Alumina production technology invention at Northeastern University solves world problems

Alumina is a basic raw material for the production of metallic aluminum, and it is also used as an organic reaction catalyst, abrasive, polishing agent, and refractories in ceramics, medicine, electronics, machinery, and other industries. Its correlation with the national economy is as high as 90% or more. China's alumina production is about 50 million tons per year, accounting for about 50% of the world's total. It is the world's largest alumina producer. Innovation and breakthroughs in alumina production technology are particularly important. The traditional Bayer process for alumina production (up to 99%) has two basic defects: First, it requires high quality grades of bauxite, and second, it produces large amounts of highly alkaline red mud. Among them, for every 1 ton of alumina produced, 1 to 2 tons of red mud is produced in addition, and the red mud is built for dams because it is not economically viable. It not only harms the environment but also takes up a lot of space. The use of red mud is a worldwide problem.

Recently, the China Non-Ferrous Metals Industry Association in Shenyang organized a team of experts Zhang Dongan of Northeastern University to complete the "large-scale low-cost and harmless treatment of Bayer red mud", "the calcification-carbonization method to efficiently use low-grade bauxite clean production and oxidation "Aluminum technology" was identified and it was agreed that both technical achievements have reached the international advanced level. For example, the use of this technology to treat bauxite with an Al—Si ratio of 3.29 resulted in an alumina dissolution rate of up to 86%, a significant improvement over the traditional method of less than 70%; at the same time, the waste generated by traditional methods was not available – high Alkaline red mud, alkali recovery rate increased by more than 95%, alumina recovery rate of more than 50%, turning waste into treasure, cracked the red mud can not be economically viable use of this worldwide problem.

70% of China's bauxite resources belong to middle-low grade ore, and a large number of them need to be imported. The degree of foreign dependence is more than 50%. How to effectively use low-grade bauxite in China has always been a technical bottleneck problem in China's alumina industry. The special metallurgical innovation team led by Professor Zhang Ting'an started from changing the balanced solid-phase structure in red mud. After more than ten years of intensive research, he proposed a theoretically alkali-free, aluminum-free new structure of red mud, which resulted in the above two The technical invention not only theoretically decoupled the production of alumina from the Bayer process on the alumina-silica ratio of bauxite, but also enabled the production of alumina using low-grade bauxite; furthermore, it achieved a significant reduction in sodium and aluminum in red mud. The content has fundamentally solved the large-scale, low-cost harmlessness and resource utilization of red mud, and is a disruptive technology for alumina production.

Based on technological innovation, the two technologies have also been widely practiced in industry. Including the efficient and clean use of the red mud outlet, the development of calcification and carbonization reactors, and the establishment of a test expansion demonstration system, which provided the equipment foundation for the industrialization of this technology.

The successful R&D of technology is of great significance to China's alumina industry, which is equivalent to expanding China's bauxite resources by 2 to 3 times and prolonging the bauxite service life by more than 30 years. It can get rid of the dependence of the alumina industry on imported minerals. At the same time, using this technology to treat low-grade bauxite, the production cost can be reduced by 400-500 yuan per ton compared with the existing methods; using this technology, the alkali content in the existing red mud can be reduced by 0.12% from 4% to 6%. ~0.20%, the economic benefit per ton of red mud can reach more than 150 yuan, and reduce the operation and maintenance cost of red mud stockyard by more than 60 million yuan each year. If China generally adopts this technology, alumina production can obtain an additional annual economic benefit of 500 billion yuan. If the existing Bayer process red mud is completely treated by this method, it can generate economic benefits of nearly 100 billion yuan, with significant social benefits. And economic benefits.

At present, two technical inventions have formed 15 serial invention patents and 2 international PCT patents, and have established a pilot test scale of 50,000 tons in the laboratory.