Calculation of the relative activation energies for reactions forming metal sulfides

1977 ◽  
Vol 12 (2) ◽  
pp. 213-215 ◽  
Author(s):  
Yu. N. Makurin ◽  
V. I. Dvoinin ◽  
G. A. Kitaev
Keyword(s):  
Activation Energies ◽  
Metal Sulfides ◽  
Relative Activation

Scanning Electron Microscope Study of Bacteria on Mineral Surfaces

1976 ◽  
Vol 34 ◽  
pp. 130-131
Author(s):  
V.K. Berry
Keyword(s):  
Oxidation Reaction ◽  
Electron Microscope Study ◽  
Elemental Sulfur ◽  
Thiobacillus Ferrooxidans ◽  
Physical Contact ◽  
Metal Sulfides ◽  
Low Grade ◽  
Mineral Surfaces ◽  
Mineral Surface ◽  
Scanning Electron Microscope Study

There are two strains of bacteria viz. Thiobacillus thiooxidansand Thiobacillus ferrooxidanswidely mentioned to play an important role in the leaching process of low-grade ores. Another strain used in this study is a thermophile and is designated Caldariella .These microorganisms are acidophilic chemosynthetic aerobic autotrophs and are capable of oxidizing many metal sulfides and elemental sulfur to sulfates and Fe2+ to Fe3+. The necessity of physical contact or attachment by bacteria to mineral surfaces during oxidation reaction has not been fairly established so far. Temple and Koehler reported that during oxidation of marcasite T. thiooxidanswere found concentrated on mineral surface. Schaeffer, et al. demonstrated that physical contact or attachment is essential for oxidation of sulfur.

Identification of acid-insoluble filter-plugging compounds and optimal acid-washing procedures for tubular backpulse pressure filters

TAPPI Journal ◽  
2011 ◽  
Vol 10 (1) ◽  
pp. 17-23
Author(s):  
KEVIN TAYLOR ◽  
RICH ADDERLY ◽  
GAVIN BAXTER
Keyword(s):  
Calcium Sulfate ◽  
Membrane Filter ◽  
Sulfamic Acid ◽  
Xrd Analysis ◽  
Metal Sulfides ◽  
X Ray Diffraction ◽  
X Ray ◽  
Gypsum Formation ◽  
Acid Washing ◽  
Hydrolysis Of

Over time, performance of tubular backpulse pressure filters in kraft mills deteriorates, even with regular acid washing. Unscheduled filter replacement due to filter plugging results in significant costs and may result in mill downtime. We identified acid-insoluble filter-plugging materials by scanning electron microscope/energy-dispersion X-ray spectroscopy (SEM/EDS) and X-ray diffraction (XRD) analysis in both polypropylene and Gore-Tex™ membrane filter socks. The major filter-plugging components were calcium sulfate (gypsum), calcium phosphate (hydroxylapatite), aluminosilicate clays, metal sulfides, and carbon. We carried out detailed sample analysis of both the standard acid-washing procedure and a modified procedure. Filter plugging by gypsum and metal sulfides appeared to occur because of the acid-washing procedure. Gypsum formation on the filter resulted from significant hydrolysis of sulfamic acid solution at temperatures greater than 130°F. Modification of the acid-washing procedure greatly reduced the amount of gypsum and addition of a surfactant to the acid reduced wash time and mobilized some of the carbon from the filter. With surfactant, acid washing was 95% complete after 40 min.

Deep level study in epitaxial 4H-SiC grown on substrates inclined toward

2002 ◽  
Vol 719 ◽  
Author(s):  
Masashi Kato ◽  
Masaya Ichimura ◽  
Eisuke Arai ◽  
Shigehiro Nishino
Keyword(s):  
Deep Level Transient Spectroscopy ◽  
Deep Level ◽  
Activation Energies ◽  
Thickness Dependence ◽  
Epitaxial Layers ◽  
Transient Spectroscopy

AbstractEpitaxial layers of 4H-SiC are grown on (0001) substrates inclined toward <1120> and <1100> directions. Defects in these films are characterized by deep level transient spectroscopy (DLTS) in order to clarify the dependence of concentrations and activation energies on substrate inclination. DLTS results show no such dependence on substrate inclination but show thickness dependence of the concentration.

Activation energies of technological termodonors in neutron doped silicon

2015 ◽  
Vol 19 (1/2) ◽  
Author(s):  
L. I. Panasjuk ◽  
V. V. Kolomoets ◽  
V. N. Ermakov ◽  
S. A. Fedosov ◽  
L. V. Yashchynskiy
Keyword(s):  
Activation Energies ◽  
Doped Silicon
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