Selective comminution and grinding mechanisms of spent carbon anode from aluminum electrolysis using ball and rod mills

The overvoltage on the carbon anode in aluminum electrolysis has been measured against a CO2/C reference electrode placed in the cryolite melt. The behavior of the reference electrode was first investigated against the aluminum cathode. This galvanic cell showed a stable potential of 1.15 V, which was close to the reversible potential for the cell reaction in aluminum electrolysis. Similar measurements were made with CO/C and CO2,CO/C electrodes. The potential of the CO/C electrode was in fair agreement with the reversible potential for the most probable cell reaction. The potentials obtained with CO2–CO mixtures were intermediate between those for the pure gases, increasing with increasing CO2 content. An explanation for the behavior of the CO2,CO/C electrode is suggested.The anodic overvoltage depended only to a limited extent on the chemical reactivity of carbon with respect to oxygen. Graphite anodes showed higher overvoltage than all other types of carbon anodes. Catalyzing and inhibiting additives to the carbon had small but significant influences on the overvoltage. Straight Tafel plots were obtained with slopes varying between 0.26 and 0.27. On this basis it is shown that the overvoltage may be due either to slow transport of oxygen ions through the double layer or to slow reaction between chemisorbed oxygen and carbon.

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Anodic Bubble Behavior in a Laboratory Scale Transparent Electrolytic Cell for Aluminum Electrolysis

Metals ◽

10.3390/met8100806 ◽

2018 ◽

Vol 8 (10) ◽

pp. 806 ◽

Cited By ~ 3

Author(s):

Yipeng Huang ◽

Zhaowen Wang ◽

Youjian Yang ◽

Bingliang Gao ◽

Zhongning Shi ◽

...

Keyword(s):

Bubble Dynamics ◽

Aluminum Electrolysis ◽

Electrolytic Cell ◽

Laboratory Scale ◽

Carbon Anode ◽

Electrolysis Cell ◽

Bubble Behavior ◽

Electrolysis Process ◽

Graphite Anodes ◽

Carbon Anodes

In the Hall-Héroult process for extracting aluminum, the evolution and dynamics of anodic bubbles have a significant influence on the efficiency of the overall electrolysis process. In this study, the behavior of the bubbles beneath the carbon anode in cryolite-alumina molten salt was studied for the first time using a laboratory-scale transparent electrolysis cell to view the anode from the bottom. The bubble dynamics and the relevant characteristic parameters of bubbles were obtained using video cameras and image processing. It was found that the bubbles were observed to preferentially generate at several areas on the underside of the anode and the morphologies of coalesced bubbles show excellent similarity. Moreover, the behavior of gas on carbon and graphite anodes was significantly different, where the carbon anode favored the forming of larger bubbles. These observations confirmed different types of carbon anodes cause different bubble behavior. These findings are expected to be useful in optimizing the aluminum electrolysis process on an industrial scale.

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Aluminum Electrolysis Anti-Oxidation Coating Carbon Anode

Light Metals 2012 ◽

10.1007/978-3-319-48179-1_226 ◽

2012 ◽

pp. 1307-1309

Author(s):

Shaohua Yang ◽

Fengli Yang ◽

Lin Wu ◽

Mingzhou Li ◽

Xianwei Hu ◽

...

Keyword(s):

Aluminum Electrolysis ◽

Carbon Anode

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Advances in the Safe Disposal and Comprehensive Utilization of Spent Carbon Anode From Aluminum Electrolysis: Prospects for Extraction and Application of Carbon Resources From Hazardous Waste

Frontiers in Energy Research ◽

10.3389/fenrg.2021.779476 ◽

2021 ◽

Vol 9 ◽

Author(s):

Bin Li ◽

Jun Zhou ◽

Zhen Yao ◽

Qian Peng ◽

Mengnan Liu ◽

...

Keyword(s):

Large Scale ◽

Raw Materials ◽

Aluminum Electrolysis ◽

Carbon Anode ◽

Physical Activation ◽

Fluidized Bed Combustion ◽

Safe Disposal ◽

Comprehensive Utilization ◽

Advantages And Disadvantages ◽

Alkali Fusion

Spent carbon anode (SCA) is a dangerous solid waste that is continuously discharged from the aluminum electrolysis industry and has a large number of valuable resources and a high risk of environmental pollution. Its safe disposal and resource utilization have become a resource and environmental problem that must be solved urgently. Current methods for SCA disposal include flotation, vacuum metallurgy, physical activation, roasting, bubbling fluidized bed combustion, alkali fusion, alkali leaching, and chemical leaching combined with high temperature graphitization. In this paper, the material composition, resource properties, and environmental risks of SCA are discussed. Working principle, treatment process, advantages and disadvantages of the above methods are also briefly described and compared. Results showed that flotation is the safest disposal and comprehensive utilization technology that is suitable for characteristics of SCA raw materials and has the most large-scale application potential. In addition, characteristics of SCA recovery products are correlated to the recycling of aluminum reduction cells. This technology can alleviate the shortage of high-quality petroleum coke resources in China’s carbon material industry and the high cost of raw materials in aluminum electrolysis industry.

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Thiophenic Sulfur Transformation in a Carbon Anode during the Aluminum Electrolysis Process

Energy & Fuels ◽

10.1021/acs.energyfuels.6b03018 ◽

2017 ◽

Vol 31 (4) ◽

pp. 4539-4547 ◽

Cited By ~ 12

Author(s):

Qifan Zhong ◽

Jin Xiao ◽

Haojin Du ◽

Zhen Yao

Keyword(s):

Aluminum Electrolysis ◽

Carbon Anode ◽

Electrolysis Process ◽

Sulfur Transformation

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Analyze the effect of phosphorus on the mechanical properties and microstructure on cast iron

MATEC Web of Conferences ◽

10.1051/matecconf/201820405008 ◽

2018 ◽

Vol 204 ◽

pp. 05008

Author(s):

Achmad Sambas ◽

Ananto Gamawan ◽

Sophiadi Gunara

Keyword(s):

Mechanical Properties ◽

Tensile Strength ◽

Cast Iron ◽

Mechanical Testing ◽

Aluminum Electrolysis ◽

Point Of View ◽

Carbon Anode ◽

Electrolysis Process ◽

Microstructure Observation ◽

Phosphorus Alloy

Cast Iron FC250 with phosphorus alloy is used as electrode connector in the aluminum electrolysis process at PT. Indonesia Asahan Aluminium (Inalum), that is used to connect the rod with carbon anode. It will be crushed after the carbon anode dimension is reduced, that takes approximately 30 days. In order to make crushing process easier, phosphorus alloy then added into such FC250. The objective of the study is determining phosphorus effect on FC 250. The methodology consists of determine the test specimens, initiate such specimen of casting by varying the amount of phosphorus percentage of 0.3%, 0.5%, 0.7% and 0.9%, then perform mechanical testing and microstructure observation on each specimen. The result is, as the percentage of phosphorus in FC 250 increased, so its hardness value whereas the value of the tensile strength even decreased. Form the microstructure point of view, the “steadit” increased as well in line with the rise of phosphorus.

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Influence of Ultrafine Powder on the Properties of Carbon Anode Used in Aluminum Electrolysis

Light Metals 2011 ◽

10.1007/978-3-319-48160-9_193 ◽

2011 ◽

pp. 1143-1147

Author(s):

Xiao Jin ◽

Deng Songyun ◽

Li Jie ◽

Lai Yanqing ◽

Liu Yexiang

Keyword(s):

Aluminum Electrolysis ◽

Ultrafine Powder ◽

Carbon Anode

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Investigating Effects of Different Flue-Wall Deformation Modes on the Performance of Anode Baking Furnaces for Aluminum Electrolysis

Volume 8: Heat Transfer and Thermal Engineering ◽

10.1115/imece2019-10507 ◽

2019 ◽

Author(s):

Abdul Raouf Tajik ◽

Mouna Zaidani ◽

Tariq Shamim ◽

Rashid K. Abu Al-Rub

Keyword(s):

Gas Flow ◽

Aluminum Electrolysis ◽

Deformation Mode ◽

Carbon Anode ◽

Operational Parameters ◽

Aluminum Reduction ◽

Wall Deformation ◽

Anode Temperature ◽

Carbon Anodes ◽

Deformation Modes

Abstract In carbon anode baking furnaces, temperature and quality of carbon anodes are significantly affected by the deformation of the flue-walls, where the flue-gases flow and combustion occur. Flue-walls aging gives rise to non-homogeneous baking of the carbon anodes and results in deterioration of the anode quality, which eventually causes instabilities in aluminum reduction cells and overconsumption of anodes and energy. It is imperative to develop a fully coupled 3D multi-physics computational model which takes into account a large number of physical phenomena that play vital roles in the baking process and are affected by the flue-wall deformation mode. In the present study, the effects of flue-wall deformation modes on flue-wall cavity gas flow and anode temperature distribution are investigated. The pressure and flow distributions for different levels of flue-wall deformation are demonstrated. It is perceived that a 100 mm convex mode of flue-wall deformation leads to under-baking of anodes by almost 20 degC. For the concave mode of deformation, since the packing coke thickness reduces, overbaking of anode occurs. The methodology and results presented in the present research can be employed effectively by the aluminum industry in modifying the furnace geometrical and operational parameters to enhance baking uniformity after flue-wall is deformed.

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