Review of the Development of Aluminum electrolysis Technology in China in the past 40 years (part two) Electrolytic Aluminum-- the brilliant Road of Scientific and technological Innovation

IX. From 320kA to 400kAmuri-leapfrogging towards the whole world

The success of the 280kA super-large aluminum reduction cell test in the national large-scale aluminum test base makes China a country with extra-large aluminum reduction cell technology above 280kA after Alcoa and French Aluminum in the world. Its birth is known as a milestone in the development of aluminum electrolysis technology in China, which provides a strong technical guarantee for the rapid development of China's aluminum electrolysis industry.

Jin Baoqing, chairman of Jiaozuo Wanfang Aluminum Co., Ltd., is acutely aware of the great significance of 280kA electrolytic cell technology to the development of electrolytic aluminum industry. The entrepreneur, who came from a military background and dared to be the first to eat crabs, almost started successfully in the experimental trough. Taking advantage of the favorable conditions of being in a favorable time and place, he was the first to reach an agreement with the Nonferrous Corporation to obtain the right to use the first technology with a technology use fee of 5 million yuan. Unfortunately, this is also the only electrolytic series that is industrially produced with the current capacity of the test cell 280kA, and it is also the only company that provides technology royalties. In 1998, "Jiaozuo Wanfang 68000 t / a 280kA Aluminum electrolysis demonstration Project" was listed as a key project of the State Economic and Trade Commission. Guiyang Institute undertook the engineering design and successfully built and put into production. "Jiaozuo Wanfang"-from then on, it has become a new benchmark in the industry!

However, the technological progress of electrolytic aluminum has not stopped there, and the new record of "Jiaozuo Wanfang" has been constantly refreshed in just a few years.

Experience of pingguo aluminum 320. Although the 280kA test cell has been successful and has been promoted to industrial application, the speed of large-scale electrolytic cell is still accelerating in the world at that time. The AP28 of French aluminum has been developed into an AP30, with an actual operating current that exceeds that of 300kA.

Must surpass the international level! This is a complex of the older generation of aluminum experts.

In the late 1980s, Kang Yi, then director of Qingtongxia Aluminum Plant, and Yang Shijie, deputy director of Guizhou Aluminum Plant, went with a delegation to a large country in the western aluminum industry to participate in training and study. During this period, Kangyi and other students asked to visit the most advanced 320kA electrolysis test cell newly developed in the country. The host smiled mysteriously and agreed that up to five people could visit. They took the cadets to one end of a workshop, then to a crane, pointed to the hazy distance and said, "there's OK,!" Called a visit, it is actually a blockade, which is like a sharp sword deeply pierced into the hearts of Kang Yi and Yang Shijie. After thinking for a long time, Kang Yi said to Yang Shijie, "Lao Yang, we must fight for this breath!" Surpass them! " Yang Shijie nodded silently. The responsibility of developing electrolytic cells above 300kA level and climbing the peak of aluminum electrolysis in the world is always on the heart of that generation of "electrolytic people".

In 1997, pingguo aluminum successfully achieved the goal of reaching the production standard in two years, and the development of 280kA super-large tank has been successful. Yang Shijie, then general manager of pingguo Aluminum, and Yin Ensheng, deputy general manager, thought that the conditions for developing aluminum reduction cells above 300kA were ripe. In July, Yang Shijie went to Beijing to give a special report to Professor Kang Yi, who has served as deputy general manager of Nonferrous Metals Corporation (transferred to deputy director of the State Administration of Nonferrous Metals Industry in April 1998), and received Kang Yi's approval.

In September 1998, the State Economic and Trade Commission key technological innovation project "pingguo Aluminum 320kA Super large Aluminum reduction Cell Technology demonstration Project", which was personally promoted by Deputy Director Kang Yi, was implemented. The capacity determined in the initial plan was 300kA, and later adjusted to 320kA. The project is jointly undertaken by pingguo Aluminum Company and Guiyang Hospital. The six-point power supply mode is adopted in the busbar design. at the same time, the tank condition diagnosis and process parameter control are equipped with expert decision intelligent support system, and the alumina concentration distribution adopts fuzzy control technology. In June 1999, all 30 electrolytic cells were completed and started, and it took only 9 months from design to completion.

Experimental accident. However, the design of 320kA electrolytic cell is not a simple geometric magnification of 280kA electrolytic cell, the biggest problem is the simulation of electromagnetic field. The voltage of the first batch of 10 electrolytic cells swings violently, the aluminum liquid fluctuates frequently and the range is large, and the situation is very unstable. What shall I do? Continue or abort? At the same time, there were serious differences between Yang Shijie and Yin Ensheng, two old classmates, good friends and good partners of Guizhou Institute of Technology. Yang Shijie, as general manager, believes that the whole line must be put into production as scheduled, otherwise it will not be able to explain to the state! But Yin Ensheng, as a senior aluminum electrolysis expert, firmly opposes: the magnetic field problem is the innate gene of the electrolytic cell, and once it is put into production, it will no longer be changed, so we must find out the reason and solve it thoroughly.

This incident shocked the Guiyang Hospital, the chief design officer, Weng Wencheng, the former chief engineer of the Guiyang Hospital, and actively suggested to the leaders of the hospital: the author should take the lead in organizing a key research team and work out a solution as soon as possible. The leading group of the institute conducted a serious study, and at that time, the vice president in charge of the scientific research work of the institute, on behalf of the group, found the author: this matter is of great importance, please be sure to take part in it, and everyone trusts you. Otherwise, Guiyang courtyard can't live with people!

However, what is done is done, how to solve it? I'm not sure.

In order to ensure the solution of the problem, pingguo Aluminum also organized an inspection team led by Yin Ensheng to inspect Alcoa (Alcoa). Five days later, the inspection team also received a reply: a similar situation has occurred abroad, which has led to interruptions in the development of large slots, but it is inconvenient to provide technical details. Later, according to public data, Alcoa 280kA slot after the completion of two series in the 1980s, due to electromagnetic field problems can not be solved, never used again.

Successfully resolved. After carefully checking the simulation data and design scheme of the electrolytic cell, the cause of the problem was found after 8 days: the distance between the two workshops of the experimental workshop was only 21m, and the compensation for its influence and ferromagnetic material was insufficient during the design; at the same time, due to the 44 anode scheme adopted in the 320kA electrolytic cell, the lack of certain modulus and rules led to the congenital deficiency of electromagnetic characteristics. The transformation plan was submitted to the technical committee of the hospital for discussion on the same day and was unanimously approved.

All personnel at the construction site were ready and a medical rescue team was sent at the same time. Under the condition of non-stop production, after the construction units 11 smelter and 7 smelter construction personnel work hard, the transformation is successful! It should be said that we are lucky.

As a matter of fact, the Technical Committee of Guiyang Hospital had serious differences when it discussed the 320kA plan. Part of the opinion is that we have solved the problem of electromagnetic field, so there is no need to worry. When we started to transform 160kA, it was proved that there were no problems in 180kA and 280kA. However, problems that should not have arisen have emerged unexpectedly.

From April to August 2000, 8 test tanks and 30 test tanks were tested, and the main technical indexes obtained are: current intensity 322.456kA, current efficiency 95.04% (average 94.43% of 30 sets), DC power consumption 13191kWh/tAl (30 sets of average 13323kWh/tAl), which has reached the international advanced level as a whole.

At the appraisal meeting, Academician Liu Yexiang, head of the expert group, said: "the successful development and application of 320kA super large aluminum reduction cell technology indicates that China's aluminum reduction cell technology has a complete scientific system, which makes China's aluminum electrolysis technology leap to a new level." Professor Kang Yi, deputy director of the State Administration of Nonferrous Metals Industry, said with mixed feelings: "320kA electrolytic cell is the direction of the development of modern aluminum electrolysis, and its successful development has made it exciting for China's aluminum electrolysis industry to take the lead in the new century, and greatly boost the aspirations of the Chinese people!"

Summing up the successful experience of the 320 test, the issue of anode "modulus" was raised for the first time. Most experts of the Technical Committee of Guiyang Hospital believed that it was necessary to re-recognize the importance of anode modulus optimization and electromagnetic field simulation of electrolytic cells. Master Yao Shihuan later clearly emphasized that the application of the later 320kA electrolyzer in Henan Zhongfu Industrial Co., Ltd. (Zhongfu Industrial Co., Ltd.) was further optimized and perfected. It has become the main cell type of aluminum electrolysis industry in China.

Shenyang Hospital is developing rapidly. Since the mid-1990s, Shenyang Institute has taken the lead in introducing the internationally renowned numerical analysis software ANSYS, led by Yang Xiaodong and others, to complete the simulation design of Henan Xinwang 160kA four-point entry electrolysis tank in 1996, which has achieved good results and attracted national attention. Then, the major design institutes have purchased ANSYS one after another. The introduction of this powerful simulation tool further strengthens the physical field simulation of the electrolytic cell. at the same time, it also confirms the reliability of the simulation software developed by our country, combined with our research for more than 20 years. A large number of reliable boundary conditions have been mastered. Through the cross-application and mutual verification of the two kinds of software in the design work, the pace of the development of large-scale aluminum reduction cell is accelerated. The new electrolytic cell which is constantly updated and improved is directly applied to the series production.

With the successful development of super-large electrolytic cell, the development of aluminum electrolysis industry has undergone fundamental changes. In 2001, the 200000 ton / year 300kA electrolysis series designed by Shenyang Institute of Yichuan Electric Power Group was completed in only one year, which created a historical record of reaching the production capacity of electrolytic aluminum engineering construction. In 2002, Henan Zhongfu Industrial Co., Ltd. started the annual output of 250000 tons / year, and the 320kA electrolysis series improved by Guiyang Institute started construction. In the same year, under the leadership of Vice President he Zhihui, Guiyang Institute exported 320kA electrolytic cell technology to India and signed the largest export order for electrolytic aluminum technology in history. The basic structures of these two types of cells follow the 280kA model, and then aluminum electrolysis technology began to export to the international market on a large scale. At the same time, the pace of large-scale electrolytic aluminum technology in China is still moving forward.

Industrialization of 350kA large trough. On the basis of joint investigation and investigation, Shenyang Aluminum-magnesium Design and Research Institute and Henan Shenhuo Group Co., Ltd. adopted 156sets of 350kA super large aluminum electrolysis series new technology in April 2002. the construction of a large-scale aluminum electrolysis project with an annual output of 140000 was approved. Led by chief engineer Yang Xiaodong, the first phase was officially launched on August 16, 2004. The operation of the electrolytic cell is normal, the production is stable, the current efficiency reaches 94.15%, and the DC power consumption is 13474 kWh per ton of aluminum. The comprehensive technology has reached the international advanced level, which indicates that China's electrolytic aluminum technology has the strength to participate in the world competition. It has important demonstration significance and promotion value to improve the overall level of China's aluminum industry. It lays a foundation for the formation of SY series electrolytic cell technology in Shenyang Institute.

At the same time, Guiyang Hospital designed and built 350kA aluminum electrolysis series in Qingtongxia Aluminum Plant. The industrial application of 350kA aluminum reduction cell has promoted the large-scale technology of aluminum electrolysis in China to a new height. The "350kA extra-large pre-baked anode aluminum electrolysis cell development" completed by Yang Xiaodong and Li Mengzhen won the second prize of national scientific and technological progress in 2007.

The appraisal committee pointed out that the 350kA aluminum reduction cell has the following characteristics and innovation: first, the magnetic field optimization design is carried out by using the asymmetrical 6-terminal power input bus to make the cell run smoothly; second, by using the new design method of "system heat balance", which combines the thermal balance simulation of the electrolytic cell body with the ventilation simulation of the factory building, a good thermal balance of the electrolytic cell and ventilation design effect of the factory building are obtained. Third, the narrow processing surface, the addition of heat sink in the tank shell and the structure of large spacing cradle are adopted, and the good results of low material consumption, compact structure, small deformation of the tank shell and stable thermal working conditions are obtained, and the fourth is to develop the three-stage smoke exhaust technology. it is beneficial to improve the gas collection efficiency and improve the environment.

The current breaks 400kA for the first time. After that, Shenyang Institute successfully applied 350kA electrolytic cell technology to the new series of Lanzhou Aluminum Plant. The enhanced current test was carried out on 16 electrolytic cells. Using 30% graphite cathode carbon block, the current was raised to 403kA for the first time under the condition of anode current density 0.82A/cm2, and it was started in May 2007. after 10 months of operation, the current efficiency reached 94.16%, ton aluminum DC power consumption 13263kWh/tAl. And passed the appraisal of scientific and technological achievements on March 21, 2008.

The first 400kA series production line was born-the rise of the East Courtyard. Since March 2007, Zhongfu Industrial Technology Center and the Design and Research Institute of Northeastern University (East Courtyard) carried out joint design. On the basis of the improvement test of 320kA electrolytic cell, the design and construction of 400kA aluminum electrolysis production line with a capacity of 240000 tons / year began. After seven months of technical research and design, the 400kA prototype electrolytic cell was successfully developed, which was completed and started successfully on August 18, 2008. The new production line adopts a number of new technologies: the anode size is the same as that of the 320kA electrolytic cell, and the number of anodes is 48 groups, and through the accurate physical field simulation design, the 6-point feed bus configuration mode is adopted, and the electromagnetic field compensation bus structure of "end strong compensation, bottom asymmetric weak compensation" is created for the first time, which makes the electrolytic cell obtain superior magnetohydrodynamic stability. On the basis of accurate simulation of electrothermal characteristics, the lining structure designs a "compressible structure", which effectively prolongs the life of the slot, and designs a new truss load-bearing beam structure on the groove, which not only meets the strength and stiffness requirements of the long-span structure, but also reduces the amount of steel by 30%. In the new gas collecting structure of the upper part of the cell, when changing the anode, shelling or aluminum, the electrolytic cell is equipped with a double-exhaust smoke collection system to ensure that the leaked gas can be reduced to the maximum extent, and the gas collection efficiency can be increased to more than 99%. It is the first 400kA aluminum electrolysis industrial production line in the world.

Using 400kA to build the world's first electrolytic aluminum production line was a very bold decision at that time. Since the controlling shareholder of Zhongfu Industry is Russian investor-controlled Vimetco (headquartered in Amsterdam, the Netherlands, a London-listed company), the company specially hired Sam, a former aluminum electrolysis expert from Kaiser Aluminum of the United States. Marattana and Pierre, the former technical manager of Pechiney, act as technical consultants and CEO of the company. As there was no successful experience of a 400kA industrial production line in the world at that time, the international team of experts hired by Vimetco raised objections on the selection of electrolytic cells and did not agree with the technical proposal put forward by the Chinese side to adopt 400kA electrolytic cells. On the basis of a great deal of scientific research and careful design, the Chinese team pushed forward the implementation of the project while constantly persuading the major shareholders and their team of experts. At the beginning of 2008, the author and Chairman Zhang Hongen personally went to Amsterdam to report to the Vimetco board of directors, introducing a large number of scientific basis and practical experience that China has gained. In the end, on the premise that Chairman Zhang Hongen guaranteed with honor and agreed to his board of directors to appoint international experts to review the design plan, the board of directors conditionally approved the plan.

The story of Urata. In June 2008, when the production line was about to be completed, Vimetco hired an American expert, Professor N.Urata, on the recommendation of Mr. Sam, to review the Chinese technical plan. Urata is a famous physical field simulation expert in the world. As early as 1970s, he put forward the famous electromagnetic stability equation of aluminum reduction cell-Urata equation, which was widely recognized and quoted. Entrusted by the Chinese team, the author received Mr. Urata at the Zhongfu Industrial Construction headquarters. Urata comes straight to the point: "I am entrusted by major shareholders to analyze and evaluate the physical field of your 400kA electrolytic cell. Please provide all the calculation data and drawings." In the face of this prestigious aluminum senior, this is a dilemma: if given, it means that all our technical achievements will be mastered by others free of charge; if not, it will mean that if there are any problems in the future project, we must bear full responsibility in the face of major shareholders, and we will lose an opportunity to learn from the international community. The chairman only said one sentence: I know you can handle it! The author said to Mr. Urata with regret: "I know that you are a world-class leader in the simulation of aluminum electrolysis physical field, and my colleagues and I admire you very much, but because of technical confidentiality, I cannot provide the information you want." Mr. Urata said angrily, "Mr. Liang, I have learned about your achievements in this area." But don't you think the interests of the company and the risks of this project are much more important than your personal honor? " . I understand the old gentleman's feelings, and I feel ashamed of his sincerity. In order to live up to the old man's wishes, I said: "I believe you, although I can not provide you with the detailed information and drawings you want, but I can provide you with the schematics you need for simulation, and I hope you can give me sincere guidance." The old man said with regret, "well, then I can finish my task."

Two months later, although the author did not see Mr. Urata's detailed report, but got a reply from Vimetco headquarters: Mr. Urata has no objection, the project can be put into production on schedule!

After the 400kA electrolytic cell is put into production, the production operation condition is good, and the working voltage of the cell is kept at 3.93V / m3.95V. After the adjustment of technical conditions, the DC power consumption per ton of aluminum is less than 12800kWhh, the anode effect coefficient is less than 0.05and the current efficiency is more than 93%. The effect of environmental protection has also been further improved. The project won the first prize of China Nonferrous Metals Science and Technology.

In 2009, in the electrolytic aluminum technology and environmental protection project implemented by APP in seven Asia-Pacific countries, the Light Metal Research Center of the University of Auckland in New Zealand tested the cell's stability: it can maintain a high degree of stability even when the working voltage is 3.6V, which proves that the reliability of the cell's electromagnetic field design is beyond imagination, creating conditions for low-voltage operation.

The innovation alliance was established. In September 2008, led by Zhongfu Industry, 15 units, including Central South University, Northeast University, Institute of process of the Chinese Academy of Sciences, Institute of Electrical Engineering and Changchun Institute of Chemical Engineering, as well as large domestic aluminum enterprises, were jointly set up. The Ministry of Science and Technology "Aluminum electrolysis High efficiency and Energy Saving Technology Innovation Strategic Alliance" was established in Zhengzhou, with Zhang Hongen, chairman of Henan Yulian Group, as chairman, and Ding Jilin, general manager of Yunnan Aluminum Industry, as vice chairman. Academician Liu Yexiang, Academician Qiu Dingfan, Academician Zhang Guocheng and Academician Zhang Yi served as members of the Advisory Committee.

Since then, he has declared and undertaken the "Eleventh five-year Plan" national science and technology support plan "New Technology Development of low temperature and low Voltage Aluminum electrolysis" in the name of the Alliance, which has been successfully implemented in the 400kA production line of Linfeng Aluminum Power Company.

Then, in early 2011, the 400kA production line successfully developed by Shenyang Hospital and Qingtongxia Aluminum Plant was successfully put into operation. In the following years, 400kA super-large electrolytic cell quickly promoted more than 20 production lines in the industry, and became the backbone type of electrolytic aluminum industry in China.

A year later, Mr. Marchesky, chairman of Vimetco Group, said to his British partners at a victory banquet held at the Yuda International Trade Hotel in Zhengzhou: the Chinese team is going to make 800kA electrolytic cells in the future, and we all believe them! But what he does not know is that we have initially worked out the development plan of 600kA electrolytic cell.

X. a number of major technological breakthroughs-- achieving connotative upgrading

When it comes to electrolytic aluminum, many people may immediately think of the silly, black and thick picture of heavy industry, which is wrong. After more than 130 years of continuous development, electrolytic aluminum technology has developed from the initial small workshop production to a modern process industry with high scale, intensification, automation and high efficiency. People in the industry have a very popular saying: "Electrolytic aluminum can be introduced in three days, but you can't learn it in 30 years." the technology of electrolytic aluminum is by no means simple. It is one of the most difficult metals in common use, and so far there is only one method of industrial production. Due to the complexity of disciplines and theories involved in the process of aluminum electrolysis, various technical problems are also intertwined, in addition to the basic fields such as thermodynamics, kinetic processes, electrolyte components and physicochemical properties of molten salt electrochemical reactions. electrical, thermal, magnetic, structural mechanics and magnetohydrodynamic properties are also the core fields of research in recent decades, and anode, cathode materials and structural materials are also involved. There are many difficult problems in the field of materials, such as corrosion resistance, high temperature resistance and impermeable materials, as well as a large number of industrial and engineering problems. Electrolytic cell is not only the core equipment of electrolytic aluminum industry, but also characterized by mass large-scale production, which is energy-intensive, investment-intensive and technology-intensive, which can be said to affect the whole body, even if it is the wrong screw. it can also cause hundreds of waste products. In the process of large-scale electrolytic aluminum in China, the improvement of quality has never been ignored, and a large number of achievements in scientific and technological innovation have been firmly supporting the brilliant development of electrolytic aluminum in our country today. Especially in the fields of electrolysis process control, continuous and stable operation process and equipment, environmental protection technology and the innovation and research of new cathode structure, it has achieved remarkable results and attracted the attention of the world.

Process and control-- the key technology of efficient operation. The process and control technology of aluminum electrolysis in China has been greatly improved from the introduction of "daily light" technology, which is also the starting point of our research in this field. Based on the research and understanding of aluminum electrolysis process at that time, the "daily light" technology at that time was relatively backward. From the later research, it is proved that the mass production problem of the early introduction project has something to do with its backward technology. Its main performance is as follows: first, the feeding system is unreasonable, the feeding interval is long (30 minutes), and the feeding amount is large (4 × 15=60kg/ times each time), which is often called "overeating", and a pneumatic feeder is used at that time (in fact, it is blown by a small pneumatic chute), the accuracy is very low, resulting in great fluctuations; The other is the control mode of alumina content in electrolyte, which was still a "black box" model at that time, which was called "effect control" model.

As far as the electrolytic cell is concerned, although it is technically complex to realize the normal operation control by computer, there is no theoretical difficulty. The input information of the system is voltage and current, and the output is the two variables of shell feeding and lifting anode. Zhao Qingyun, an expert in automatic control and former vice president of Zhengzhou Light Metals Research Institute, once defined the control technology of electrolytic aluminum: if the optimal operation of the process is not considered, the control of the electrolytic cell is the same as the general industrial process, which is not difficult. However, the complexity of aluminum electrolysis process lies in that it is very difficult to realize the optimal operation of the process.

The process of "low temperature, low voltage, low molecular ratio, low alumina concentration and high efficiency" ("four low and one high") is the development trend of international aluminum electrolysis process, and its core difficulty lies in the control of alumina concentration. the solution to this problem has experienced a long and difficult process. In the 1980s, the main index of the new electrolytic cell has been significantly improved, and the application of control technology has made a certain contribution, which is the first stage of the development of control technology. But in fact, in this stage, in addition to the contribution of the design of the electrolytic cell and the improvement of the electromagnetic field, the contribution of the control system mainly comes from the new feeder and the improvement of the feeding system. That is to say, the process of "diligent processing and less feeding" greatly reduces the fluctuation of alumina concentration, and the successful development of the barrel feeder with the capacity below 1.8kg is the key. The "anode effect" is a warning signal emitted by the system when the alumina concentration in the electrolytic cell reaches the extremely low limit. The higher anode effect coefficient indicates that the problem of alumina concentration control has not been really solved at this stage.

After continuous research and development in this field, great progress has been made in this field, which makes the technical index of electrolytic aluminum operation in our country to a new level. There are many representative achievements, and the evaluation is mainly based on the study of the concentration curve of "slot resistance-alumina" and the establishment of the control model, which breaks through the limitation of the black box model of alumina concentration. the anode effect coefficient is reduced from 1 / tank day to less than 0.05 / tank day.

The intelligent control system and its popularization and application of aluminum electrolysis process completed by Li Kun and Ding Fengqi of Central South University, the third-degree optimization control technology of aluminum electrolysis completed by Tian Qinghong of Guiyang Institute, the intelligent fuzzy control technology of aluminum electrolysis completed by Canming of Guiyang University and Li Jinhong of Northern University of Technology, and the intelligent operation and control technology of aluminum electrolysis holography developed by Shenyang Institute. Many achievements have reached the international advanced level, which also marks that China's aluminum electrolysis technology has entered the advanced ranks of the world in an all-round way. In 2005, the research achievements in this field won the second prize of national scientific and technological progress.

Series of continuous operation technology and equipment-solve the bottleneck restricting large-scale development. For the electrolytic series composed of more than 300 electrolytic cells, if a cell is turned off or opened, there will be a power outage of 100 to 200 times a year. The power outage of 30-40 minutes not only reduces aluminum production, but also destroys various technical conditions of the electrolytic cell. the physical characteristics of the electrolytic cell have been changed, the electrochemical process has been seriously disturbed, the efficiency of the electrolytic cell has decreased and the energy consumption has increased, and the annual loss of a series has reached tens of millions of yuan. Moreover, the occurrence of anodic effect is greatly increased, and greenhouse gas emissions are greatly increased (the amount of perfluorocarbon produced by Greenhouse Effect during anodic effect is more than 6600 times that of CO2), especially the frequent and heavy load short-term shutdown / start-up shocks, which pose a serious threat to the safety of the power supply equipment of the aluminum plant and even Electroweb.

Continuous process is a major issue in the process industry, and the harm of frequent power outages to the production of electrolytic aluminum is self-evident. This is a world technical problem that has perplexed the development of electrolytic aluminum for a long time, and it is bound to become a bottleneck restricting the large-scale electrolysis of aluminum.

Since January 1995, the author has searched all over the country for electric power experts, but can not find a feasible solution. Until 1997, an opportunity for ou ran ran into Professor Li Guoxing, chief engineer of Hubei Ultra High Voltage Bureau on the train. "I am responsible for the external power transmission of the three Gorges, and I can do it." Professor Li believes that it is possible to turn off the electrolytic cell without a power outage. Because of this accident, the author made up his mind to develop this technology and agreed to develop it together. Until 2004, the author, who came to Henan Zhongfu Industry as the chief engineer, boldly applied to the state for the establishment of the project, which received special support for the technological development of the country's major industries, and the project was officially launched. However, after a year of cooperation with a well-known German company, the technology has failed. The realization is in trouble.

Li Guoxing, an electric power expert in the department of aluminum electrolysis. In 2005, Professor Li Guoxing, who has retired for many years and lived in the United States, was invited back to China to make good on his agreement to co-develop the technology eight years ago. However, after understanding the principle of operation and inspecting the scene, Professor Li thought that the problem was more complicated than he thought, and the original scheme would not work. As he was already unable to retire, he decided to support it to the end and strongly recommended Dr. he Junjia, deputy dean of the School of Electric Power of Huazhong University of Science and Technology, who had just returned from Japan to teach. Through continuous exploration and in-depth communication and cooperation with electric power experts, the development ideas have been gradually clarified.

Similar to the dam current closure, according to the electrolytic cell stop / open process, the key group conceived such a principle, that is, "first shunt, then short circuit, and then cut off (cell current)". An original variable resistance shunt test method is created to test the changes of shunt current, voltage, time and temperature and related safety parameters, which solves the problem of super-large current test. Then from small to large, from 70kA electrolytic cell, and then expanded to 320kA electrolytic cell. After the continuous full-current start-up slotting test of more than 120 320kA cells, all the problems have been solved successfully. In September 2006, after eleven years of twists and turns and exploration, this problem was finally declared to be completely overcome!

"continuous and stable operation process and equipment of large aluminum electrolysis series" has finally been successfully developed. Kangyi, then director of the China Nonferrous Metals Industry Association, personally presided over the appraisal meeting. An expert group composed of four academicians identified that its principle and method were pioneered in the world, and complete sets of technology and equipment reached the international leading level. The continuous, efficient and long-term stable operation of aluminum electrolysis series has been realized. This achievement was selected as the "Top Ten Engineering and Technical Progress in China in 2006". CCTV "News broadcast", "People's Daily" and "Science and Technology Daily" reported one after another; CCTV's "Economic half hour" featured the research and development process of this achievement.

This achievement won the "China Patent Gold Award" in 2010 and the second prize of national technological invention in 2012, which is the only national technological invention award in the field of aluminum electrolysis technology in China.

Special-shaped cathode and new structural cathode technology-- similar innovation. Due to the gradual improvement of the traditional electrolysis process, Alcoa began to explore a new alternative aluminum smelting technology-chlorine hua aluminum electrolysis process in the 1960s, and began to study the inert anode electrolysis process in the 1990s. However, after careful study, Professor Feng Naixiang of Northeastern University believes that inert anodes can not greatly save energy and reduce consumption, and the material problem is also difficult to solve. During a conference in Shenyang in 2007, Professor Feng talked about his idea: looking at the cathode of the electrolytic cell, he decided to follow the traditional electrolytic aluminum process, starting with improving the flow of liquid aluminum in the production process (improving magnetohydrodynamics) to find a shortcut to improve current efficiency and reduce cell voltage. Since the end of 1990s, Feng Naixiang invented the structure of discharge current electrolytic cell and opened the study of aluminum electrolytic cell with new cathode structure. after many improvements for more than ten years, it formed a "wave blocking" effect on the flow of molten aluminum in the electrolytic cell by changing the shape of the cathode. in order to obviously reduce the amplitude of liquid aluminum magnetic fluid flow, the basic theory of aluminum reduction cell with new cathode structure with high efficiency and energy saving was established. From July 2007 to September 2008, he and Professor Tian Yingfu carried out experiments on three 168 kA electrolytic cells of Chongqing Tiantai Aluminum Co., Ltd., and finally achieved unexpected results: DC power consumption per ton of aluminum decreased from 13393 to 12300k 1000kWh, energy-saving TAL per ton of aluminum. After that, the demonstration and promotion was carried out on 94 200kA electrolytic cells of East China Aluminum Co., Ltd. The technology completed by Feng Naixiang and others has produced great repercussions at home and abroad, attracted the attention of many enterprises, and quickly promoted and tried out in more than 20 aluminum factories in the industry. This technology was published in the United States in 2010 and won the TMS Association Aluminum electrolysis Innovation Technology Award. 2010 China Patent Excellence Award.

At the end of 2008, Professor Gu Songqing and Professor Liu Fengqin of Aluminum Corporation of China successfully tested the new cathode structure diversion cell technology which has not been studied abroad for many years on two 160kA electrolytic cells of Qinyang Aluminum electrolysis Plant. It is reported that the voltage of the electrolytic cell is stably controlled at 3.7 ~ 3.8V, which also achieves the goal of energy saving 1000kWh per ton aluminum. After that, it was popularized and used in Guizhou Aluminum Plant and Lanzhou Aluminum Industry, which belongs to Chinalco. Aluminum Corporation of China held a special press conference to announce this major achievement.

The similarities between Feng Naixiang's special-shaped cathode electrolyzer and Chinalco's new structure diversion cell are that the focus of innovation is focused on the change of cathode structure. the difference is that the special-shaped cathode designs a set of cathode "bumps" on the cathode surface according to certain requirements and rules, which has a physical blocking effect on the flow of molten aluminum. On the other hand, the new structure diversion groove opens a group of "grooves" on the cathode surface, which also forms a concave-convex structure on the cathode surface. because the liquid aluminum is constrained in the groove, it also slows down the flow of the liquid aluminum. One convex and one concave, it can be said that there are similarities and differences!

"Breaker" (Wave Breaker). The special-shaped cathode technology is also called "breaker" in some foreign literature, although it is due to the following two problems: one is that the protruding part of the cathode after the electrolytic cell has been running for a period of time (about half a year) due to thermal stress and erosion of molten aluminum, it will fall off or wear off, which weakens or loses its effect on the flow of molten aluminum. However, the shape, height and layout of bumps or grooves have different effects on different grooves. Accurate simulation is needed in the future to achieve the best results. But in any case, the birth of this technology has pointed out a new technical direction for substantial power saving in aluminum electrolysis production.

Due to the similarity of technical principles, the two teams finally declared the achievement after painstaking negotiations. Feng Naixiang and Gu Songqing won the second prize for national scientific and technological progress in 2014.

Slot life-1500 days to 3000 days of disc change. Anyone who hears the term "slot life" can feel the weight in it. Is there anything more important than "life span"? Since the introduction of technology, the service life of electrolytic cell has been a difficult problem for aluminum electrolysis production in China. Once the electrolytic cell is damaged and shut down, the cost of maintenance is very high, including the start-up cost, the cost of an overhaul is equivalent to more than 1 / 3 of the total investment of the electrolytic cell. As the electrolytic cells in aluminum electrolysis plants are generally installed and operated in series (there are more than 300 electrolytic cells in one electrolytic series), the life problem is a major economic problem of electrolytic aluminum, which is directly related to the economic benefits of aluminum plants.

How to improve the life of electrolytic cell? Material problems, design problems, construction problems, roasting start-up methods, production process and management problems are intertwined, and its complexity can be imagined. It can be said that any link may lead to early damage of the electrolytic cell. as a result, the life of the cell is shortened, but any kind of technology and improvement is difficult to ensure the real extension of the life of the electrolytic cell. Moreover, if the results of theoretical research are to be verified in actual production, they must be tested for a long time, and it is difficult to get convincing results in a short period of time. Therefore, for quite a long time, no one dared to be sure that the 1500-day design goal could really be achieved in the factory, and no one knew how many years it would take us to achieve the international 2700-day goal. However, it is not clear when it began, the issue of slot life gradually ceased to be the focus of discussion. Today, the trough life of some of our aluminum plants has even exceeded 3000 days (the number of 400kA grooves of Zhongfu Industries for more than 10 years accounts for more than 30%). Such a great technological progress can be called disc change!

Research and improvement of material technology. The production technology of the carbon cathode block improves the conductivity of the cathode and the penetration of electrolytes and sodium ions, and the development and application of the bottom impervious material effectively acts as the corrosion and destruction of the insulation layer caused by the electrolyte permeation. the high-strength impervious castable (mainly used in the lower part of the side of the electrolytic cell) effectively improves the anti-leakage effect and temperature distribution around the cathode. The application of side silicon carbonitride material greatly improves the side heat dissipation, promotes the formation of furnace side in the tank, and can effectively protect the inner lining of the electrolytic cell from erosion.

The perfection of design theory. The most basic influence is on the establishment and perfection of the design theory. The first is the development of thermoelectric model and simulation technology, which lays the foundation for the reasonable optimization of thermal design of the electrolytic cell, and the temperature distribution and energy balance in the cell can be accurately predicted. Secondly, it is clear that the best region position of the characteristic value of the isotherm at the bottom of the electrolytic cell, that is, the electrolyte solidification isotherm is located below the carbon block of the cathode, which is beneficial to weaken and delay the destructive effect of electrolyte infiltration on the cathode. the precipitation temperature of sodium ion is between the insulation layer and the refractory layer. Thirdly, a "compressible structure" (also called "flexible" structure) is designed, which can effectively absorb the expansion deformation of the cathode and reduce the cathode damage caused by temperature and sodium absorption expansion. the fourth is to define the ideal furnace side and the method to realize the ideal furnace side shape through the side heat dissipation structure design, that is, the liquid aluminum-electrolyte interface and the horizontal current distribution of the aluminum liquid layer are taken as the judgment criteria.

The improvement of construction technology and technology is the key to the engineering of material research and design results. No matter how perfect the construction rules are, it is sometimes difficult to obtain good results. the excellent construction quality of electrolytic aluminum is established in continuous practice and exploration. the understanding of the key links of the construction process and strict standard operation is the core of the technology.

The technology has been continuously improved. After 40 years of development, the technology from roasting start-up to production operation has been greatly improved and changed. From learning and worshipping the imported technology from Japan to completely abandoning the start-up technology of liquid aluminum roasting; from the use of 280kA test to the gradual improvement and popularization and application of coke roasting technology; from "effect" control, large feeding process to "four low and one high", point feeding stable operation, the production process and operation management of electrolytic aluminum have made a qualitative leap.

Technological progress-depends on the continuous innovation of the whole industry. It is undeniable that the improvement of cell life is indeed a major achievement of aluminum electrolysis technology in China, a remarkable achievement, which embodies the collective wisdom of electrolytic people and the result of 40 years of unremitting exploration. There are many improvements and innovations in electrolytic aluminum technology, and there are still many innovations such as cell life, precisely because there are too many people's painstaking efforts and contributions, and it is not easy for a unit or individual to get corresponding rewards. Each progress is accomplished by many scientific and technological personnel in different units at the same time, resulting in a lot of scientific and technological achievements can not be explained clearly, but the electrolytic aluminum industry is actually making great strides forward.

National Day holiday, 500 ~ 600kA super large-scale-- leading the world

The overcoming of a series of difficult problems has promoted the process of industrial scale development of electrolytic aluminum. Since 2008, the development of electrolytic aluminum production capacity has become unstoppable, such as the flood of sluice discharge. 400kA electrolytic cell quickly began to be popularized on a large scale. At the same time, the development of 500kA and 600kA super-large electrolytic cell has also been put on the agenda.

International aluminum industry-- advancing in exploration. French company Pichiney used ten years from 1989 to 1999 to upgrade the current of three test cells in (LRF), its test base in Saint-Jean-Morin, France, from 400kA to 500kA (AP50). However, up to now, this technology has not been industrially applied.

500kA muri-Chinalco leads the way. In September 2011, the world's first 500kA aluminum electrolysis production line designed by Shenyang Institute was established and put into production in Chinalco Liancheng Branch. The cold wind is chilly in winter. Next to the 500kA electrolytic cell of the No. 1 electrolysis plant, several electrolysis workers are changing poles. The fiery anode block is clamped out of the cell by the multi-function crane, and the first batch of 500kA electrolytic cells are officially put into operation after the hard work of the on-site personnel. In order to ensure the smooth start-up work, during the start-up of the second zone electrolytic cell, the start-up experience of the first zone of the 500kA electrolysis series was carefully summarized, and the continuous roasting start-up scheme: fully applying the technology of no power outage and opening, greatly reducing the disassembly time of the short intersection, optimizing the production organization, strictly enforcing the process system, strengthening technical training, formulating emergency plans and organizing drills. Strictly control the consumption of raw materials needed for start-up, reduce the start-up cost, and create conditions for ensuring the safe and stable operation of the series. The process is smoother than the first batch (Zone 1).

By October 12, 2011, 92 electrolytic cells in 500kA Zone 2 were all started successfully, 188 grooves were opened, and 65% of them were completed. The third zone will be powered on in mid-November as planned, and the start-up of a full series of 288 electrolytic cells will be completed by the end of the year. Although the process method is complicated and tortuous, it finally achieves the success of one-off industrialization, which opens the 500kA era of the electrolytic cell and lays the foundation for moving forward to 600kA.

Rapid industrialization. In 2011, CUHK Metallurgical Design Institute designed the 520kA electrolysis series in Xinjiang. A total of 320 electrolytic cells were installed with an annual production capacity of 450000 tons. The first 80 units were successfully launched in August 2012. During this period, after continuous design and optimization, the last 240 electrolytic cells were further improved and became the single series with the largest production capacity in the world at that time. The following techniques are mainly applied: the bus configuration is optimized, the compensation effect is further improved, and the amount of single slot aluminum bus is reduced by 3.2 tons; the cathode multi-steel bar technology is improved, from 4 cathode rods to 3 per cathode carbon block. the anti-leakage design of cathode structure is further improved; the layout of upper horizontal bus and feeding point is optimized; the structural layout of safe operation is fully taken into account in the design of large aisle bus. After putting into operation, the operation of the electrolytic cell is stable, especially the improved 240 cells.

Reproduce the inflection point. From 400kA to 500kA, with the increase of capacity, although there is no essential change in the design theory and the method of physical field simulation, the contradiction between economy and technology gradually appears at this stage, which is reflected in two aspects:

1) in the design of the bus system, in order to compensate the electromagnetic field, most of the current (more than 80%) from the cathode on the upstream side of the electrolytic cell must be bypassed from the end, increasing the length and cross-sectional area of the busbar, and increasing the investment and voltage consumption of the busbar, and a large number of compensation busbars need to take up a large amount of space between the electrolytic cells, so that the spacing between the cells must also be increased. It leads to an increase in investment and operating costs; Another alternative is to appropriately reduce the amount of compensation of the busbar around the electrolytic cell and use a specially set small unit for compensation (special compensation busbar), which is called "external compensation". Relatively speaking, the way of external compensation is simple, and the cost of investment and travel to Yunnan is also slightly lower. However, no matter which compensation method is adopted, the unit investment and operation cost of the bus bar is still increased compared with the 400kA.

2) in the structural design of the electrolytic cell, in addition to properly changing the aspect ratio and increasing the anode length of the electrolytic cell, thus increasing the total weight of the upper part, the span of the electrolytic cell in the length direction is also larger, and the superstructure also needs to be further strengthened. There are also two approaches: one is to increase a lot of height and increase the cross-sectional area of girders to meet the strength and stiffness needs of the superstructure of the electrolytic cell, of course, changing solid web girders into tube truss girders can greatly save investment (such as Zhongfu 400kA, later for Weiqiao 600kA); another kind is to add a support column in the middle on the basis of solid web plate girders (Liancheng 500kA, later used in Liancheng 600kA above).

On the one hand, the super-large electrolytic cells above 500kA are quickly favored by the industry, and many enterprises quickly adopt them, such as Gansu Dongxing, Oriental Hope, Shenhuo Group and so on. Xinjiang Qiya directly applies its series of improved designs to the construction of the second series. But on the other hand, there is a second inflection point in the development of large-scale pre-baked cell. No matter how excellent the 500kA electrolytic cell is, in addition to the increasing technical difficulty, its superiority is increasingly unable to be reflected: first, the increase of busbar and structural materials in design not only loses its own investment advantage, but also offsets the investment saved by large-scale public facilities; Second, the production technical index is stagnant, judging from the current operation situation: the current efficiency is less than 93%, and the advanced index of DC power consumption 12600kWh/tAl is difficult to surpass even the 500kA slot.

If we say that the leapfrogging of the pre-baked cell from 160kA to 180kA is due to the breakthrough in technical and theoretical research such as the influence of magnetohydrodynamics, then solving the economic problem of the super-large electrolytic cell above 500kA also needs the second technical breakthrough.

600kA talk-the new benchmark of electrolytic aluminum in the world. Since the beginning of the new century, the international aluminum smelting giants have not stopped their research and development in the field of super-large electrolytic cells. In 2010, LRF, owned by the international mining giant Rio Tinto (RTA), began to develop its groundbreaking APXe technology, and in December 2010, it started the construction and development of the AP60 (600kA trough) smelter. Rio Tinto approved the world's first large-scale deployment of AP60 electrolytic cells, starting with 38 AP60 (the number necessary for industrial verification of AP60 technology) as part of the modernization of its Jonquiere smelter in Quebec, Canada. The second stage of the original plan, that is, the industrialization series demonstration line, will be designed to be composed of 272 electrolytic cells according to the conditions of the construction site.

AP60's development model replicates its "AP18 and AP30 success model". Debugging and start-up were completed in 2013 and all performance tests were completed in September 2014: the current efficiency is 95.9%, and the industrial test calculation index only reaches the level of 13090 kWh/tA per ton of aluminum DC power consumption. From the results of this index, it has not yet reached the 12900kWh/tAl level of industrial series operation of its AP30 cell, and there is an obvious gap between its 400kA cell and our country. This result is related to the delay in the industrial application of AP50 and the lack of implementation of the second stage industrialization plan of AP60, and is also consistent with the "second inflection point theory" mentioned by the author. However, the development and application of 600kA super-large electrolytic cell in our country continue to advance by leaps and bounds.

SY600-- Chinalco renewed force. Shenyang Yuan cooperated with Chinalco Liancheng Aluminum Plant again to undertake the key projects of the National 863 Program of the Eleventh five-year Plan, the major science and technology project of Chinalco, and the technology research and development of 600kA super-capacity aluminum reduction cell. In the course of the test, the original design plan is to adopt the "bottom discharge" mode (a design that makes the conductive characteristics of the cathode and anode structure form a symmetrical distribution, which can minimize the current of the liquid aluminum layer). As it is considered that there is a certain risk in the structure of the bottom discharge, it is proposed to the Ministry of Science and Technology to cancel the plan and leave it for further exploration in the future. The expert group of the Ministry of Science and Technology held a special meeting to study this, and adjusted the target energy consumption target for test and acceptance (from 12000 to 12200kWh/tAl).

In August 2012, all 12 test tanks were started successfully. The electrolytic cell adopts 56 groups of single anodes, the current density is 0.796A / cm ~ 2, and the anode is positively corresponding to the cathode, with seven-point blanking, beam middle support structure, segmented double smoke pipe exhaust system and three-stage lifting mechanism; the design of the bus around the cell is simplified by the scheme of internal compensation and external compensation, so as to reduce the increase of cell spacing; when the average vertical magnetic field is less than 5.0gauss, the melt flow rate is reduced by 40% (close to 400kA cell). The test results show that the average DC power consumption of 12 trough tons of aluminum is 12136kWhh, and the average current efficiency is 92.77%.

On April 21, 2014, the China Nonferrous Metals Industry Association organized the appraisal of scientific and technological achievements. Academician Zhang Guocheng served as the expert group leader, and the author and Niu Qingren professor-level senior engineer served as the deputy group leader. The appraisal opinion is that the technological achievements have reached the international leading level.

Cooperation between NEUI600-- East Courtyard and Wei Qiao. One day in 2013, Lu Dingxiong, president of the East Courtyard, pushed open the door of Zhang Shiping, chairman of Weiqiao Group, and made a statement that moved the head of this 100 billion enterprise, determined to contribute to the scientific and technological progress of the aluminum industry. After demonstration, design and construction, the world's first (186sets) 600kA aluminum electrolysis production line officially started construction.

NEUI600 adopts the mode of "numerical simulation + experience": the "double compensation" technology and bus device for magnetic fluid stability are developed, and the amount of bus used in the electrolytic cell is reduced by 12% compared with the traditional "single compensation" technology. The first multi-stage split tube truss structure technology improves the safety and stability of the super-long-span upper steel structure of the NEUI600kA aluminum reduction cell, reduces the rail top height of the electrolysis workshop by about 1 meter, and reduces the civil investment of the electrolysis workshop by about 5%. The developed complete set of environmental total quantity control technologies, such as high-level regional gas collection structure and phase flow flue gas dry purification technology, have achieved 99.6% gas collection efficiency and 99.7% purification efficiency. After more than half a year of operation test: the average voltage of the slot is 3.95V; the current efficiency is 94.6%; the DC power consumption is 12443 kWhhand t Al; the anode effect coefficient is 0.01 times / slot day.

On June 5, 2015, China Nonferrous Metals Industry Association held an evaluation meeting on "Weiqiao Aluminum Power NEUI600kA Aluminum reduction Cell Technology Development and industrialization Application of Scientific and technological achievements". President Chen Quanxun attended the review meeting, with Professor Jia Xing, vice president and chairman, as the expert group leader, and Academician Qiu Dingfan and Professor Li Gong as the deputy group leader. The expert evaluation believes that the overall technology of the project has reached the international leading level.

Since then, the new series established by Shenyang Institute in Xinfa, Shandong Province has increased the current intensity to 660 Ka.

Standing on top of the world. Although there is a debate on the maturity and advanced nature of the cell above 500kA in the industry, there is no doubt that China's electrolytic aluminum technology has stood on top of the world. Hall and Elut, who founded Alcoa and French Alcoa, may not have imagined that this magical aluminum smelting method they invented can really blossom and bear fruit in China today, carry forward, and benefit the world!

XII. The riddle of the vigorous Development of Electrolytic Aluminum

The spring breeze of reform and opening up, which began in the 1970s, brought the spring of science and technology. The scientific and technological workers in China's electrolytic aluminum industry, with their full enthusiasm and love for the motherland, have staged a great drama of the vigorous rise of electrolytic aluminum technology: on the basis of digesting the imported technology, we have studied and developed the "mathematical model and simulation software system of aluminum reduction cell", mastered the basic theory and design tools for the development of large-scale aluminum reduction cell, and have independently developed super-large aluminum reduction cell technology above 165kA, 186kA and 280kA. Marked by the successful development of "280kA test cell of national large-scale aluminum electrolysis test base", China has stepped into the leading ranks of the world in the field of modern aluminum electrolysis technology, and has formed its own modern aluminum electrolysis technology system. Since then, the technologies of 320kA, 400kA and 500 '600 kA super-large pre-baked anode aluminum reduction cells have been born one after another, and each technical index has reached or exceeded the international advanced level.

Some people say that electrolytic aluminum belongs to "two high and one capital" and should be restricted! High energy consumption and high pollution? After reading this article, I believe you already have the correct answer: yes! Advantage industry, electrolytic aluminum is a rare advantage industry in China! This is the truth behind the incredible development speed of the electrolytic aluminum industry!

Academician Gan Yong said: up to now, the iron and steel industry is still the "pressing stone" of the national economy. What about electrolytic aluminum? There is no doubt that the electrolytic aluminum industry is a bright gem in the national economy!

The solution of future resources. The rapid development of electrolytic aluminum amazed the world, and naturally caused people to worry about the problem of resources.

The raw material for smelting aluminum is mainly alumina, which is obtained through bauxite processing. The world is rich in bauxite resources, mainly distributed in Australia, Brazil, Guinea and other countries. China used to be the main producing country of bauxite. Shanxi, Henan, Guizhou and Guangxi are the main provinces, with reserves of less than 2 billion tons (non-authoritative figures, and constantly adjusting and changing), accounting for about 4% of the world's bauxite reserves, ranking seventh in the world. With the rapid development of China's electrolytic aluminum industry, domestic bauxite resources have obviously failed to meet the needs. Although the proved reserves have been increasing in recent years, new bauxite resources have been discovered one after another. New alumina plants have also been built in some provinces, such as Yunnan and Chongqing. But on the whole, the shortage of bauxite resources is inevitable, which is the resource concern for the development of electrolytic aluminum.

However, as expected by many people in the industry, the development of China's electrolytic aluminum industry is not restricted by alumina resources, this is because: first, alumina is an international resource, and the worldwide alumina trade is very active. Some large alumina producing countries in the world do not have the production capacity of electrolytic aluminum, and the alumina produced by these countries (such as Australia) is mainly used for sales to other countries. Second, alumina is produced through a very complex chemical process, and it is also a valuable resource. Proper import is conducive to alleviating the contradiction of domestic resource shortage. From another point of view, precisely because our country has a good foundation of electrolytic aluminum industry, obtaining foreign aluminum resources through the development of electrolytic aluminum is also a mode of sound economic development of our country. The practice of producing alumina by directly importing bauxite by some large enterprises in Shandong, as well as the industrial characteristics of aluminum industry in some provinces, have confirmed the rationality of this model.

On the other hand, it is also a historical necessity for today's aluminum industry to go out.

"Belt and Road Initiative"-- going to the world. The investment in the construction of electrolytic aluminum plants using Chinese electrolytic aluminum technology is only that of developed countries. Moreover, because the quality standards of electrolytic aluminum products are global, the primary aluminum produced in the United States and the primary aluminum produced in China can meet the same quality standards. At present, China's independently innovative electrolytic aluminum technology has achieved large-scale technology exports, such as India, Kazakhstan, Malaysia, Iran, and even to European developed countries. and through engineering general contracting, engineering design, engineering construction and other ways to promote the domestic export of related equipment, materials and labor services, which has a great impact in the world.

"Belt and Road Initiative", the new era of electrolytic aluminum is the right time!

I used to look at drawing at that time. Is there a surplus of electrolytic aluminum? Yes, the development of electrolytic aluminum is really too fast, but does the surplus mean that the industry is "big" from another point of view? China's electrolytic aluminum has low energy consumption, low investment and leading technology! Is it "strong"? To put it another way: that is to say, China's electrolytic aluminum is really "bigger and stronger", isn't it? A bigger and stronger electrolytic aluminum is already in front of us.

"Don't be surprised that all the peaks look familiar. I looked at the drawing at that time." Wang Yangming's poem is a true portrayal of today's electrolytic aluminum industry! The ideals of the older generation have become a reality today!

Electrolytic aluminum-- make people proud! (end)