Issue 44/2015 - Northeastern University invents alumina production technology

A few days ago, the China Nonferrous Metals Industry Association organized experts to identify the "large-scale low-cost harmless treatment of Bayer red mud technology" and "calcification-carbonization method efficient utilization of medium and low-grade bauxite clean production alumina technology" completed by the team of Professor Zhang Ting'an of Northeastern University, and unanimously agreed that both technical achievements have reached the international leading level
.

The two technologies are outstanding in the application of this technology to treat bauxite with an aluminum-silicon ratio of 3.
29, and the alumina dissolution rate is as high as 86%, which is a significant improvement compared with less than 70% of the traditional method.
At the same time, the alkaline recovery rate of highly alkaline red mud, which cannot be used by traditional methods, has been increased to more than 95%, and the recovery rate of alumina has been increased to more than 50%, which has solved the worldwide problem
that red mud cannot be used economically.
At present, the two technical inventions have formed 15 series of invention patents, 2 international PCT patents, and established an annual test scale test line
of 50,000 tons in the laboratory.

Alumina is the basic raw material for the production of metal aluminum, and is also used as an organic reaction catalyst, abrasive, polish, refractory in ceramics, medicine, electronics, machinery and other industries, and the correlation with the national economy is as
high as 90%.
China's alumina output is about 50 million tons per year, accounting for about 50% of the world, and is the world's largest alumina producer
.
The traditional Bayer method for producing alumina (up to 99% utilization) has two basic defects: one is the high grade requirements for bauxite, and the other is to produce a large amount of highly alkaline red mud
.
Among them, every 1 ton of alumina produced on average, incidentally produces 1~2 tons of red mud, red mud because there is no economic feasible use method to build a dam and store, not only endanger the environment, but also occupy a lot of space
.

70% of China's bauxite resources belong to low- and medium-grade minerals, and high-grade ores need to be imported in large quantities, and the dependence on foreign countries is more than
50%.
How to effectively use medium and low-grade bauxite 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 of red mud, and after more than ten years of painstaking research, proposed a new structure of red mud that theoretically does not contain alkali and aluminum, thereby obtaining the above two technical inventions
.
This not only theoretically gets rid of the limitation of the specific grade of bauxite aluminum-silicon produced by Bayer method of alumina, but also realizes the use of low-grade bauxite to produce alumina; Moreover, greatly reducing the content of sodium and aluminum in red mud fundamentally solves the large-scale, low-cost harmless and resource utilization of red mud, which is a subversive technology
for alumina production.

On the basis of technological innovation, two technologies have also been widely practiced
in industry.
Including the direct efficient and clean utilization of red mud at the export; Calcification and carbonization reaction devices have been developed, and expansion demonstration systems have been established, which have provided a equipment foundation
for the industrialization of this technology.

The successful research and development of the two technologies is of great significance to China's alumina industry, which is equivalent to expanding China's bauxite resources by 2~3 times, extending the service life of bauxite for more than 30 years, and getting rid of the dependence
of the alumina industry on imported minerals 。 At the same time, the use of this technology to treat medium and low-grade bauxite, the production cost can be reduced by 400~500 yuan per ton compared with the existing method; Reduce the alkali content in the existing red mud from 4%~6% by 0.
12%~0.
20%, the economic benefits per ton of red mud can reach more than 150 yuan, and reduce the operation and maintenance cost of the red mud yard by more than
60 million yuan per year.
If this technology is widely adopted in China, alumina production can obtain an additional economic benefit of 50 billion yuan per year; If all the existing Bayer red mud is treated by this method, it can produce economic benefits of nearly 100 billion yuan, with significant social and economic benefits
.
(Jade)