Tellurium is L1 J 1782 Nian Lai Hing Stein found in the gold-containing ore, there are also claims that in 1798 MH carat Puluo Zi in a white metal was first discovered tellurium. Selenium and tellurium, rhenium and the like are generally known as "rare elements", "dispersing element" or "scattered metal."
It has a low average abundance in the earth's crust (6×10-5), and strontium and cadmium , strontium , gallium , selenium, indium , strontium , barium , strontium, etc. are all dispersed elements. In nature, tellurium minerals in addition to natural Tellurium, mainly telluride, tellurium sulfur (selenium) compound and a tellurium oxide forming metal elements Au, Ag and platinum group elements as well as Pb, Bi, Cu, Fe, Zn, Ni , etc. And mineral type L2 J such as oxygenated salt. At present, rare elements are increasingly valued by people for their important position in the fields of modern high-tech industry, national defense and cutting-edge technology.
1. Awkward resources
Since before the 1990s, it was widely believed that most of the world's recoverable tellurium in copper deposits are associated, so the United States Bureau of Mines copper resources on the basis of terms of copper per ton of recyclable 0.065kg tellurium, calculate The global reserves are about 22,000 tons, and the reserves are 38,000 tons. They are mainly distributed in the United States, Canada, Peru, Chile, Zambia, Zaire, the Philippines, Australia, Japan, Europe and other countries and regions [3]. However, the discovery and exploration of geological studies at home and abroad a number of important telluride gold and silver deposits in recent years show that the geochemical traits dispersed elements tellurium than the traditional understanding much more active, it can be a large-scale enrichment of mineralization formation of an independent industrial ore deposits or economic value, such as Sichuan asbestos Dashuigou bismuth telluride gold deposits HJ, Shandong return 5, Henan Northridge telluride type gold deposits in gold Chong tellurium [6] and so on. This has caused humans to have a new understanding of the distribution of resources. China has now proved that the associated sputum reserves are in the third place in the world. The associated antimony ore resources are abundant. The country has found about 30 associated antimony ore deposits, with reserves of nearly 14,000 tons. The antimony mining areas are scattered in 16 provinces (regions) across the country, but the reserves are mainly concentrated in Guangdong (accounting for 42% of the national total). Jiangxi, 41% and Gansu (11%). Of tellurium ore mainly associated to copper, zinc and other metal lead minerals, the mineral reserves estimated according to the main, not counted as well as our reserves
The antimony resource is about 10000t [47|. China's antimony ore resources have been concentrated in hydrothermal polymetallic deposits, skarn type copper deposits and magmatic copper- nickel sulfide deposits, which account for 44.77%, 43.89% and 11.34% of China's associated plutonium reserves, respectively. Guangdong Dajiangshan Qujiang and Jiangxi Jiujiang Chengmen are composed of copper mines (accounting for 23.6% of the national associated strontium reserves, and bismuth ore grades of 0.0028%). Gansu Jin JII's own mouth is the three large and one large-scale associated strontium deposits in China. The sum of reserves is 94% of the national associated strontium reserves. In August 1991, the world's first independent antimony deposit was discovered in Dashuigou, Shimian County, Sichuan Province, China, thus completely breaking the dispersing element 碲 “can form independent minerals, but no exploitable independent deposits [7], ' Traditional understanding has filled a gap in the theoretical theory of mineral deposits and will change the understanding of the mineralization ability of rare elements. At the same time, it will also change the existing status of extracting associated cockroaches from other minerals and change the 碲 resources. The distribution pattern may make China a major resource for antimony resources. In addition to the large amount of by-products stored in the identified copper deposits of industrial grades, there are some sources of by-products: the source of lead deposits. The strontium contained in the bismuth is 25% of the bismuth in the industrial copper deposit. However, it is rarely used to extract lead by electrolysis. Only by this method can the hydrazine be recovered by the way; a small amount of strontium can be recovered from the bismuth ore. development, tellurium contained insufficient number of industrial grade, or not yet discovered copper and other metals of industrial resources are identified tellurium copper several times, it is estimated that the average coal mine tellurium containing 0.015 × 10-4% ,
2, the use of 碲
The rare element 碲 is known as “the vitamin of modern industry, national defense and cutting-edge technology, creating a bridge of human miracles†and “a supporting material for contemporary high-tech new materialsâ€. This is because with the increasing demand for rare metals including helium in the fields of aerospace, atomic energy, and electronics industry, he has become a supporting material for new materials required for electronic computer, communication, and aerospace development, energy, and medical and health.
2.1碲Application in the metallurgical industry
Industrially pure niobium (99%) is widely used as an alloying additive to improve the machinability of steel and steel. Simply adding a small amount of niobium can improve the cutting and processing properties of low carbon steel and stainless steel; it can increase the life of cutting tools and achieve excellent finish. In the casting process, the addition of less than 0.1% by weight of bismuth can be used to control the cooling crystallization depth, and the addition of bismuth to the lead ( tin or aluminum ) alloy can improve its fatigue and corrosion resistance, and can improve its hardness and elasticity.
2.2碲Application in the chemical industry
In the chemical industry, ruthenium is mainly used as an additive for petroleum cracking catalysts, a secondary catalyst for rubber, and a catalyst for preparing ethanol. The ruthenium compound can also be used as various catalysts for medicine (as a fungicide), glass coloring. Agents, ceramics, plastics, printing and dyeing, paints, skin care products and enamel industries.
2.3碲Application in the electronics industry
Higher quality germanium (99.99% or higher) can be used in a variety of electronics. For example, a compound semiconductor bismuth telluride available temperature difference along with the electrical device antimony telluride. Bismuth telluride is an important material in temperature difference refrigeration because it is a "multi-valley" semiconductor with high electron mobility, high conductivity and high effective mass capable of generating high temperature difference power. Therefore, bismuth telluride with good refrigeration performance can replace Freon and become an ideal material for reducing air pollution and the environment. Other electronic applications of germanium and its compounds are infrared detectors and emitters, solar cells, and xerography. A small amount of tellurium is used as a gallium arsenide device electron donor dopants.
3, 分离 separation and extraction technology
At present, the main source of bismuth is the anode mud of copper refinery, which contains up to 9%. Other possible sources are mud from sulphuric acid plants and dust from electrostatic precipitators in sulphuric acid plants and smelters. Therefore, the way to obtain plutonium is mainly extracted from the anode mud. This article will focus on several methods for extracting plutonium:
3.1 Soda Ash Roasting Method
Sodium carbonate and water are thoroughly mixed with the anode slime to form a thick paste which is calcined at a temperature of 530 to 650 ° C and completely converted into a hexavalent state without considering the volatilization of hydrazine. After the calcined pellets or agglomerates are ground, they are leached with water. Since another element of selenium in the anode mud has formed sodium selenate in this process, it is extremely difficult to dissolve in such a strong alkaline solution due to sodium citrate. It remains in the slag. At this time, the selenium-free soda leaching residue is treated with dilute sulfuric acid to convert the insoluble sodium citrate into soluble tannic acid:
Na2Te04 (insoluble) + H2S04 = HzTe04 (soluble) + Na2S04 decanoic acid reduced to hydrazine can be treated with hydrochloric acid and sulfur dioxide:
H2Te04+2HCl=H2Te03+H20+C12H2Te03+HzO+2S02=2H2S04+Te Under certain acidic conditions, citric acid is reduced to cerium oxide by sodium sulfite, and a dense, pale yellow solid can be recovered from the hot solution. The best method for converting H2Te04+Na2S03=TeOz+Na2S04+H20 into metal ruthenium is dissolved in sodium hydroxide and completed by electrolytic sodium citrate: Na2Te03+H20+4e=Te+2Na20H+02 regenerated alkali It can be reused in the process of returning to the dissolved cerium oxide. The method commonly used in industrial oxidation pressurized or pressurized chlorinated alkaline leaching implemented, several oxidative leaching process is primarily an oxygen pressure leaching or chlorine, or leaching (e.g., ferric chloride) with chlorine carrier, can also several The combination of steps facilitates the rapid reaction. Since the reaction speed of ferric chloride and telluride is faster than that of ferric chloride and selenium, care should be taken to prevent insoluble hexavalent ruthenium compounds from separating tetravalent selenium into soluble compounds [8]. The pressure leaching process has the advantage of ensuring that the ruthenium is completely converted to the hexavalent form to achieve complete insolubility in the alkaline leaching solution. In addition, the medium can be made non-corrosive, the selenium has no loss of volatilization, no washing or gas purifying process, and the extraction of cerium can be substantially quantitatively realized. However, the shortcomings are also obvious, that is, the amount of oxygen and sodium hydroxide consumed by the entire process is large. The oxidation process should consider not only the oxidation of niobium, but also the oxidation of selenium and the oxidation of organic matter introduced by the use of additives as growth regulators in the process of refining copper.
3.2 Sulfation roasting
The sulphation roasting technique is based on the volatility of the tetravalent oxides of selenium and tellurium at a calcination temperature of 500 to 600 ° C. After selective extraction of selenium from the positive mud, since hydrochloric acid can dissolve the hexavalent and tetravalent cerium, the hydrazine can be recovered directly by leaching with hydrochloric acid from the remaining baking slag. Acidic calcination uses sulfuric acid as an oxidizing agent to convert selenium or selenide and tellurium or telluride into their respective quaternary oxides. The oxidation reaction of ruthenium is: Cu2Te+6H2S04=2CuS04 J+Te02 l+4S02 f+6H20 t This process is not recommended in industrial production because leaching of hydrochloric acid causes the conversion of silver in the anode mud to be extremely insoluble. Silver chloride makes the recovery of silver more difficult. At the same time, if hexavalent ruthenium is present, it can oxidize hydrochloric acid to release chlorine gas, and then it will dissolve the gold in the anode mud, which will be in the subsequent bismuth and gold. Separation has some substantial problems L9 J. According to actual data from industrial production, a complete hydrometallurgical process including alkaline oxide pressure leaching and pressure vulcanization of copper, nickel, precious metal, selenium and tellurium anode muds enables good precipitation of all components. Separated selenium and tellurium can be more than 90% pure.
3.3 liquid membrane separation method
Liquid membrane separation material is a new high-tech separation method with high efficiency, rapidity and energy saving. In 2003, Wang Xianke [10] proposed the preparation of emulsion film with primary amine N192, which can rapidly migrate and enrich enrichment, in recovery and treatment extraction. And the analysis and determination of trace bismuth has a good application prospect, and also lays a foundation for further development and utilization of enriched cesium from complex component feedstock or low-grade antimony ore. Liquid film enrichment of Te4+ is achieved by flow carrier N1923. According to the separation process and the principle of solvent extraction, N1923 is represented by RN, and the elements are extracted by the principle of ion association. First, HCl generates RNH+C1 in the outer phase of the membrane phase, while Te4+ in the outer phase reacts with RNH+C1 in the membrane phase to form [RNH]22[TeBr6]2-, dissolved in the organic membrane, and passed through. The liquid phase diffusion internal phase interface acts and dissociates in aqueous NaOH solution, and Te.Br62- and H+ migrate into the internal phase, which is the result of the competition between Cl- and TeBr6 and N1923. Separation and enrichment of lanthanum by emulsion membrane confirmed that the membrane phase consisted of 7% N1923 (primary amine), 4% Lll3B and 89% kerosene (including n-octanol), the internal phase was 0.3 mol/L NaOH aqueous solution, and the external phase acidity It is 5 mol/L HCl medium, R. l is 1:1, R. . The recovery rate of ruthenium is from 99.5% to 100% at room temperature (15-36 °C) from 20:50 to 20:100, and the internal phase is enriched with a higher concentration of ruthenium. Generally, the common anions are not migrated and enriched, and the selectivity is quite high. However, this method has not been promoted in industry.
3.4 Microbial method
Biometallurgy has a broad industrial application prospect for its low cost and non-polluting development and utilization of low-grade and difficult-to-smelt mineral resources. Liao Mengxia et al. [11] proposed the path of biometallurgy in the development strategy of China's first independent antimony deposit resource in 2004. In fact, in 2003, Rajwade et al. [12] used the continuous stirring of microorganisms to propose a biological reduction process containing strontium noble liquid, that is, in the solution containing 碲10 mg/L, the pH was controlled at 5.5-8.5, and the temperature was 25-45. °C, the use of microorganisms to reduce the precipitation of elemental cerium, can effectively replace the strong reducing agent, thereby improving efficiency and reducing production costs. This theory pioneered the application of biometallurgy in the extraction process of strontium. Liao Mengxia et al. L11J believes that the asbestos content of the asbestos in the Dashui Ditch Ore Deposit is 0.00X-0.0X%, and the reserves of gold and silver content of 0.X-Xg/t are large, and the traditional process is difficult to effectively achieve economic development and utilization. The purpose is to propose a method for microbial extraction of strontium, and summarize the research on the biooxidation of sulfide ore at home and abroad, mainly the isolation and identification of leaching bacteria, the culture conditions of bacteria and the conditions of bacterial oxidation process, and the leaching of sulfide concentrates by bacteria. The physical and chemical factors of bacterial leaching during the powder process, as well as the leaching kinetics and leaching mechanism of bacterial leaching. In the face of the problematic problems of biometallurgy (long oxidation cycle leads to low production efficiency), the research group uses metal ions, surfactant catalysis, magnetization strengthening and other methods to accelerate the rate of bacterial oxidation reaction, so that this problem can be solved. Some new ideas.
4 Conclusion
With its important position in the fields of modern high-tech industry, national defense and cutting-edge technology, the rare metal bismuth has been paid more and more attention and its application scope is becoming wider and wider. However, due to the short time since the discovery, and the development of independent antimony ore is only a matter of recent years, most of the process technology is still in the experimental research stage, which makes it difficult to assert which process is the best. However, with the deepening of people's understanding of rare elements and the wide application of 碲 in various fields, we believe that the development of 碲 will be further developed, and the new process of separation and extraction of research and development æ›´åŠ is more practical.
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