| Sn is a silver-white metal with strong luster, a relative density of 7.0, a low melSng point (230℃), a hardness of 3.75, and good soft ductility. Sn content in the crust is only 2×10^-6~3×10^-6. Sn belongs to the cuprophile group, but in the upper lithosphere has the amphoteric characteristics of oxygen and sulfur. Sn reacts with sulfur to form two compounds, Sn monosulfide and Sn disulfide, which are highly volatile at high temperatures. Sn can also combine with oxygen to produce Sn monoxide and Sn dioxide. Although Sn has both bivalent and quadrivalent states, under natural conditions, quadrivalent compounds are relatively stable, especially Sn oxide (SnO2), which is one of the most stable compounds on the Earth’s crust. |
| More than 50 Sn-bearing minerals are known in nature, and there are about 20 major Sn minerals. At present, cassiterite is the main economic significance, followed by yellow Sn ore. In some ore deposits, thiostannite, antimonite stannite, cylindrical Sn, sometimes black thiostannite, black boroSn, malayite, kaisarite, maisarite can also be relatively enriched, forming industrial value. |
| (1) The chemical composition of cassserite is SnO2, Sn 78.8, O 21.2. Tetragonal system in which the crystals are biconical, conical, and sometimes acicular. Often containing mixed iron, niobium, tantalum, in addition to manganese, scandium, titanium, zirconium, tungsten and disperse elements iridium, gallium, etc. The presence of Fe3+ often affects the magnetism, color and specific gravity of cassite. Cassiterite is the main raw material of Sn. |
| (2) The chemical composition of tetrahedrite, also known as tetrahedrite, is Cu2FeSnS4, Cu 29.58, Fe 12.99, Sn 21.61, S 29.82. Tetragonal system. Crystals are rare, pseudotetrahedron, pseudooctahedron, plate and so on. The yellow Sn deposit is common in the Sn sulfide metasomatic deposit and filling type tungsten-Sn deposit in Guangxi and the high school hydrothermal type lead-zinc deposit in Hunan. |
| (3) The chemical composition of pyrostannite is Pb5Sb2Sn3S14, Pb 49.71, Sb 11.64, Sn 17.04, S 21.51, with iron and zinc mixed in the composition. The crystals are lamellar, often curved, twin-crystal complex. The aggregate is massive, radial, or globular. Produced with antimonite and Sn, also in Sn veins. |
| (4) The chemical composition of thiostannite is PbSnS2, Pb 53.05, Sn 30.51, S 16.44. Rhombic system. The crystal is plate – like and nearly square in shape. Usually lumpy aggregates. It is often found in Sn veins with cassiterite, galena, sphalerite and pyrite. |
| (5) The chemical composition of cylindrical Sn ore is Pb3Sb2Sn4S14. Rhombic system. Forming a cylindric or lumpy and spherical mass. It is produced in Sn veins along with sphalerite, sphalerite and pyrite. |
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Economic use | | | |
| Sn is mainly used in the production of Snplate (Snplate) and various alloys in the metallurgical industry. Sn plaSng is the main consumption area of Sn, accounSng for about 40% of the consumption of Sn, it can be used as food and beverage containers, various packaging materials, household appliances and dry battery casings. A low melSng point alloy of Sn lead and a small amount of antimony is solder, which accounts for about 20% of the amount of Sn. Bearing alloy is an alloy of Sn, lead, antimony and copper. Sn bronze is widely used in ships, chemicals, construction, money and many other aspects. Sn can also be made with other metals Babbitt alloy, movable type alloy, titanium base alloy, niobium Sn alloy, etc., used in the atomic energy industry, aviation industry and other fields |
| Sn in the chemical industry is mainly used to produce Sn compounds and chemical reagents. The organic compounds of Sn are mainly used as wood preservatives, pesticides and so on, while the inorganic compounds of Sn are mainly used as catalysts, stabilizers, additives and emulsifiers in the ceramic industry. |
| Sn concentrate is the main raw material for Sn refining. |
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