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Since 2007, the world's largest supplier of aluminum electrolyte Alcan Trading has continuously supplied more than 6,000 tons of electrolytes to Chinese electrolytic aluminum enterprises. This not only enabled the Chinese aluminum industry to enter the global electrolyte market circulation system, but more importantly, it enabled related companies to reduce the start-up costs and operating costs of the electrolyzer, and at the same time promoted the technical practice of domestic all-electrolyte roasting start-up.
Excess electrolyte is a by-product of electrolytic aluminum plants. With the continuous expansion of aluminum plants, the amount of excess electrolyte is increasing. It is estimated that a 200,000-ton electrolytic aluminum plant will have an electrolyte surplus of about 2,800 tons a year. This does not include the amount of electrolyte produced by electrolytic cell production instability and overhaul, anode replacement and other reasons. Many domestic companies do not pay enough attention to the use of this resource and have stored a large amount of electrolytes in this company for a long period of time without entering the market cycle. At the same time, domestic electrolytic aluminum companies only add electrolytes in small amounts when they start roasting electrolytic cells, and they also need to purchase and use cryolite in large quantities.
The situation in foreign countries is very different from the current situation in China. The foreign advanced large-scale pre-baked aluminum electrolytic cell series adopts the excess electrolyte to suck out, and after cooling, it is broken into electrolyte pieces (powder) less than 4mm in size. Instead of artificial cryolite, it is used as a roasting starting material and not as a cover material to the electrolytic cell. in.
At present, almost all electrolytic aluminum plants in the West do not use cryolite baths, and all use excessive electrolyte to open the tank. Western electrolytic aluminum plants also rarely use cryolite to supplement the loss of fluoride salts in the electrolytic cell. According to data from Shangmiao Times Metal Company, in 2007, the consumption of cryolite for aluminum in China was approximately 140,000 tons, most of which was used for the start of new tanks. In 2007, the total consumption of cryolite in electrolytic aluminum plants in other countries was only 35,000 tons. . In other words, China produces 34% of the world's electrolytic aluminum, but consumes about 80% of the world's cryolite. It is roughly estimated that China currently consumes 11.2 kilograms of cryolite per ton of electrolytic aluminum, while there are only 1.2 to 1.5 kilograms in foreign countries, and the gap is very obvious. Advantages of using all-electrolyte starter: reducing the production cost of electrolytic aluminum enterprises
At present, the sales price of pure electrolyte imported from the international market to China is around 6,000 yuan/ton, and the price of cryolite is already close to 10,000 yuan/ton, which can save at least 4,000 yuan/ton. An electrolytic aluminum plant with a capacity of 200kt/a and 300kA is installed from the electrolytic cell, and the roasting is started and transferred to normal production. Each tank needs to add 40 tons of cryolite. If all the electrolytes are used to replace cryolite, it can save costs 4.09 million yuan. . If some of the electrolytes are used, the total cost of using cryolite will be more than 10 million yuan. In 2007, China's electrolytic aluminum production capacity increased by approximately 3.2 million tons. If all electrolytes are used instead of cryolite, it will save the industry about 400 million yuan. If all electrolyzers in the country are started after overhaul and all use electrolytes, the cost savings will be even more impressive. Environmental friendly
Due to the significant reduction in the consumption of cryolite, the consumption of fluorite resources will be reduced, and the pollution and waste discharge in cryolite production will be reduced. The promotion of full-electrolyte roasting start-up technology will also reduce the current backlog of electrolytic aluminum plant electrolytes and reduce waste and environmental pollution. Guarantee the stability of electrolytic cell work
Because the electrolyte has the same composition as the electrolyte in the electrolytic cell, adding electrolyte to a normal working cell is more stable than adding cryolite. The more stable the electrolytic cell, the higher the current efficiency. Ensure metal quality
The electrolyte contains less impurities than cryolite, so the use of electrolytes helps to increase the quality of the aluminum metal.
At present, the excess electrolyte in electrolytic aluminum plants in Western countries is used for its own normal production, and some of the excess electrolyte is sold as a commodity. A market of excess electrolyte has been formed globally and used for the newly-produced electrolytic aluminum plant. In addition to China, the market trades more than 50,000 tons of electrolytes each year, of which 80% was purchased by Alcan Trading Company on a long-term contract basis and distributed worldwide, effectively revitalizing this resource. At the same time, Alcan Trading Company guarantees the stability and reliability of product supply with its quality standards and logistics system. At present, Alcan and its Chinese partner, Sunlight Times Metals, are promoting China's electrolytic aluminum plant to join this material recycling system.
Experts in the industry believe that China's electrolytic aluminum companies can learn from the international recycling mode of excessive electrolytes and all-electrolyte tank technology, and strive to carry out this work.
1. Newly-built aluminum plants and existing aluminum plants should actively use excessive electrolyte resources at home and abroad, use all-electrolyte roasting technology, or increase the proportion of electrolyte applications, gradually replace cryolite, and significantly reduce costs.
2. The existing aluminum plants can actively participate in domestic and international exchanges of excessive electrolytes, revitalize corporate resources, exert resource efficiency, and create new business opportunities for electrolytic aluminum plants.
3. It is necessary to formulate process specifications and standards so that the collection, processing, trade, and use of electrolytes have unified standards that can be referenced to ensure product quality and stability and reliability in use.
Some domestic aluminum plants such as Nanshan Aluminum, Shenhuo Aluminum, Haoao Aluminum and Zhongdian Huohong Hongjun Aluminum have all started relevant practices in the past two years and have achieved very good results. They have further promoted the domestic aluminum industry. The electrolyte roasting chute provided successful experience and examples.
From 2008 to 2009, due to the launch of several large-scale aluminum plants in the Middle East, the global market for quality electrolytes will become tight. Therefore, it is a good business opportunity for aluminum plants with a large excess of electrolytes in the country, and companies that plan to start their own businesses should seize the time to purchase stable and reliable electrolyte resources at home and abroad. Actively adopting all-electrolyte start-ups to further reduce emissions and reduce emissions is particularly important for electrolytic aluminum companies that are currently in the midst of difficulties and for the new electrolytic aluminum projects that are about to start. It is an inevitable path.