The article is reproduced from the "Strategic Key Metal Science Popularization Platform"
Youth is not a few years, the epidemic accounts for three years.
The sudden outbreak of new crown pneumonia has stopped many people from chasing their dreams.
In the days of the epidemic, mobile phones and computers have become important media for us to work and learn, and screens have become important windows for us to spy on the world. When we understand the world through the screen in front of us, have we ever wondered how this small screen can transform into a colorful world?
In fact, the mobile phone touch screen glass itself does not emit light, nor does it conduct electricity. One of the secrets of its ability to present a variety of vivid, figurative words and images, and the ability to touch and slide as we please, lies in the fact that behind the screen is a transparent conductive film that is less than one-fifth the diameter of a human hair, that is, ito (Indium Tin Oxides) film.
As can be seen from the name, tin and indium are important raw materials for the production of this conductive film. Among them, tin is a common metal in our daily life, and the mainland also has rich tin resources. Compared with tin, indium is extremely rare on the earth, much rarer than the rare earths we often hear, and the distribution in the world is extremely uneven, but because it has an irreplaceable role in the electronics industry, indium's strategic reserves have a non-negligible role in the national economy and national security, and have become a key mineral resource coveted by governments around the world.
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I. Consequences of "indium" before |: Tracing the origin of indium
I. Consequences of "indium" before |: Tracing the origin of indium
II |" Indium " material convergence: the application of research and development of indium
iii |" Indium": Exploring the Origin of Indium
IV |" Indium" changes from time to time: grasping the business opportunities of indium
Five |" Indium "Yi": Looking forward to the prospects of indium
1
The consequences of the former "indium" – tracing the origin of indium
Indium is a soft silvery-white metal with the chemical symbol In, located in periodic cycle 5, group IIIA, element 49 of the periodic table.
In 1863, German scientists Ferdinand Reich and H. Theodor Richter were using spectroscopy in the laboratory to determine the content of thallium (Tl) in zinc ore, when they "accidentally" discovered an indigo brightline spectrum in a beamsplitter. They used the Greek word "indigo" to name the newly discovered element indium.
Figure 1 Two discoverers of indium (quoted from diarystore.com)
In 1867, at the World's Fair in Paris, France, indium was exhibited for the first time. Since then, indium has been considered the so-called "metal in the laboratory.". By the mid-1930s, the former Soviet Union had taken the lead in exploring the mineral exploration and production process of indium. In 1938, the former Soviet Union produced indium metal for the first time in industrial applications. Indium gradually entered the public eye after people discovered that it could be made into semiconductor materials. With the increasing interest in indium, indium has gradually become the "darling of science and technology" (Li Xiaofeng et al., 2019)
Fig. 2 Physico-chemical properties of indium
Physico-chemical properties of indium:
Indium is relatively soft, nails can be carved, good ductility, strong plasticity.
Fig. 3 Indium softer properties shown
Indium can burn, and the flame is indigo blue.
Fig. 4 Indium burns in air
(Source: https://music.163.com/#/video?id=4919BE15F7A76D2CEB9CC4758785ECFC)
Indium easily forms alloys with other metals.
Fig. 5 Formation of indium gallium alloy
(Source: https://haokan.baidu.com/v?vid = 1140409826336110727&pd=bjh&fr=bjhauthor&type=video)
Other physico-chemical properties of indium.
2
"Indium" material convergence - the application of research and development of indium
Indium application areas involve a wide range of applications, due to low melting point, good superconductivity and corrosion resistance and other characteristics, so it is widely used in the electronics industry, aerospace, alloy manufacturing, solar cell new materials and other high-tech fields.
Fig. 6 Application of indium
More than 50% of Indium in China is used in the production of ITO (Indium Tin Oxide), and a small part is used in the production of alloys and LEDs (light emitting diodes). With the development of the new energy industry in recent years, indium is also used to make CIGS (copper indium gallium selenium).
Figure 7 Indium consumption history and application trend in China
(Source: Zhou Yanjing, 2021)
(1) ITO (Indium tin oxide) target
Indium oxide and tin oxide powder are mixed in a certain proportion, processed and molded, and then sintered at high temperature (1600 °C) to form a black gray ceramic semiconductor.
In recent years, with the widespread popularity of displays, touch screens, etc. around the world, more and more ITO targets have been consumed. This is because the important raw material for ITO films and ITO electrodes used to make displays and touch screens is the ITO target. In addition, ITO targets are often used in aircraft anti-fog glass, optical coatings, nuclear reactor control rods and other "high", "fine" and "sharp" fields.
The core technology of ITO target has long been in the hands of large companies in Japan and South Korea. In 2021, with the unremitting efforts of the R&D team of Academician He Jilin of Zhengzhou University, it broke through the key technology of the mainland ITO target being "stuck neck", and achieved a breakthrough in high-end application from 1, so that the mainland finally has a "Chinese target"!
Figure 8 ITO targets
(Source: https://haokan.baidu.com/v?pd=wisenatural&vid=7886266237669575708)
(2) CIGS (Copper Indium Gallium Selenide) solar thin film batteries
The absorbing layer is a crystalline thin-film solar cell composed of four elements: copper (Cu), indium (In), gallium (Ga), and selenium (Se) in the best proportion.
CIGS solar thin-film batteries are one of the research hotspots in the international photovoltaic community, and their biggest advantage is the high photoelectric conversion efficiency. It can be widely used in precision poverty alleviation projects such as independent power stations, agricultural and optical complementary, and fishery-light complementary in remote mountainous areas; it can also realize the integration of photovoltaic buildings, large-scale ground photovoltaic power plants, urban garden landscapes, transportation and other fields.
With the rapid development of green, clean energy and 5G technology, CIGS solar thin-film batteries are becoming more and more favored by the market and are expected to become an important area to drive indium consumption.
Figure 9 Introduction to CIGS solar thin-film batteries
(Source: https://v.qq.com/x/page/n0390amei9l.html)
(3) LED (Light Emitting Diode)
A light-emitting diode is a solid-state semiconductor device capable of converting electrical energy into light energy, using semiconductor chips as a light-emitting material.
LED has red, orange, yellow, green, blue, purple, white and other light colors, with small size, low power consumption, long life, high brightness, low heat, environmental protection, durability and other excellent characteristics. It is mainly made of GaN (gallium nitride), InGaN (gallium nitride), InP (indium phosphide) and other materials.
In recent years, the output of indium semiconductors represented by InP (Indium phosphide) has increased rapidly, and the scope of applications in facial recognition and detection will continue to expand in the future, or the demand for indium will be greatly increased.
3
Where does indium come from – explore the origin of indium
Indium is a rare metallic element (Liu Yingjun, 1984) with extremely low levels in the Earth's crust (0.056 ppm), oceanic crust (0.072 ppm), meteorites (0.08 ppm), and seawater (0.2 to 0.7 ppb) (Rudnick et al., 2014).
Due to its geochemical properties, indium is difficult to form independent deposits. Worldwide, no independent deposits of indium have been found, and they are often recycled as associated mineral resources (Tu Guangzhi et al., 2004) (recovery can be considered when the indium content in the ore reaches 5 to 10 ppm).
Compared with other metals (e.g., Fe, Al, etc.), indium needs to achieve a hundredfold or even a thousandfold enrichment if it is to form deposits and be exploited by humans, a phenomenon known as extraordinary enrichment (Chen Jun, 2019).
Fig. 10 Comparison of the ease with which indium and common metals form deposits
(Note: Concentration coefficient = lowest recoverable grade of an element in the ore / percentage of the average content of that element in the Earth's crust.) The larger the concentration coefficient, the more difficult it is to enrich the ore)
(1) "Indium" fruit off "tin"
Over the years, depositologists have concluded that indium-related deposit types are mainly divided into sedimentary type lead-zinc deposits, granite-related deposits, massive sulphide deposits, silica-type deposits, shallow low-temperature hydrothermal deposits, porphyry-type deposits, etc. (Xu Jing and Li Xiaofeng, 2018).
Figure 11 Distribution of typical indium-containing deposits in the world
Although depositologists have concluded that there are many types of indium-related deposits, the most important types of deposits to date can be summarized as lead-zinc polymetallic deposits associated with magma hydrothermal fluid. Indium reserves account for about 81.2% of the world's total indium reserves (Werner et al., 2017).
In the past indium ore exploration and research process, oreologists found that in this type of lead and zinc polymetallic deposits, there is still a common phenomenon, we can call "zinc and zinc" phase "tin" (pity each other) and "zinc zinc" phase "indium" (heart to heart). That is, indium-rich zinc polymetallic deposits are often also rich in tin. These interesting phenomena have inspired ore depositologists to delve further, not only satisfying their "curiosity", but also promoting scientific progress related to indium metallogenic theory.
In the field of earth science, the progress of science is inseparable from practical work in the field. In recent years, researchers on the mainland have also discovered indium-rich ultra-rich integrated ore in tin-free magmatic hydrothermal lead-zinc polymetallic deposits (Chen Cheng and Zhao Taiping, 2021). This discovery, which broke the original regularity of understanding, on the one hand, prompted depositologists to further "examine" the relationship between indium and tin, and on the other hand, helped prospectors open up the possibility of finding new indium deposits.
Figure 12 Open pit of Dulong Deposit in Maguan County, Yunnan (Source: Baidu)
(2) "Indium" tolerates "phase" appearance
Indium is mainly refined in zinc ore, copper and zinc ore. Among these ores, sphalerite is the main carrier mineral of indium (about 95% of indium metal is "parasitic" in sphalerite), followed by chalcopyrite, diasite and a small number of indium independent minerals (such as indium sulfate, indium, Sakurai mine, etc.).
Fig. 13 Refined indium metal, like a "silver leaf"
(Source: Kidd Creek Deposit, Canada, Schwarz-Schampera and Herzig, 2002)
Natural indium belongs to the mineral system of tetragonal crystals, and its atomic space type shows the characteristics of the quadrilateral centroid structure.
Figure 14 Crystal structure of indium (Ridley, 1965)
It is worth mentioning that among the few indium independent minerals (18 species) currently discovered, there are two: damiaoite and yixumite, which were discovered by mainland scientists Yu Zuxiang in Hebei in 1997.
Fig. 15 The main independent mineral of indium
Figure 16 Indium mineral output process
Figure 17 Typical characteristics of indium minerals under microscopy (Valkama et al., 2016; Jonsson et al., 2013; Márquez-Zavalía et al., 2014）
(3) The group of "indium" is gathered
Based on the 1512 known indium deposits worldwide, the researchers estimate that the global indium resource is at least 356,000 tons, of which the total indium metal resources of the 101 deposits that have published resource data are about 76,000 tons (Werner et al., 2017). Indium is widely distributed worldwide, mainly in China, Peru, the United States, Canada and other countries.
Figure 18 (1) Indium (red, N=101) ;(2) actually quantified indium (red, N=101) ;(2) in indium deposits of lead-zinc (blue, N=591) and copper (N=576) inferred (white, N=219) ;(3) (in t; Wenger et al, 2017)
The world's largest indium resource deposits are the Gaiskoye deposit in Russia, followed by the Guangxi Dachang and Yunnan Dulong deposits in the mainland.
Figure 19 World ranking of indium deposit resources
(Source: Wenger et al, 2017)
The indium resources of the mainland account for 18.2% of the world (Werner et al., 2017), which are concentrated in the southwest edge of the South China Plate, the South Ridge, the southern edge of the North China Plate and the southern section of the Daxing'anling Mountains, involving the provinces mainly including Yunnan, Guangdong, Inner Mongolia, Qinghai, Hunan, Henan, Heilongjiang and so on.
Figure 20 Indium resource reserves in various provinces of China
(Source: Zhou Yanjing, 2021)
Figure 21 Distribution map of continental indium deposits (points).
(Zhao Taiping, Xu Jing, et al., 2022)
4
"Indium" changes from time to time - to grasp the business opportunities of indium
According to the refining method of indium, it can be divided into primary indium (directly from primary ore) and recycled indium (recycled waste).
Regenerated indium
At present, more than 50% of the indium in the global market comes from recycled indium. Recycled indium ensures the recyclability of resources, under the premise of improving smelting technology, the cost of recycled indium is also very considerable, so more and more recycled indium is put into the market.
Figure 22 Global indium production map 2009-2017
(Source: Zhang Weibo et al., 2019)
Native indium
In the past 10 years, the average annual production of primary indium in the world is about 715 tons, mainly from China, South Korea, Japan, Canada, Belgium, France, Peru and Russia. China is the world's largest producer of primary indium. With the help of indium in industrial production is becoming increasingly important in industrial production, a number of companies producing indium have emerged at home and abroad.
Figure 23 Major primary indium producing countries and production in the world in recent years
(Source: USGS)
Figure 24 Global indium-related companies (Source: USGS)
Globally, indium consumption in recent years has shown an overall upward trend, with the development of science and technology, society, it is expected that the global demand for indium will gradually increase in the future.
Figure 25 Global and China indium consumption status and forecast
(Source: Xiaomo Zhang, 2018; Yanjing Zhou, 2021)
In the past 20 years, the price of indium has fluctuated greatly, reaching its highest in 2005 and gradually declining since 2014.
Figure 26 Price trend of fine indium in the United States in recent years (Data source: USGU)
5
"Indium" is the "Yi" - looking forward to the prospects of indium
Indium is an indispensable supporting material in modern industry, national defense and cutting-edge science and technology fields, which has important strategic significance for national economy, national security and scientific and technological development, and has been called an important strategic resource in the 21st century by many countries in the world. Therefore, we should "indium" snobbish guidance and strengthen research in the following aspects:
(1) Exploring New Mineral Deposits (Native Indium)
Find out the bottom of indium ore, strengthen the exploration and prospecting of indium resources, and find new types of deposits.
——Increase the reserves of indium resources and consolidate the foundation of the family!
Figure 27 (Source: Hualian Zinc Indium official website)
Figure 28 Yunnan Dulong indium Mine (Zhao Taiping, 2021)
(2) Research and development of new technologies (recycled indium)
The research and development of indium recycling technology in target waste materials will improve the level of recycling of indium resources, further ensure the supply of indium resources, and reduce tailings pollution.
——Reduce the waste of indium resources and protect the homeland!
Figure 29 (Source: Hualian Zinc Indium official website)
(3) Sort out the state of indium (smelting indium)
Strengthen the study of the storage state of indium and improve the smelting technology of indium.
——Improve the smelting rate of indium resources and reduce costs!
Figure 30 (Source: Tu worm network)
(4) Breakthrough manufacturing technology (development of indium)
Overcome the key technology of "card neck" required for the processing of indium products, highlighting the strength of the mainland in the fields of "high", "fine" and "sharp".
——Enhance the core competitiveness of the great power game and escort the national strategy!
Figure 31 (Source: Hualian Zinc Indium official website)
Figure 32 Strategic (key) mineral overlap diagram between China, the United States and Europe
(Source: Chen Jiabin et al., 2020)
Figure 33 Comparison of the external dependence of strategic minerals between China and the United States
( Source: Li Wenchang et al., 2022)
End
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