scholarly journals Vaporization of Vanadium Pentoxide from CaO-SiO2-VOx Slags During Alumina Dissolution

2021 ◽  
Author(s):  
Tetiana Shyrokykh ◽  
Xingwen Wei ◽  
Seshadri Seetharaman ◽  
Olena Volkova
Keyword(s):  
Surface Tension ◽  
Gas Phase ◽  
Vanadium Pentoxide ◽  
Molten Slag ◽  
Slag Viscosity ◽  
Crucible Material ◽  
Gas Treatment ◽  
Treatment Regimens ◽  
High Vapor ◽  
Alumina Dissolution

AbstractThe vaporization of vanadium pentoxide from CaO-SiO2-VOx ternary slags using different gas treatment regimens and parallel vacuum gas extirpation to treat V-bearing slags at 1873 K has been developed in the present study. The novelty of the present study is to monitor the effect of parallel alumina dissolution on the vaporization phenomenon. Vanadium pentoxide has high vapor pressure at the temperatures over 1500 K. When CaO-SiO2-VOx ternary slags, kept in dense alumina crucibles, are injected with oxygen, V2O5 gas bubbles are formed which are forced out by using vacuum extirpation. The vanadium pentoxide could be then collected in the exhaust gases. The mechanism of the process phenomenon is described as the formation of V2O5 gas phase resulting from the oxidation of the lower-valent oxides present in the slag. This gas phase would form microbubbles in the molten slag bulk phase due to low surface tension between the gas phase and the slag, thereby increasing the contact surface. At the same time, the crucible material would dissolve in the slag causing an increase in the slag viscosity. Due to the high slag viscosity of the bulk slag, these microbubbles formed would have difficulty in coalescing and reaching the slag surface. The escaping of the bubbles into the gas phase is enabled by the vacuum extirpation.

Non-Arrhenius Viscosity Models for Molten Silicate Slags with Constant Pre-Exponential Parameter: A Comparison to Arrhenius Model

2016 ◽  
Vol 35 (3) ◽  
pp. 261-267 ◽  
Author(s):  
Lei Gan ◽  
Chaobin Lai ◽  
Huihui Xiong
Keyword(s):  
Low Temperature ◽  
Molten Slag ◽  
Slag Viscosity ◽  
Arrhenius Model ◽  
Exponential Parameter ◽  
Viscosity Models ◽  
Lower Viscosity ◽  
Molten Silicate ◽  
Parameter Values

AbstractThe accuracies of molten slag viscosity fitting and low-temperature extrapolation were compared between four two-variable models: Arrhenius, Weymann–Frenkel (WF), and Vogel–Fulcher–Tammann (VFT) and Mauro, Yue, Ellison, Gupta and Allan (MYEGA) models with constant pre-exponential parameter, based on a molten slag viscosity database consisting of over 800 compositions and 5,000 measurements. It is found that over wide ranges of pre-exponential parameter, the VFT and MYEGA models have lower viscosity fitting errors and much higher low-temperature viscosity extrapolation accuracies than Arrhenius and WF models. The pre-exponential parameter values of –2.8 for VFT and –2.3 for MYEGA are recommended.

scholarly journals Gaseous, PM<sub>2.5</sub> Mass, and Speciated Emission Factors from Laboratory Chamber Peat Combustion

2019 ◽  
Author(s):  
John G. Watson ◽  
Junji Cao ◽  
L.W. Antony Chen ◽  
Qiyuan Wang ◽  
Jie Tian ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Gas Phase ◽  
Flow Reactor ◽  
Combustion Efficiency ◽  
Emission Factors ◽  
Water Soluble ◽  
Atmospheric Aging ◽  
High Vapor ◽  
Southern Florida ◽  
Northern Alaska

Abstract. Peat fuels representing four biomes of boreal (western Russia and Siberia), temperate (northern Alaska, U.S.A.), subtropical (northern and southern Florida, U.S.A), and tropical (Borneo, Malaysia) regions were burned in a laboratory chamber to determine gas and particle emission factors (EFs). Tests with 25 % fuel moisture were conducted with predominant smoldering combustion conditions (average modified combustion efficiency [MCE] = 0.82 ± 0.08). Average fuel-based EFCO2 (carbon dioxide) are highest (1400 ± 38 g kg−1) and lowest (1073 ± 63 g kg−1) for the Alaskan and Russian peats, respectively. EFCO (carbon monoxide) and EFCH4 (methane) are ~12 %‒15 % and ~0.3 %‒0.9  % of EFCO2, in the range of 157‒171 g kg−1 and 3‒10 g kg−1, respectively. EFs for nitrogen species are at the same magnitude of EFCH4, with an average of 5.6 ± 4.8 and 4.7 ± 3.1 g kg−1 for EFNH3 (ammonia) and EFHCN (hydrogen cyanide); 1.9 ± 1.1 g kg−1 for EFNOx (nitrogen oxides); as well as 2.4 ± 1.4 and 2.0 ± 0.7 g kg−1 for EFNOy (reactive nitrogen) and EFN2O (nitrous oxide). An oxidation flow reactor (OFR) was used to simulate atmospheric aging times of ~2 and ~7 days to compare fresh (upstream) and aged (downstream) emissions. Filter-based EFPM2.5 varied by >4-fold (14‒61 g kg−1) without appreciable changes between fresh and aged emissions. The majority of EFPM2.5 consists of EFOC (organic carbon), with EFOC/EFPM2.5 ratios in the range of 52 %‒98 % for fresh emissions, and ~15 % degradation after aging. Reductions of EFOC (~7‒9 g kg−1) after aging are most apparent for boreal peats with the largest degradation in organic carbon that evolves at <140 °C, indicating the loss of high vapor pressure semi-volatile organic compounds upon aging. The highest EFLevoglucosan is found for Russian peat (~16 g kg−1), with ~35 %‒50 % degradation after aging. EFs for water-soluble OC (EFWSOC) accounts for ~20 %‒62 % of fresh EFOC. The majority (>95 %) of the total emitted carbon is in the gas phase with 54 %‒75 % CO2, followed by 8 %‒30 % CO. Nitrogen in the measured species explains 24 %‒52 % of the consumed fuel nitrogen with an average of 35 ± 11 %, consistent with past studies that report ~one- to two-thirds of the fuel nitrogen measured in biomass smoke. The majority (>99 %) of the total emitted nitrogen is in the gas phase, with an average of 16.7 % fuel N emitted as NH3 and 9.5 % of fuel N emitted as HCN. N2O and NOy constituted 5.7 % and 2.9 % of consumed fuel N. EFs from this study can be used to refine current emissions inventories.

scholarly journals Gaseous, PM<sub>2.5</sub> mass, and speciated emission factors from laboratory chamber peat combustion

2019 ◽  
Vol 19 (22) ◽  
pp. 14173-14193 ◽  
Author(s):  
John G. Watson ◽  
Junji Cao ◽  
L.-W. Antony Chen ◽  
Qiyuan Wang ◽  
Jie Tian ◽  
...  
Keyword(s):  
Gas Phase ◽  
Flow Reactor ◽  
Combustion Efficiency ◽  
Emission Factors ◽  
Water Soluble ◽  
Semivolatile Organic Compounds ◽  
Atmospheric Aging ◽  
High Vapor ◽  
Southern Florida ◽  
Northern Alaska

Abstract. Peat fuels representing four biomes of boreal (western Russia and Siberia), temperate (northern Alaska, USA), subtropical (northern and southern Florida, USA), and tropical (Borneo, Malaysia) regions were burned in a laboratory chamber to determine gas and particle emission factors (EFs). Tests with 25 % fuel moisture were conducted with predominant smoldering combustion conditions (average modified combustion efficiency (MCE) =0.82±0.08). Average fuel-based EFCO2 (carbon dioxide) are highest (1400 ± 38 g kg−1) and lowest (1073 ± 63 g kg−1) for the Alaskan and Russian peats, respectively. EFCO (carbon monoxide) and EFCH4 (methane) are ∼12 %–15 % and ∼0.3 %–0.9 % of EFCO2, in the range of 157–171 and 3–10 g kg−1, respectively. EFs for nitrogen species are at the same magnitude as EFCH4, with an average of 5.6 ± 4.8 and 4.7 ± 3.1 g kg−1 for EFNH3 (ammonia) and EFHCN (hydrogen cyanide); 1.9±1.1 g kg−1 for EFNOx (nitrogen oxides); and 2.4±1.4 and 2.0 ± 0.7 g kg−1 for EFNOy (total reactive nitrogen) and EFN2O (nitrous oxide). An oxidation flow reactor (OFR) was used to simulate atmospheric aging times of ∼2 and ∼7 d to compare fresh (upstream) and aged (downstream) emissions. Filter-based EFPM2.5 varied by > 4-fold (14–61 g kg−1) without appreciable changes between fresh and aged emissions. The majority of EFPM2.5 consists of EFOC (organic carbon), with EFOC ∕ EFPM2.5 ratios in the range of 52 %–98 % for fresh emissions and ∼14 %–23 % degradation after aging. Reductions of EFOC (∼7–9 g kg−1) after aging are most apparent for boreal peats, with the largest degradation in low-temperature OC1 that evolves at < 140 ∘C, indicating the loss of high-vapor-pressure semivolatile organic compounds upon aging. The highest EFLevoglucosan is found for Russian peat (∼16 g kg−1), with ∼35 %–50 % degradation after aging. EFs for water-soluble OC (EFWSOC) account for ∼20 %–62 % of fresh EFOC. The majority (> 95 %) of the total emitted carbon is in the gas phase, with 54 %–75 % CO2, followed by 8 %–30 % CO. Nitrogen in the measured species explains 24 %–52 % of the consumed fuel nitrogen, with an average of 35 ± 11 %, consistent with past studies that report ∼1/3 to 2∕3 of the fuel nitrogen measured in biomass smoke. The majority (> 99 %) of the total emitted nitrogen is in the gas phase, with an average of 16.7 % as NH3 and 9.5 % as HCN. N2O and NOy constituted 5.7 % and 2.9 % of consumed fuel nitrogen. EFs from this study can be used to refine current emission inventories.

scholarly journals Surface Tension of CaO-SiO2-Al2O3 and CaO-Al2O3 Slags. (Study on surface tension of molten slag-I )

1966 ◽  
Vol 52 (9) ◽  
pp. 1427-1429 ◽  
Author(s):  
Kazumi OGINO ◽  
Tetsuro SUETAKI ◽  
Ryoichi TSUKUDA ◽  
Akira ADACHI
Keyword(s):  
Surface Tension ◽  
Molten Slag

scholarly journals Effect of MgO and K2O on High-Al Silicon–Manganese Alloy Slag Viscosity and Structure

Minerals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 810 ◽  
Author(s):  
Xiangdong Xing ◽  
Zhuogang Pang ◽  
Jianlu Zheng ◽  
Yueli Du ◽  
Shan Ren ◽  
...  
Keyword(s):  
Molten Slag ◽  
Photoelectron Spectra ◽  
Slag Viscosity ◽  
High Melting Point ◽  
Manganese Alloy ◽  
Flow Activation Energy ◽  
Slag Structure ◽  
Phase Spinel ◽  
Flow Activation ◽  
Manganese Slag

The viscosity, melting proprieties, and molten structure of the high-Al silicon–manganese slag of SiO2–CaO–25 mass% Al2O3–MgO–MnO–K2O system with a varying MgO and K2O content were studied. The results show that with the increase in MgO content from 4 to 10 mass%, the measured viscosity and flow activation energy decreases, but K2O has an effect on increasing those of slags. However, the melting temperature increases due to the formation of high-melting-point phase spinel. Meanwhile, Fourier transform infrared (FTIR) and X-ray photoelectron spectra (XPS) were conducted to understand the variation of slag structure. The O2− dissociates from MgO can interact with the O0 within Si–O or Al–O network structures, corresponding to the decrease in the trough depth of [SiO4] tetrahedral and [AlO4] tetrahedral. However, when K2O is added into the molten slag, the K+ can accelerate the formation of [AlO4] tetrahedra, resulting in the increase in O0 and O− and the polymerization of the structure.

Experimental Study of Thermal Plasma Processing Waste Circuit Boards

2013 ◽  
Vol 652-654 ◽  
pp. 1553-1561 ◽  
Author(s):  
Song Bai Wang ◽  
Chang Ming Cheng ◽  
Wei Lan ◽  
Xian Hui Zhang ◽  
Dong Ping Liu ◽  
...  
Keyword(s):  
Thermal Plasma ◽  
Molten Slag ◽  
Plasma Processing ◽  
Experimental Result ◽  
Exhaust Gas ◽  
Circuit Boards ◽  
Processing Waste ◽  
Gas Treatment ◽  
Thermal Plasma Processing ◽  
Co Gas

This study aimed to that waste circuit boards in batches were incinerated by thermal plasma. Firstly, the working principle of plasma incinerator and the exhaust gas treatment main process were introduced, then, the experimental results was analyzed and discussed. Due to the thermal plasma processing waste incineration furnace has high temperature (1200 0C above), all the organic ingredients in waste circuit boards, including dioxin, can be decomposed completely in a few milliseconds, no showing the secondary pollution and no producing furans and other carcinogens. In addition, after main exhaust gas (CO, NO) concentration change with time was carefully tracked, it was found that a large amount of CO gas was produced and NO gas concentration was within national safety limits during experiment. Although 44.4 kg sample was incinerated, more than 1 kg of small pieces of metal like Copper was obtained from the cooling molten slag. Finally, it was obvious that the volume and weight of molten slag was far less than the ones of sample. The experimental result has important practical significance for protecting the environment, obtaining more CO gas resource and retrieving a variety of rare metals (such as Gold, Copper, Silver, Platinum, etc.).

Biofilters based on the action of fungi

2001 ◽  
Vol 44 (9) ◽  
pp. 227-232 ◽  
Author(s):  
J.W. van Groenestijn ◽  
W.N.M. van Heiningen ◽  
N.J.R. Kraakman
Keyword(s):  
Pressure Drop ◽  
Gas Phase ◽  
Fungal Growth ◽  
Cost Effective ◽  
Bacterial Biofilms ◽  
Gas Treatment ◽  
Waste Gas ◽  
Hydrophobic Compounds ◽  
Waste Gas Treatment ◽  
Degradation Activity

Traditional biofilters for waste gas treatment are mainly based on the degradation activity of bacteria. The application of fungi in biofilters has several advantages: fungi are more resistant to acidification and drying out, and the aerial mycelia of fungi form a larger surface area in the gas phase than bacterial biofilms, which may facilitate the uptake of hydrophobic volatile compounds. The research described here identifies important conditions for the operation of fungal-based biofilters. Biofilters with perlite packing were operated at different pHs and relative inlet gas humidities. Toluene was used as a model pollutant. It was shown that a low pH is a prerequisite for fungal growth in biofilters. Also, the fungal biofilters were more resistant to drying out and more active than the bacterial biofilters. Fungal biofilters eliminated 80-125 g toluene/m3 filterbed/h. Several measures that could limit the clogging of fungal biofilters with fungal biomass were investigated. The introduction of mites helped to control excessive fungal growth and pressure drop. The pressure drop of a perlite/fungi/mites filter of 1 m height, loaded with 200 m3 gas/m3 filter/h stabilised around 130 Pa. Biofilters based on the action of fungi are cost-effective for the treatment of waste gases containing aromatic compounds, alkenes and other hydrophobic compounds.

Scattering from Gas-Phase Synthesized Particles

1989 ◽  
Vol 172 ◽  
Author(s):  
Alan J. Hurd
Keyword(s):  
Surface Tension ◽  
Gas Phase ◽  
Fiber Optics ◽  
High Purity ◽  
Rational Design ◽  
High Porosity ◽  
Phase Synthesis ◽  
Shape Distribution ◽  
Design And Optimization ◽  
Fundamental Knowledge

Rational design and optimization for the next generation of fiber optics requires fundamental knowledge of the processes at each step of production [1], not the least of which is the formation and deposition of the glass precursor particles. Currently, gas-phase synthesis dominates the industry, owing, in part, to the high purity possible for gaseous reagents. However, the production engineer has relatively little control over the microstructure of the boule from which the fiber is drawn because many complex mechanisms take part in the growth and thermophoretic deposition of the precursors. Although it is desirable, for example, to obtain a porous boule in order to facilitate the removal of deleterious hydroxyls, connected porosity is by no means guaranteed. The successful attainment of high porosity depends on a number of variables such as the size distribution [2], internal structure, shape distribution, viscosity, and surface tension of the particles at the instant of deposition.

scholarly journals Removal of arsenic from liquid blister copper during remelting in an induction vacuum furnace

2021 ◽  
pp. 33-33
Author(s):  
J. Łabaj ◽  
L. Blacha ◽  
A. Smalcerz ◽  
B. Chmiela
Keyword(s):  
Mass Transfer ◽  
Liquid Metal ◽  
Gas Phase ◽  
Blister Copper ◽  
Vacuum Furnace ◽  
Reduced Pressure ◽  
Liquid Metal Surface ◽  
High Vapor ◽  
Surface Liquid ◽  
Removal Of Arsenic

Using a reduced pressure during the smelting and refining of alloys removes dissolved gasses, as well as impurities with a high vapor pressure. When smelting is carried out in vacuum induction furnaces, the intensification of the discussed processes is achieved by intensive mixing of the bath, as well as an enhanced mass exchange surface (liquid metal surface) due to the formation of a meniscus. This is due to the electromagnetic field applied to the liquid metal. This study reports the removal of arsenic from blister copper via refining in an induction vacuum furnace in the temperature range of 1423-1523 K, at operating pressures from 8 to 1333 Pa. The overall mass transfer coefficient kAs determined from the experimental data ranged from 9.99?10-7 to 1.65?10-5 ms-1. Arsenic elimination was largely controlled by mass transfer in the gas phase. The kinetic analysis indicated that the arsenic evaporation rate was controlled by the combination of both liquid and gas-phase mass transfer only at a pressure of 8 Pa.

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