Alumini electrolític
L'alumini electrolític és l'alumini obtingut per electròlisi. La producció industrial moderna d'alumini electrolític adopta el mètode d'electròlisi de sal fosa d'alúmina-criolita. La criolita fosa és el dissolvent, l'alúmina s'utilitza com a solut, el cos de carboni s'utilitza com a ànode i el líquid d'alumini com a càtode. Tant electròlisi.
Nom xinès Alumini electrolític
Substancialment alumini obtingut per electròlisi
Mètode Criolita-electròlisi de sal fosa d'alúmina
Requisits de temperatura 950grau-970grau
Indústria moderna
L'alúmina s'utilitza com a solut, el cos de carboni s'utilitza com a ànode i el líquid d'alumini com a càtode. Després d'aplicar un fort corrent continu, la reacció electroquímica es porta a terme als dos pols de la cel·la electrolítica a 950grau-970grau, és a dir, electròlisi.
La producció d'electròlisi d'alumini es pot dividir en tres categories:-vareta d'ànode inserida lateralment-dipòsit de cocció, dipòsit de-vareta d'ànode inserida a la part superior-dipòsit de cocció i pre{{4} }}tanc d'ànode cuit.
La tecnologia d'alumini electrolític de producció de tancs de cocció automàtica té les característiques d'un equip senzill, un període de construcció curt i una inversió baixa, però és difícil tractar els gasos de combustió, la contaminació ambiental greu, la mecanització difícil, la intensitat laboral alta, no és fàcil. a gran-escala, baixa producció per tanc, etc. Les mancances que s'han superat s'han eliminat bàsicament actualment.
Actualment, la majoria de països i empreses de producció del món fan servir tancs pre-precuits a gran{0}}escala. La intensitat actual del dipòsit és molt gran, que no només té un alt grau d'automatització, un baix consum d'energia i una gran producció per tanc, sinó que també compleix els requisits de la normativa de protecció del medi ambient.
el meu país ha completat la prova industrial i la industrialització dels moderns tancs pre-cuits de 180 kA, 280 kA i 320 kA. La millora i transformació tecnològica centrada en l'estalvi d'energia, l'augment de la producció i el compliment de la protecció del medi ambient han promogut la transformació de la tecnologia de producció de tancs d'auto-cocció en tancs de pre-cocció i han aconseguit un gran èxit.
Segons el procés de producció d'alumini electrolític, el cost de producció de l'alumini electrolític es compon aproximadament de les parts següents:
(1) Matèries primeres: alúmina, criolita, fluorur d'alumini, additius (fluorur de calci, fluorur de magnesi, etc.), materials d'ànode;
(2) Costos energètics: electricitat (corrent continu i corrent altern), fuel-oil;
(3) Costos laborals: salaris i altres despeses de gestió;
(4) Altres despeses: pèrdues i amortitzacions d'equips, despeses financeres, despeses de transport, impostos, etc.
Flux del procés
Procés d'electròlisi d'alumini: la producció moderna de la indústria de l'alumini adopta el mètode d'electròlisi de sal fosa d'alúmina-criolita. La criolita fosa és el dissolvent, l'alúmina s'utilitza com a solut, el cos de carboni s'utilitza com a ànode i el líquid d'alumini com a càtode. Això és electròlisi. La reacció química es realitza principalment per aquesta equació: 2Al2O3 més 3C==4Al més 3CO2. Ànode: 2O2ˉmés C-4eˉ=CO2↑Càtode: Al3 més 3eˉ=Al. Els productes de l'ànode són principalment diòxid de carboni i monòxid de carboni, que contenen una certa quantitat de gasos nocius com ara fluorur d'hidrogen i pols sòlid. Per protegir el medi ambient i la salut humana, el gas de l'ànode s'ha de purificar i abocar a l'atmosfera després d'eliminar els gasos i la pols nocius. El producte del càtode és alumini fos, que s'extreu del dipòsit mitjançant una cullera de buit i s'envia a la foneria. Després de la purificació i clarificació al forn de retenció, es col·loca en lingots d'alumini o es processa directament en palanxes i perfils de filferro.
El seu procés de producció és el següent:
Ànode de carboni de sal de fluor d'alúmina DC
↓ ↓ ↓ ↓↓
Electrolitzador de gas------ànode d'escapament
↑ ↓ ↓
Gas d'escapament←Purificació de gasos d'alumini líquid
↓ ↓
Recuperació de fluorur, purificació i clarificació
↓ ↓ ↓
Torneu a l'electrolitzador
Abocament Rolling o Casting
↓ ↓
Lingots d'alumini Billets o perfils de filferro
Equació:
L'alumini electrolític és l'alumini obtingut per electròlisi.
És important seguir aquesta equació: 2Al2O3 més 3C-energitzat→4Al més 3CO2.
Ànode: 2O2ˉmés C-4eˉ=CO2↑
Càtode: Al3 més més 3eˉ=Al
The latest technology
La nova tecnologia d'estalvi d'energia-de l'alumini electrolític surt i la indústria estalvia 27.500 milions de kWh d'electricitat anualment.
On March 17, 2012, China's electrolytic aluminum industry made a new breakthrough in energy saving and emission reduction. "Low-temperature and low-voltage aluminum electrolysis new technology" successfully passed the acceptance of the Ministry of Science and Technology in China Aluminum and Power Company on the same day. It has dropped to 11819 degrees, a drop of 10.7 percent , and many technologies have reached the international leading level. If the whole industry is promoted, the annual electricity saving of my country's electrolytic aluminum industry will be 27.5 billion kwh.
After more than 30 years of development, the electrolytic aluminum industry has gradually become an important basic industry in China. However, due to the high power consumption in the production process, it has always been called a "high energy-consuming industry" and is also one of the key industries controlled by the state. The research and development of low-temperature and low-voltage new technologies is the development direction of energy saving and consumption reduction in the electrolytic aluminum industry, and it is also a major technical problem faced by the world aluminum industry.
In 2009, "low temperature and low voltage aluminum electrolysis new technology" was included in the national science and technology support plan project. Project leader Liang Xuemin and other experts in the project team made unremitting efforts to successfully develop electromagnetic and magnetic fluid stabilization technology, low-temperature and low-voltage electrolytic cell structure, and low-temperature and low-voltage process operation technology for the first time in the world. The world's leading 400KA "static flow" aluminum electrolytic cell has realized large-scale industrial production and a series of high-efficiency and stable operation at low temperature, low voltage and long cycle under high current density.
According to reports, according to the estimated domestic production of electrolytic aluminum in 2012 of 20 million tons, after the promotion of this technology in the whole industry, the annual electricity saving of my country's electrolytic aluminum industry can achieve 27.5 billion kWh, which is equivalent to 265.9 billion kWh of electricity consumption in Henan Province in 2011. More than 10 percent of the time, calculated at 0.53 yuan per kWh, directly creating economic benefits of 14.575 billion yuan, equivalent to 8.8 million tons of standard coal, and reducing carbon dioxide and other greenhouse gas emissions by 15.66 million tons, which will promote the aluminum industry and my country's energy saving and reduction. The platoon work has played a good exemplary and leading role.
Característiques de la indústria
Tot l'alumini del món es produeix per electròlisi. La producció industrial d'electròlisi d'alumini adopta el mètode d'electròlisi de sal fosa d'alúmina de Hall-criolita-, és a dir, la sal de fluorur a base de criolita-s'utilitza com a flux i l'alúmina s'utilitza. s'utilitza com a fosa per formar un sistema d'electròlits multi-fàsics. Entre ells, el sistema binari Na2AlF6-Al2O3 i el sistema ternari Na3AlF6-AlF3-Al2O3 són la base dels electròlits industrials. La indústria de l'alumini electrolític té un gran impacte en el medi ambient i és una indústria de gran consum energètic i alta contaminació. El gas residual descarregat de la producció d'alumini electrolític és principalment CO2 i el fluorur gasós sòlid es compon principalment de gas HF. El CO2 és un gas d'efecte hivernacle i és la principal causa de l'escalfament global. L'efecte hivernacle de CF4 i C2F6 en fluorur és de 6.500 a 10, 000 vegades el del diòxid de carboni, i tindrà diferents graus d'impacte sobre la capa d'ozó. L'HF és un gas altament tòxic que entra al cos humà a través de la pell o les vies respiratòries, i només 1,5 g pot ser mortal.
Hi ha un problema
The actual operating index is poor. Due to the short development time, the in-depth development of China's large-scale aluminum electrolytic cells in the production field is obviously insufficient, resulting in a large gap between the production indicators of actual operation indicators and the international advanced level. Most of them operate in a large load and small grid environment, and there are many hidden dangers. The joint operation of aluminum and electricity is one of the development trends of electrolytic aluminum enterprises in China, but at the same time, there are corresponding problems in technology. Since large-capacity electrolyzers are generally large in scale (one series can produce more than 200,000 tons), and the huge electricity load is concentrated on one production series (generally more than 400,000 KW), any fluctuation in the production of electrolysis series will cause The power grid or self-provided power plants have a greater impact, and even threaten the security of power supply.
Lack of "fine design" technology and comprehensive technical measures to improve the life of the cell based on a thorough grasp of the mechanism and laws of cathode damage, it is difficult for the electrolytic cell to reach the design life and the early damage rate is high. Problems Affecting the Life of Large-scale Electric Cells in China In addition to the quality of cathode carbon materials generally considered in China, there are also some problems in the design of electrolytic cells, furnace construction materials, furnace construction quality, roasting start-up, normal production operations and production management. . The deep-seated reason for these problems is that China still lacks in-depth understanding of the mechanism and laws of aluminum electrolytic cell damage (often called cathode damage), as well as the "fine design" technology and comprehensive technical measures to improve the life of the cell based on this. With the continuous expansion of electrolytic cell capacity, the problem of cell life becomes more prominent.
Lack of advanced production operation technology, high operating costs. China's 300KA class super-large pre-baked aluminum electrolytic cells have been put into industrial application for a short time. And can not completely copy the previous experience in large pre-bake tanks (these experiences also have great limitations). The problem of uneven current distribution during the roasting start-up process is more prominent and the energy consumption during the roasting start-up process is large; the physical field (electric field, magnetic field, flow field) of the electrolytic cell after being put into operation is easy to fluctuate, and it is difficult to maintain thermal balance; It is easy to fluctuate due to external interference, and it is difficult to extinguish after the anode effect occurs, and due to the large inertia of the electrolytic cell, once the cell condition fluctuates or the cell condition is abnormal, it is difficult to quickly return to normal. As far as the overall production status of electrolytic aluminum in China is concerned, the comprehensive energy utilization efficiency is about 15 percent lower than the international advanced level, mainly as follows: the difference in current efficiency is 2-3 percentage points; The difference in energy consumption in the production process is about 3Gj/t; the difference in the consumption of electrolytic aluminum anode is 30-60Kg (equivalent to about 75-150Kg of standard coal); the difference in the life of the cell is about 1000 days; the international advanced anode effect coefficient is 0.1 times/day. Below the cell, The best level in China is around 0.3 times/day.
Sobrecapacitat
Since 2002, China's electrolytic aluminum industry has had a surplus of electrolytic aluminum production. Affected by the decline in demand from downstream industries, China's electrolytic aluminum surplus in 2008 is expected to reach 500,000 tons. The growth rate of electrolytic aluminum demand has slowed down. Affected by the economic crisis, the growth rate of demand from the real estate and automobile industries has dropped sharply, while the demand from the power equipment industry has maintained rapid growth. The demand for electrolytic aluminum in the packaging industry has remained stable. In 2008 The growth rate of electrolytic aluminum demand is around 10 percent . China's bauxite resources are scarce, and the bauxite resources can only be maintained for another 10 years, and it is impossible to support the average annual expansion rate of the electrolytic aluminum industry by about 20 percent . The production cost of electrolytic aluminum is between 15,000 yuan / ton and 17,500 yuan / ton, while the price of electrolytic aluminum is only 13,400 yuan / ton, and the industry has suffered serious losses. Raw materials have fallen further, and the average production cost of Chinese electrolytic aluminum enterprises is also around 15,000 yuan, so the possibility of a sharp drop in aluminum prices is very small. Around June 2009, the aluminum price may return to 15,000 yuan/ton.
When energy prices continue to rise, the world's major aluminum companies began to reduce the cost of electrolytic aluminum production in all aspects to ensure the price competitiveness of aluminum production. From the perspective of domestic policies, the national industrial policy positions the aluminum industry to meet domestic demand, and there will be differences in policies for high-precision products and low-tech products. Therefore, grasping the development trends of transportation, electric power, packaging, household appliances and other industries, and actively introducing advanced equipment, improving technical capabilities and reducing production costs have become the main development direction of the current aluminum company.
Com resoldre encara més la sobrecapacitat de l'alumini electrolític
On the basis of the just promulgated "Guiding Opinions of the State Council on Resolving Serious Overcapacity Contradictions" hereinafter referred to as "Guiding Opinions", researchers from China Industry Insight Network believe that policy implementation and support should be strengthened to further suppress supply and expand demand, and improve both supply and demand. policy, and strive to resolve the overcapacity of electrolytic aluminum. Specific suggestions are as follows.
Pel que fa a l'oferta, es suggereix que s'han d'adoptar múltiples estratègies per reduir estrictament la capacitat de producció d'alumini electrolític. En particular, s'hauria d'accelerar la reforma dels preus de l'electricitat per dissipar l'impuls d'ampliar ràpidament la capacitat de producció.
First, the "Guiding Opinions" should be strictly implemented, "it is strictly forbidden to build new production capacity projects", "categorically and properly handle illegal projects under construction", "clean up and rectify the construction of illegal production capacity", "eliminate and withdraw outdated production capacity", and suggest that violations can be dealt with. Fines are charged for building production capacity to establish a fund for eliminating outdated production capacity, and specific support policies have been introduced for the elimination and withdrawal of production capacity in terms of financial subsidies, enterprise conversion, and employee placement.
Second, effectively eliminate policy obstacles, implement the "integration of a group", and promote the merger and reorganization of enterprises. On the basis of entering the fast exemption/fast review channel for key industries, further study and reduce the cost of mergers and acquisitions of listed companies in the same industry; it is recommended to adjust the power policy to allow leading enterprises to build or absorb existing power generation enterprises to provide cheap electricity for their electrolytic aluminum production Supply; it is recommended to increase support in finance, taxation and other aspects, encourage leading enterprises as the main body of integration, and effectively promote cross-regional, cross-industry, and cross-ownership corporate restructuring.
En tercer lloc, equilibrar el preu de l'electricitat regional, accelerar la reforma del sistema elèctric i eliminar l'expectativa d'enormes beneficis. Tot i que, a llarg termini, les indústries d'alt consum-energètic, com ara l'alumini electrolític, tenen tendència i necessiten transferir-se a les regions occidentals-riques energètiques com Xinjiang, però a curt i mitjà termini, el La transferència completa de la capacitat de producció entre regions requereix un procés gradual, i tenint en compte en termes de capacitat de transport i recursos i factors ambientals, l'expansió de la capacitat de producció a Xinjiang i altres regions occidentals només a causa dels preus preferents de l'electricitat no s'hauria de fer a passos de gegant. Per tant, es recomana prendre mesures per equilibrar el preu de l'electricitat regional i accelerar la reforma de la xarxa nacional. Per exemple, pot ser el primer a pilotar la indústria de l'alumini electrolític al país, i la tarifa del servei de connexió a la xarxa es pot unificar entre 1 i 3 cèntims a tot el país, o permetre la indústria de la construcció en diversos llocs. La xarxa de transmissió d'energia regional pot eliminar la desigualtat dels preus de l'electricitat causada per motius polítics i dissipar l'expectativa de les empreses rellevants d'obtenir excés de beneficis a les regions occidentals com Xinjiang, restringint així l'impuls d'invertir en capacitat de producció i fer que les empreses s'aturin voluntàriament. creació de noves capacitats de producció.
On the demand side, based on the current situation of sluggish external demand and escalating trade frictions, it is suggested to increase domestic demand for aluminum by means of purchasing and storing, expanding the scope of application, etc., effectively "digesting a batch", and improving the processing level of aluminum materials through technological innovation , to obtain higher returns. One is to appropriately increase the country's reserves of aluminum. The country's expansion of the scale of purchase and storage when the current aluminum price has hit a new low in two years is not only conducive to digesting part of the production capacity, promoting the preservation and appreciation of assets, but also building market confidence. The second is to increase RD and financial and taxation support, and actively expand the application scope of aluminum. The third is to actively strive to improve the processing level of my country's aluminum materials and obtain higher profits through technical research and innovation.
Situació de l'oferta i la demanda
The global production of electrolytic aluminum has grown steadily, and the driving force for the increase in production still comes from China. In 2005, the world's electrolytic aluminum output was 31.91 million tons, an increase of 6.45 percent year-on-year, of which China's output was 7.67 million tons, a year-on-year increase of 15.07 percent . In 2006, the global production of electrolytic aluminum reached 33.8 million tons. In June 2006, the global average daily output (excluding China) was 82,200 tons, an increase of 700 tons compared with the average daily output in May, and a month-on-month increase of 0.09 percent . The domestic output of electrolytic aluminum in June was 780,300 tons, and the average daily output of electrolytic aluminum was 26,000 tons, an increase of 1,975 tons compared with the average daily output in May, a month-on-month increase of 7.59 percent . China is still the main driving force for the increase in global electrolytic aluminum production. Since China's production accounts for 24.9 percent of global production, the changing trend of China's production has played a decisive role in global electrolytic aluminum supply. The development of China's electrolytic aluminum industry has determined that China's domestic electrolytic aluminum supply has always been relatively abundant. In 2005, the average production capacity of electrolytic aluminum was 10.7 million tons, and the capacity utilization rate was 75 percent . From the domestic data in June, China's production capacity has been released to a certain extent. . China has built 11 electrolytic aluminum projects with a total construction capacity of 1.12 million tons, and there are still 10 proposed electrolytic aluminum projects with a total capacity of 1.4 million tons. The production capacity of electrolytic aluminum reached 11.6 million tons in 2006 and 12.5 million tons in 2007. The electrolytic aluminum construction process is simple, the technical content is low, the construction period is short, and there is sufficient capital investment. It only takes 9 months from the start of construction to the completion and production.
The alumina production capacity of the upstream industry of electrolytic aluminum has rapidly expanded, and the industrial chain has been extended to the electrolytic aluminum industry, which has become the main driving force for the growth of electrolytic aluminum production capacity. The growth and development stage of the electrolytic aluminum industry determines that production growth is the main keynote. The competition, restructuring and mergers and acquisitions of electrolytic aluminum enterprises, continuous expansion, and increased industry concentration will also promote the growth of production capacity. The buyers of the electrolytic aluminum industry are aluminum consumers. The rapid development of China's economy and the urbanization process of China's infrastructure, public utilities, housing and automobiles and other consumer goods have greatly boosted China's electrolytic aluminum consumption demand. The electrolytic aluminum industry is in the stage of rapid development and growth, the industry survives the fittest, and the industry concentration continues to increase. From 2003 to 2005, the total output of electrolytic aluminum increased from 5.54 million tons to 7.67 million tons, an increase of 2.13 million tons, of which only the top ten electrolytic aluminum plants in China achieved an increase of 910,000 tons. The number of manufacturers decreased from 141 to 95, and the average production scale of a single manufacturer increased from 39,000 tons in 2003 to 80,000 tons in 2005.
Anàlisi del sector
From January to November 2012, China's primary aluminum output was 18.15 million tons, showing a slight downward trend year-on-year. The serious overcapacity situation has eased. By the end of October, the industry's goal of eliminating outdated production capacity of 270,000 tons has been more than half completed.
En aquesta etapa, les empreses d'alumini electrolític haurien d'evitar ampliar cegament la capacitat de producció, transformar els avantatges industrials originals en rendibilitat i utilitzar els recursos existents per combinar l'energia del carbó, la fosa i el processament en termes d'avantatges originals per formar una cadena industrial completa i ampliar l'escala. de l'empresa. S'ha convertit en un objectiu important de les empreses d'alumini electrolític fer-se més grans, reforçar la capacitat de producció i perfeccionar la tecnologia de processament.
Després de més de 70 anys de desenvolupament, la indústria de l'alumini electrolític a la Nova Xina ha aconseguit grans èxits en tots els aspectes, però també s'enfronta a molts reptes i problemes, que s'han de resoldre correctament, en cas contrari, serà desfavorable per al proper desenvolupament.
sobrecapacitat
As of the end of 2013, China's primary aluminum production capacity has exceeded 32,000kt/a, and it is necessary to develop to foreign countries to mine bauxite, extract alumina and produce aluminum ingots for remelting in places with relatively rich resources and energy. Joint venture or sole proprietorship to ship the obtained products back to the country. The amount of aluminum and aluminum products to be exported by 2020 is processed with imported aluminum ingots for remelting, not equivalent to imported aluminum resources (bauxite, alumina, scrap aluminum). By 2030, about 50 percent of the remelting aluminum ingots for domestic apparent consumption will be imported. The ideas of Japan, South Korea and Taiwan region to develop the primary aluminum electrolysis industry are worth learning from, as well as the practices of the United States and some European countries.
Going out to develop aluminum resources is risky. In some places, the risk is still very high. It may be necessary to "pay a certain amount of tuition fees". Tuition fees may be unavoidable, and strive to pay less. At present, Japan and other countries have all shut down domestic primary aluminum production (Japan also retains a Urahara aluminum plant with a production capacity of 15kt/a, which uses the power of a small hydropower station on Mount Fuji. The power station was built by an aluminum plant. The aluminum plant will then use the segregation method to extract high-purity aluminum to reduce environmental pollution), and in the past 30 years, the production of primary aluminum in industrially developed countries such as the United States and Germany has decreased. The output of primary aluminum in China has declined somewhat, while the output of enterprises abroad has risen by more than 35 percent .
In 2021, the world's per capita aluminum consumption (calculated by 7 billion people, primary aluminum consumption of 51,400kt) is 7.34 kg/person, and China's per capita aluminum consumption (calculated by 1.35 billion people, primary aluminum consumption of 25,500kt) is 18.89 kg/person , has far exceeded the world average consumption, which is 2.57 times, and is close to 21.4 kg/person of industrially developed countries. Our main task now is to improve the quality of raw material consumption and to do as much as possible with as little raw material consumption as possible. The domestic scale should no longer be expanded, and the measures of "reducing the east and increasing the west, and reducing the fire and increasing the water" can be adopted.
Reptes tècnics
Although the tank capacity of some electrolytic aluminum plants in China has caught up with or exceeded the world's leading level, the technical and economic indicators of similar tank types still need to be improved compared with the advanced level abroad.
At present, the anode effect coefficient of electrolytic cells of electrolytic aluminum plants in my country is relatively high; the power consumption per ton of aluminum is higher than that of the European leading level; the average cell life is generally shorter; the current efficiency of the foreign leading level has reached 96 percent , while more than 75 percent of China's The current efficiency of the enterprise is only 92.5 percent -93.5 percent , and the calculation of the rectification efficiency of a considerable number of factories is low; under the same power consumption conditions, the anode current density of Chinese electrolyzers is designed to be only 0.7-0.735A/cm2. This means that the output per unit area of the same electrolytic cell is low. Therefore, in the future, one of the main tasks of China Aluminum Electrolysis is to maximize the output per unit area of the electrolytic cell.
China's current development of electrolytic aluminum industry also has many advantages, such as the low investment per unit product of electrolytic aluminum plants, which is about 1/3 of that of industrially developed countries; the low labor cost, which is 1/5-1/2 of the corresponding labor costs in the primary aluminum cost of industrially developed countries. 4. The environmental protection requirements are low, so the investment in environmental protection facilities is also low, which should not be the case. Now is the time to increase investment in environmental protection. Thousands of saving, environmental protection cannot be saved, environmental protection standards should be raised, and those that do not meet the standards should be shut down, and environmental protection standards should become high-voltage lines.
