Rhenium has a wide range of applications, especially in the aerospace and petrochemical industries. In 2017, China successfully used locally purified rhenium to produce rhenium-nickel alloy single crystal blades required for aircraft engines, achieving an exciting "engine freedom".
Rhenium is a silvery-white rare heavy metal with the chemical symbol of RE and atomic number 75, which belongs to the seventh group of transition metals in the 6th period. It was the last stable element to be discovered in 1925, and its English name Rhenium is derived from the Latin Rhenus, which means "Rhine", and there is a romantic story behind the name.
Rhenium has an extremely high melting point and density, second only to tungsten, carbon, platinum, iridium and osmium, and is also the element with the highest boiling point of all stable elements. Although the reserves of rhenium in the earth's crust are very scarce, only about 2,500 tons, its unique physical and chemical properties make it important applications in various fields.
Mendeleev had foreseen the existence of an unknown element at a location on the periodic table, which he named "submanganese" and thought that this element would be similar to manganese.
In 1914, British physicist Henry Mosley determined some of the properties of "Element 75" through calculations. The rhenium element is generally believed to have been discovered by German scientists.
In 1922, Walter Nodak, a young chemist at the University of Berlin, and his colleague Ida Tucker began to search for traces of rhenium, and the two hit it off. Ida Tucker is a German female chemist with a Ph.D. and the first female chemist in Germany to hold a teaching position at a university.
They believe that rhenium should be a very rare element that may coexist in platinum and niobium. However, they did not anticipate that rhenium is a typical dispersed element that would be very difficult to enrich.
In their long-term research, they did not find any clues, and they were somewhat disappointed and even depressed.
When the miracle happened, the Hungarian radiochemist Hevexi and the Dutch spectroscopist Koster used X-ray spectroscopy to discover the unprecedented hafnium element in zircon.
Inspired by this, Nordak and Tucker enlisted a spectroscopist to explore rhenium. After several years of hard work, in May 1925, they announced that they had found this mysterious element in platinum ore and the mineral niobium.
During this period, the relationship between Nodak and Tucker also changed from acquaintance to love, and in honor of Tucker's birthplace, the Rhine, they named the newly discovered element "rhenium", which may be a Nodak's affectionate confession to Tucker.
Finally, in 1926, the scientific couple entered the palace of marriage, and their love story became a romantic story in the history of science.
In the course of their research, the Nodaks accidentally discovered rhenium in gadolinium pyroxene and molybdenite. Through their efforts, they succeeded in extracting 1 gram of rhenium from 660 kilograms of molybdenite in 1928, allowing the world to understand this mysterious element.
At present, molybdenite is the main commercial ** rhenium element, and its main component is molybdenum disulfide, of which the content of rhenium can reach up to 02%。With the continuous progress of science and technology, rhenium is more and more widely used in real life.
The first important use of rhenium is as a raw material for the production of alloys. Nickel-based rhenium superalloy is a high-temperature superalloy that is mainly used in the manufacture of combustion chambers, turbine blades, and exhaust nozzles of jet engines.
These alloys contain up to 6% rhenium, which is the largest single use of rhenium, and about 80% of the world's rhenium production is used in this field.
In addition to being widely used in aviation, electronics and other fields, rhenium also plays an important role as a catalyst. It can be used as a hydrogenation and isomerization catalyst for catalytic reforming (rhenifying process) of naphtha in gasoline to produce high-quality unleaded, high-octane gasoline.
Due to the rarity and importance of rhenium, it was once very high, reaching an all-time high of US$10,600 per kilogram. However, with the increase in the rate of rhenium ** and the decrease in the demand for rhenium in the catalyst, the rhenium ** has dropped to US$2,844 per kilogram.
Despite this, rhenium** still fluctuates between $2,300 and $2,500 per kilogram, which is as high a value as platinum.
According to CCTV reports, Chengdu Aerospace Superalloy Technology Co., Ltd. cooperated with Hunan Nonferrous Metals Research Institute to successfully develop the purification technology of rare metal rhenium, which took one and a half years to successfully manufacture a single crystal blade that is indispensable for aircraft engine production.
The total proven rhenium metal mineral resources in the world are about 2,453 tons, and the total basic reserves are about 10,180 tons, of which Chile, the United States, Russia and Kazakhstan and other countries are relatively rich in reserves.
China has discovered a rhenium mine with reserves of about 176 tons in Shaanxi Province, accounting for 7% of the world's reserves, second only to the above-mentioned countries. Zhang Zheng, chairman of the company, has set up a professional team through the national talent recruitment plan, and the single crystal blades produced have been experimentally verified, and the tensile performance and endurance performance at high temperature are in line with European and American quality standards.
As the core component of the engine, the importance of single crystal blades to China's aviation industry is self-evident.
Aircraft engines are extremely complex mechanical systems, which require stable operation in high-heat, high-pressure, high-speed, and high-load environments, and must have the characteristics of high power, light weight, long life, and high reliability.
Rhenium solves the problem that engine blades are easy to deform under high temperature and high pressure, so that the flight speed and distance can be greatly improved. China began to extract rhenium from molybdenum concentrate roasting smoke in the 60s of the 20th century, and realized the mass production of single crystal blades of aircraft engines in 2017.
We have mastered the preparation and processing technology of high-performance rhenium-containing single crystal blades, broken through the bottleneck of rhenium purification and processing in aero engines, and achieved a technological breakthrough.
Rhenium is an important strategic material for any country, especially in areas with developed cutting-edge technology. A few years ago, there was news that "China has a large reserve of rhenium", because rhenium is a necessity needed for the development of engines.
China has been facing challenges in the development of aircraft engines, because China's rhenium demand has been unable to meet due to export restrictions from Europe and the United States. In this case, the research and development of engines in China is progressing slowly, like a clever woman who has no rice to cook.
However, with the production of domestic rhenium-nickel alloy single crystal blades, Chinese-made aircraft can rest assured that they can use the "Chinese heart" to avoid "heart disease". Although China is one of the world's top ten rhenium ore resource countries, the static guarantee period of rhenium does not exceed 15 years according to the calculation of reserves and consumption rate.
Rhenium is widely used in aerospace and petrochemical fields, so the current dependence on foreign countries has reached 50%. In the aerospace field, rhenium is indispensable.
With the upgrading of single crystal blades, the amount of rhenium is also increasing. According to statistics, the demand for rhenium will increase by more than 2 times in the next 10 years.
The unique catalytic properties of rhenium and its compounds make it in great demand in the field of petroleum reforming catalysts. The 30% rhenium contained in the rhenium-platinum alloy is a key catalyst in the catalytic reforming process, which can significantly increase the octane number of naphtha.
In 2020, Ding Shiqi, a deputy to the National People's Congress, put forward the "Proposal on the Implementation of the National Collection and Storage of Rare and Scattered Metal Rhenium and the Control of Important Strategic Resources", calling for the national collection and storage to control key strategic resources, protect the self-sufficiency and safety of key materials, and ensure the safety of key materials for major national equipment.
According to Ding Shiqi, with the development of China's aviation industry, the level and output of aircraft engine manufacturing are improving. However, in order to achieve the special properties of the material, some specific metal elements need to be added during the manufacturing process.
However, the development of China's aero engine industry is still in its infancy, and the demand for some rare and scattered metals in China, such as rhenium metal, is relatively small, which restricts the development of the industry to a certain extent.
In recent years, the demand for rhenium in various countries has been increasing, of which the annual consumption in Europe has increased from 2-3 tons to nearly 10 tons, the annual consumption in the United States has also increased from 20-25 tons to 45-50 tons, Japan's consumption has also grown to about 2-3 tons per year, and Russia's annual demand is about 5 tons.
It is worth noting that 50% of the world's annual rhenium production comes from Chile, and the American Molybdenum Metal Company is the world's largest rhenium producer. The company has long-term contracts with Chile, Mexico and Kazakhstan and monopolizes most of its rhenium production.
In contrast, China's rhenium metal production capacity is small, and the output is also very low.
Ding Shiqi said that by treating the sewage or soot of copper-molybdenum metal smelting enterprises, it can be concentrated and purified to make ammonium rhenate, which can be further refined into rhenium metal. However, with the implementation of China's rhenium metal project, overseas rhenium metal manufacturers began to dump at low prices, resulting in rhenium ** continuing**, which is now only one-third of the market ** three years ago.
This practice of overseas companies has seriously hit the production enthusiasm of domestic rhenium enterprises, and most of the rhenium resources have been disposed of at will, resulting in a great waste of resources. At present, the domestic aviation industry's demand for rhenium is growing slowly, and the actual rhenium metal production capacity is about 8 tons per year, while the consumption is only about 2 tons per year, most of which can only meet the needs of individual R&D enterprises.
However, with the breakthrough of our engine technology, the demand for rhenium will increase significantly in the future, and then there may be problems with the ** of rhenium, which will have serious consequences.
Therefore, we need to take precautions to ensure that the first rhenium can keep up with the development of engine technology.
The progress of the country is closely linked to the development of science, and the acquisition and reserve of rhenium resources is one of the key strategies for China's long-term development. In addition, increasing investment in the aerospace field and upgrading machinery and equipment is also a necessary measure to improve China's manufacturing level in related fields and face the future.
China has abundant natural resources, among which the total amount of rhenium resources is not high, but its importance is self-evident. We should cherish the gifts of nature, make good use of these precious resources, and contribute to the construction of the motherland.
If we lack the technology to use rhenium, we may export it, causing losses to our country. Therefore, we need to think from a long-term strategic perspective and protect these scarce resources, not just for short-term gains.