scholarly journals Conversion of mineral components manganese ore at temperature conditions of formation of agglomerates

2019 ◽  
pp. 42-51
Author(s):  
Mianovska Yana ◽  
Proidak Yuriy ◽  
Kamkina L
Keyword(s):  
Experimental Data ◽  
Heat Treatment ◽  
Weight Loss ◽  
Manganese Oxides ◽  
Kinetic Studies ◽  
Manganese Ore ◽  
Manganese Ores ◽  
Temperature Range ◽  
Natural Minerals ◽  
Mineral Components

Purpose: to determine the effect of temperature and duration of firing on the dissociation-reduction reaction of mineral components of manganese ores. Recovery of manganese ore is carried out in four stages, which are determined by temperatures: <150°C, 150°C - 300°C, 300°C - 480°C, above 480°C. Topicality. Ores and concentrates undergo a number of complex transformations during heat treatment (agglomeration, firing of pellets and briquettes, preheating). The nature of such transformations is largely determined by chemical, mineralogical and particle size distribution, as well as other properties of the source ore. In addition to external conditions (temperature, pressure, nature of recovery, gas flow rate), the reaction rate is influenced by the physicochemical properties of the renewable substance, its mineralogical composition, structure, surface condition. The kinetic features of the reduction of pure manganese oxides are difficult to apply to manganese ores and concentrates with a rather complex structure and chemical composition. Understanding the basic chemical processes occurring in the smelting of manganese alloys is important for finding and justifying technological solutions to increase the efficiency of smelting of alloys. Method. Kinetic studies at different temperatures and fractional composition of the components under study. Results. The available literature data clearly indicate the dependence of the kinetic parameters of the processes occurring when heating manganese oxides in reducing conditions, from their physicochemical nature. To a lesser extent, process performance differs for natural minerals, although the composition of minerals may vary depending on the place of extraction. In this paper, it seems more appropriate to study the transformations that occur with manganese ores when heated, to use as an object of study the natural minerals that are part of these ores. Experimental data obtained in the study of physicochemical characteristics of the reducing processes of natural minerals can be used in the analysis of ore reduction and improvement of ferroalloy production processes. Scientific novelty. Kinetic studies of the process of interaction of minerals with reducing gas were performed at a constant heating rate of 14 degrees in the temperature range of 25-1000°C. Oxide concentrate and natural minerals lose moisture in the first 5-6 minutes. Their recovery proceeded at high speeds at temperatures of 300-4000C. A significant increase in speed was observed during the transition from a temperature of 4000C to a temperature of 6000C. Subsequent heating at 2000C led to a small increase in the total process speed. The total weight loss of the samples during heat treatment consisted of weight loss due to dissociation of manganese dioxide, weight loss due to dehydration and dissociation of carbonates that are part of the concentrate, as well as oxygen loss due to reduction. Calculations showed that the temperature of the beginning of the dissociation of MnO2 in a helium atmosphere is 460K. Dissociation of pure MnO2 is thermodynamically possible in the studied temperature range. The final decomposition product can only be manganese oxide. Practical significance. The obtained experimental data allowed to draw a conclusion about the inefficiency of grinding of oxidative manganese materials smaller than to the fraction -2.0 +1.5 mm before their heat or reduction-heat treatment in the processes of preparation of the charge for melting manganese ferroalloys. Key words: manganese ore, minerals, dissociation, kinetics, ore fractions

Diffusion Coefficients of Interest for the Simulation of Heat Treatment in Rare-Earth Transition Metal Magnets

2012 ◽  
Vol 727-728 ◽  
pp. 163-168 ◽  
Author(s):  
Marcos Flavio de Campos
Keyword(s):  
Experimental Data ◽  
Heat Treatment ◽  
Activation Energy ◽  
Rare Earth ◽  
Transition Metal ◽  
Impurity Atom ◽  
Diffusion Coefficients ◽  
Arrhenius Equation ◽  
Atom Diffusion ◽  
Essential Input

In the case of the modeling of sintering and heat treatments, the diffusion coefficients are an essential input. However, experimental data in the literature about diffusion coefficients for rare-earth transition metal intermetallics is scarce. In this study, the available data concerning diffusion coefficients relevant for rare-earth transition metal magnets are reviewed and commented. Some empirical rules are discussed, for example the activation energy is affected by the size of the diffusing impurity atom. Diffusion coefficients for Dy, Nd and Fe into Nd2Fe14B are given according an Arrhenius equation D=D0exp (-Q/RT). For Dy diffusion into Nd2Fe14B, Q 315 kJ/mol and D08 . 10-4m2/s.

Exoelectron emission from unexcited metallic glasses Fe78B13Si9 during heat treatment

1992 ◽  
Vol 7 (6) ◽  
pp. 1396-1399 ◽  
Author(s):  
Yoshihisa Watanabe ◽  
Tadayoshi Kubozoe ◽  
Yoshikazu Nakamura
Keyword(s):  
Heat Treatment ◽  
Metallic Glasses ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Exoelectron Emission ◽  
Radiation Chemical ◽  
Temperature Range ◽  
High Vacuum Condition ◽  
Before And After ◽  
Ultra High Vacuum Condition

Exoelectron emission from the surface of unexcited metallic glasses Fe78B13Si9 during heat treatment has been studied under ultra high vacuum condition. In the first heating cycle, exoelectrons are emitted from the as-cast ribbon in the temperature range from approximately 423 K to 773 K (150 °C to 500 °C), although the surface of the specimen is not excited by ionizing radiation, chemical processes, or mechanical treatments prior to measurements. In the second and subsequent heating cycles, however, there is no anomalous emission observed in the same temperature range. In order to elucidate the mechanism of emission, the surface of the specimen is observed by the atomic force microscope (AFM) before and after measurements. In the AFM image, many crystallites in the amorphous matrix can be found in the surface of the heated specimen. These experimental results show that exoelectrons are emitted in the same temperature range as the early stages of crystallization on the surface of metallic glasses. We hypothesize that the two effects are correlated.

scholarly journals High temperatures during microsporogenesis fatally shorten pollen lifespan

2021 ◽  
Author(s):  
Maurizio Iovane ◽  
Giovanna Aronne
Keyword(s):  
Experimental Data ◽  
Heat Treatment ◽  
Heat Stress ◽  
High Temperature ◽  
Male Gametophyte ◽  
Crop Productivity ◽  
Anther Dehiscence ◽  
Optimal Temperature ◽  
Drastic Reduction ◽  
Crop Species

AbstractMany crop species are cultivated to produce seeds and/or fruits and therefore need reproductive success to occur. Previous studies proved that high temperature on mature pollen at anther dehiscence reduce viability and germinability therefore decreasing crop productivity. We hypothesized that high temperature might affect pollen functionality even if the heat treatment is exerted only during the microsporogenesis. Experimental data on Solanum lycopersicum ‘Micro-Tom’ confirmed our hypothesis. Microsporogenesis successfully occurred at both high (30 °C) and optimal (22 °C) temperature. After the anthesis, viability and germinability of the pollen developed at optimal temperature gradually decreased and the reduction was slightly higher when pollen was incubated at 30 °C. Conversely, temperature effect was eagerly enhanced in pollen developed at high temperature. In this case, a drastic reduction of viability and a drop-off to zero of germinability occurred not only when pollen was incubated at 30 °C but also at 22 °C. Further ontogenetic analyses disclosed that high temperature significantly speeded-up the microsporogenesis and the early microgametogenesis (from vacuolated stage to bi-cellular pollen); therefore, gametophytes result already senescent at flower anthesis. Our work contributes to unravel the effects of heat stress on pollen revealing that high temperature conditions during microsporogenesis prime a fatal shortening of the male gametophyte lifespan.

RATIONAL PROCESS PARAMETERS OF CHOPPED SEMI-FINISHED PRODUCTS PRODUCTION USING EMULSIONS FROM COLLAGENCONTAINING RAW MATERIALS

2020 ◽  
pp. 199-213
Author(s):  
I. Kaltovich
Keyword(s):  
Heat Treatment ◽  
Weight Loss ◽  
Connective Tissue ◽  
Raw Materials ◽  
Steam Treatment ◽  
Point System ◽  
Technological Parameters ◽  
Genus Lactobacillus ◽  
Rational Process

The article presents the results of research on the determination of rational technological parameters for the production of chopped semi-products using emulsions from collagen-containing raw materials fermented by bacteria of the genus Lactobacillus. Water dosages are installed in the composition of chopped semi-finished products: 12% – with emulsions from pork skin and tails and 11% - with emulsion from connective tissue. Duration of ingredients mixing (5 minutes), sequence of raw materials laying during manufacture of articles, as well as duration of heat treatment of chopped semiproducts is determined: 25 minutes – during steaming (t = 95–100 °С), 20 minutes – during baking (t = 180 °C), 15 minutes – during frying (t = 110 °C), while recommended methods of bringing semifinished products to culinary readiness are steam treatment and baking, which allow for improved functional and technological (TUS – 79.3-81.8%, weight loss during heat treatment – 5.1–7.9%), structural and mechanical (PNS - 1413.9–1470.4 Pa) and organoleptic indicators (juiciness, appearance, consistency, taste, smell) of these products (9 points according to the 9-point system).

scholarly journals Температурная зависимость ширины запрещенной зоны монокристаллов MnAgIn-=SUB=-7-=/SUB=-S-=SUB=-12-=/SUB=-

2019 ◽  
Vol 53 (12) ◽  
pp. 1621
Author(s):  
И.В. Боднарь ◽  
Б.Т. Чан ◽  
В.Н. Павловский ◽  
И.Е. Свитенков ◽  
Г.П. Яблонский
Keyword(s):  
Experimental Data ◽  
Temperature Dependence ◽  
Band Gap ◽  
Single Crystals ◽  
Spinel Structure ◽  
Semiconductor Materials ◽  
Transmittance Spectra ◽  
Temperature Range

AbstractMnAgIn_7S_12 single crystals 16 mm in diameter and ~40 mm in length are grown by planar crystallization of the melt. It is shown that the material grown crystallizes with the formation of the cubic spinel structure. From the transmittance spectra recorded in the region of fundamental absorption in the temperature range 10–320 K, the band gap E _ g of the single crystals and its temperature dependence are determined. The dependence has a shape typical of most semiconductor materials: as the temperature is lowered, the band gap E _ g increases. A calculation is carried out, and it is shown that the calculated values are in agreement with the experimental data.

scholarly journals Подавление температурной зависимости длины волны излучения в светодиодных структурах со ступенчатым гетеропереходом II типа InAsSb/InAsSbP

2021 ◽  
Vol 55 (3) ◽  
pp. 277
Author(s):  
А.А. Семакова ◽  
В.В. Романов ◽  
Н.Л. Баженов ◽  
К.Д. Мынбаев ◽  
К.Д. Моисеев
Keyword(s):  
Experimental Data ◽  
Solid Solution ◽  
Active Region ◽  
Molar Fraction ◽  
Type Ii ◽  
Ternary Solid Solution ◽  
Dominant Contribution ◽  
Temperature Range ◽  
Radiative Transitions ◽  
Operating Wavelength

The results of a study of the electroluminescence of the asymmetric InAs/InAs1−ySby/InAsSbP LED heterostructures with a molar fraction of InSb in the ternary solid solution in the active region y=0.15 and y=0.16 in the temperature range 4.2−300 K are presented. Based on the experimental data, the formation of a staggered type II heterojunction at the InAs1−ySby/InAsSbP heterointerface was determined. The dominant contribution of the interface radiative transitions at the type II heterointerface in the temperature range 4.2−180 K was shown, which makes it possible to minimize the temperature dependence of the operating wavelength of the LEDs.

Development of liquidus thermobarometer for the simulation of equilibrium olivine-melt

2019 ◽  
pp. 62-74
Author(s):  
E. V. Koptev-Dvornikov ◽  
D. A. Bychkov
Keyword(s):  
Experimental Data ◽  
Liquidus Temperature ◽  
Small Error ◽  
Silicate Melt ◽  
System Of Equations ◽  
Temperature Range ◽  
Calculated Liquidus ◽  
Wide Range ◽  
Multidimensional Statistics

A system of equations of the liquidus thermobarometer of olivine — silicate melt was obtained by processing the sample of 772 experimental equilibria of olivines with basic melts using methods of multidimensional statistics. Equations reproduce with small error experimental data in a wide range of basite compositions (from komatiites to dacites), temperatures from 1040 to 1500 ᵒС, pressures from 1 bar up to 30 kbar. Thermobarometer testing demonstrated that the deviations of the calculated liquidus temperature from the experimental one in most of the temperature range do not exceed ±3 ᵒC.

scholarly journals The Role of Hydrothermal Activity in the Formation of Karst-Hosted Manganese Deposits of the Postmasburg Mn Field, Northern Cape Province, South Africa

Minerals ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 408
Author(s):  
Brenton J. Fairey ◽  
Martin J. Timmerman ◽  
Masafumi Sudo ◽  
Harilaos Tsikos
Keyword(s):  
Hydrothermal Fluid ◽  
Hydrothermal Activity ◽  
Ore Deposits ◽  
Manganese Ore ◽  
High Grade ◽  
Ore Formation ◽  
Manganese Ores ◽  
Manganese Deposits ◽  
Northern Cape

The Postmasburg Manganese Field (PMF), Northern Cape Province, South Africa, once represented one of the largest sources of manganese ore worldwide. Two belts of manganese ore deposits have been distinguished in the PMF, namely the Western Belt of ferruginous manganese ores and the Eastern Belt of siliceous manganese ores. Prevailing models of ore formation in these two belts invoke karstification of manganese-rich dolomites and residual accumulation of manganese wad which later underwent diagenetic and low-grade metamorphic processes. For the most part, the role of hydrothermal processes and metasomatic alteration towards ore formation has not been adequately discussed. Here we report an abundance of common and some rare Al-, Na-, K- and Ba-bearing minerals, particularly aegirine, albite, microcline, banalsite, sérandite-pectolite, paragonite and natrolite in Mn ores of the PMF, indicative of hydrothermal influence. Enrichments in Na, K and/or Ba in the ores are generally on a percentage level for most samples analysed through bulk-rock techniques. The presence of As-rich tokyoite also suggests the presence of As and V in the hydrothermal fluid. The fluid was likely oxidized and alkaline in nature, akin to a mature basinal brine. Various replacement textures, particularly of Na- and K- rich minerals by Ba-bearing phases, suggest sequential deposition of gangue as well as ore-minerals from the hydrothermal fluid, with Ba phases being deposited at a later stage. The stratigraphic variability of the studied ores and their deviation from the strict classification of ferruginous and siliceous ores in the literature, suggests that a re-evaluation of genetic models is warranted. New Ar-Ar ages for K-feldspars suggest a late Neoproterozoic timing for hydrothermal activity. This corroborates previous geochronological evidence for regional hydrothermal activity that affected Mn ores at the PMF but also, possibly, the high-grade Mn ores of the Kalahari Manganese Field to the north. A revised, all-encompassing model for the development of the manganese deposits of the PMF is then proposed, whereby the source of metals is attributed to underlying carbonate rocks beyond the Reivilo Formation of the Campbellrand Subgroup. The main process by which metals are primarily accumulated is attributed to karstification of the dolomitic substrate. The overlying Asbestos Hills Subgroup banded iron formation (BIF) is suggested as a potential source of alkali metals, which also provides a mechanism for leaching of these BIFs to form high-grade residual iron ore deposits.

scholarly journals The system CaO-MgO-FeO-SiO2 and its bearing on the origin of ultrabasic and basic rocks

1960 ◽  
Vol 32 (249) ◽  
pp. 459-470 ◽  
Author(s):  
Peter J. Wyllie
Keyword(s):  
Experimental Data ◽  
Temperature Interval ◽  
Wide Temperature Range ◽  
Multicomponent System ◽  
Small Temperature ◽  
Experimental Procedure ◽  
Temperature Range ◽  
A Value ◽  
Basaltic Magmas ◽  
Basic Rocks

SummaryExperimental data in the system CaO-MgO-FeO-SiO2 suggest that there may be a plateau on the liquidus and solidus of the multicomponent system basalt-peridotite. If this is so, fusion of peridotite would produce only basaltie magmas over a wide temperature range; when the temperature reached a value such that the liquid crossed the threshold of the plateau, there would be a rapid increase in the amount of fusion for small temperature increases, with the formation of picritic magmas; basaltic magmas containing suspended forsteritic olivine crystals could dissolve them if the temperature rose slightly above that of the plateau threshold; a high proportion of a picritic magma would crystallize in a small temperature interval, with the precipitation of forsteritic olivine that was only slightly zoned. These possibilities are compared with current theories, and it is concluded that several petrological axioms may require critical re-examination. An experimental procedure is outlined to determine the shape of the liquidus and solidus in the basalt-peridotite system.

Sign in / Sign up

Export Citation Format

Share Document