Volatilization of MgO from Ludwigite in Carbothermal Reduction-Nitridation Process

2011 ◽  
Vol 295-297 ◽  
pp. 31-35
Author(s):  
Ran Liu ◽  
Yong Liang Gao ◽  
Xing Juan Wang ◽  
Qing Lu ◽  
Xiang Xin Xue
Keyword(s):  
Mass Loss ◽  
Carbothermal Reduction ◽  
Loss Rate ◽  
Tube Wall ◽  
Mass Loss Rate ◽  
Experimental Result ◽  
Total Mass Loss ◽  
Nitridation Process ◽  
Result Show ◽  
Furnace Tube

Based on thermodynamic analysis, the reduction and volatilization of magnesium in ludwigite were studied using carbothermal reduction-nitridation method. The experimental result show that the total mass loss rate of samples increase with temperature rising, which the maximum is 52.88 wt% in the range from 1440°C to 1470°C. Magnesia in ludwigite was reduced and volatilized as gaseous magnesium vapour in the process of carbothermal reduction, and its mass loss rate go up to 98.138%. Part of the volatilized matter formed white powder deposited at the opening of furnace tube and adhered to tube wall together with boride/silicon volatilized. It was proved that there is volatilization of MgO from ludwigite in the process of carbothermal reduction-nitridation.

scholarly journals A new mass-loss rate prescription for red supergiants

2020 ◽  
Vol 492 (4) ◽  
pp. 5994-6006 ◽  
Author(s):  
Emma R Beasor ◽  
Ben Davies ◽  
Nathan Smith ◽  
Jacco Th van Loon ◽  
Robert D Gehrz ◽  
...  
Keyword(s):  
Mass Loss ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Substantial Effect ◽  
Evolutionary Models ◽  
Total Mass Loss ◽  
Red Supergiants ◽  
Current Mass ◽  
The Impact ◽  
Loss Rates

ABSTRACT Evolutionary models have shown the substantial effect that strong mass-loss rates ($\dot{M}$s) can have on the fate of massive stars. Red supergiant (RSG) mass-loss is poorly understood theoretically, and so stellar models rely on purely empirical $\dot{M}$–luminosity relations to calculate evolution. Empirical prescriptions usually scale with luminosity and effective temperature, but $\dot{M}$ should also depend on the current mass and hence the surface gravity of the star, yielding more than one possible $\dot{M}$ for the same position on the Hertzsprung–Russell diagram. One can solve this degeneracy by measuring $\dot{M}$ for RSGs that reside in clusters, where age and initial mass (Minit) are known. In this paper we derive $\dot{M}$ values and luminosities for RSGs in two clusters, NGC 2004 and RSGC1. Using newly derived Minit measurements, we combine the results with those of clusters with a range of ages and derive an Minit-dependent $\dot{M}$ prescription. When comparing this new prescription to the treatment of mass-loss currently implemented in evolutionary models, we find models drastically overpredict the total mass-loss, by up to a factor of 20. Importantly, the most massive RSGs experience the largest downward revision in their mass-loss rates, drastically changing the impact of wind mass-loss on their evolution. Our results suggest that for most initial masses of RSG progenitors, quiescent mass-loss during the RSG phase is not effective at removing a significant fraction of the H-envelope prior to core-collapse, and we discuss the implications of this for stellar evolution and observations of SNe and SN progenitors.

Study on Mass Loss of Ludwigite in the Process of Carbothermal Reduction

2012 ◽  
Vol 487 ◽  
pp. 15-19
Author(s):  
Ran Liu ◽  
Xing Juan Wang ◽  
Yong Liang Gao ◽  
Qing Lu ◽  
Xiang Xin Xue
Keyword(s):  
Mass Loss ◽  
Carbon Content ◽  
Carbothermal Reduction ◽  
Loss Rate ◽  
Orthogonal Experiment ◽  
Mass Loss Rate ◽  
Influential Factor ◽  
Raw Material ◽  
Reduction Temperature ◽  
Magnesium Vapor

Using ludwigite as raw material, mass loss of ludwigite on the procedure of carbothermal reduction was studied. The effects of reduction temperature, carbon content, holding time were investigated by orthogonal experiment. Reduction temperature was the most influential factor for affecting the mass loss of ludwigite. The experimental results showed that the mass loss rate of samples increases with rising temperature, of which the maximum is 52.6wt% in the range from 1410°C to 1470°C. Mass loss rate of magnesia in ludwigite went up to 98.0% because it was reduced as gaseous magnesium vapor in the process of carbothermal reduction. The main phase of the reduction product was Fe2B, FeB and SiC. The paper can provide significant references for selective separation of valuable elements form ludwigite.

scholarly journals Glacier Variations at Xinqingfeng and Malan Ice Caps in the Inner Tibetan Plateau Since 1970

2020 ◽  
Vol 12 (3) ◽  
pp. 421
Author(s):  
Zhen Zhang ◽  
Shiyin Liu ◽  
Zongli Jiang ◽  
Donghui Shangguan ◽  
Junfeng Wei ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Mass Loss ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Glacier Area ◽  
Srtm Dem ◽  
The West ◽  
Ice Caps ◽  
Total Mass Loss ◽  
Observation Period

The inner Tibetan Plateau is a glacierized region where glaciers show heterogeneous change. The Xinqingfeng and Malan ice caps are located in this region, and a transition zone exists with shifting influences between the westerlies and Indian summer monsoon. However, there is a lack of detailed information regarding glacier area and mass changes in this region before 2000. In the present study, we describe an integrated view of the glacier area and its mass changes for Mt. Xinqingfeng and Mt. Malan as derived from topographic maps, Landsat, ASTER, SRTM DEM, and TerraSAR-X/TanDEM-X from 1970 to 2012 and from 1970 to 2018, respectively. Our results show that the glaciers experienced a slight shrinkage in area by 0.09 ± 0.03% a−1 from 1970 to 2018 with a median mass loss rate of 0.22 ± 0.17 m w.e. a−1 and 0.29 ± 0.17 m w.e. a−1 between 1999 and 2012 at Mt. Xinqingfeng and Mt. Malan, respectively. The glaciers of Mt. Malan had a total mass loss of 0.19 ± 0.14 m w.e. a−1 during the period 1970–1999. A minimum of seven glaciers at Mt. Xinqingfeng and Mt. Malan showed heterogeneous variations with either surging or advancing during the observation period. Among them, the West Monuomaha Glacier, Monuomaha Glacier, and Zu Glacier were identified as surging glaciers, and the others may also be surging glaciers, although more evidence is required. These glaciers showed a long active period and low velocities. Therefore, we suggested that thermal controls are important for surge initiation and recession.

scholarly journals An Experimental Investigation for Seepage-Induced Instability of Confined Broken Mudstones with Consideration of Mass Loss

Geofluids ◽  
2017 ◽  
Vol 2017 ◽  
pp. 1-12 ◽  
Author(s):  
Luzhen Wang ◽  
Zhanqing Chen ◽  
Hailing Kong
Keyword(s):  
Pressure Gradient ◽  
Mass Loss ◽  
Loss Rate ◽  
Progressive Failure ◽  
Mass Loss Rate ◽  
Failure Process ◽  
Testing System ◽  
Pressure Gradients ◽  
Total Mass Loss ◽  
General Mass

To study and prevent water-mud-outburst disasters of tectonic fracture zones in geotechnical engineering, we tested seepage stability of confined broken mudstones with consideration of mass loss using syringe seepage method and a self-designed seepage testing system, obtained the variation laws of seepage instable duration, total mass loss, and mass loss rate of broken mudstones under different pressure gradients and Talbol power exponents (simplified as Talbol hereafter), and explained their instable seepage behaviors. The results showed that the mass loss is the internal cause of seepage-induced instability of broken rocks and pressure gradient is the external cause, and the persistent migration and loss of particles result in progressive failure process, while the large enough pressure gradient causes sudden overall instability. The seepage instable duration shortens with pressure gradient increasing, with the longest and shortest duration at Talbol of 0.5 and 0.1, respectively. In general, mass loss increases with pressure gradient increasing and with Talbol decreasing. Mass loss rate increases with pressure gradient increasing but shows no monotonic changes with Talbol. Their expressions can be used to establish dynamic model in the further seepage stability researches.

scholarly journals SN 2009ip: CONSTRAINTS ON THE PROGENITOR MASS-LOSS RATE

2013 ◽  
Vol 768 (1) ◽  
pp. 47 ◽  
Author(s):  
E. O. Ofek ◽  
L. Lin ◽  
C. Kouveliotou ◽  
G. Younes ◽  
E. Göğüş ◽  
...  
Keyword(s):  
Mass Loss ◽  
Loss Rate ◽  
Mass Loss Rate

Effect of Sample Width on Downward Flame Spread over Typical Energy Conservation Material at a High Elevation Area

2014 ◽  
Vol 664 ◽  
pp. 199-203 ◽  
Author(s):  
Wei Guang An ◽  
Lin Jiang ◽  
Jin Hua Sun ◽  
K.M. Liew
Keyword(s):  
Mass Loss ◽  
Flame Spread ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
High Elevation ◽  
Flame Height ◽  
Spread Rate ◽  
Flame Spread Rate ◽  
Sample Width ◽  
Downward Flame Spread

An experimental study on downward flame spread over extruded polystyrene (XPS) foam at a high elevation is presented. The flame shape, flame height, mass loss rate and flame spread rate were measured. The influences of width and high altitude were investigated. The flame fronts are approximately horizontal. Both the intensity of flame pulsation and the average flame height increase with the rise of sample width. The flame spread rate first drops and then rises with an increase in width. The average flame height, mass loss rate and flame spread rate at the higher elevation is smaller than that at a low elevation, which demonstrates that the XPS fire risk at the higher elevation area is lower. The experimental results agree well with the theoretical analysis. This work is vital to the fire safety design of building energy conservation system.

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