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Product promotion for Shandong Chenyang Carbon Co., Ltd Product promotion for Shandong Chenyang Carbon Co., Ltd
Research & Development of Low-consumption Carbon in Aluminum
Industry
Yu Yiru
Company profile
Project R&D
Project effectiveness
ContentContent
Basic theory
Experimental study
Technology evaluation
Industrial application test
Shandong Chenyang Carbon Co., Ltd established in 1987, is the largest wholly-owned
subsidiary of Jining Carbon Group Co., Ltd and is one of the national high-tech enterprises in
China. It has the R&D base for the production and technology of carbon anode used for
aluminum electrolysis, with output of carbon anode 500,000tpy. It is the leading enterprise in
the industry carbon used for aluminum electrolysis in China, the syndic units of China
Nonferrous Metals Industry Association and CHINALCO; the member of The National
Nonferrous Standardization Technical Committee; the vice-president unit of Carbon Branch;
Postdoctoral innovation experimental base of Wuhan University of Science and Technology;
Standard R&D demonstration base of carbon used for aluminum electrolysis; and it owns the
state-certified carbon testing laboratory and provincial enterprise technology center. It has
firstly passed the ISO9000 Quality Management System Certification, ISO14000 Environment
Management System Certification and OHSAS18000 Occupational Safety and Health
Management System Certification. The company with international reputation of the industry
was awarded as the Shandong Technological Innovation Enterprise, National High-tech
Enterprise and Shandong Star Enterprise of China’s Patent.
Company profileCompany profile
The company has always focused on the experiment & research of technology of carbon anode
used for aluminum electrolysis; tracking and being responsible for drafting the national and
industrial standards for a long term and conducting technical cooperation with scientific
research institutions at home and abroad. By cooperating with universities and employing
experts from home and abroad for technical guidance, with the bringing in, learning and re-
innovation, the company studied the new techniques of carbon anode used for aluminum
electrolysis, improved the performances of carbon anode continuously and then realized the
carbon creating perfectly from carbon producing. The company creates values for customers
by providing technology and services, and promotes the energy saving, consumption
reduction, emission reduction, benefits increase effectively in electrolytic aluminum
production, which improve the production technology of carbon anode, strengthen the
improvement of technology of carbon used for aluminum electrolysis and lead to the
continuous development of the whole industry.
Company profileCompany profile
The company has become the model of comprehensive utilization and circular economy. The
scientific and technological achievements of waste gas utilization and cogeneration founded the
beginning of the industry. For recent years, the company has achieved 10+ National Invention
Patents, 20+ utility model patents and 30+ innovations; it has drafted 30+ standards and 100+
papers as well. The company has compiled a series of professional publication “Carbon anode
production technology”, translated and publicly published many professional publications
including ”The technology of carbon anode used for aluminum electrolysis” , which have
promoted the carbon anode production technology progress in China.
During the period of 13th Five Year Plan, the company will make greater contributions to the
industry development and technology progress based on the principles of energy saving &
environmental protection, circular economy and sustainable development, to speed up the
pace of new carbon material series product R&D and industrialization.
Company profileCompany profile
Carbon anode, a material for making aluminum electrolysis, is hailed as the heart for
electronic tank, playing an important role of breakover in the whole process. The
carbon consumption is 334kg / t-A1 in theory while in practice it betweens 480—
530Kg/t-A1. The extra carbon
consumption is for overconsumption or just residuals. The reason that the process
consumed more carbon is related with the cell condition, temperature of electrolysis,
the shape of carbon anode, the quality and residual hardness. More anode consumed,
more electrolysis carbon discharged and it will undercut the electric current efficiency,
increase fuel consumption and CO2 emission which are bound to push up the
production cost.
Project developmentProject development
The project starts with influencing factors of carbon anode’s electrolysis
consumption in the tank, effect of the raw material nature and production parameter
setting. In addition, developing new technique, increasing pitch wetting and
adhesiveness for the carbon anode grain, enhancing thermal shock resistance of carbon
anode, improving roasting curve, decreasing reactivity of carbon anode and selective
oxidation, cutting slags discharge, boosting anti-oxidation performance, lowering
secondary reaction and extra consumption are all the goals the project intends to
achieve.
The project made huge contributions to the electrolytic aluminium industry concerning
energy saving, consumption cut, emission reduction and efficiency improvement.
Project overviewProject overview
• Shape of electric tank/ anode size
• Current efficiency• Electrolyte temperature• Carbon anode fluting• Anode quality
Reactivity of CO2 Air reactive Thermal conduction
Basic theoryBasic theory
• 1. Electrochemical consumption (electrolytic reaction)
2 Al 2 O 3 + 3 C = 4 Al + 3 CO 2
• 2. Chemical consumption
Chemical consumption which includes CO2 and air reactions is not only a
major factor that causes anode overload, but also an evaluation indicator for
carbon anode quality and performance.
CO2 reaction : C + CO2 = 2CO
Air reaction : C + O2 = CO2
• 3. Mechanical consumption
The mechanical consumption is partly due to the selective oxidation of
carbon anode. Because the carbon anode is anisotropic body, the reaction
first occurs in active points, and isolates the weak activated charcoal
granules, making them falling off into the electrolytic cell to form carbon
residue. The poor thermal shock resistance of carbon anode is another
cause. During electrolysis, carbon anode may fall off or broke as a result of
the arris defect, chip off-falling, fragmentation or even fracture.
Electrical consumption of carbon anodeElectrical consumption of carbon anode
In the electrolytic cell, the oxidation reaction mainly occurs on the top of the anode
which is exposed to the air and the lateral surface where the temperature is 400~600 . This ℃
reaction is not only associated with the quality of carbon anode, but also with the actual
operation during electrolysis, for example, the anode will be oxidized if the cell temperature is
too high, or the coverage of carbon anode isn’t good. And this kind of consumption accounts
for about 5%~10% of the total consumption. The reaction is as follows:
≤713℃
C + O2 CO2
> 713℃ 2C + O2 2CO
The chemical consumption of carbon anode: air reactionThe chemical consumption of carbon anode: air reaction
In the process of electrolysis, the composition of primary anode gas is almost pure
CO2, but the actual anode gas contains only 70% ~ 80% CO2, while the rest is CO,
which is no doubt the product of secondary reaction or even higher level reaction. CO2,
which is a primary reaction product, will precipitate on anode bottom palm, making
carbon anode surrounded by CO2, and the following reaction is bound to occur:
CO2 + C 2CO
This reaction is endothermic reaction, which occurs mainly on carbon anode where the
temperature is over 900 . With electrolytic process going on, carbon anode erosion ℃
which is caused by CO2 is becoming more and more serious, and the reaction occurs not
only on the surface of the carbon anode, but also deep into the internal anode 5 ~ 10cm.
This reaction does great harm to carbon anode, and makes up 2%-10% of the total
anode consumption.
The chemical consumption of carbon anode: CO2 reaction The chemical consumption of carbon anode: CO2 reaction
Oxidation resistance of anode is poor
Oxidation slag off
Increase carbon consumption of electrolysis
Oxidation slag off
Anode pressure drop rise, heating, promoting oxidation
Decrease conductive area
Increase electric current density
Increase the contents of electrolyte carbon slag
Resistance increases and voltage rise
High energy consumption, heat cells , instable of cells condition
Carbon slag accumulated and gathered at the bottom of anode
Isolate aluminaCause sudden effect, high energy consumption and instable of cells condition
Carbon slag accumulated and gathered
Anode has lumps, short circuit of the two poles, voltage swing, partial overheat
Reduce current efficiency and increase power consumption
The impact of anode carbon slag to electrolysis productionThe impact of anode carbon slag to electrolysis production
• Decrease bubble layer of anode bottom, reducing pressure drop of anode
• Enhance electrolyte movement in order to help alumina dissolve
• Decrease turbulent fluctuation of electrolyte causing by bubble and reduce
the surface metal vibration of electrolytic cell in order to reduce the noise
of electrolytic cell
After carbon anode slotting The resistance of the bubble may be reduced from 200-300mv to
10-100mV
Longitudinal slot is the center of material preparation for oblique
electrolytic cell, thus electrolyte can blend batter and alumina can
get better melting.
Carbon anode slottingCarbon anode slotting
Dense degree Dense degree
Mechanical strength Mechanical strength
Pore conditionsPore conditions
ConductivityConductivity
Heat-conducting property
Heat-conducting property
Cover material conditions
Cover material conditions
Electrolytic operation
Electrolytic operation
Chemical purity
Chemical purity
Chemical activity
Chemical activity
Chemical property of carbon anode
Electrolytic cell environment
Influence factors of carbon anode electrical consumptionInfluence factors of carbon anode electrical consumption
Thermal fieldThermal field
Magnetic fieldMagnetic field
Electrolyzing temperature
Electrolyzing temperature
Physical property of carbon anode
Based on experimental studies, production tooling control is improved; production
process parameters are optimized; petroleum coke blending scheme is tested;
production formula is studied; performance of asphalt wetting is promoted; baking curve
is optimized; technologies like reducing carbon anode reactions are improved;
performance of anodic anti-oxidation is enhanced; hardness of residual anode is
improved to reduce the anode electrolytic consumption.
Technical AssessmentTechnical Assessment
Industrial tests show that the carbon anode with low consumptions developed by the company is active in resistance to air and CO2 erosions, contains less carbon residues, performs well in hardness of residual anode and regularity and can withstand high current density with low consumption rate for electrolysis. The extension of one day for such kind of carbon anode can reduce 0.35-0.4 replacement period for anode. One ton of aluminum can lower carbon consumption by 15kg in electrolytic process and CO2 emissions from electrolytic aluminum by about 55Kg/t-Al, which is in accordance with the requirements of low carbon industrial policies and environmental protections, promoting the development of carbon anode technology in aluminum production and electrolytic aluminum industry.
Project resultsProject results
1. Low electrolytic consumption rate can prolong the life cycle by one day
More than 90% residues are left after the interaction between carbon anode of low consumption
with air and CO2 respectivity. Such carbon anode of low consumption performs excellently in
resistance to air and CO2 erosions with high inoxidizability and the consumption rate is better
than that of other common anodes.
Based on the same consumptions, its life cycle can be prolonged by one day. (0.4—0.6 mm/d)
2. The hardness of residual anode is better with high regularity
Low consumption carbon anode is powerful in resistance to air and CO2 erosions with no
oxidation dregs, blocks and anode pieces and etc. It belongs to hard residual anode with well
performance in shocking and washing and high regularity, which can withstand high power
currents and is favorable for the electrolytic operations with high currents.
3. The carbon consumption is low in the electrolytic process with less carbon residues.
Carbon anode of low consumption bears high inoxidizability and low chemical consumption and
the life cycle can be prolonged by one day with carbon consumption reduced by 15kg in
electrolytic process. In addition, it is also lower in selective oxidation with less carbon residues.
Project resultsProject results
1. Lower carbon consumption, lower production cost
Low consumption carbon anode could reduce 15kg carbon consumption for every ton of electrolytic
aluminum, indicating direct economic benefit of 3,000tpy of carbon anode consumption reduction for
a 200,000tpy electrolytic aluminum plant, which would certainly lower the production costs.
2. Less carbon slag, lower fluoride salt consumption
Low consumption carbon anode features with a high anti-oxidization property, a low selective
oxidization property and generates less carbon slag, which could not only reduce the fluoride salt lose
in the carbon slag filtering process (according to test, carbon slag contains 60-70% of electrolyte) but
also let out less pollutants.
3. Larger current density, more yields
The hardness of anode scrap endows it with high resistance against erosion and corrosion, as well as
good regularity, so that it could bear larger current density, which will strengthen the current and raise
the output of electrolytic aluminum.
Economic benefits Economic benefits
1. Lower labour intensity
Low consumption carbon anode requires 0.35-0.4 times fewer of anode
replacement frequency, indicating a 3,000-piece reduction of anode replacement
every year for a 200,000tpy electrolytic aluminum plant. Also, as it produces less
carbon slag, the difficulty of carbon slag processing has also been weakened.
2. Less heat lose and less pollution gas discharge
Low consumption carbon anode could effectively avoid the heat lose in anode
replacement and the discharge of fluorides and dust, which could reduce the
energy consumption and the air pollution of the process.
3. Less emission of Co2
Low consumption carbon anode could reduce 15kg carbon consumption and
55kg of Co2 gas emission for every ton of electrolytic aluminum, which will help
reduce the Greenhouse Effect.
C + O2 = CO2
44×15÷12=55 kg/tAl
C + O2 = CO2
44×15÷12=55 kg/tAl
Social benefitsSocial benefits
Research prospectResearch prospect
Taking the development of carbon industry as our own duty, base on the
development requirement of electrolytic aluminum production, Chenyang will conduct
deeper research and experiments, further develop the technology of low consumption
carbon anode for electrolytic aluminum use, produce more “green” products of low
carbon consumption, and make more contribution for the advance of aluminum use
carbon production technology and the development of the aluminum industry.