scholarly journals Selective Recovery of Tellurium from the Tellurium-Bearing Sodium Carbonate Slag by Sodium Sulfide Leaching Followed by Cyclone Electrowinning

Metals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1176
Author(s):  
Zhipeng Xu ◽  
Zoujiang Li ◽  
Dong Li ◽  
Xueyi Guo ◽  
Ying Yang ◽  
...  
Keyword(s):  
Energy Consumption ◽  
Current Efficiency ◽  
Sodium Carbonate ◽  
Flow Rate ◽  
Current Density ◽  
Sodium Sulfide ◽  
Cell Voltage ◽  
Promising Alternative ◽  
Selective Recovery ◽  
Solid Ratio

The rigorous environmental requirements promote the development of new processes with short and clean technical routes for recycling tellurium from tellurium-bearing sodium carbonate slag. In this paper, a novel process for selective recovery of tellurium from the sodium carbonate slag by sodium sulfide leaching, followed by cyclone electrowinning, was proposed. 88% of tellurium was selectively extracted in 40 g/L Na2S solution at 50 °C for 60 min with a liquid to solid ratio of 8:1 mL/g, while antimony, lead and bismuth were enriched in the leaching residue. Tellurium in the leach liquor was efficiently electrodeposited by cyclone electrowinning without purification. The effects of current density, temperature and flow rate of the electrolyte on current efficiency, tellurium recovery, cell voltage, energy consumption, surface morphology, and crystallographic orientations were systematically investigated. 91.81% of current efficiency and 95.47% of tellurium recovery were achieved at current density of 80 A/m2, electrolyte temperature of 45 °C and electrolyte flow rate of 400 L/h. The energy consumption was as low as 1.81 kWh/kg. A total of 99.38% purity of compact tellurium deposits were obtained. Therefore, the proposed process may serve as a promising alternative for recovering tellurium from tellurium-bearing sodium carbonate slag.

Metal Instabilities and its Effect on Cell Performance during Aluminium Smelting

2013 ◽  
Vol 828 ◽  
pp. 45-54 ◽  
Author(s):  
Anupam Agnihotri ◽  
Shail Umakant Pathak ◽  
Jyoti Mukhopadhyay
Keyword(s):  
Energy Consumption ◽  
Current Efficiency ◽  
Cell Voltage ◽  
Aluminum Electrolysis ◽  
Cell Performance ◽  
Consumption Pattern ◽  
Magnetic Current ◽  
Zero Current ◽  
Aluminium Smelting ◽  
Rolling Noise

The Hall-Heroult process for the production of aluminium is based on the electrochemical reduction of alumina (Al2O3) dissolved in a cryolite (Na3AlF6) based electrolyte. Instability in cell voltage is referred to as noise. Normal voltage noise is inevitable due to bubble evolution and it has little effect on performance parameters such as, current efficiency and power consumption. Metal rolling noise (wavy noise) is caused by the disturbances in cell magnetic field and it affects the cell current efficiency adversely. Investigating the causes of the cell instability in the aluminium smelting cells can lead to better cell performance. Understanding the variation in cell voltage is critical for cells, because magnitude of voltage determines the energy consumption pattern in the process and hence, any saving on voltage can save energy. Voltage affects the current efficiency of the cell and an optimum cell voltage leads to higher current efficiency without compromising on energy consumption. Magnetic, current distribution, heat loss and voltage at zero current measurements along with online current and voltage signal can help to identify the problems and their combined effects on the performance of the cells. In order to estimate the loss in current efficiency of the aluminum electrolysis cells due to metal instabilities, measurements were performed and data analyzed. The present paper analyses the effect of voltage fluctuations (noise) during metal instability along with cause of instability and its effect on current efficiency of the cell. Measurements carried out to estimate the deviations from the normal cell operations are also discussed.

scholarly journals INVESTIGATION OF ELECTROCHEMICAL COLOR REMOVAL FROM ORGANIZED INDUSTRIAL DISTRICT (OID) WASTEWATER TREATMENT PLANTS USING NEW GENERATION Sn/Sb/Ni-Ti ANODES

2018 ◽  
Vol 21 (2) ◽  
pp. 106-112
Keyword(s):  
Energy Consumption ◽  
Current Efficiency ◽  
Current Density ◽  
Wastewater Treatment Plants ◽  
Salt Content ◽  
Color Removal ◽  
Ozone Production ◽  
Ambient Conditions ◽  
Operational Parameters ◽  
Oxidation Efficiency

<p>In this study, the application of Sn/Sb/Ni-Ti electrodes for the treatment of waste streams were investigated which is promising for ozone production by electrolysis of water because of their stability and high potential for ozone evolution reaction. These series of anodes have a high electrochemical ozone generation potential at ambient conditions (approximately up to 40% current efficiency). But using and testing of these novel anodes for real wastewater are too limited in the literature. Titanium mesh substrate coated with Sn/Sb/Ni-Ti alloy was used as anode immersed in wastewater at room temperature with platinized titanium cathode. These electrodes used for COD and color removal from OID wastewater in Inegol, Bursa, Turkey. Five operational parameters were evaluated for electrochemical COD and color removal processes, such as pH, salt content, applied voltage/current, current efficiency and contact time. Experimental results showed that after 30 min the electrochemical oxidation efficiency of COD and color could reach up to 98% and 99% respectively at pH 8.2 and temperature of 25°C as the optimum conditions. Current density observed as the most effective parameter for COD and color removal efficiencies. The lowest energy consumption was between 10-25 mA cm-2 of current density with only 0.6 kWh gCOD−1, while the highest energy consumption was 100 mA cm-2 of current density with 9.12 kWh gCOD−1 . The optimum current density value has been found as 50 mA cm-2 with 4.05 kWh gCOD−1 . These results were also supported with ANOVA test.</p>

scholarly journals The Optimum Electrolyte Parameters in the Application of High Current Density Silver Electrorefining

Metals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1596
Author(s):  
Arif T. Aji ◽  
Jari Aromaa ◽  
Mari Lundström
Keyword(s):  
Energy Consumption ◽  
Current Density ◽  
Specific Energy ◽  
Composition Range ◽  
High Current Density ◽  
Specific Energy Consumption ◽  
Production Capacity ◽  
Cell Voltage ◽  
Process Efficiency ◽  
High Current

Increasing silver production rate has been a challenge for the existing refining facilities. The application of high current density (HCD) as one of the possible solutions to increase the process throughput is also expected to reduce both energy consumption and process inventory. From the recently-developed models of silver electrorefining, this study simulated the optimum electrolyte parameters to optimize the specific energy consumption (SEC) and the silver inventory in the electrolyte for an HCD application. It was found that by using [Cu2+] in electrolyte, both objectives can be achieved. The suggested optimum composition range from this study was [Ag+] 100–150 g/dm3, [HNO3] 5 g/dm3, and [Cu2+] 50–75 g/dm3. HCD application (1000 A/m2) in these electrolyte conditions result in cell voltage of 2.7–3.2 V and SEC of 0.60–1.01 kWh/kg, with silver inventory in electrolyte of 26–39 kg silver for 100 kg per day basis. The corresponding figures for the conventional process were 1.5–2.8 V, 0.44–0.76 kWh/kg, and 15.54–194.25 kg, in respective order. These results show that, while HCD increases SEC by app. 30%, the improvement provides a significant smaller footprint as a result of a more compact of process. Thus, applying HCD in silver electrorefining offers the best solution in increasing production capacity and process efficiency.

Preparation of CMC-PVA/PAN-FePc(COOH)8/CS-PVA Bipolar Membrane and its Application in Electro-Oxidized Synthesis of Dialdehydle Starch

2015 ◽  
Vol 1120-1121 ◽  
pp. 141-147
Author(s):  
Zhong Gui Li ◽  
Ting Jin Zhou ◽  
Ri Yao Chen ◽  
Xiao Chen ◽  
Xi Zheng ◽  
...  
Keyword(s):  
Polyvinyl Alcohol ◽  
Current Efficiency ◽  
Current Density ◽  
Cell Voltage ◽  
Contact Angle Measurement ◽  
Angle Measurement ◽  
Experimental Results ◽  
Bipolar Membrane ◽  
Electrospinning Technique ◽  
A Current

The polyacrylonitrile (PAN)-iron octocarboxyphthalocyanine (FePc(COOH)8) nanofibers were prepared using electrospinning technique and introduced into the interlayer of a carboxymethyl cellulose (CMC)-polyvinyl alcohol (PVA)/chitosan (CS)-polyvinyl alcohol bipolar membrane (BPM), which was characterized using SEM, contact angle measurement, current-voltage characteristics, AC impedance spectroscopy and so on. The experimental results showed that after modification by PAN-FePc(COOH)8 nanofibers, the membrane impedance of the BPM and its cell voltage were decreased. That indicated that the water splitting efficiency in the interlayer of the BPM was increased. Then the prepared CMC-PVA/PAN-FePc(COOH)8/CS-PVA BPM was used in the electro-oxidized preparation of dialdehydle starch (DAS). The experimental results indicated that a current density of 20mA·cm-2 was suitable to obtain high current efficiency. When the electrolysis time was 3h at a current density of 20 mA·cm-2 , the current efficiency of the CMC-PVA/PAN-FePc(COOH)8/CS-PVA BPM-equipped cell was as high as 67%.

Current Efficiency and Energy Consumption of Electrochemical Oxidation for Ammonia Removal from Coking Wastewater Using Boron-Doped Diamond Electrodes

2013 ◽  
Vol 295-298 ◽  
pp. 1327-1332 ◽  
Author(s):  
Chun Rong Wang ◽  
Sha Chang ◽  
Min Ye ◽  
Qin Yi Ren
Keyword(s):  
Energy Consumption ◽  
Current Efficiency ◽  
Current Density ◽  
Chloride Concentration ◽  
Chloride Ion ◽  
Ammonia Removal ◽  
Ion Concentration ◽  
Coking Wastewater ◽  
Concentration Increase ◽  
Density Decrease

The electrochemical treatment of ammonia using born-doped diamond (BDD) as advanced treatment of coking wastewater was investigated. The effects of chloride ion concentration and current density on current efficiency and energy consumption were also analyzed. The results show that the current efficiency increases with chloride ion concentration increase and current density decrease. And 30% of current efficiency is obtained when current density is less than 19.7mA cm-2, and it decreases above 19.7mA cm-2. The energy consumption decreases with the chloride ion concentration increase and current density decrease. And energy consumption of 0.50kWh g-1 and ammonia removal rate of 84.7% can be achieved at initial ammonia concentration of 100mg L-1, chloride concentration of 900mg L-1 and current density of 29.6mA cm-2.Therefore, BDD electrodes have high current efficiency and low energy consumption, which attributed to its high oxygen evolution overvoltage (2.6V vs. SCE) and low chloride evolution overvoltage (1.5V vs. SCE).

Electro-Crystallization of Antimony from Acidic and Alkaline Baths in Diaphragm-Less Cell

2013 ◽  
Vol 828 ◽  
pp. 65-72 ◽  
Author(s):  
Chinmaya Kumar Sarangi ◽  
Ayonbala Baral ◽  
Jayasmita Panigrahi ◽  
Kali Sanjay ◽  
Tondepu Subbaiah ◽  
...  
Keyword(s):  
Energy Consumption ◽  
Current Efficiency ◽  
Current Density ◽  
Cathodic Current ◽  
Antimony Concentration ◽  
Morphological Studies ◽  
Alkaline Bath ◽  
Alkaline Baths ◽  
Acidic Bath

Studies based on electrocrystallization of antimony were carried out to evaluate the effects of current density and antimony concentration in the electrolytic bath on cathodic current efficiency, energy consumption, and quality of the deposits during electrowinning of antimony from Sb2O3-HCl and Sb2S3-NaOH systems. In acidic bath, current efficiency for electrodeposition of antimony increases with the increase in current density till 150 A/m2, beyond which it follows a trend of gradual diminution. On varying antimony concentration in the bath, current efficiency was found to improve significantly and the optimum antimony concentration in Sb2O3-HCl system was evaluated to be about 60 g/L. In alkaline bath, current efficiency was observed to be maximum at 50 A/m2and further, with the increase in current density it progressively decreases. However, energy consumption for electrowinning of antimony in both of the baths gradually increases with the increase in current density. At a current density less than 150 A/m2, alkaline bath was found to be more current efficient in comparison to the acidic bath. Crystallographic studies by XRD, imaging by optical microscopic technique and morphological studies by SEM were also carried out to differentiate antimony deposits obtained from acidic and alkaline baths.

scholarly journals A novel gradient current density output mode for effective electrochemical oxidative degradation of dye wastewater by boron-doped diamond (BDD) anode

2020 ◽  
Vol 82 (10) ◽  
pp. 2085-2097
Author(s):  
Ting Liu ◽  
Dongtian Miao ◽  
Guoshuai Liu ◽  
Qiuping Wei ◽  
Kechao Zhou ◽  
...  
Keyword(s):  
Energy Consumption ◽  
Current Efficiency ◽  
Current Density ◽  
High Energy ◽  
Molecular Structures ◽  
Constant Current ◽  
Dye Wastewater ◽  
Output Process ◽  
Boron Doped Diamond ◽  
General Applicability

Abstract In order to solve the problems of high energy consumption and low current efficiency in electrochemical oxidation (EO) degradation under the traditional constant output process (COP), a gradient output process (GOP) of current density is proposed in this paper. That is, the current density is gradually reduced in a fixed degradation time, and the Reactive Blue 19 simulated dye wastewater was used as the degradation target. The general applicability of the process was further confirmed by studying the optimal gradient current density output parameters, the dye concentration, electrolyte concentration and other dye compounds with different molecular structures. The corresponding results show that the chemical oxygen demand (COD) removal (78%) and the color removal (100%) under the GOP are similar to those in the COP, and the overall energy consumption is reduced by about 50% compared with that in the traditional constant current mode. Moreover, the current efficiency in the middle and late stages of EO process has increased by 8.6 times compared with COP.

Recovery of Heavy Metal from Scrap Metal Pickling Wastewater by Electrolysis

1993 ◽  
Vol 28 (7) ◽  
pp. 223-229 ◽  
Author(s):  
Ju-Sheng Huang ◽  
I-Chung Lee ◽  
Biing-Jauh Lin
Keyword(s):  
Energy Consumption ◽  
Current Efficiency ◽  
Deposition Rate ◽  
Current Density ◽  
Specific Energy ◽  
Specific Energy Consumption ◽  
Copper Ion ◽  
Surface Loading ◽  
Electro Deposition ◽  
Continuous Flow Reactors

When the influent surface loading of copper ion in the four-stage continuous-flow reactors of electrolysis were controlled at 143.9, 94.0, 52.7 and 33.2 mg/min-dm2, respectively, and current density were controlled at 3.9, 2.6, 1.3 and 1.3A/dm2, respectively, the concentration of copper decreased from 13,900 to l,900mg/l (i.e., the electro-deposition rate of copper were 2,700, 2,240, 1,500 and 750 mg/dm2-h, respectively). The purity of copper depositing on the cathode reached over 98%. When the current density was ranged from 1.3 to 3.9A/dm2, the electro-deposition rate of copper increased with the increasing current density. However, when the current density was raised above 5.2 A/dm2, the electro-deposition rate of copper decreased with the increasing current density. The increase of current density decreased the current efficiency and increased the specific energy consumption. The increase of influent surface loading of copper ion increased the current efficiency and decreased the specific energy consumption.

scholarly journals Removal of Cadmium from Simulated Wastewaters Using a Fixed Bed Bio-electrochemical Reactor

2020 ◽  
Vol 26 (12) ◽  
pp. 110-130
Author(s):  
Duaa R. Saad ◽  
Ziad T. Alismaeel ◽  
Ali H. Abbar
Keyword(s):  
Energy Consumption ◽  
Current Efficiency ◽  
Removal Efficiency ◽  
Applied Voltage ◽  
Ph Value ◽  
Fixed Bed ◽  
Cell Voltage ◽  
Packed Bed ◽  
Electrochemical Reactor ◽  
Operating Conditions

In this research, the removal of cadmium (Cd) from simulated wastewater was investigated by using a fixed bed bio-electrochemical reactor. The effects of the main controlling factors on the performance of the removal process such as applied cell voltage, initial Cd concentration, pH of the catholyte, and the mesh number of the cathode were investigated. The results showed that the applied cell voltage had the main impact on the removal efficiency of cadmium where increasing the applied voltage led to higher removal efficiency. Meanwhile increasing the applied voltage was found to be given lower current efficiency and higher energy consumption.  No significant effect of initial Cd concentration on the removal efficiency of cadmium but increasing the initial concentration would be given higher current efficiency and lower energy consumption. The results established that using a pH value lower than three results in a sharp decrease in the removal efficiency as well as  using a pH value higher than seven results in decreasing the removal efficiency. Using a mesh number higher than 30 gave a lower removal efficiency. The best operating conditions were found to be an applied potential of 1.8 V, an initial Cd concentration of 125 ppm, and a pH of 7. Under these operating conditions with the using a stack of stainless with mesh number 30 as a packed bed cathode, a complete removal efficiency of Cd(100%)  was obtained at a current efficiency of 83.57% and energy consumption of 0.57 kWh/kg Cd.

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