Scattered metals usually refer to a group of chemical elements composed of seven elements: gallium (Ga), germanium (Ge), selenium (Se), indium (In), tellurium (Te), rhenium (Re) and thallium (Tl).But others include rubidium, hafnium, scandium, vanadium and cadmium.These seven elements were discovered from tellurium in 1782 to rhenium in 1925.The reason why this group of elements is called scattered metals is that, on the one hand, they are similar in physical and chemical properties, so they are divided into a group;Second, because they often exist in the form of isomorphismmineralAmong them, it is difficult to form an independentexploitationScattered metal of valuedeposit, (in Sichuan ProvinceShimian CountyA tellurium basedTelluriteBed);Three is that they areCrustMedium average content is low, in a rare and dispersed stateassociatedAmong other minerals, only the main metal can be mineddepositComprehensive recovery and utilization shall be carried out in beneficiation and metallurgy.
Chinese name
scattered metals,SM
Reason for division
Similar physical and chemical properties
Include elements
Gallium, germanium, selenium, indium, tellurium, rhenium and thallium
Chinascattered metals,SM mineral productsAbundant, providing better resource conditions for the development of scattered metal industry.
Scattered elements innatureIt mainly consists ofdispersedState assignment relatedMetallic mineralsMedium, such assphaleriteGenerally, they are rich in cadmium, gallium, germanium, indium, etc., and some of them also contain thallium, selenium and tellurium;chalcopyrite、TetrahedriteandArseniteThey are often rich in thallium, selenium and tellurium, and some are also rich in indium and germanium;Galena is also rich in indium, thallium, selenium and tellurium;MolybdeniteandBorniteIt is rich in rhenium, and some are also rich in selenium;PyriteIt is often rich in thallium, gallium, selenium, tellurium, etc.
At present, although nearly 200 kinds of rare element minerals have been found, they have not been enriched into independent deposits with industrial exploitation due to their scarcity. So far, only rare independent deposits have been foundGermanium ore、Selenite、TelluriteHowever, the deposit scale is not large.
Gallium Introduction
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Gallium is a white lusterSoft metal。The melting point is surprisingly low, only 29.78 ℃.Take a small grain of gallium and put it in the palm of your hand. After a while, it will melt into small liquid beads and roll around like mercury beads.
People know the history of gallium
Gallium has been known for more than 100 years.It was founded by French chemists in 1875BuwabodelandFound.For example, the amount in the crust is about 0.0004%, about the same as tin, not too little.However,Tin oreThe gallium is relatively concentrated, but the distribution of gallium in nature is very scattered, and there is almost no single galliumGallite。Therefore, gallium is also called "scattered metal".Gallium sometimes andaluminumMixed together, existing inbauxiteLi.This is because gallium and aluminumperiodic table of ele mentsBoth of them belong to the third main group, and gallium ions and aluminum ions are about the same size, so they are easy tomineralCoexistence.And because the size of gallium and zinc atoms is also similar, gallium and zinc are also easy to be dispersed togetherZinc oreMedium.Gallium also easily coexists with germanium in coal.Therefore, trace gallium and germanium are contained in the flue ash left after coal combustion.
Valuable properties of gallium
Gallium has many valuable properties and itspurityofRefining with ordinary chemical methods can only get 99. 5% at most99% purity, that is, the four nines.For nearly half a century, people have made great progress in the purification of gallium, thus promoting the application of gallium.
Chemical properties of gallium
The chemical properties of gallium are very similar to that of aluminum, as well as indium and thallium of the same family.Gallium does not change in dry air at ordinary temperatures.Only when it is red hot can it be oxidized by air.Gallium is also very stable to water.At room temperature, gallium can strongly react with chlorine or bromine.Gallium is easily dissolved by sulfuric acid, especially hydrochloric acid.Gallium is also easily dissolved in strong acid solution or ammonium hydroxide solution.GallichydroxideIt can also be dissolved in strong alkaline solution to form galliate.Acidity ratio of gallium hydroxideAluminium hydroxideBetter.Chemically, this is called "amphoteric".In other words, this substance is both alkaline and acidic.
Melting point of gallium
Gallium has a very low melting point.It is not easy to solidify after melting.When gallium is in liquid state, its volume expands evenly after heating.The boiling point of gallium is up to 2070 ℃.The temperature range from melting point 30 ℃ to boiling point 2070 ℃ is very wide, so gallium can be used as the material of high-temperature thermometer.commonMercury thermometerFor the measurement of steelmaking furnaceatomic reactorIt can't do anything because mercury turns into steam at 356.9 ℃.
People also take advantage of the low melting point of galliumtinIndium and these metals are mixed together to makeLow melting point alloy, use it on the switch of the automatic fire hydrant.In case of fire, the temperature risesFusible alloyWhen the switch fuse is melted, water will automatically spray from the faucet to extinguish the fire.
Liquid gallium
Liquid gallium is also used to replace mercuryVacuum pump, or an ultraviolet light bulb.stayAtomic reactorGallium is also used as a heat transfer medium to transfer the heat in the reactor.Gallium can stick tightlyGlassTherefore, it can be made into a reflector and used in some special optical instruments.
Gallium has wonderful characteristics of cold expansion and heat contraction
Gallium also has some wonderful properties.Most metals areThermal expansion and cold contractionOf.Gallium, however, isCold expansion and heat contraction。When gallium condenses from liquid to solid, its volume will expand by 3%.Therefore, as opposed to most metals, the specific gravity of liquid is larger than that of solid.Therefore, metal crops should be stored inPlasticOrrubberIn the container.If it is put in a glass bottle, once the liquid gallium solidifies, its volume will expand and the bottle will burst.
Gallium - semiconductor material
Gallium belongs toperiodic table of ele mentsThe third family of.It is associated with the fifth group elements - arsenicantimony, phosphorusnitrogenAfter combination, a series of compounds with semiconductor properties are formed.for exampleGallium arsenide、gasb 、Gallium phosphideThey all have good semiconductor properties and are currently widely used semiconductor materials.
Most of the electronic devices originally based on vacuum tubes are bulky.Since the emergence of semiconductors based on gallium and other metals, the volume of many electronic devices has been greatly reduced, thus realizing miniaturization, miniaturization, and even making integrated board circuits.It has caused a profound revolution in the entire field of electronic industry technology.Gallium arsenide, a compound of arsenic and gallium, is a newly developed semiconductor material with excellent performance in recent years.It can be made from gallium arsenideGaAs laser。This is a new type of laser with high efficiency and small volume.Gallium phosphide, a compound of gallium and phosphorus, is a semiconductor light-emitting material.It can emit red or green light.People make it into various Arabic numerals.In some electronic computers, it is used to display the calculation results.
Andrare earthThe situation is similar. Gallium is also a dominant resource in China. As an importantsemiconductor material Japan and South Korea, which started with manufacturing and electronics industries, are obviously dependent on gallium due to their own resource shortage.The United States and Japan have positioned gallium as a "strategic resource" for storage several years ago, and the European Commission has also released the "Vital and Vital Raw Materials News for the EU", listing 14 important mineral raw materials on the "short list", including gallium.For a long time, the low-cost export of gallium has caused the loss of scarce resources in China.In recent years, the Chinese government has also begun to pay attention to the collection and storage of gallium.At the end of 2011, a "12th Five Year Plan" for nonferrous metal industry attracted great attention from the industry.According to the plan, the state has made a special plan for the development of strategic small metals such as tungsten, molybdenum, tin, antimony, gallium and rare earth, and proposed to "establish a complete national reserve system".[1]
Gallium metal
Gallium metalAnother strange feature is that it has good "superconductivity" at low temperatures.When it is close to absolute zero, i.e. - 273 ℃, the resistance becomes extremely low, almost equal to zero.At this time, its conductivity is very good.If the power is turned on at such a low temperature, the loss of current is negligible.This property is called superconductivity.As early as 1911, people discovered superconductivity.Using superconducting materials to make motors can not only save energy consumption, but also greatly save raw materials.A conventional eight thousand horsepower motor weighs 379 tons, and only 40 tons after using superconducting materials.The total cost was cut by half.Superconducting technology is almost necessary to build large motors of more than 5 million kilowatts.It is very economical to use superconducting materials as long-distance transmission lines, with transmission efficiency of more than 99.5% and little loss.
Now people are trying their best to find new materials that can maintain superconductivity at higher temperatures, even at room temperature.A compound formed by the combination of an atom and three vanadium atoms (commonly known as "vanadium gallium") isSuperconductive material。
