Kinetics Analysis on Process of Direct Smelting and Alloying between High-Carbon Ferrochrome and Molybdenum Oxide

2015 ◽  
Vol 1095 ◽  
pp. 766-769
Author(s):  
Hong Ming Wang ◽  
Yang Li ◽  
Xiao Jian Fan ◽  
Gui Rong Li
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Contact Area ◽  
Reduction Rate ◽  
Phase Contact ◽  
High Carbon ◽  
Dissolved Carbon ◽  
Carbon Ferrochrome ◽  
Direct Smelting ◽  
Co Gas

Based on the direct reduction alloying theory, the kinetics investigations on process of direct smelting and alloying between high-carbon ferrochrome and molybdenum were conducted. The results indicate that at the high temperature MoO3(g) can easily reduced by carbon dissolved in iron liquid. Reducing the volatilization loss of MoO3is the most effective measure to increase the Mo yield. With regard to the reaction between CaMoO4(l) and dissolved carbon at steelmaking temperature, the increases of mass transfer coefficient of CaMoO4in slag and phase contact area between metal and slag make for increasing the reduction rate. CO gas generated from extra carbon acting as reducing agent can provide favorable kinetics conditions for reduction reaction. The reaction between Cr7C3(l) and MoO3(l) in liquid steel is similar to the reaction between CaMoO4(l) and dissolved carbon. The incensement of mass transfer coefficient of MoO3(l) in slag can improve the reduction rate effectively. The CO gas generated from reaction can stir molten bath promote foam slag formation, so as to increase the phase contact area, which provides favorable kinetics condition.

Experiment on Direct Smelting and Alloying Process between High-Carbon Ferrochrome and Molybdenum Oxide

2014 ◽  
Vol 633-634 ◽  
pp. 116-119
Author(s):  
Hong Ming Wang ◽  
Xiao Jian Fan ◽  
Gui Rong Li ◽  
Wei Wen Chen ◽  
Lei Cao ◽  
...  
Keyword(s):  
Molybdenum Oxide ◽  
Direct Reduction ◽  
Reduction Rate ◽  
Melting Process ◽  
Critical Factors ◽  
High Carbon ◽  
Yield Rate ◽  
Carbon Ferrochrome ◽  
Wide Range ◽  
Direct Smelting

Based on the direct reduction alloying theory, experiments on chromium molybdenum alloy prepared through the direct reduction and alloying reactions between the high-carbon ferrochrome and molybdenum oxide were conducted in a laboratory scale. The critical factors that would impact the reduction rate of molybdenum oxide and the yield rate of molybdenum were analyzed. The results indicate that the reduction rate of molybdenum oxide can exceed 90%, meanwhile, the yield rate of molybdenum is affected by many factors and fluctuates in a wide range. As temperature rising, the reduction rate of molybdenum oxide is increased whereas the yield rate of molybdenum is decreased. With the amount of molybdenum oxide added increasing, the reduction rate of molybdenum oxide and yield rate of molybdenum are decreased simultaneously. Making slag during melting process and molybdenum oxide roasted by addition of lime are effective measures to improve the yield rate of molybdenum.

scholarly journals Decarburization of ferrochrome and high alloy steels with optimized gas and slag phases towards improved Cr retention

2013 ◽  
Vol 49 (2) ◽  
pp. 175-181 ◽  
Author(s):  
H. Wang ◽  
M.M. Nzotta ◽  
L. Teng ◽  
S. Seetharaman
Keyword(s):  
Mass Transfer ◽  
Induction Furnace ◽  
Refining Process ◽  
Endothermic Reaction ◽  
High Carbon ◽  
High Alloy ◽  
High Alloy Steel ◽  
Carbon Ferrochrome ◽  
Alloy Steels ◽  
Gas Molecules

Chromium is a high value metal and the retention of the same during the refining of high carbon ferrochrome as well as high alloy steel has significant economic and environmental impacts. The loss of chromium during the decarburization is generally minimized using argon-oxygen mixtures thereby reducing the oxygen partial pressure (PO2) of the oxidant gas. In the current study, experiments were carried out in an induction furnace and CO2 was introduced with the view to partly reduce PO2 and partly as an oxidizer. During these experiments, the decarburization of molten Cr-alloy was conducted using pure O2, pure CO2 or O2+CO2 mixtures. The results demonstrated that the Cr loss can be minimized under CO2 introduction. The kinetic analysis showed that the mass transfer is effective due to the production of 2CO gas molecules from one CO2 molecule during the reaction which will improve the stirring of the bath. Besides, CO2 reacts with carbon in melt is an endothermic reaction, introduction of CO2 could be a cooler during the refining process, hence the temperature could be controlled by controlling the diluting gas amount, in this case, the over heat of bath refractory could be prevented and the lifetime of refractory could be extended.

Absorption of oxygen into solutions of polymers

1986 ◽  
Vol 51 (10) ◽  
pp. 2127-2134 ◽  
Author(s):  
František Potůček ◽  
Jiří Stejskal
Keyword(s):  
Mass Transfer ◽  
Aqueous Solutions ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Flow Rate ◽  
Liquid Flow ◽  
Flow Curve ◽  
Liquid Flow Rate ◽  
Polymer Concentration ◽  
Newtonian Liquids

Absorption of oxygen into water and aqueous solutions of poly(acrylamides) was studied in an absorber with a wetted sphere. The effects of changes in the liquid flow rate and the polymer concentration on the liquid side mass transfer coefficient were examined. The results are expressed by correlations between dimensionless criteria modified for non-Newtonian liquids whose flow curve can be described by the Ostwald-de Waele model.

scholarly journals Development of mass and heat transfer coupled model of hollow fiber membrane for salt recovery from brine via osmotic membrane distillation

2021 ◽  
Vol 33 (1) ◽  
Author(s):  
Sher Ahmad ◽  
Gabriela Vollet Marson ◽  
Waheed Ur Rehman ◽  
Mohammad Younas ◽  
Sarah Farrukh ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Heat And Mass Transfer ◽  
Hollow Fiber ◽  
Hollow Fiber Membrane ◽  
Membrane Distillation ◽  
Fiber Membrane ◽  
Salt Recovery ◽  
Osmotic Solution

Abstract Background In this research work, a coupled heat and mass transfer model was developed for salt recovery from concentrated brine water through an osmotic membrane distillation (OMD) process in a hollow fiber membrane contactor (HFMC).The model was built based on the resistance-in-series concept for water transport across the hydrophobic membrane. The model was adopted to incorporate the effects of polarization layers such as temperature and concentration polarization, as well as viscosity changes during concentration. Results The modeling equations were numerically simulated in MATLAB® and were successfully validated with experimental data from literature with a deviation within the range of 1–5%. The model was then applied to study the effects of key process parameters like feed concentrations, osmotic solution concentration, feed, and osmotic solution flow rates and feed temperature on the overall heat and mass transfer coefficient as well as on water transport flux to improve the process efficiency. The mass balance modeling was applied to calculate the membrane area based on the simulated mass transfer coefficient. Finally, a scale-up for the MD process for salt recovery on an industrial scale was proposed. Conclusions This study highlights the effect of key parameters for salt recovery from wastewater using the membrane distillation process. Further, the applicability of the OMD process for salt recovery on large scale was investigated. Sensitivity analysis was performed to identify the key parameters. From the results of this study, it is concluded that the OMD process can be promising in salt recovery from wastewater.

scholarly journals Hydrodynamics and Mass Transfer in a Concentric Internal Jet-Loop Airlift Bioreactor Equipped with a Deflector

Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4329
Author(s):  
Radek Šulc ◽  
Jan Dymák
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Liquid System ◽  
Gas Holdup ◽  
Gas Velocity ◽  
Liquid Phase Mass Transfer ◽  
Homogenization Time ◽  
Standard Design ◽  
Superficial Gas Velocity

The gas–liquid hydrodynamics and mass transfer were studied in a concentric tube internal jet-loop airlift reactor with a conical bottom. Comparing with a standard design, the gas separator was equipped with an adjustable deflector placed above the riser. The effect of riser superficial gas velocity uSGR on the total gas holdup εGT, homogenization time tH, and overall volumetric liquid-phase mass transfer coefficient kLa was investigated in a laboratory bioreactor, of 300 mm in inner diameter, in a two-phase air–water system and three-phase air–water–PVC–particle system with the volumetric solid fraction of 1% for various deflector clearances. The airlift was operated in the range of riser superficial gas velocity from 0.011 to 0.045 m/s. For the gas–liquid system, when reducing the deflector clearance, the total gas holdup decreased, the homogenization time increased twice compared to the highest deflector clearance tested, and the overall volumetric mass transfer coefficient slightly increased by 10–17%. The presence of a solid phase shortened the homogenization time, especially for lower uSGR and deflector clearance, and reduced the mass transfer coefficient by 15–35%. Compared to the gas–liquid system, the noticeable effect of deflector clearance was found for the kLa coefficient, which was found approx. 20–29% higher for the lowest tested deflector clearance.

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