dangerously affect all components of the environment and man. The purpose of the study is to assess the level of risk of adverse effects on the health of the population living under the influence of mechanical processing of secondary polymers, depending on the presence or absence of the stage of mechanical activation in the processing process. Research methods: sanitary-epidemiological examination; risk assessment of dangerous factors for public health; instrumental assessment methods; statistical processing of results – determination of arithmetic mean values, standard error, quadratic deviation. It was found that the total indicators of air pollution, calculated on the maximum concentrations of specific pollutants at distances for the processing of polymers without the stage of mechanical activation of 15 m – the level of pollution was assessed as alarming, and at distances of 25 and 50 m as acceptable. For the process of processing polymers with a stage of mechanical activation, at all distances from the emission source (15, 25 and 50 m) the level of contamination was assessed as acceptable. To assess the impact of air pollution in the area of impact of polymer processing on the health of the population, the risk factors for the development of non-carcinogenic effects are more informative than the indicators of pollution. The critical human organs and systems most affected by polymer processing are: the respiratory system, the cardiovascular system, the liver, the kidneys, the central nervous system, and the blood. In order to reduce the man-caused load of enterprises for mechanical processing of secondary polymer raw materials, it is necessary to introduce in-depth purification units for air emitted into the atmosphere and switch to safer fuels.

scholarly journals THERMAL DECOMPOSITION OF GRANULAR BIOFUEL OBTAINED BY DIFFERENT METHODS OF ACTIVATION

2020 ◽  
Vol 42 (4) ◽  
pp. 50-58
Author(s):  
T.V. Korinchevska ◽  
V.A. Mykhailyk
Keyword(s):  
Thermal Decomposition ◽  
Mechanical Activation ◽  
Thermal Activation ◽  
Raw Materials ◽  
Average Rate ◽  
Indirect Evidence ◽  
Decomposition Process ◽  
Raw Material ◽  
Organic Substances ◽  
Wood Sawdust

The article considers the effect of the granulometric composition of pine wood sawdust and granulation modes on the thermal decomposition of biofuel. Mechanical activation and thermal activation of raw materials before pressing were used in the study. Thermal decomposition of granular fuel was carried out by the methods of thermogravimetry and differential thermal analysis. The temperature ranges of dehydration, thermal decomposition of organic and mineral substances, moisture and ash content of the fuel have been determined. The rates of thermal decomposition of organic substances in granular fuel were also determined. The thermal effects of thermal decomposition of the granule samples were compared. It is registered that the equilibrium moisture content of granules obtained after thermal activation of the raw material is lower than that for granules made by cold pressing. This is indirect evidence of their increased density. It has been determined that most of the heat of thermal decomposition of organic substances in granular fuels is released in the high-temperature period at a decomposition rate of 1,12 to 1,37 % dry matter per minute. It was revealed that the thermal effect of thermal decomposition of granules depends on the fractional composition of the ground raw materials. This may be due to the difference in the chemical composition of the fractions. The analysis of obtained results made it possible to determine that the mechanical activation of raw materials increases the average rate of granule decomposition, and thermal activation reduces it. That is, the mechanical activation of raw materials has a positive effect on the thermal decomposition process. Grinding wood sawdust to particles smaller than 0,2 mm can lead to partial destruction of complex macromolecular compounds (hemicellulose, cellulose and lignin). Thus, this leads to a decrease in the degree of intermolecular interaction and intensification of the decomposition process.

Energy stored in mineral raw materials during mechanical activation

2008 ◽  
Vol 44 (2) ◽  
pp. 197-202 ◽  
Author(s):  
E. V. Bogatyreva ◽  
A. G. Ermilov
Keyword(s):  
Mechanical Activation ◽  
Raw Materials ◽  
Mineral Raw Materials

Synthesis, Characterization and Properties of Forsterite Refractory Produced from Thai Talc and Magnesite

2018 ◽  
Vol 940 ◽  
pp. 46-50
Author(s):  
Surapattanapong Kullatham ◽  
Sakdiphon Thiansem
Keyword(s):  
Physical Properties ◽  
Mechanical Activation ◽  
Ball Mill ◽  
Milling Time ◽  
Raw Materials ◽  
True Density ◽  
X Ray Diffraction ◽  
X Ray ◽  
Xrf Scanning ◽  
Subsequent Calcination

This paper reports the synthesis, characterizations, microstructure and properties of forsterite powder produced in Thailand from talc and magnesite as raw materials by using mechanical activation with subsequent calcination. The synthesis forsterite powder were mixed by using talc and magnesite at 1:5 mole ratio. The maximum milling time was 24 h in a planetary zirconia ball mill. Afterward, the mixtures were calcined in an electric furnace for 1 h at 900, 1000, 1100, 1200 and 1300°C respectively. The synthesized powder was characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy (SEM) and physical properties. Results of the physical properties of synthesized forsterite showed an increased in density as the calcining temperature increased. In contrast, porosity was decreased with an increase of the calcining temperature. Therefore, forsterite that was calcined at 1300°C provided the best results which were 2.96 g/cm3 of true density and 15.41% of true porosity. Results of XRD of synthesized powder indicated that the forsterite crystallization was constant for which sharpen appeared after 5 h of mechanical activation. Fraction of forsterite was appeared after being calcined at 1000°C for 1 h with an increasing of calcination temperature, the fraction of forsterite phase increased. Based on the mentioned characteristics, the forsterite produced from Thai talc and magnesite exhibited properties of an insulator and can potentially be used as refractory devices.

scholarly journals Kineticand thermodynamic aspects of flotation beneficiation of polymetallic raw materials

2021 ◽  
Vol 266 ◽  
pp. 02015
Author(s):  
T.D. Kalmykova ◽  
V.V. Kuznetsov
Keyword(s):  
Mechanical Activation ◽  
Thermodynamic Parameters ◽  
Research Methods ◽  
Raw Materials ◽  
Kinetic And Thermodynamic Parameters ◽  
Flotation Beneficiation ◽  
Preliminary Mechanical Activation

The article presents the results of the development of a method-ological approach to the analysis of kinetic and thermodynamic parameters for improving the efficiency of flotation processing of polymetallic raw materials.The kinetic dependences of flotation, the hydrophobizing ability of butyl potassium xanthogenate, and the effect of reagents on preliminary mechanical activation were studied, and flotation modeling with and with-out an oxidizer was performed. The best results of convergence with the kinetic dependences of flotation are shown by the Beloglazov equation, the Kelsall and the modified Kelsall models. Technological indicators of sul-fide flotation in the presence of oxidants are higher, which can be ex-plained by the intensive oxidation of the formed transient ions on the sur-face of minerals, which contributes to the alignment of the flotation properties of the surface.It is possible to integrate the proposed research methods into technological schemes in order to optimize technological in-dicators and increase profits.

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