scholarly journals Mineral Phases and Release Behaviors of As in the Process of Sintering Residues Containing As at High Temperature

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Xingrun Wang ◽  
Fengsong Zhang ◽  
Zexi Nong
Keyword(s):  
Structural Changes ◽  
Sintering Temperature ◽  
Raw Materials ◽  
Environmental Safety ◽  
Fixed Rate ◽  
Microstructure Observation ◽  
Sintering Time ◽  
Mineral Phases ◽  
The Matrix ◽  
Arsenic Leaching

To investigate the effect of sintering temperature and sintering time on arsenic volatility and arsenic leaching in the sinter, we carried out experimental works and studied the structural changes of mineral phases and microstructure observation of the sinter at different sintering temperatures. Raw materials were shaped under the pressure of 10 MPa and sintered at 1000~1350°C for 45 min with air flow rate of 2000 mL/min. The results showed that different sintering temperatures and different sintering times had little impact on the volatilization of arsenic, and the arsenic fixed rate remained above 90%; however, both factors greatly influenced the leaching concentration of arsenic. Considering the product’s environmental safety, the best sintering temperature was 1200°C and the best sintering time was 45 min. When sintering temperature was lower than 1000°C, FeAsS was oxidized into calcium, aluminum, and iron arsenide, mainly Ca3(AsO4)2and AlAsO4, and the arsenic leaching was high. When it increased to 1200°C, arsenic was surrounded by a glass matrix and became chemically bonded inside the matrix, which lead to significantly lower arsenic leaching.

scholarly journals Calcination of Clay Raw Materials in a Fluidized Bed

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 3989
Author(s):  
Katarzyna Kaczyńska ◽  
Konrad Kaczyński ◽  
Piotr Pełka
Keyword(s):  
Energy Expenditure ◽  
Fluidized Bed ◽  
Lower Energy ◽  
Structural Changes ◽  
High Efficiency ◽  
Raw Materials ◽  
Calcination Process ◽  
Mineral Phases ◽  
Time Period ◽  
Burning Coal

Clay raw materials are diverse in terms of their mineral composition, as well as the content of colouring oxides and their physical properties. Determining the suitability of raw materials for various purposes requires comprehensive studies on their properties, as well as their appropriate correction, which is possible through the use of appropriate modification techniques. One of the most commonly used technologies for the enrichment of clay raw materials is to subject them to high temperatures, which, depending on the temperature regime used in the technological process, may cause the decomposition and removal of some addditional components (e.g., carbonates), as well as the removal of water and dehydroxylation of clay minerals, reversible structural changes, and the complete and permanent reconstruction of the mineral phases. This paper presents a new application for fluidization technology in the calcination of clay raw materials. The results of the experiment show that the fluidization method is competitive compared to the technologies that have been used so far, as a result of, inter alia, the much shorter time period required to carry out the calcination process and, consequently, the much lower energy expenditure, the high efficiency of burning coal, and the lower CO2 emissions resulting from the mixing taking place in the reactor.

scholarly journals Characterization of mechanically milled and spark plasma sintered Al2124-CNT nanocomposites

2015 ◽  
Vol 47 (2) ◽  
pp. 119-129 ◽  
Author(s):  
N. Saheb
Keyword(s):  
Grain Size ◽  
Ball Milling ◽  
Milling Time ◽  
Lattice Strain ◽  
Sintering Temperature ◽  
Aluminum Matrix ◽  
Sintering Time ◽  
The Matrix ◽  
Spark Plasma ◽  
Aluminum Phase

In the present work, ball milling and spark plasma sintering were used to develop Al2124-CNT nanocomposites. The effect of milling time on the grain size and lattice strain of the ball milled Al2124 alloy powder and the effect of sintering time and temperature on the grain size of the matrix in spark plasma sintered Al2124 alloy and CNT-reinforced Al2124 nanocomposites were investigated. The density and hardness of the developed materials were evaluated as functions of the sintering parameters. It was found that ball milling not only reduced the particle size of the Al2124 powder but also decreased the grain size of the ?-aluminum phase to 50 nm and increased its lattice strain. A milling time of 6 hours was found to be the optimum time to reach a nanostructured ?-aluminum matrix. The grain size of the ?-aluminum phase in the sintered samples increased with increasing sintering temperature and time to reach maximum values at a sintering temperature of 500?C and a sintering time of 20 minutes. Although sintering led to grain growth, the grain size of the ?-aluminium matrix remained in the nanometer range and did not exceed 150 nm. The relative density and hardness of the sintered samples increased with increasing sintering temperature and time to reach maximum values at a sintering temperature of 500?C and a sintering time of 20 minutes.

One-step Carbothermal Reduction Synthesis of Li3V2(PO4)3 /C as Cathode Material for Lithium Ion Batteries

2011 ◽  
Vol 233-235 ◽  
pp. 1123-1131
Author(s):  
Mei Lin Li ◽  
Li Li Meng ◽  
Fan Wang ◽  
Hai Feng Su ◽  
Yun Fei Long ◽  
...  
Keyword(s):  
Carbon Content ◽  
Carbothermal Reduction ◽  
Sintering Temperature ◽  
Raw Materials ◽  
Retention Rate ◽  
Rate Capability ◽  
Lithium Ion ◽  
X Ray Diffraction ◽  
Sintering Time ◽  
One Step

Li3V2(PO4)3/C has been synthesized by a simple one-step carbothermal reduction technology using LiH2PO4, V2O5as the raw materials and sucrose as carbon source. X-ray diffraction (XRD) and scanning electron microscope (SEM) measurements showed that Li3V2(PO4)3/C synthesized by one-step carbothermal reduction had monoclinic structure. The structure and particle-size of the as-prepared Li3V2(PO4)3/C can be adjusted by the amount of carbon content, sintering temperature and sintering time in the synthesis processes. Li3V2(PO4)3/C prepared with a carbon content 0.4, sintering temperature 800°C and sintering time 20 h showed the largest discharge capacity 121.4mAh.g−1and an capacity retention rate of 98.3% after 50 cycles at 0.5C. The Li3V2(PO4)3/C obtained also exhibits an excellent rate capability with high discharge capacities of 111.0 mAh.g−1at 2.0C and 102.1 mAh.g−1at 5.0C.

The Research of by Blend and Flux Method SrFe12O19 Magnetic Particle Preparation and Magnetic Properties

2010 ◽  
Vol 160-162 ◽  
pp. 1513-1517
Author(s):  
Wei Guo ◽  
Hang Wu ◽  
Zhen Zhong Zheng ◽  
Qing Chang Chen ◽  
Qing Guo Chu
Keyword(s):  
Particle Size ◽  
Magnetic Properties ◽  
Magnetic Particles ◽  
Magnetic Particle ◽  
Sintering Temperature ◽  
Raw Materials ◽  
Molar Ratio ◽  
Flux Method ◽  
Sintering Time ◽  
Particle Preparation

According to the influence of sintering time, sintering temperature, different amount of flux and different molar ratio of Fe / Sr to the magnetic properties of prepared SrFe12O19 magnetic particles, the optimum SrFe12O19 conditions were concluded. They are: sintering time: 3 hours; sintering temperature: 1073.15 k; flux NaCl amount: 15% wt of the reaction raw materials; Fe / Sr molar ratio: 11.4; the sample magnetic properties: Ms = 63.39emu / g; Mr = 33.44emu / g; Hc = 5798Oe, Mr / Ms = 1 : 1.90 ≈ 1:2. The prepared SrFe12O19 should be single crystal particles and in the shape of flake, and the particle size should be generally about 80-90nm with uniform distribution.

Microstructure and Luminescent Properties of the YAG: Ce Phosphor-Doped Glass of the P2O5-ZnO-SiO2 System

2012 ◽  
Vol 509 ◽  
pp. 288-293
Author(s):  
Li Hong ◽  
Hua Ning ◽  
Ye Qing
Keyword(s):  
Energy Consumption ◽  
Energy Saving ◽  
Yttrium Aluminum Garnet ◽  
Sintering Temperature ◽  
Matrix Material ◽  
Luminescent Properties ◽  
Emission Peak ◽  
Affect Intensity ◽  
Sintering Time ◽  
The Matrix

Lminescent glass is widely used in building, energy saving, emergency lighting and art crafts; The energy consumption for global illumination is rising year by year, and the energy consumption has become a global problem; the research of luminescent glass is important for the developing of the energy-saving light. In this paper, the glass of the P2O5-ZnO-SiO2 system was used as matrix material, the matrix material was doped with yttrium aluminum garnet crystals containing Ce (YAG:Ce phosphors) and then were sintered for the preparation of the luminescent glass. Using X-ray diffraction and fluorescence spectrometer, the effects of the doping quantity, sintering temperature and sintering time on luminescent properties were studied. The results show that, for the P2O5-ZnO-SiO2 glass, excitation at 340 nm and 468 nm, produced emission at 544 nm; Doping quantity, sintering temperature and sintering time affect intensity of emission peak, but do not affect the position of emission peak.

TECHNOLOGICAL ASPECTS OF HIGH QUALITY RAW MATERIAL OBTAINING FOR PECTIN PRODUCTION

1970 ◽  
pp. 47-50
Author(s):  
I. A. Ilina ◽  
I. A. Machneva ◽  
E. S. Bakun
Keyword(s):  
Raw Materials ◽  
Thermal Characteristics ◽  
Environmental Safety ◽  
Raw Material ◽  
High Quality ◽  
Temperature Conductivity ◽  
Drying Temperature ◽  
Plant Raw Materials ◽  
Gel Forming Ability

  The article is devoted to the study of the chemical composition, physical and thermal-pfysical characteristics of damp apple pomaces and the identifying patterns of influence of drying temperature the functional composition and gel-forming ability of pectin. The research is aimed at obtaining initial data for the subsequent calculation of the main technological, hydro-mechanical, thermal, structural and economic characteristics of devices for drying the plant raw materials, ensuring the environmental safety and high quality of pectin-containing raw materials, the reducing heat and energy costs. As a result of the study of the thermal characteristics of apple pomaces, the critical points (temperature conductivity – 16.5 x 10-8 m2/s, thermal conductivity – 0.28 W/m K, heat capacity – 1627 j/(kg K)) at a humidity of 56 % are determined, which characterizing the transition from the extraction of weakly bound moisture to the extraction of moisture with strong bonds (colloidal, adsorption). It was found that the pomaces obtained from apples of late ripening have a higher content of solids (21-23 %), soluble pectin and protopectin (2.5-4.5 %). Dried pomaces obtained from apple varieties of late ripening contain up to 25 % pectin, which allow us to recommend them as a source of raw materials for the production of pectin. The optimum modes of preliminary washing of raw materials are offered, allowing to the remove the ballast substances as much as possible. It is established that when the drying temperature increases, the destructive processes are catalyzed: the strength of the pectin jelly and the uronide component and the degree of pectin esterification are reduced. The optimum drying temperature of damp apple pomaces is 80 0C, at which the quality of pectin extracted from the dried raw materials is maintained as much as possible. It is shown that the most effective for the pectin production is a fraction with a particle size of 3-5 mm, which allow us to extract up to 71 % of pectin from raw materials.

Ukraine’s foreign trade in meat and meat products: trends and geographical aspects

2020 ◽  
pp. 48-52
Author(s):  
Olena Lyakhovska
Keyword(s):  
Small Businesses ◽  
Structural Changes ◽  
Raw Materials ◽  
Meat Products ◽  
World Market ◽  
Poultry Meat ◽  
Positive Development ◽  
Meat Production ◽  
Meat Industry ◽  
Geographical Structure

Current trends in meat and meat products exports are considered. The dynamics and structural changes in meat exports by types and degree of processing (beef and veal, pork, poultry, finished meat products) are analyzed. The paper proves that in recent years, only meat and edible poultry by-products have taken a competitive position in the world market. Accordingly, the dynamics of exports of this type of meat is positive, and the share of these products in the structure of exported meat is the largest (86.09%). Possible threats to the growth of import dependence on certain types of meat products, in particular, chilled and frozen beef and veal, pork, are indicated. The rating of the largest countries-importers of meat and meat products (by types) from Ukraine is built, their share in the structure of meat exports is determined. Changes in the geographical structure of exports have been studied, which indicate a low level of diversification of the geography of exports of certain types of meat (pork, beef). At the same time, a positive development of the geographical structure of poultry meat exports (exported to more than 100 countries) was revealed. Problems of the export potential development in the meat industry of Ukraine are revealed. In particular, the problems of livestock development (outdated technologies and production techniques that reduce the efficiency and productivity; inefficiency of the organization of purchase and processing of meat, which leads to reduced breeding in small businesses and households; inefficiency of state incentives, etc.) and industrial meat production (lack of raw materials, obsolescence of fixed assets and production technologies, poorly developed logistics, etc.). The solution of these problems requires: a systematic approach, which will encourage the cooperation of agricultural and industrial production, cooperation with importers of meat products and protection of domestic producers in the domestic and international markets, creating a favorable investment and information environment that will promote the meat industry development.

scholarly journals Pressureless Sintering of YIG Ceramics from Coprecipitated Nanopowders

2021 ◽  
Vol 7 (5) ◽  
pp. 56
Author(s):  
Yimin Yang ◽  
Xiaoying Li ◽  
Ziyu Liu ◽  
Dianjun Hu ◽  
Xin Liu ◽  
...  
Keyword(s):  
High Temperature ◽  
Calcination Temperature ◽  
Sintering Temperature ◽  
Raw Materials ◽  
Secondary Phase ◽  
Coprecipitation Method ◽  
Pressureless Sintering ◽  
Densification Behavior ◽  
Sintering Process

Nanoparticles prepared by the coprecipitation method were used as raw materials to fabricate Y3Fe5O12 (YIG) ceramics by air pressureless sintering. The synthesized YIG precursor was calcinated at 900–1100 °C for 4 h in air. The influences of the calcination temperature on the phase and morphology of the nanopowders were investigated in detail. The powders calcined at 1000–1100 °C retained the pure YIG phase. YIG ceramics were fabricated by sintering at 1200–1400 °C for 10 h, and its densification behavior was studied. YIG ceramics prepared by air sintering at 1250 °C from powders calcinated at 1000 °C have the highest in-line transmittance in the range of 1000-3000 nm. When the sintering temperature exceeds 1300 °C, the secondary phase appears in the YIG ceramics, which may be due to the loss of oxygen during the high-temperature sintering process, resulting in the conversion of Fe3+ into Fe2+.

scholarly journals Alkali-Hydrothermal Treatment of K-Rich Igneous Rocks for Their Direct Use as Potassic Fertilizers

Minerals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 140
Author(s):  
Aaron Mbissik ◽  
Abdellatif Elghali ◽  
Muhammad Ouabid ◽  
Otmane Raji ◽  
Jean-Louis Bodinier ◽  
...  
Keyword(s):  
Hydrothermal Treatment ◽  
Inductively Coupled Plasma ◽  
Structural Changes ◽  
Raw Materials ◽  
Hydrothermal Process ◽  
Atomic Emission ◽  
Igneous Rocks ◽  
Gravimetric Analysis ◽  
African Countries ◽  
Naoh Solution

Due to the increasing demand for conventional sources of potassium (K) and their inaccessibility by African countries, K-rich igneous rocks are increasingly studied as potential alternative sources. In this study, six potassic igneous rocks (syenites and trachytes) from the Tamazeght, Jbel Boho, Ait Saoun, and El Glo’a regions (Morocco) were sampled and characterized. Then they were hydrothermally treated to enhance their K release for potential use as potassic fertilizers. The raw materials are mainly formed by microcline (up to 74%), orthoclase (20–68%), albite (36–57%), biotite-muscovite (15–23%), and titanite, calcite, hematite, and apatite as accessory minerals. These samples were crushed and milled to reach a particle size <150 µm and mixed with 4 N NaOH solution in an autoclave. The liquid/solid (L/S) ratio was about 44 mL/50 g. The powders were allowed to react with the solution at 170 °C for 7 h. For all tests, NaOH reacted completely with the powders and no liquid was observed after the treatment. X-ray diffraction (XRD), thermal gravimetric analysis (TGA), infrared spectroscopy (IRTF), and scanning electron microscopy (SEM-EDS) were carried out on treated samples to characterize the mineralogical and structural changes due to the alkali-hydrothermal treatment. Indeed, the treated samples revealed the presence of sodic neoformed phases such as thermonatrite, sodalite, analcime, and cancrinite. The treated material was leached for a week using deionized water and the elements released were measured using inductively coupled plasma–atomic emission spectroscopy (ICP-AES). The hydrothermal process showed a strong effect on structure breakdown as well as on the release of K and other nutrients such as P, Fe, Si, Mg, and Ca. Therefore, the alkali-hydrothermal treatment allowed the release of 50.5 wt% K. Moreover, the release of Mg, Ca, Fe, P, K, and Si were significantly increased. Mg, Ca, Fe, P, K, and Si release within raw materials was about (0.5–3.6), (3.5–31.4), (0.01–0.4), (0.01–0.3), (20–55), and (4.6–8) mg/kg, respectively, whereas treated samples showed a higher release of these elements. Quantitatively, Mg, Ca, Fe, P, K, and Si releases were about (10–11.8), (60–70), (7–20), (1.2–15), (218–1278), and (1119–2759) mg/kg, respectively. Consequently, the treated igneous rocks (syenite and trachyte) could be directly used as potassic fertilizers that would also be a source of other nutrients.

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