scholarly journals Selective Leaching of Molybdenum from Bulk Concentrate by Electro-Oxidation

Metals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1904
Author(s):  
Kyeong Woo Chung ◽  
Ho-Sung Yoon ◽  
Chul-Joo Kim ◽  
Ho-Seok Jeon
Keyword(s):  
Current Density ◽  
Ultrasonic Irradiation ◽  
Pulp Density ◽  
Density Current ◽  
Selective Leaching ◽  
Nacl Solution ◽  
Oxidation Method ◽  
Cu Complex ◽  
Electro Oxidation

This paper proposes selective leaching of molybdenum from Mo/Cu complex bulk concentrates in a 5 M NaCl solution using the electro-oxidation method. Here, the effects of several factors such as pH, pulp density, current density, and temperatures were investigated. A higher leaching yield of Mo increased with increasing pH from 5 to 9 and decreased with increasing pulp density from 1 to 10%. A rise in current density did not help enhance Mo, and the elevating temperature did not always result in a higher leaching yield. Application of ultrasonic led to higher leaching yield of Mo. Ninety-two percent of leaching yield was obtained upon leaching of Mo in 5 M NaCl at 25 °C, pulp density of 5%, and the current density of 0.292 A/g under ultrasonic irradiation with a power of 27 kW. The resultant residue mainly consisted of chalcopyrite.

Radial Spreading of Localized Corrosion-Induced Selective Leaching on α-Brass in Dilute NaCl Solution

CORROSION ◽  
10.5006/0611 ◽  
2013 ◽  
Vol 69 (5) ◽  
pp. 468-476 ◽  
Author(s):  
Mattias Forslund ◽  
Christofer Leygraf ◽  
Changjian Lin ◽  
Jinshan Pan
Keyword(s):  
Localized Corrosion ◽  
Selective Leaching ◽  
Nacl Solution ◽  
Radial Spreading

Controlling factors in localised corrosion morphologies observed for magnesium immersed in chloride containing electrolyte

2015 ◽  
Vol 180 ◽  
pp. 313-330 ◽  
Author(s):  
Geraint Williams ◽  
Nick Birbilis ◽  
H. Neil McMurray
Keyword(s):  
Current Density ◽  
Radial Growth ◽  
Cathodic Current Density ◽  
Nacl Solution ◽  
High Concentration ◽  
Cathodic Current ◽  
Density Distributions ◽  
Filiform Corrosion ◽  
Density Values ◽  
Current Densities

The early stages of localised corrosion affecting magnesium (Mg) surfaces when immersed in aqueous sodium chloride (NaCl) solutions involves the propagation of dark regions, within which both anodic metal dissolution and cathodic hydrogen evolution occur. For nominally “pure” Mg, these dark areas can either take the form of discs which expand radially with time, or filiform-like tracks which lengthen with time. For Mg surfaces which display disc-form corrosion features in concentrated NaCl electrolyte, a transition to filiform corrosion (FFC) is observed as the concentration is decreased, indicating ohmic constraints on radial propagation. A similar effect is observed when Mg specimens of different iron impurity are immersed in a fixed, high concentration NaCl solution, where disc-form corrosion is observed on samples having ≥280 ppm Fe, but FFC predominates at ≤80 ppm Fe. An in situ scanning vibrating electrode technique (SVET) is used to determine current density distributions within the propagating corrosion features. Cathodic current density values of between −100 and −150 A m−2 measured in central areas of disc-like features are sufficient to sustain the radial growth of a local anode at the perimeter of the discs. However, for high purity Mg specimens (≤80 ppm Fe), cathodic current densities of −10 A m−2 or less are measured over FFC affected regions, indicating that linear propagation arises when there is insufficient cathodic current produced on the corroded surface to sustain radial growth. The results are consistent with surface control of localised corrosion propagation in concentrated electrolyte, but ohmic control in dilute, lower conductivity NaCl solution.

Electro-oxidation of landfill leachate using boron-doped diamond: role of current density, pH and ions

2019 ◽  
Vol 79 (5) ◽  
pp. 921-928 ◽  
Author(s):  
F. Agustina ◽  
A. Y. Bagastyo ◽  
E. Nurhayati
Keyword(s):  
Current Density ◽  
Organic Content ◽  
Cod Removal ◽  
Boron Doped Diamond ◽  
Leachate Treatment ◽  
Ammonium Removal ◽  
Boron Doped ◽  
Wide Range ◽  
Electro Oxidation

Abstract Electro-oxidation using a boron-doped diamond (BDD) anode can be used as an alternative to leachate treatment. Aside from the hydroxyl radical, BDDs are capable of generating chloride and sulfate radical species that play significant roles in the oxidation of pollutants. This research investigated the role of Cl−:SO42− ions at molar ratios of 237:1, 4:1 and 18:1, and the influence of applied current density (i.e. 50, 75 and 100 mA cm−2) on the removal of organic and ammonium contaminants. The results show that current density had considerable effects on chemical oxygen demand (COD) and colour removal, while ion composition of Cl−:SO42− at pH 3, 5 and 8.5 (original pH) gave different effects on COD and ammonium removal. The pH had a significant effect on the COD removal at the ratio of 237:1, but showed no dramatic effect at the ratio of 18:1, giving ∼40% of COD removal at all pHs tested. This indicates that electro-oxidation at the ratio of 18:1 could be effectively conducted at a wide range of pH. Furthermore, the optimum ammonium removal was obtained at pH 8.5 with the ratio of 237:1. This process was found to be ineffective in increasing the biodegradability index of the leachate; instead, it exhibited mineralization of organic content.

The Application and Research of Electrochemical Method Treating Acid Red 3R Simulation Wastewater by Response Surface Method

2013 ◽  
Vol 295-298 ◽  
pp. 1258-1262
Author(s):  
Jun Sheng Hu ◽  
Lei Guan ◽  
Jia Li Dong ◽  
Ying Wang ◽  
Ying Yong Duan
Keyword(s):  
Response Surface ◽  
Electrochemical Oxidation ◽  
Current Density ◽  
Electrochemical Method ◽  
Electrolyte Concentration ◽  
Ph Value ◽  
Removal Rate ◽  
Oxidation Method ◽  
Surface Method ◽  
Optimal Value

Using electrochemical oxidation method treats the acid red 3R simulation wastewater, investigates the influence of current density, electrolyte concentration, pH-value and aeration and their interaction on the removal rate of chroma. Through the design of Box-Benhnken Design(BBD) and the response surface analysis, the influence sequence of all variables is current density > aeration > electrolyte concentration > pH-value, the influence sequence of all interaction is electrolyte concentration-aeration > current density-aeration ,electrolyte concentration-pH value > current density-pH value > pH value-aeration > current density-electrolyte concentration. Ultimately, the optimal value is 98.4915% under the condition of current density of 6.51mA/cm2,electrolyte concentration of 0.04mol/L,pH-value of 4.17 and aeration of 0.24m3/h.

Electromigration Damage of Flexible Electronic Lines Printed With Ag Nanoparticle Ink

2020 ◽  
Vol 142 (3) ◽  
Author(s):  
Daiki Saito ◽  
Kazuhiko Sasagawa ◽  
Takeshi Moriwaki ◽  
Kazuhiro Fujisaki
Keyword(s):  
Grain Growth ◽  
Current Density ◽  
High Density ◽  
Metal Nanoparticle ◽  
Density Current ◽  
Ag Nanoparticle ◽  
Severe Problem ◽  
Atomic Transport ◽  
Current Loading ◽  
Nanoparticle Ink

Abstract Flexible printed circuits (FPCs) are widely used in electronic equipment such as mobile devices and wearable sensors. The conductive electric lines in these circuits are printed using nanoparticle metal ink and ink-jet direct write methods. Physical characteristics such as flexibility and mechanical durability of metal nanoparticle ink lines have been evaluated by bending or tensile tests. In contrast, the electrical characteristics of these lines have not been sufficiently evaluated, and the failure mechanism under high-density current has not been clarified. When electric devices are scaled down, current density and Joule heating increase in conductive lines and electromigration (EM) damage becomes a severe problem. Therefore, reducing the EM damage is extremely important to enhance the device reliability. In this study, a failure analysis of Ag nanoparticle ink lines were assessed using current loading tests and microscopic observations to discuss the damage mechanism and evaluate electrical reliability under high-density current. Atomic transport due to EM was observed at 60 kA/cm2 current loading, and relatively large aggregates and grain growth were observed at 120 kA/cm2 current loading. The time to open circuit was longer at 120 kA/cm2 than at 60 kA/cm2. The formation of large aggregates and unstable changes in the potential drop were observed at the two values of current density. It is considered that aggregate formation and grain growth affected the atomic transport by EM.

Corrosion Characteristics of Surface-Modified DET Magnesium Powders

2004 ◽  
Vol 449-452 ◽  
pp. 369-372
Author(s):  
W.S. Chung ◽  
W.Y. Yoon ◽  
Kwang Jin Kim
Keyword(s):  
Corrosion Resistance ◽  
Surface Layer ◽  
Current Density ◽  
Nacl Solution ◽  
Composition Distribution ◽  
Passive Behavior ◽  
Modified Surfaces ◽  
Modified Surface ◽  
Surface Modified ◽  
Modified Surface Layer

Magnesium powders having inactive surface layer have been processed easily and intentionally by DET under fluoride, chromate, and bromide salt. The modified surfaces play an important role in preventing contact with active environments to improve corrosion resistance of Magnesium powders; the image of the surface modified powders was observed using SEM. The composition distribution and characteristics was determined and analyzed by using XRD, XPS, and EIS. Compared with bare Magnesium, the Magnesium having chromate modified surface layer showed a more passive behavior such as smaller current density and nobler potential in 4wt% NaCl solution.

Cathodic Protection of Iron In the Temperature Range 25 C-92 C★

CORROSION ◽  
1958 ◽  
Vol 14 (4) ◽  
pp. 54-56 ◽  
Author(s):  
G. R. HOEY ◽  
M. COHEN
Keyword(s):  
Current Density ◽  
Cathodic Protection ◽  
Cathodic Polarization ◽  
Open Circuit ◽  
Cathodic Current Density ◽  
Oxygen Solubility ◽  
Nacl Solution ◽  
Cathodic Current ◽  
Temperature Range ◽  
Higher Temperature

Abstract The cathodic protection of iron was studied in the temperature range 25 C to 92 C. The limiting protective current density and the open circuit cathodic current density for iron in dilute NaCl solution goes through a temperature maximum at roughly 75 C. This is explained in terms of the effect of decreasing oxygen solubility at the higher temperature on the local cathodic reaction, 2H+ + O2 + 4e = 20H- Iron corrodes under cathodic control at room temperature, whereas at the higher temperatures there is a mixed cathodic-anodic control. Cathodic polarization curves for iron in dilute NaCl solution were obtained in the temperature range 25 C to 92 C. Unsteady potentials were observed in the vicinity of the limiting protective current, whereas at higher and lower currents, steady potentials were observed. The current density at which the potential of the iron reaches —0.5 volt on the hydrogen scale gives satisfactory protection. The nature of the corrosion products of iron is unaffected by temperature in the range studied. 5.2.2

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