5,254 research outputs found
GreenCare for Children -- Measuring Environmental Hazards in the Childcare Industry
Presents findings from a two-year survey administered to a random sampling of childcare providers. Developed and interpreted by a diverse team of industry, technical, and educational experts
Production of Silicomanganese Alloy from Low Manganese Containing Leached Sea Nodules Residue
Leached sea nodules residue was used for the present study for exploring its utilization. The residue generated in ammoniacal-SO2 pressure leaching was water washed to reduce the sulphur content. To improve the Mn/Fe ratio in the residue, it was blended with Fe-Mn slag or Mn ore in the calculated amount and smelting was carried out in 50 kVA submerged arc furnace. Various parameters such as holding time, amount of reductant, power input etc. were investigated. The maximum recovery of Mn from residue blended with Fe-Mn slag and Mn ore was 58% and 65% respectively in the form of silicomanganese
Different applications of waste generated in reduction roasting – ammonia leaching of manganese nodules.
CSIR-NML, Jamshedpur has been engaged in technology development to recover valuable metals (Cu, Ni & Co) from manganese nodules (MN). Extensive R&D work led to development of a process based on reduction roast – ammonia leaching – solvent extraction (SX) – electrowining (EW) route. This process generates large amount of waste/residue (70% of the MN weight) after selective leaching of Cu, Co and Ni, which may be considered hazardous, if untreated, due to its fineness and heavy metal contents. Characterisation studies have shown that this leaching residue waste contains oxides/oxyhydroxides of Fe, Mn, Al and Si with a high porosity and surface area, which are suitable for catalytic activity and adsorption of various aqueous pollutants. In addition, appreciable amount of manganese content of the manganese nodule leached waste may be recovered for the improvement of the economics of MN processing. Keeping these in view, studies for utilisation of waste leach residue have been carried out in three different ways:
i) The use of leaching residue as catalyst has been successfully assessed for decolourisation of methylene blue (MB). The surface complex between wMNR and MB at a rate limiting step followed by electron transfer from MB to active metal centre of wMNR and release of products has been found to be operative during the decolourisation process.
ii) The potential of water washed leaching residue as adsorbent has been evaluated for removal of anionic pollutants phosphate (PO43-), selenite (SeO32-) and cationic pollutants like Cu2+ and Cd2+, showing a maximum phosphate uptake of 9.88 mgP g-1 and selenite uptake of 15.17 mg Se g-1 for wMNR calcined at 400 C. The monolayer adsorption capacities (Qo) has been found to be temperature dependent showing 26.95 mg g-1 and 40.32 mg g-1 at 303 and 323 K, respectively for Cu2+ ion while the values are 32.23 and 38.14 mg g-1 at 303 and 323 K, respectively for Cd2+ adsorption.
iii) In the third application of leached residue, a value added material like silicomanganese alloy has been produced by smelting of MN leaching waste in a 50 kVA electric arc furnace, with manganese recovery of about 77%
Thermodynamics and Viscosity aspects in Manganese Nodule Residue Smelting for Silicomanganese Production
Among several under trial processes for extraction of base metals (Cu, Co and Ni) from manganese nodules (M79, the reduction-roast ammoniacal leaching {N1140H/ (NH4)2CO3) process is considered very attractive. After the leaching of base metals from roast-reduced MN, a substantial quan-tity of residue left behind (about 70 wt. % by mass) as wastes for disposal or further use. Smelting studies showed that leached manganese nodules residue (WMNR) can be successfully utilized as raw material for silicomangan-ese production after maintaining proper metallurgical aspects like thermodynamics, viscosity etc Literature survey on slag liquidus and viscosity aspects of silicoman-ganese smelting has been done. The slag liquidus has been found to be closely associated to slag basicity i.e. (Ca0+-MgO/S102) showing significant increase above a 7 slag basicity. Charge mix basicity of 0.2 was found to give maximum Mn and Si recoveries. Increasing or decreasing charge basicty from 0 2 resulted in lower metallic yield and Mn and Si recoveries. This has been explained with liquidus calculations of final slags obtained at those charge mix basicities. Addition of CaF2 during holding time i.e. time given after complete melting of charge mix was found to be beneficial. The optimum amount of CaF2 was 4% of WMNR+Mn ore blend, which gave rise to maximum Mn and Si recoveries and metallic yield. Further addition of CaF2 (4%) produced a high basicity slag (basicity =a 83) having very high liquidus leading to decrease in metallic yield and Mn and Si recoveries
Lead sorption by sea nodule residue generated in reduction roasting – ammonia leaching.
Residue generated in reduction roast – ammonia leaching of sea nodules has been utilised for the remediation of aqueous lead. Characterization of sea nodule residue (SNR) reveals fine granulometry (d50 = 11.4 µm) and high surface area of 66.7 m2 g-1. Batch adsorption experiments have been performed varying different parameters. Equilibrium experimental data fitted well in the Langmuir isotherm and derived maximum adsorption capacity (qm) of lead onto SNR has been found to be 840.34 mg Pb(II)/g SNR at 303 K. The qm enhanced to very high value of 2500 mgPb/gSNR upon raising the temperature to 323 K. The pseudo second-order model has been found applicable to the lead removal kinetics
Sorption characteristics of aqueous copper onto residue generated in ammoniacal leaching of manganese nodules
The present paper reports the studies on copper removal from its aqueous solution using residue generated in the process of reduction roast- ammonia leaching of manganese nodules. The leached residue was washed with water to remove the entrapped liquor containing metals from leaching operation, dried and used for adsorption of aqueous Cu(II) under varying experimental conditions. The particle size analyses of manganese nodule residue (wMNR) showed very fine particles with mean diameters (d50) of 17.8 µm. The BET surface area of wMNR was found to be 66.7 m2g-1. Adsorption studies of copper aqueous solution by batch equilibrium method indicated that the equilibrium was attained within 4 h. The percentage of Cu(II) adsorption increased with increase of leached residue dose but decreased with increase of initial Cu(II) concentrations. The adsorption was found to be dependent on initial pH of Cu(II) solution, which increased with increase in initial pH. During uptake of Cu(II), various metal ions, especially Mn and Fe, were found to be released from leached residue, which decreased with increase of pH. Pseudo second-order kinetics was applicable for the Cu(II) adsorption. Adsorption data were satisfactorily fitted to the Langmuir isotherms. The maximum adsorption capacity determined by Langmuir isotherm was found to be 26.95 mg g-1 at pH 5.5 and 303 K. Thus the leach residue found to be useful for removal of heavy metal like copper from the industrial effluent
Transient Free Convection in a Vertical Channel with Variable Temperature and Mass Diffusion
Effects of thermal radiation and constant mass diffusion on the transient laminar free convective flow in a vertical channel with have been analyzed. The exact solutions of the governing equations have been obtained by using the Laplace transform technique. The influences of the parameters on the velocity field, temperature distribution, concentration in the fluid, shear stress, rate of heat and mass transfers have been presented either graphically . It is seen that the velocity and temperature fields decrease with an increase in radiation parameter. On the other hand, the rate of heat transfer at the plate  decreases with an increase in either radiation parameter or Prandtl number. Further, the shear stress at the plate  increases with an increase in either radiation parameter or thermal Grashof number or mass Grashof number. Keywords: MHD flow, Transient Free convection, thermal Grashof number, mass Grashof number, thermal radiation, Heat transfer, and Mass transfer
Hall effects on unsteady MHD natural convective flow past an impulsively moving plate with ramped temperature and concentration
517-534This paper deals with the study of an unsteady magnetohydrodynamic natural convective flow of a viscous incompressible electrically conducting fluid past an impulsively moving infinite vertical plate with ramped temperature and mass concentration taken into account the Hall effects. A uniform magnetic field is applied transversely to the direction of the flow. The flow consideration is subjected to small magnetic Reynolds number. Induced magnetic field is absent. The Rosseland approximation is used to describe the radiative heat flux in the energy equation. Analytical solution of the governing equations has been obtained by employing the Laplace transform technique. The influences of the pertinent parameters on the velocity field, temperature distribution, mass concentration in fluid, shear stress and rate of heat and mass transfer are discussed with the help of graphs. Hall current is found to elevate the fluid velocity components. It is observed that significant difference can be observed between the velocity profiles due to ramped and isothermal boundary conditions
Making standard grade FeSiMn alloy by blending of different low grade materials.
NML has developed a process for extraction of Cu, Ni, & Co from sea nodules by reduction roast - ammonia leaching - solvent extraction - electrowinning route on pilot scale. This process generates leach liquor (Cu, Ni & Co) and a fine residue having low Mn/Fe ratio (not suitable for direct silicomanganese smelting). The utilization of huge quantity of leached residue is therefore, a matter of great concern. Development of another process of direct smelting of sea nodules in arc furnace to separate Cu, Ni & Co in alloy is being carried out which generates Mn rich slag with high Mn/Fe ratio. In this endeavor these two low Mn containing materials are blended to have suitable Mn/Fe ratio and smelted in 50 KVA DC arc furnace to produce standard grade FeSiMn alloy
Post-TTM Rebound Pyrexia after Ischemia-Reperfusion Injury Results in Sterile Inflammation and Apoptosis in Cardiomyocytes
Introduction. Fever is frequently observed after acute ischemic events and is associated with poor outcome and higher mortality.
Targeted temperature management (TTM) is recommended for neuroprotection in comatose cardiac arrest survivors, but
pyrexia after rewarming is proven to be detrimental in clinical trials. However, the cellular mechanisms and kinetics of post-
TTM rebound pyrexia remain to be elucidated. Therefore, we investigated the effects of cooling and post-TTM pyrexia on the
inflammatory response and apoptosis in a cardiomyocyte ischemia-reperfusion (IR) injury model. Methods. HL-1
cardiomyocytes were divided into the following groups to investigate the effect of oxygen-glucose deprivation/reperfusion
(OGD/R), hypothermia (33.5°C), and pyrexia (40°C): normoxia controls maintained at 37°C and warmed to 40°C, OGD/R
groups maintained at 37°C and cooled to 33.5°C for 24 h with rewarming to 37°C, and OGD/R pyrexia groups further warmed
from 37 to 40°C. Caspase-3 and RBM3 were assessed by Western blot and TNF-α, IL-6, IL-1β, SOCS3, iNOS, and RBM3
transcriptions by RT-qPCR. Results. OGD-induced oxidative stress (iNOS) in cardiomyocytes was attenuated post-TTM by
cooling. Cytokine transcriptions were suppressed by OGD, while reperfusion induced significant TNF-α transcription that was
exacerbated by cooling. Significant inductions of TNF-α, IL-6, IL-1β, and SOCS3 were observed in noncooled, but not in cooled
and rewarmed, OGD/R-injured cardiomyocytes. Further warming to pyrexia induced a sterile inflammatory response in
OGD/R-injured groups that was attenuated by previous cooling, but no inflammation was observed in pyrexic normoxia groups.
Moreover, cytoprotective RBM3 expression was induced by cooling but suppressed by pyrexia, correlating with apoptotic
caspase-3 activation. Conclusion. Our findings show that maintaining a period of post-TTM “therapeutic normothermia” is
effective in preventing secondary apoptosis-driven myocardial cell death, thus minimizing the infarct area and further release of
mediators of the innate sterile inflammatory response after acute IR injury
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