[review of the Development of Aluminum electrolysis Technology in China in the past 40 years] Electrolytic Aluminum-- the brilliant Road of Scientific and technological Innovation (part I)

Preface-what is electrolytic aluminum?

When it comes to "electrolytic aluminum", many people may know about it today, but what is electrolytic aluminum? I'm afraid there are not many people who know about it, and even fewer people who can explain it clearly.

Aluminum is a metal. Because of its light weight, good electrical conductivity, excellent processing performance and special oxidation resistance, aluminum is widely used in various fields such as electric power, transportation, construction, packaging, national defense, aerospace and people's life. from construction home to high-speed rail, aircraft, from food, automobiles to consumer electronics, it has been estimated that the application of aluminum involves about 112 industries. The aluminum we are talking about here is also called primary aluminum, that is, pure aluminum. As the original manufacture of aluminum has always been based on molten salt electrolysis, it is usually called "electrolytic aluminum".

Electrolytic aluminum-a young metal. The process of smelting copper was first discovered and mastered by human beings about 3000 ~ 4000 years ago, and the history of human ironmaking has been more than 3000 years. China's ironmaking technology has been greatly developed as early as the Han Dynasty. However, the birth of human aluminum smelting technology is only 130 years old. Academician Yin Ruiyu, a famous metallurgical scientist and expert in iron and steel, said: "because the melting point of copper is lower than that of iron, people first learn to make copper and then learn to make iron; ironmaking needs to open the molecular bond, while the temperature of reducing aluminum is higher, so it is necessary to use electrolysis to open the ion bond, so human beings did not master the technology of making aluminum until direct current."

In 1886, a young man named Charles M.Hall in the United States invented a process for smelting aluminum, called "electrolysis of alumina in molten fluoride salts." But when he went to the United States Patent Office to file a patent application, he learned that a Frenchman named Paul L.T. H é roult had applied to the United States Patent Office for aluminum to combine roughly the same elements, almost exactly like Hall's invention. Moreover, Elut applied for a patent in Europe a few months ago. Since then, the two men have entered a long-running patent dispute, which is said to have lasted for 15 years.

Hall and Elut patent application dispute after a long negotiation, the United States Patent Office finally ruled in favor of Hall, because Elut did not submit the required "original report." As a result of this ruling, Hall and Elut became inventors who owned the same patent in the Americas and Europe at the same time, and later called it the "Hall-Elut aluminum electrolysis process". However, the fate between Hall and Elut is much more than that. with the technical support of Hall and Elut, they founded two aluminum metallurgical companies as founders, namely Alcoa (Alcoa, formerly Pittsburgh Metallurgy) and French Aluminium (Pechiney, formerly French electric metallurgical company (SEMF). Hall and Elut were destined to be born for aluminum. They were born in the same year (1863), died in the same year (1914), and filed the same patent in the same year (1886). Even in an era marked by surging wealth and massive accumulation, Hall's story became an American legend, winning the greatest wealth in the history of American patents. Hall's stake in Alcoa when he died in 1914 was worth nearly $30 million.

The proud son of New China. The development of electrolytic aluminum in China is relatively late, and the first electrolytic aluminum plant (Fushun Aluminum Plant) was completed and put into operation in 1954. Until the 1980s, as an industrial industry or a product, the production process and industrial characteristics of electrolytic aluminum were rarely understood by the public. With the development of electrolytic aluminum technology and the expansion of the production scale of electrolytic aluminum, especially since 2005, whether it is the five major industries of "iron and steel, cement, electrolytic aluminum, automobile, and real estate" issued by the state, or the macro-control of the three major industries of "iron and steel, cement, electrolytic aluminum", as well as the restricted industries of "two high and one capital", electrolytic aluminum is on the list. From then on, the public gradually became familiar with and understood electrolytic aluminum. It should be said that whether it is the formulation of "three major industries" or "five major industries", it is a real "lift" to the electrolytic aluminum industry, because only based on the national production capacity of several million tons of electrolytic aluminum in that year, the total output value is less than 100 billion yuan. Tens of billions of total assets, no matter how can be said to have nothing to do with big industries. Compare with other industries: in 2005, the national output of crude steel was 350 million tons, cement output was 1.07 billion tons, and electrolytic aluminum was only 7.79 million tons. Compared with automobile real estate, not to mention, the scale of the industry differs by more than an order of magnitude. In any case, although electrolytic aluminum is small, it is very famous. However, "high energy consumption and high pollution" has also become a lingering business card and label for electrolytic aluminum.

After the founding of the people's Republic of China and even in the early days of reform and opening up, electrolytic aluminum in China has always been a shortage of products, and it has been listed as strategic materials, and it has been dependent on imports for a long time. China's early electrolytic aluminum plants and alumina plants matched with electrolytic aluminum have their own names. For example, Fushun Aluminum Plant is also called 301 Plant, Guizhou Aluminum Plant is 302 Plant. From this kind of secrecy nature similar to that of military industrial enterprises, we can see its strategic position at that time. At the beginning of the establishment of China Nonferrous Metals Industry Corporation in April 1983, it first put forward and determined the policy of "giving priority to the development of aluminum" to the country, from which we can also see the urgent demand for "aluminum" and the importance attached to the aluminum industry.

Thrive-unexpected. Over the past 40 years of reform and opening up, especially since the end of the last century, China's electrolytic aluminum industry has developed rapidly. After 2003, with the introduction of the national macro-control policy, the electrolytic aluminum industry not only has not been contained, but also shows explosive growth. In 1998, the production capacity of electrolytic aluminum in China was only 2.56 million tons / year, and the output was 2.43 million tons / year. From then on, an unknown "big" industry has constantly refreshed its historical record: power generation enterprises and coal enterprises began to invest in electrolytic aluminum, and the textile industry and aquaculture industry also came to invest in the feast of electrolytic aluminum. Among them, there are private enterprises, state-owned enterprises, and large central enterprises. Some of the private enterprises involved in aluminum have been among the richest people in China, many of them have become the richest people in a certain province, and there are many people on the rich list. People do not understand, electrolytic aluminum has what kind of magic, can continue to attract a large number of enterprises cross-bank investment, and enjoy it, set off round after round of investment boom? From 1998 to 2018, the production capacity and output of electrolytic aluminum in China have exceeded 43.97 million tons and 36.48 million tons respectively, and aluminum output has increased by nearly 20 times, accounting for 56.7% of the world's total output, ranking first in the world for 17 consecutive years.

In the family of non-ferrous metals in China, the rapid growth of aluminum makes "copper, aluminum, lead and zinc." The ranking was rewritten as "Aluminum, Copper, lead and Zinc." Electrolytic aluminum successfully "counterattacked" to become the boss of course, becoming the second largest metal material. Today, no one questions the title of "big industry" of electrolytic aluminum.

With the continuous development of electrolytic aluminum industry, coupled with the related industries such as mining, alumina, aluminum processing, carbon and power generation in the upper and lower reaches, its scale and volume have reached a considerable extent. Electrolytic aluminum has actually become an important basic raw material industry in China. However, the more basic things are, the more indispensable for people, and the impact of the electrolytic aluminum industry, which has become a large industry, on the national economic construction of our country can not be ignored. Its healthy, stable and sustainable development also needs our great attention.

So, since the new century, under the strict restrictions of the state and various government decrees, what is the truth that has led to the crazy development of electrolytic aluminum?

Electrolytic aluminum is a high energy-consuming industry? There is no doubt about this. At present, about 13000 tons of electricity is consumed for every ton of electrolytic aluminum, plus the main raw materials and energy consumption of the production process consume 680 tons of standard coal for every ton of electrolytic aluminum. However, up to now, electrolysis is still the only way to produce primary aluminum in the world. Alcoa and other international giants began to explore alternative technologies for electrolytic aluminum smelting in the 1960s, but so far they have not been successful.

The author believes that there are several reasons for the rapid development of electrolytic aluminum: first, electrolytic aluminum is an energy-consuming link in the whole aluminum industry chain, and in the follow-up application and processing of aluminum products, it more reflects the industrial characteristics of high-tech and fine processing, which not only has the irreplaceable role of other materials, but also, It shows its remarkable energy-saving effect in many fields (such as electric power, aerospace, transportation, etc.). Second, aluminum is easy to oxidize to form a strong protective film so that it will no longer be eroded in the process of use, so that the oxidation loss of aluminum products in the application process is very small, and it is very easy to recover. The recovery rate can reach more than 95%, so aluminum can be recycled and applied repeatedly, so it has the reputation of "energy storage product" and "energy bank". The regeneration and recovery of aluminum greatly reduces its energy consumption in the future recycling. Third, the technical and equipment level of aluminum production in China is first-class in the world, and its energy consumption has reached or has been lower than that consumed by most developed countries, that is to say, the energy consumption of aluminum production in domestic aluminum enterprises is even lower than that of aluminum plants in the United States.

Although the energy consumption of electrolytic aluminum accounts for more than 7.9% of the total electricity consumption in the country, compared with the energy consumption of hundreds of millions of household cars in China, the energy consumption of the whole electrolytic aluminum industry is even less than a tenth of it.

Is electrolytic aluminum a highly polluting industry? To be exact, this statement is not accurate and unfair. Fluoride, the main pollutant emitted in the process of electrolytic aluminum production, is also the raw material needed for electrolytic aluminum production, and the fluoride emitted in the form of flue gas has a natural affinity with alumina, another main raw material for electrolytic aluminum production. they can adsorb immediately after they meet in the reactor, and the reaction efficiency is more than 99%. The "dry purification" system developed based on this principle is widely used in aluminum plants all over the world. Excluding management factors, the problem of electrolytic aluminum pollution was no longer a technical problem as early as the early 1980s. More importantly, the production system design of modern electrolytic aluminum plant has already integrated the flue gas treatment system and raw material supply system into a whole, 365 days of the year continuous operation, uninterruptible for a moment.

For a small amount of solid pollutants produced by the overhaul of the electrolytic cell, there have always been strict environmental protection measures. In recent years, the state has put forward more stringent standards and requirements for the environmental protection of electrolytic aluminum. On the one hand, it increases the restrictions on the emission of SO2 in the flue gas of electrolytic aluminum; on the other hand, the new Environmental Protection Law of 2016 classifies most of the solid wastes discharged from the electrolysis process as hazardous pollutants. After long-term technology accumulation and research and application in recent years, the corresponding treatment technology has begun to industrialization, especially the electrolytic aluminum flue gas desulfurization technology and electrolytic aluminum overhaul waste residue treatment and comprehensive utilization technology has gradually matured, and applied to industrial production. At present, the research and development of electrolytic aluminum solid waste recycling technology has also made positive progress.

As a scientific and technological worker in the industry engaged in the design, research and management of electrolytic aluminum for more than 30 years, the author has personally experienced the whole process of technological innovation and industrial development of electrolytic aluminum. It is well known that it leads to the vigorous development of electrolytic aluminum industry and even "overheating of investment" or "overcapacity", not only because electrolytic aluminum belongs to "two high and one capital", labor-intensive or "high input and high output" industries. Although many people think that electrolytic aluminum has some problems of one kind or another, in-depth analysis found that there are extremely far-reaching industrial background and deep-seated economic and technological reasons behind it, which led to the vigorous development of electrolytic aluminum industry today.

Explore the truth-how awesome is electrolytic aluminum? Since the reform and opening up, China's economy has been in a period of rare development in a thousand years, which provides a broad development space for the production of primary aluminum. However, what many people do not understand is that the fruitful achievements and amazing scientific and technological achievements resulting from the hard work and unremitting exploration of several generations of scientists and technicians in China's electrolytic aluminum industry are the real internal reasons behind the leading position of China's electrolytic aluminum industry in the world. Especially in the field of large-scale technology of aluminum electrolysis, from scratch, from digestion and absorption to independent innovation, from theoretical field to experimental development, and then to large-scale application and promotion, the design and production technology of aluminum electrolysis is becoming more and more perfect. formed its own design and technical system. Nowadays, in the world, where there is the growth of electrolytic aluminum, there is the figure of China. The electrolytic aluminum industry has become one of the rare advantageous industries in the manufacturing industry and even the industrial field in the world. Under the guidance of "Belt and Road Initiative" strategy, hold your head high and go to the world.

The forty years of scientific and technological innovation of aluminum electrolysis in China is the forty years in which several generations of scientific and technological workers work together to create miracles. Looking back on the course of the past 40 years, we can see vividly the magnificent pictures of scientific and technological innovation, and the inspiring orders of our predecessors to tackle key problems and the earnest teachings of solving difficult problems still reverberate in my mind.

Second, the introduction of "Japanese light" technology.

Speaking of the electrolytic aluminum factory, the veteran comrades in the industry described it as this: if you enter the electrolytic workshop less than 10 meters away, you can't see anyone; when the electrolytic worker comes out of the electrolytic workshop, just like a coal miner, you can see a pair of eyes on his whole face, and the working environment is bad. Unimaginable, this is also the earliest impression of electrolytic aluminum. Before the 1970s, the technology of self-baking anode electrolytic cell introduced by the former Soviet Union was basically the main technology of electrolytic aluminum plant in China, and the scale of single series was generally no more than 10,000 tons / year. Aluminum plants with an annual output of more than 30,000 tons are all national backbone enterprises.

In the early 1980s, with the spring breeze of reform and opening up, all fronts of the national economy ushered in an epoch-making change. At the same time, we also ushered in the spring of science and technology. Proceeding from the strategy of promoting the development of the national economy, the state has decided to introduce technology to build a number of major construction projects from developed countries. The most typical is the construction of the first phase of the Shanghai Baosteel project, which was conceived in 1977 and held on the first day after the end of the third Plenary session of the Eleventh Central Committee in December 1978. The CPC Central Committee and the State Council decided to build a modern iron and steel joint enterprise-Baosteel, introduced a full set of equipment from Nippon Steel Company of Japan, and built China's first modern iron and steel enterprise with the world level in the 1980s. This is also the first large-scale construction project in history to be voted on by the National people's Congress (another is the famous three Gorges Project). Probably many people know that the construction of Baosteel laid the foundation for the rapid development of China's iron and steel industry and reached the advanced level of the world.

Why choose "Sun Light" technology? Like the iron and steel industry, with the active advice of the older generation of experts in the aluminum industry, including Cheng Zonghao and Yao Shihuan, and the efforts and support of the former leaders of the Ministry of Metallurgy, in the first year after the reform and opening up, the construction of a number of large aluminum plants was included in the national plan. but what electrolytic cell technology to use has become a difficult problem for decision-makers. At the end of 1970s, Alcoa, French Aluminum and other international aluminum companies have successfully developed large-scale pre-baked cell technology above 160~180kA, and aluminum electrolysis technology began to show the development trend of large-scale and prebaked. According to the recollection of teacher Yao Shihuan and other predecessors, and according to the development of electrolytic aluminum technology at that time, the expert group divided the advanced electrolytic cell types in the world into three modes and compared them.

The first is the North American electrolytic cell. At that time, (Alcoa) was the largest multinational aluminum company in the world. (Alcoa) of Alcoa and (Alcan) of Alcan used 150~220kA large pre-baked anode electrolytic cell (referred to as pre-baked cell) in aluminum plants in Canada and Brazil, which had the advantage of adding alumina in the middle and good tightness, and more than 98% of the harmful flue gas was recycled to meet the environmental protection requirements. However, this type of slot follows the route of high efficiency and high slot voltage, and the power consumption per ton of aluminum is also relatively high, so it is suitable for areas with rich hydropower and low electricity prices in North America.

The second is the European type electrolytic cell. It is a low power consumption slot developed by (Pechiney), a French aluminum company, to represent areas with high electricity prices. As its 180kA pre-baked cell technology (AP18) is still in the experimental stage (only four test cells have just been put into operation, although preparation for the F-series has begun in mid-1977), and as the most advanced 180kA technology just developed by French aluminum, it is unlikely to be transferred. Pechiney recommended to the Chinese side that the maximum current of the mature application at that time was only the 135kA prebaked cell, which added alumina on the edge, and 30% of the harmful gases were discharged unorganizationally. This type of tank seriously pollutes the environment and has to be treated by skylight washing in some areas, which is expensive, and it is obvious that this technology is not in line with China's national conditions.

The third type of cell is the Japanese type of electrolytic cell. With the rapid development of Japanese aluminum industry in the 1960s and 1970s, Japanese companies introduced various types of grooves from the United States, France and Switzerland. After digestion and improvement, the three companies combined the advantages of good environmental protection in the United States and low energy consumption in France. A kind of prebaked cell with low power consumption and good tightness has been developed, with a capacity of 160 to 170kA, which is very suitable for use in China. Several Japanese aluminum companies, led by Japanese Light Metals Corporation, have been entering China since 1976, actively recommending their independent research and development of large-scale pre-baked cell technology. And because of the friendly environment between China and Japan at that time, the use of Japanese technology could obtain the support of long-term loans from the Japanese government.

Since then, the Ministry of Metallurgy has sent a delegation headed by Wang Zhe, a member of the party group, and Cheng Zonghao, secretary general, to inspect 10 aluminum electrolysis plants, carbon plants and aluminum processing plants out of 13 aluminum plants of Japan's six major aluminum companies. Finally, according to the inspection recommendations, it was decided to adopt the large-scale intermediate feeding and closed pre-baking cell technology of 160kA of Japan Light Metal Co., Ltd.

On February 21, 1978, the former State Planning Commission approved the 80,000 ton aluminum electrolysis project of Guizhou Aluminum Plant (referred to as Guizhou Aluminum second electrolysis or the first 80,000 tons of Guizhou Aluminum). On January 7, 1979, Guizhou Aluminum Plant signed an import contract for the construction of 80,000 tons / year aluminum electrolysis plant with Japan Light Metals Company. Based on the prototype of four electrolytic cells newly tested by Japanese Light Metals Company at that time, the second Electrolytic Aluminum Plant of Guizhou Aluminum Plant, China's first 160kA intermediate blanking prebaked cell series with low power consumption and good tightness, was built in Guizhou Aluminum Plant with complete sets of technology and equipment. Guiyang Aluminum magnesium Design and Research Institute (Guiyang Institute) is responsible for the design of the imported project, and China Seventh Metallurgical Construction Company undertakes the task of construction and installation. A total of 208 electrolytic cells have been installed in the series, with an annual production capacity of 80,000 tons, including supporting carbon pre-baked anode manufacturing and anode assembly systems. On December 18, 1981, the aluminum electrolysis project, which had the largest single series production capacity and the most advanced equipment in China at that time, was officially put into production.

How to evaluate the "daily light" technology? The introduction and construction of "Riqing" 160kA electrolysis series was the first large-scale pre-baked cell series in China at that time, which belonged to the advanced level in the 1970s. In order to let everyone see clearly, the design features and main index parameters are described as follows:

(1) the design current intensity is 160kA, the working voltage of the cell is 4.05V, the current efficiency is 87.5%, the DC power consumption is 13600kWhptAl, and the number of anode effects is once per cell day. This index does not look very advanced today, but it is much more advanced than the domestic self-baking cell current efficiency of 840.86% and DC power consumption above 15000kWh/tAl at that time.

(2) the bus configuration is designed for power supply at both ends, and there is a compensation bus drawn from the middle to the end at the bottom of the slot, and the design mode of power supply at both ends is not the most advanced at that time, but the influence of magnetic field is considered and reasonable compensation is carried out at the bottom of the slot.

(3) the middle feeding mode is adopted, the material is cut at two points, the capacity of the feeder is 15kg, the material is fed once for 20 minutes, the amount of material is 90kg per hour, the pneumatic feeder (chute control) is adopted, and a special fan is arranged at the end of each trough. The control system adopts the effect control mode to control the alumina concentration. The design of the structure and capacity of the blanking device is the biggest short board of the Japanese technology, and it is also the main cause of many problems, such as the precipitation of the electrolytic cell, the fluctuation of the cell condition and so on.

(4) the size of anode is 1400 × 660x540, the number of anode group is 24, and the current density of anode is 0.72A / cm ~ 2.The selection of anode is proved to be reasonable, and the later development in our country is basically improved on this basis.

(5) the anode lifting mechanism adopts four-point lifting, which is a turbine worm mechanism with stable and reliable operation.

(6) the processing surface is: large noodle 525, small noodle 595, anode seam 250. This is also one of the manifestations of its backward design, due to the influence of European technology edge processing (feeding), the processing area is larger.

7 there are 208160kA electrolytic cells installed in the electrolysis workshop, which are arranged in four factory buildings, which are divided into 8 zones, with 26 cells in each zone. The factory building adopts a two-story structure with an operating platform of + 2.4m and an all-steel structure. The span of the workshop is 20.5m, the distance between the two buildings is 25m, the distance between the electrolytic cells is 6.575m, which is determined by the operation requirements of the electrolytic cell and the design of the busbar configuration, the anode tray is transported to the short end of the electrolytic cell by a special vehicle, and the 5t aluminum table bag is transported from the crane to the short end of the electrolytic cell to complete the aluminum discharge operation, this design scheme is reasonable.

(8) the technology of SCR rectifier and dry purification flue gas treatment of Fuji Company of Japan was adopted. The rectifier station and the flue gas purification system are respectively installed at the two ends of the electrolysis workshop, which is different from our configuration today. The advantage of this configuration is that the distance between the electrolytic cell row and the row can be smaller, and every two factory buildings (two rows of tanks) correspond to a set of purification system. Because the length of the factory building is relatively short, the distance of the flue gas pipeline is also short. This plane configuration scheme was reasonable at that time, and it was copied in the design of the third electrolysis of Guizhou Aluminum and Qinghai Aluminum Plant. With the increase of the scale of the series, our later design adopted the mode of arranging the purification system between the electrolysis plants.

The "Riqing" 160kA intermediate cutting pre-baked electrolytic cell with an annual capacity of 80, 000 tons introduced by Guizhou Aluminum Plant

The main results are as follows: (1) the transportation of alumina materials adopts two forms: fresh alumina from alumina plant is fed into 8000t silo (steel structure circular silo), and 400t daily consumption silo is sent by pneumatic conveying (chute) and bucket elevator; 85% of the fresh alumina is added to the purification system to absorb the fluoride in the flue gas, and the fluorine-loaded alumina recovered from the purification is fed into the 300t fluorine-carrying public electrolytic cell through the chute and the hoist, and the automatically controlled electric trolley regularly sends the fluorinated alumina to the 5t tank wall material box set by each electrolytic cell for each electrolytic cell to use. Another 15% of the fresh alumina is added to the electrolytic cell by crane feeding as an anode insulation covering material.

(2) the workshop is equipped with 8 multi-function operating units produced by ECL in France to complete the main operations such as aluminum discharge, pole changing and busbar lifting in the electrolytic cell.

Today's large-scale slot technology has changed a lot, and the core technology of the main body is not what it used to be, but in many engineering details, experts can still see the traces of "daily light" technology at that time.

Unexpected-- the problem is exposed when it is put into production. There is something wrong with the "Sunlight" technology! Many people still remember it. The development of things is often beyond people's expectation, due to the technology itself and construction quality, operation level, management factors and other reasons, in the initial period of production for as long as 3 or 4 years, there are a variety of problems in the production and operation of the imported "solar light" electrolytic cell: high temperature, poor furnace side formation, long legs, too much precipitation at the bottom, frequent problems, low efficiency and high energy consumption. What is particularly prominent is that the early damage of the electrolytic cell is serious, and the life of most of the cells is less than 1000 days (the life of the designed cells is 1500 days).

As a major project introduced by the state, the emergence of major problems will inevitably cause a great reaction, and even attract the attention of national leaders. As the largest aluminum factory in the country, the industry benchmark is a famous brand among Guizhou enterprises. State leaders must inspect Guizhou aluminum when they come to Guizhou. Today, you know that Guizhou has Maotai liquor, but you do not know that Guizhou aluminum paid more attention than Maotai in the 1980s. Therefore, there is a lot of pressure on all aspects of the problems after the project is put into production. Han Peichuan, the first factory director transferred from Guiyang Hospital, was removed from his post (an outstanding aluminum electrolysis expert entrusted with an important task, called "carrying the pot" in today's words), and the design, construction and construction parties were all very nervous. So what are the causes of these problems?

On the one hand, of course, they actively negotiate with the Japanese side, believing that the technology of the other side is not mature (according to veteran comrades, the technology sold by "Nikko" to China is indeed the latest, but there are only four industrial test tanks). From the legal point of view of the performance of the contract, the other party is required to bear responsibility. Japan also feels aggrieved. Although it cooperates actively, it still does not recognize China's doubts about its technology, believing that there is something wrong with the construction quality and production management of the Chinese side. As a matter of fact, during the construction and commissioning of the project, there was indeed a conflict between the personnel of the two sides because of lax supervision over the project: a Chinese personnel did not work according to the rules, causing dissatisfaction among Japanese personnel and began to beat Chinese personnel. because this incident also led to diplomatic disputes, all these have become other people's "evidence". Some conflicts were spread as anecdotes by many people at that time. It is hard for people to imagine these things in the early days of reform and opening up. As a result, the two sides carried out long-term seesaw research, analysis, verification and negotiations. On the other hand, based on the domestic environment at that time, these problems also attracted the attention of industry leaders and experts, aroused the enthusiasm of research and discussion in colleges and universities, major designers and research institutes across the country, and made a lot of research results and conclusions. however, all kinds of views and views are not the same, of course, they may not be correct today. In retrospect, due to the influence of the Cultural Revolution in the past ten years, the technical foundation in China at that time was relatively weak, and this kind of discussion and research itself was very meaningful.

Appearance of electrolysis series introduced by Guizhou Aluminum Plant

The impact is far-reaching. In fact, the introduction of the second electrolysis series of Guizhou aluminum has been highly concerned by the aluminum industry and the whole society. For a long time from the early 1980s to the 1990s, it represents the highest level of China's electrolytic aluminum industry, and it is also a template for many domestic electrolytic aluminum enterprises to learn and emulate. Although there are problems of one kind or another, the majority of aluminum industry scientific and technological workers still maintain a modest and realistic attitude towards it, from which they learn and understand a large number of new technological concepts and achievements of modern aluminum electrolysis.

The important decision of adopting the technology introduced from Japan to build the second electrolytic series of Guizhou aluminum has made China's electrolytic aluminum industry and the pace of reform and opening up maintain the rapid development of Synchronize, and opened the prelude to the development of modern large-scale aluminum electrolysis technology in our country. it has had an extremely far-reaching impact on the development of China's electrolytic aluminum industry in the next 40 years. Today, this decision is very wise. While we are proud of the development of electrolytic aluminum today, we should thank the older generation of aluminum industry scientists for their great foresight and historic contribution to the electrolytic aluminum industry.

Digestion and absorption of imported technology in the whole industry

From the perspective of national strategy, the decision to introduce the project of Guizhou Aluminum Plant is not only to build an aluminum plant, but also to change and upgrade an industry.

From 60kA small pre-baked cell to 135kA. Before the introduction of Japanese technology into Guizhou Aluminum, some research work has been carried out in the development of pre-baked electrolytic cell technology in China. According to the records of "60 years of New China Nonferrous Metals", the earliest pre-baked anode electrolytic cell in China was built in Zhengzhou Aluminum Plant in 1964. Because the anode of the 75kA side-inserted self-baking cell introduced by the former Soviet Union is too wide (3600 × 2500), the voltage is too high and the needle pendulum is serious, so it must be reformed. In this case, the 80kA pre-baking cell without groove cover is designed for the first time.

In 1978, Fushun Aluminum Plant cooperated with Shenyang Aluminum-magnesium Design Institute (Shenyang Institute) to transform part of the fourth series of electrolytic cells into 23 135kA edge feeding pre-baked cells under the guidance of experts such as design masters Yang Ruixiang and Han Fuye. The pre-baked cell expansion test was carried out and was put into production in November 1979, which was the first on the road of large-scale. The groove was later applied in the construction of Baotou Aluminum Plant and won the second prize of national scientific and technological progress in 1987.

However, it was not until the introduction of your aluminum 160kA pre-baked cell that it quickly attracted the attention of the whole aluminum industry, changed the process of technological progress of electrolytic aluminum, and really opened the curtain of the technological development of large-scale pre-baked cells in our country.

How to evaluate the introduction project of "Japan Light"? Decades later, the debate on the "Japanese light" technology has gradually died down, but what kind of problems these problems belong to has not formed a unified conclusion in the end. At that time, a group of domestic experts rationally realized that Japan's technology as a whole should be said to be advanced, and that various problems were to some extent due to our lack of thorough eating and lack of experience in a short period of time. In addition, there is indeed a certain gap between the domestic industrial foundation, construction and production management level and the modernization level at that time. Yin Ensheng, the first group of experts directly involved in the introduction project at that time (an outstanding aluminum expert and later general manager of Guangxi pingguo Aluminum), believed that at that time, China was still a "white hat" in the technology and management of large-scale pre-baked tanks.

After calmly analyzing and evaluating the advantages and disadvantages of the "Japan Light" technology, people gradually found that: first, the Japanese technology was indeed advanced at that time, and it is not an exaggeration to call it the international advanced level in the 1970s; second, under the overall technical background at that time, the design scheme provided by the Japanese side is basically impeccable, even perfect; Third, the technology provided by the Japanese side at that time was complete and detailed, which was not found in our later imported projects and any domestic engineering design.

In the process of introducing the "Riqing" project into Guizhou Aluminum Plant, many people have noticed the fact that the technical data and drawings provided by the Japanese side of the project are very detailed, including the project feasibility study report, project basic design documents (preliminary design) and construction drawings. In the archives of Guiyang Hospital, it is not too much to describe the technical documents of this project in tons. In addition to the normal engineering and technical drawings, the technical data provided by the Japanese side also include the determination of various working procedures of the whole plant, various technical schemes, research and discussion of various technical problems, and so on, with detailed calculation and detailed data and analysis basis. some calculation methods and programs are also provided. For example, "the selection of the machining surface of the electrolytic cell", "the calculation and determination of the furnace depth of the electrolytic cell", "the calculation and determination of the thickness of the covering material in the electrolytic cell" and so on, all have special information to provide. It also includes some "three fields" calculation data and programs, computer control models and software data, and so on.

It should be said that Japan's attitude towards technology transfer in that year was sincere. As for why Japan can be so generous? The author understands that there are several explanations: first, it is related to the background of Sino-Japanese friendship at that time; second, Japan is facing a serious energy crisis in the 1970s, and the high energy-consuming electrolytic aluminum industry has lost its survival conditions in Japan and has been faced with a situation of total shutdown. these technologies have no prospect for them, and technology transfer may be the only way out. There is also a possibility, because at that time, the project was introduced in complete sets, except for the design and construction of supporting projects, almost all materials and equipment were from or purchased by Japan, and the contract also included technology transfer. that is to say, Japan's operation in accordance with the contract is in line with international practice. According to the relevant data, this situation is very similar to the introduction of Baosteel at that time. There may be other explanations for the real reason, but in any case, some people think that the introduction spent a lot of money (about 200 million US dollars) on a pile of junk, and some even think that we were deceived by the Japanese. These are serious misunderstandings that do not know the inside story.

Digestion, absorption and research have been carried out in an all-round way. The introduction of the project has refreshed the experts in China's electrolytic aluminum industry, and has since opened the door for the exploration of new technologies. While actively studying and discussing the problems existing in the introduction of technology, industry experts have reached a consensus (of course, this is also the requirement of the state): we must organize forces to digest and absorb and master the imported technology as soon as possible, to prepare for the next development of China's electrolytic aluminum industry. Under the organization and arrangement of relevant industry leaders of the state, a number of research groups on digestion and absorption of imported technology have been organized by Guiyang Institute, Shenyang Institute, Guizhou Aluminum Plant, Zhengzhou Light Metals Research Institute, Qinghai Aluminum Plant, Baiyin Aluminum Plant (a large-scale electrolytic aluminum plant planned by the state), Central South Mining and Metallurgical Institute, Northeast Institute of Technology, etc. A series of research work has also been carried out. The country has set off a long-lasting process of digesting and absorbing the best part of the imported technology.

Although the electrolytic cell technology provided by "Riqing" lags behind today, it brings us a brand-new technology and design concept in terms of the overall development level of aluminum electrolysis technology at that time. At the same time, because the Japanese side has provided very detailed technical data, it has played an important role in learning and mastering the basic design methods and operation standards of modern aluminum electrolysis plants, and is of great benefit to the rapid research and development of our own large-scale electrolytic cell technology. it greatly shortens the process of our research and development of modern aluminum electrolysis technology.

At the beginning, a large number of studies on the 160kA electrolytic cell are focused on the life of the cell. Qiu Zhuxian, Yao Shihuan, Jiang Xianhuan, Yao Guangchun, Yu Zongyao and Zhao Wuwei published many articles, focusing on the damage mechanism of the electrolytic cell and the analysis of the causes of lining damage under production conditions. Wang Liruo, Sun Xiaozeng, Gan Yiren and Song Yuanwen paid more attention to the reasons that affect the life of the cell and how to prolong the life of the cell. Based on the study of the mechanism of early damage of electrolytic cell, he Zhihui, Liang Xuemin and Liao Xianan put forward the main design principles and design methods of electrolytic cell lining structure in order to prolong the life of electrolytic cell. As the problem of damage of large electrolytic cells in China is very prominent in the early stage of the introduction of technology, the research in this field has been highly valued by experts in the industry. The scope of the study is not only extensive, but also has lasted for many years, and achieved a lot of research results, which will not be detailed here. In 2002, Mr. Wei Hanguang, a leading figure in the aluminum industry, specially wrote an article to analyze and suggest the measures and significance of prolonging the life of the tank, and expressed his concern about this problem. It can also be said that the problem of cell life has always been a lingering nightmare of electrolytic aluminum technology in our country.

In order to grasp the imported technology and develop China's aluminum electrolysis industry as soon as possible, Yang Hongru and others took the lead in organizing domestic research units and electrolytic aluminum backbone enterprises to carry out a new process test for the production of domestic intermediate alumina in Guiyang aluminum 160kA intermediate blanking pre-baking cell. the results of this research provide a basis for the introduction of cell type and technology in the engineering design of Qinghai Aluminum Plant and Baiyin Aluminum Plant built in China.

Professor Shen Shiying of Northeast Institute of Technology deeply studied the electrochemical principle and energy balance of electrolytic aluminum, analyzed the energy demand of electrolytic aluminum process from the point of view of chemical thermodynamics, and put forward the famous theory of "regional energy self-consumption". Professor Li Delin carried out an enhanced current test on the imported production line. Professor Cai Qifeng of Central South Institute of Mining and Metallurgy has developed a school of his own in the research on the flow and measurement methods of liquid aluminum.

At the same time, attention has been paid to the electromagnetic field and the structural design of the electrolytic cell. Song Yuanwen and Gan Yiren made a comprehensive test and analysis of the magnetic field of the 160kA electrolytic cell by using the Bell620 three-digit Gaussian meter; Pan Yangsheng and Wu Liyang discussed the simulation calculation method of the magnetic field adopted by the Japanese side; Wuwei and Yang Hongru further studied and analyzed the corresponding relationship between the magnetic field measurement results and the distribution law of the furnace side shape in the tank, and put forward some suggestions for the improvement of the electromagnetic field.

In 1985, the newly built 100000 t / an electrolytic aluminum project of Qinghai Aluminum Plant (after the completion of the 200000 t / a scale) and the expansion project of Guizhou Aluminum Plant with 80 000 t / a selected the imported "Riqing" 160kA tank technology as the prototype, which was successful.

The upsurge of localization of supporting technology and equipment. The introduction of the project in Japan brings not only the electrolysis technology itself, but also a complete set of technology, equipment and industrialization system matched with modern aluminum plants. It includes the main operating equipment of electrolytic aluminum, power supply rectifier unit, carbon system equipment, anode assembly, alumina transportation, electrolytic flue gas dry purification and various transportation equipment, etc. As there are too many kinds of key equipment, here are only examples.

The rectifier system equipment is mainly transformer and rectifier unit. The imported project adopts the SCR rectifier technology of Fuji in Japan. By digesting the imported technology, the technical requirements of the electrolytic series production on the system are basically made clear, and the main difficulty focuses on the difference between using SCR or diode rectifier in the rectifier unit. Due to the rapid development of electrolytic aluminum, but the scale was still small at that time, the research and development of special variable voltage rectifier equipment lagged behind. From the point of view of process technology, SCR rectifier is the best choice to adapt to the voltage and current stability of electrolytic series, but there is no manufacturing capacity in China, only Japanese or European equipment is introduced, but the investment is huge. Using domestic equipment, we can only adopt the way of "diode + saturated reactor". At that time, the enterprises producing transformers for electrolytic aluminum included West change, Jiang change, Liu change, etc., and rectifier production enterprises such as West Integration and Nine Integration. Basically meet the needs of the development of domestic electrolytic aluminum, this situation has been going on for many years. In the stage of rapid development of electrolytic aluminum at the beginning of this century, the scale of electrolytic series is expanding rapidly, while the corresponding development lags behind, and all kinds of accidents caused by quality problems of transformers and rectifiers occur from time to time. So that many aluminum factory entrepreneurs still think of lingering fear. All this has become a valuable experience, which has led to the electrolysis of aluminum today.

The price of the multi-purpose crane-- one after another. Multi-function crane (unit) is the main operation equipment of electrolytic aluminum production, which undertakes the main operations of electrolytic cell, such as aluminum discharge, pole changing, busbar lifting and so on, and its importance is second only to electrolytic cell and rectifier equipment. In the world, only a few famous equipment enterprises such as French ECL, German NKM and so on can produce, and French ECL equipment is used in your aluminum import project.

Since the first domestic copying project, Guiyang Hospital, Shenyang Hospital and Guizhou Aluminum Plant, as well as Shenyang Nonferrous Metallurgical repair and Manufacturing General Plant (Shenyang smelter), the backbone equipment manufacturing enterprise in the non-ferrous metal industry, have taken on the important task of design and development. The chief designer of the unit in Guiyang Institute is Mr. Liu Zongjun, the chief engineer, who is a very excellent mechanical equipment designer. In order to solve many technical problems in unit design, he has extensively investigated and studied in different mechanical fields. The story that he discussed train anti-collision technology with railway experts on a business trip and successfully applied it to the design of multi-function units is a good story in Guiyang Hospital. The first batch of multi-function units manufactured by Shen Yexiu were applied in the third Electrolytic Aluminum Plant of Guizhou Aluminum works. In addition to special air compressors and shelling heads, the whole multi-function units were directly localized. However, equipment manufacturing is a very complex and sophisticated work. After the production of the third electrolysis of your aluminum (replica introduction), there have been a lot of problems in the multi-function crane. Mr. Liu Zongjun led the technical staff to adhere to the front line for a long time, and finally figured out the cause of the problem, which was highly praised by Mr. Yang Guang, the then factory director, but Mr. Liu Zongjun eventually fell into a heart attack due to overwork and fell at the work site of Guiyang Aluminum. Under the background that we are talking about revitalizing the equipment manufacturing industry today, we deeply admire the sense of responsibility and fearless spirit of our predecessors who bravely shouldered the heavy burden of revitalizing the aluminum industry 30 years ago.

Full localization. In order to solve the problem of localization, at that time, many equipment were first considered by the strongest domestic manufacturing enterprises to undertake the task of digestion and development. In addition to the multi-function unit and the carbon anode vibration molding machine manufactured by Shen Yexiu, the anode lifting mechanism of the electrolytic cell, the busbar lifting frame and the aluminum table bag are all commissioned by aerospace systems (such as 222 plant, 170 plant); aluminum ingot continuous casting machine is manufactured by Kunming heavy Machinery Factory; special transport vehicles are manufactured by Liuzhou Special vehicle Factory. After the third electrolysis project of Guiyang aluminum, the barrel-type feeder was first successfully developed by 170 Plant. After analyzing the shortcomings of the technology introduced in Japan, Song Lijuan and Liu Changli of Guiyang Hospital first developed an European-type feeder.

A silent feeding car. After 40 years of development, our technology in all aspects has far exceeded the level introduced by Japan at that time, and the power consumption per ton of aluminum has about reduced 1000kWh. However, there is one technology that China has not dared to try, that is, in the alumina transportation system, from the fluorine alumina silo of the purification system to the electrolytic cell, the Japanese side adopts the technology of "electric trolley", which is automatically fed by the electric trolley every day, and then automatically sends the material every day to the 5t material box (called "tank wall material box") in which each electrolytic cell is set above the smoke exhaust pipe between the pillars of the factory. This wall material box can be seen in the picture in the previous section. It has been put into production for many years and the operation of the system is very stable. Over the years, in the previous large-scale engineering design, only as an alternative, but generally have to consider the introduction, no one has ever developed this system. The author only wants to introduce that there is such an interesting technology in this project, but no one has tried it so far, which may represent the level of automation in Japan at that time.

A solid foundation. Through the introduction of engineering digestion and absorption, we have brought a lot of aluminum technology and equipment, which are not described here one by one. Over the past few decades, the waves have swept the sand, and the supporting manufacturing enterprises are no longer the ones they used to be. today, we have realized the localization of a full set of equipment for electrolytic aluminum. More importantly, the introduction project of Guizhou Aluminum Plant has laid the foundation for us to establish a modern aluminum electrolysis industrial system.

Today, in the face of the arrival of the era of industrial intelligence, the upgrading and modernization of the electrolytic aluminum equipment manufacturing industry is still the first to bear the brunt of the major proposition.

Study on four physical Fields ("three Fields")

What is a physical field? It is the abbreviation of numerical calculation and simulation technology of various physical characteristics of electrolytic cell, which is commonly known as "three fields" in the industry. People outside the industry do not know, but they do not know the "three games" in the electrolytic aluminum circle, which will be laughed at by others. People in the circle call those of us who are engaged in this field "three players", a label that has been used for many years. Once a colleague, one day saw the author, very surprised to say: so-and-so experts unexpectedly do not understand the "three games"? By implication, it is necessary to understand the "three games". It can be seen that the significance of the "three games" to the industry at that time.

Since the 1970s, with the development of computer technology, it is possible to use numerical calculation methods to establish mathematical models for computer simulation to solve all kinds of engineering science problems. It can not only reduce the cost of laboratory and industrial test, but also shorten the cycle of industrial test and greatly reduce the test risk. at that time, it has become an important means of scientific research and experiment in various fields. Computer modeling technology plays an important role in both water conservancy dam and satellite.

Open up the subject of "three fields"-- the vision of Wuwei senior engineers. In the early 1980s, fundamental changes are taking place in international aluminum electrolysis technology during this period. The research of mathematical model and computer simulation technology of aluminum reduction cell has become the core technology of aluminum electrolysis technology research. Major aluminum companies in the world have developed their own large-scale pre-baked cell technology on this basis. A number of modern large aluminum reduction cells such as French aluminum (Pechney) AP18 (180kA) and Alcoa Amur697 (~ 190kA) have been born and put into industrial operation.

Some old experts represented by Wuwei, Yao Shihuan, Jiang Xianbin, Song Yuanwen, Gan Yi people, etc., are soberly aware that in order to understand and solve the problems existing in imported technology, we must closely follow the development trend of international aluminum electrolysis technology. starting from the basic research of physical field, simple digestion and absorption is difficult to support the future development of electrolytic aluminum technology in China. In other words, we must systematically research and develop the physical field mathematical model and computer simulation technology of our own modern large-scale aluminum reduction cell in order to lay a solid foundation for China's aluminum electrolysis technology to catch up with and surpass the international advanced level.

At that time, computers were new to most people, and there were not a few people who disagreed with computers and thought it was of little value to practical work. At that time, the author often heard such a debate about the usefulness of the computer, and even some veteran engineers thought that the computer could not compete with the slide rule in his hand. Even in a "three" seminar a few years later, a veteran comrade jokingly said: just a few taps on the keyboard, "Gudu" out of a pile of paper, what's the use? It can be seen how rare it was for Wuwei people to have such foresight at that time.

The "three fields" research project was launched. In September 1983, Wu Wei and others applied to Guiyang Academy to set up a "three fields" research group to carry out "three fields" research work, which was strongly supported by Master Yao Shihuan, who was the chief engineer at that time. Mr. Cheng Zonghao, the old dean, an old comrade who came from the war of liberation, the older generation of scientists and veteran cadres who were injured and lost their left arm in the experiment, with his unique sense of smell for the cutting edge of science and technology and the courage to act vigorously, decisively decided that while applying for the establishment of the project by the government, the design institute raised 30,000 yuan to start the research of the project in advance. As a scientific research project launched without a government project at that time, it is unique. Therefore, the three research groups headed by Wuwei were set up, and the leaders of the institute personally coordinated the transfer of he Zhihui, who majored in electrical automation, Wu Youwei, who majored in mechanical equipment, and authors who had just graduated from thermal engineering, to form a research group to carry out the study of electromagnetic characteristics, structural mechanics and electrothermal field respectively.

The association of colleges and universities. Electric heating field research was jointly carried out with Central South University (then Central South Institute of Mining and Metallurgy), team members Mei Chi, Tang Hongqing, Shi Zhangming, Meng Boting, etc.; electromagnetic field research was composed of Chen Shiyu and Sun Min of the Electrical Department of Huazhong University of Science and Technology (then Huazhong Institute of Technology); structural mechanics research was jointly carried out with the Department of Mechanics of Huazhong Institute of Technology, and was carried out by Liu Liequan, Qiu Chongguang, Qin Qinghua and others. According to the level of computer development at that time, due to the limitation of memory capacity, the initial work was completed on the minicomputer of the Computing Station of Central South Mining and Metallurgical College and the Computing Center of Guizhou Provincial Planning Commission.

Since November 1983, the electrothermal analysis research started on the basis of digesting the computer simulation research report on the electrothermal analysis of the cathode of aluminum reduction cell, and the calculation results of "daily light" were completely digested and reproduced in more than half a year. And the simulation models and software of cathode and anode current field, temperature field and thermal flow field have been developed successfully. The research of electromagnetic field began to work in the first half of 1984, and important progress has been made in the second half of the year. the simulation results of electromagnetic field in Japan have been established and reproduced, and the research work of structural mechanics has also entered a substantive stage. The progress of the research work produced great repercussions in the whole project team, which encouraged the leaders of Guiyang Hospital and aroused the enthusiasm of the whole hospital to carry out this research work.

Gao Gong Pei Shangkui and Tian Tingliao of Shenyang Academy, Wu Liyang and Pan Yangsheng of Guizhou Aluminum Plant, and Song Yuanwen and Gan Yiren of Zhengzhou Light Metal Research Institute (Light Research Institute at that time) were also the earliest researchers of electrothermal and electromagnetic fields of aluminum reduction cells in China, contributing to the research in this field.

Supported by the head office. With the deepening of the research work, the project team has a clear understanding of the core technical issues of the "three fields" research. In order to establish an accurate and reliable mathematical model of physical field and computer software, a reliable mathematical model must be established by numerical method on the basis of reasonable selection of reliable physical model. The most critical factor that determines the reliability of simulation technology depends on reliable boundary conditions, which is a long-term and important work. In order to conduct a more in-depth study of the "three fields", the Guiyang Institute submitted an application for the establishment of a project to the former China Nonferrous Metals Industry Corporation (hereinafter referred to as the China Nonferrous Metals Industry Corporation or Corporation), which had just been separated from the Ministry of Metallurgy at that time, and was approved in 1984. as a key project of the sixth five-year Plan, it has received a state grant of 300000 yuan. During the same period, Shenyang Institute and Light Research Institute also set up special research groups and signed research contract assignments with Nonferrous Metals Corporation respectively to carry out research work.

Mei Chi leads the team-- foreign exchanges. Mitsubishi Light Metals Research Institute of Japan had certain advantages and influence in the field of international aluminum electrolysis technology at that time, and had world-renowned aluminum electrolysis experts such as Kohiko Ikei, whose aluminum plant 106kA located in Zhijiangjin once created the record of the world's lowest energy consumption for 12600kWh/tAl. In order to speed up the development of China's aluminum industry and promote the technological innovation of the self-baking tank aluminum plant, which is dominated by domestic production capacity, the state decided to introduce the production line at a low price. Mr. Kang Yi, the then director of Qingtongxia Aluminum Plant, a strategic entrepreneur (who later served as the chairman of China Nonferrous Metals Industry Association for a long time) was responsible for the negotiation of the introduction of the project. According to President Kang, the negotiation work was extremely difficult, and the negotiations on the whole project in Japan lasted more than half a year. With the great attention of Mr. Mei Rongchun, the new president of Guiyang Hospital, and the active efforts of Mr. Jiang Xianyu, Deputy Chief engineer, and with the opportunity of introducing the electrolytic aluminum production line of Mitsubishi Company of Japan from Qingtongxia Aluminum Plant, Guiyang Hospital proposed to use the self-developed physical field simulation technology to simulate the design of Mitsubishi 106kA electrolytic cell and to carry out technical exchange and cooperation with Japan. Proceeding from the overall situation of the technological development of the aluminum industry, Kangyi attached great importance to this exchange and cooperation, and included it in the cooperation negotiations with Mitsubishi, and finally successfully reached an agreement between the two sides on the special technology exchange.

In September 1984, dispatched by China Nonferrous Metals Industry Corporation, Professor Mei Chi (who later served as vice president of Central South University of Technology), Wu Wei and the author formed a visiting group. He was sent to Niigata and Yokohama in Japan for a 40-day study exchange with experts from Mitsubishi Light Metals Research Institute. Mitsubishi introduced to the Chinese side the advanced research achievements of Mitsubishi in the field of physical field simulation, especially in the research of two-dimensional electrothermal, electromagnetic field model and magnetohydrodynamics, by the aluminum electrolysis expert systems of Haruhiko Ikeda, Sadakuke Ikeda and Yoji Youtian, etc. At the same time, the two sides exchanged the simulation results and design scheme of 106kA cell. In the course of the exchange, the physical field simulation results and design schemes completed by the Chinese side were highly appraised by Japanese experts and were amazed at China's research progress in this field.

Through this learning exchange, we shared Mitsubishi's research achievements and experience in this field, expanded the vision of the research group, and further made the research group realize the significance and value of this work. We also realized the gap between us and the international level, which played a great role in promoting the later research work and became a new starting point for this research.

The research of each group is promoted in an all-round way. After that, the research of physical field has made rapid progress. In less than two years, important achievements have been made in the study of quasi-three-dimensional coupled electrothermal model of cathode and anode, the influence of electromagnetic field and ferromagnetic material, the simulation of magnetic fluid characteristics, the simulation of stress field of slot structure and so on. Professor Mei Chi and graduate student Tang Hongqing of the author's group have made outstanding achievements in the simulation of electrothermal field, while Professor Chen Shiyu, Associate Professor Sun Min and he Zhihui have made important contributions to the study of electromagnetic field. Professor Liu Liequan, Associate Professor Qiu Chongguang and Wu Youwei have made great contributions to the study of the structural mechanical model of the electrolytic cell. The research results form a special collection of research papers on "three fields" of aluminum reduction cell (some papers are published in Journal of Huazhong Institute of Technology (special issue) 1987.2).

At the beginning of 1985, the project team, including each undertaking unit, reported the next research progress and research plan to the Science and Technology Bureau of China Nonferrous Corporation. This meeting, on the one hand, highly affirmed the work achievements of the project research team, on the other hand, proposed to speed up the experimental verification of the research results, so as to prepare for the technical development of modern aluminum reduction cells in our country.

For the introduction of technology to do surgery-151, 15 years test. Few people in the industry may have heard of the experiment, but this little-known work is an important turning point in the self-awareness of China's aluminum electrolysis technology. The purpose of developing the mathematical model and simulation software of physical field is to guide the development of aluminum reduction cell. In order to verify the reliability of the mathematical model, it is a necessary process to verify it in the industrial electrolytic cell. But it's a big deal to operate on a Japanese electrolytic cell! If you fail.

In June 1985, with the support of Nonferrous Corporation, Guiyang Hospital and Guizhou Aluminum Plant selected two test cells in the 160kA series imported by Guizhou Aluminum, and made use of China's own "three fields" research results to carry out the transformation test of the imported electrolytic cell, which is the so-called "151,151T cell test". The person in charge of the test is a senior engineer in Wuwei, the calculation of electromagnetic field is completed by Comrade he Zhihui, and the simulation of electric field and the design of lining structure are carried out by the author. Those who took part in the experiment were Wu Shaomei, Leng Zhengxu, Wang Youlai of Guizhou Aluminum Plant, and so on. The specific test contents are as follows:

The main results are as follows: (1) in view of the causes of the early damage of the electrolytic cell, the electrothermal analysis simulation software developed independently simulates the electrolytic cell, redesigns the inner lining structure of the electrolytic cell, and carries out the transformation test of the inner lining on two sets of electrolytic cells.

(2) the blanking mechanism and process system have been improved to shorten the feeding interval;

(3) using the self-developed electromagnetic field calculation software, the experiment of "four-point power-in" bus configuration of 1500A electrolytic cell was carried out, and two column busbars were added in the middle of the large surface, and the current was 15000A each. That is, the incoming power ratio is 6.5, 1.5, 1.5, 6.5.

The experiment has been carried out for a year and a half. Although it is limited by the slot structure and many congenital conditions, the busbar configuration scheme has only made an attempt to power in the middle in a small proportion, and there is no possibility to improve the machining surface. However, great success has been achieved, and the effect of the test is very obvious: the shape of the furnace side in the test trough is improved, and the leg extension is obviously shortened, especially the magnetic field effect of the 15-inch slot has been greatly improved, which proves that the four-point power supply (especially the power supply of large noodles). Although the current is small) is a desirable direction.

According to the appraisal of experts organized by the non-ferrous Corporation, the technical index is: the current efficiency is 91.52%, the current efficiency is increased by 4%, and the DC power consumption per ton of aluminum is 13112kWhhand TA, which is reduced by about 500kWh. At the same time, the test results also found that although only 15ft cell has been reformed with four-point power supply, the magnetic field of 15T cell has also been improved to a certain extent, indicating that the two column busbars located on the large side have a positive impact on the magnetic field of the adjacent electrolytic cell.

The success of the 151 and 15 trough experiments not only broke the mystery of Japanese technology, but also greatly increased the confidence of the project team and leaders.

In January 1986, the Science and Technology Bureau of Nonferrous Metals Corporation held a symposium on the summary of research progress in "three fields" attended by research and design institutes all over the country. The meeting comprehensively summarized the scientific and technological achievements in the "three fields" research field of aluminum electrolysis in China. 25 items of work progress were made, of which the achievements of Guiyang Institute accounted for the vast majority. This summary also gives the leaders of Nonferrous Corporation a preliminary but comprehensive understanding of the development of large-scale aluminum reduction cells in China, which has become an important decision-making basis for the follow-up development plan of large-scale aluminum reduction cells.

The shaping of design theory-- the study of "three fields" has passed the appraisal. In November 1986, "Research on Mathematical Model and computer Simulation Program of Thermal, Electrical, Magnetic and Force in Aluminum reduction Cell" passed the appraisal of scientific and technological achievements organized by Nonferrous Corporation.

The main results are as follows: (1) the electrothermal analysis mathematical model and computer program of aluminum reduction cell are developed, and the anode three-dimensional model and cathode "two + three-dimensional" slice model are adopted to establish a quasi-three-dimensional electrothermal analytical integral coupling mathematical model of aluminum reduction cell. it can accurately simulate the current and voltage distribution, isotherm distribution and heat flow distribution in the aluminum reduction cell. (2) on the basis of simulating the magnetic field distribution in the electrolytic cell by using the integral equation of "Biot-Saval" law, the influence of ferromagnetic material on the magnetic field in the aluminum electrolytic cell is emphatically studied by using "magnetic dipole method" and "shielding factor method". The mathematical model and method for accurate simulation of the current field in the melt in the cell are established by using the finite element model. (3) by using the k-ε two-equation model, the simulation model and program of melt flow and interface uplift in the cell under the action of electromagnetic force are developed and established, and the finite element analysis model of the tank shell is established, and through the long-term monitoring of the deformation of the electrolytic cell, a series of studies on the stress characteristics and various loads of the electrolytic cell are carried out, which provides an effective design tool for the optimization of the electrolytic cell structure.

Conclusion: this study forms the theoretical system of large-scale electrolytic cell design in China, which exceeds the Japanese level and reaches the international advanced level. Despite the fact that the level of electrolytic aluminum in Japan is lagging behind, it is of great significance that the evaluation exceeds that of Japan at that time.

In 1992, the research achievement won the second prize of national science and technology progress. This is the first and only scientific and technological achievement awarded by the state in the field of simulation design software in China.

Wuwei Gao Gong, Mei Chi, Chen Shiyu and Liu Liequan are all the author's teachers, and they are also the leaders and pioneers in this field in our country. They have laid the foundation for our research in this field.