Recently, China has implemented export controls on gallium and germanium related items, mainly targeting the hostile behavior of the United States in suppressing and containing China's development of emerging semiconductor optoelectronic industries. According to publicly available information, there is another rare metal in China that may become the next target of regulation. According to relevant consulting agencies, the United States' reserves can last for one year, Japan's reserves can last for three months, and European countries' reserves are even lower. Once we restrict the export of this metal, the production of defense equipment in Europe, America, and Japan will face serious problems. This rare metal has been included in the "Key Strategic Shortage Mineral List" by many countries such as China, the United States, Europe, the United Kingdom, Japan, Canada, and Australia. The world's proven metal resources are only 80000 tons, and it is usually mined by associated minerals. The current industrial purification method for producing metals has a recovery rate of about 50%. However, in the high-precision technological industrial revolution that is advancing human society, it is an extremely critical and important strategic metal that cannot be ignored. It is the ternary metal indium.
In addition to having small reserves, indium metal, like gallium and germanium, belongs to the category of "associated rare dispersed metals" and is mainly associated in polymetallic zinc ores. To extract indium metal, a complete zinc metal industry chain must be established. Because the proportion of indium co occurring is very small, only large-scale production of zinc can obtain very little indium.
China ranks first in the world in terms of indium reserves, with 85% of indium reserves in China, and almost only China sells finished indium. If we impose export controls on indium, the defense, display, and aerospace industries in Europe and America will face a catastrophic disaster.
This metal is the element Indium, discovered by German scholars Reich and Richter in 1863 and ranked 49th on the periodic table. During the process of measuring the thallium content in a zinc ore using spectroscopy, they discovered a seemingly soft new element called Indium and confirmed that an indigo blue bright line in the spectrum belonged to this new element. They named it Indigo and first exhibited it at the World's Fair in Paris, France in 1867. The chemical symbol In, atomic number 49, is located in the fifth period of the periodic table. Indium is a silver white metal with a metallic luster. It is not oxidized by air or sulfur at room temperature and quickly combines with oxygen or sulfide when heated above its melting point. Melting point 156.61 ℃, boiling point 2080 ℃, density (20 ℃) 7.31 grams per cubic centimeter. Indium metal has strong plasticity and ductility, and can be made into extremely thin indium sheets. Even with sharp objects carved on its surface, it can quickly return to its original state.
1. Initial acquaintance - Indium
The use of indium and its position in economic development
The application fields of indium involve a wide range of aspects. Due to its good plasticity, ductility, and superconducting properties, indium is widely used in high-tech fields such as electronics industry, semiconductor, aerospace, alloy manufacturing, photovoltaic cell new materials, high-end medical device MRI, etc. It is an indispensable supporting material in modern industry, national defense, and cutting-edge technology fields. It has important strategic significance for the national economy, national security, and technological development, and is regarded as a scarce mineral strategic resource for cutting-edge and future industries by many countries internationally.
Key compounds and specific applications of indium
Indium is an important material for manufacturing semiconductors, solder, rectifiers, and thermocouples, and is widely used in the wireless industry. Pure indium is the material used to make silver lead indium bearings for high-speed aircraft engines. Low melting point alloys can be produced, and indium tin alloys are used as vacuum sealing materials, which can bond glass to glass or glass to metal. Alloys of gold, palladium, silver, copper, and indium are commonly used to make dentures and decorations. Indium antimonide is used as an infrared detector material, and indium phosphide can be used to make microwave oscillators.
2. Current Status and Potential of Indium Mineral Resources in China
China's indium resources account for about 18.2% of the global indium resources, ranking first in the world in terms of indium reserves. China accounts for about 72% of the global total, and is also the world's largest producer of primary indium and the largest exporter of metallic indium.
There are various types of skarn mineralization in China, which are important sources of metals such as tungsten, iron, tin, molybdenum, copper, zinc, gold, and indium. It mainly occurs in mineral deposits related to zinc, copper, and tin, and is often recovered as a by-product in zinc smelting processes. Guangxi Dachang, Yunnan Gejiu, Dulong, Bainiu Factory, Inner Mongolia Meng'en Taolegai, Sichuan Chahe, Fujian Zhongjia, etc. are typical rich indium mines in China.
The important indium deposits in China are skarn type (such as Dachang, Dulong, Gejiu) indium deposits, which are concentrated in the Late Cretaceous, such as Dachang in Guangxi (8775t), Dulong in Yunnan (5124t), and Gejiu (>4000t). Indium mineralization has also been discovered in other regions, such as in the Cambrian gold deposits in the western Qinling Mountains; The indium content in the Chahe tin polymetallic deposit in Sichuan is as high as 186.5 × 10-6, which has great prospecting prospects. The discovery of indium bearing deposits in the Bangong Lake Nujiang metallogenic belt in Xizang, among the 13 deposits (spots) with high indium content, the average grade of indium samples from five deposits (spots) meets the requirements of associated industrial grade, and indium minerals include indium hydroxylite and natural indium; The average indium content of the Lawu polymetallic deposit in Dangxiong County, which is currently being mined, is 45 × 10-6; During the study of the Zijinshan copper gold deposit in Fujian Province, sulfide indium copper deposits were first discovered, indicating that the deep mineralization temperature of the Zijinshan deposit is relatively high, and the indium content in the ore-forming fluid is high, which has the potential for exploration in medium high temperature hydrothermal mineralization systems such as porphyry type. In addition, there is a certain amount of indium present in the copper tin deposit in the Rilonggou ore field of Saishitang, Qinghai, as well as in the Qibaoshan copper deposit, Xianghualing tin deposit, and Yejiwei tin deposit in Hunan. These discoveries are of great significance for the discovery of new types of indium deposits in China and the replacement of indium resources.
3. Investment opportunities for indium
The Next Potential Rich Mining Industry - Indium Metal Recycling and Reuse
The recycling rate of indium is low. Although indium is widely used in electronic products such as smartphones, tablets, etc., most indium is eventually covered by waste and cannot be recycled. This is mainly because indium in electronic products often exists in trace amounts and is a component that is difficult to separate and recover. Currently, there is no domestic enterprise that can independently and effectively recover and extract high-purity indium metal. Therefore, China needs to increase its research and promotion efforts in indium recovery technology to improve the recycling and utilization rate of indium resources.
Detection Technology for Cracking the Shortage of Indium Resources
The geochemical properties of indium determine its difficulty in mineralization, making prospecting even more challenging. Due to the inability of indium to form minerals independently, its exploration and prospecting are more difficult. At present, there is no effective prospecting and exploration method for indium in the world. Based on the study of the enrichment distribution law of indium and the revelation of the mechanism of abnormal enrichment of indium, it is imperative to carry out geophysical and geochemical techniques and methods for effective prospecting and exploration of indium.
Indium is generally prone to enrichment in the late stage of magma crystallization, but high enrichment of indium has also been found in some mafic rocks or mafic inclusions of intermediate acidic intrusions, exhibiting a dual nature of indium geochemical properties. Therefore, a comprehensive evaluation of the enrichment and distribution patterns of indium in different geological bodies and the proposal of future exploration directions for indium are the main ways to solve the future security and stability of indium resources.
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