The Mineralogy of Tin
Posted on: Sep 4, 2021, · 3 min read.
For tin mining equipment and beneficiation EPC solution, you can find in here
Tin is a metal element, ordinary white tin is a low melting point metal with silver white luster. It is divalent or tetravalent in the compound and will not be oxidized by air at room temperature.
In nature, tin is mainly composed of dioxide (cassiterite). And various sulfides (such as sulphur cassiterite). Tin is one of the most famous metall of human history, followed by gold, silver, copper, iron, its history can be referred to the early Bronze Age.
Metallic tin is soft and easily bent, with a melting point of 231.89°C and a boiling point of 2260°C. There are three isomers.
- White tin is a tetragonal crystal system with cell parameters: a=0.5832nm, c=0.3181nm, 4 Sn atoms in the cell, density 7.28g/cm3, hardness 2, good ductility.
- Gray tin is a diamond-shaped cubic crystal system with cell parameters: a=0.6489nm, 8 Sn atoms in the cell, density 5.75 g/cm3.
- Brittle tin is an orthorhombic crystal system with a density of 6.54 g/cm3.
| Tin General Properties | |
| Symbol: | Sn |
| Atomic Number: | 50 |
| Melting Point | 231.89°C (449.402°F) |
| Boiling Point | 2260°C (4100°F ) |
| Specific Gravity | 7.3 |
| Standard atomic weight (Ar): | 118.710(7) |
| Electron configuration: | [Kr] 4d10 5s2 5p2 |
Types of tin minerals
There are more than 50 kinds of tin-containing minerals known in nature, and there are about 20 kinds of main tin minerals. The main economic significance is cassiterite, followed by yellow tin ore. In some deposits, sulphur-tin-lead ore, stibnite, cylindrical tin ore, and sometimes black sulphur-silver-tin ore, black boron-tin ore, Malayanite, schistite, brucite, etc. can also be relatively rich. Set, form industrial value.
(1) Cassiterite: The chemical composition is SnO2, Sn 78.8, O 21.2. The tetragonal crystal system, the crystals are in the shape of double cones, cones, and sometimes needles. It often contains mixed substances such as iron, niobium, and tantalum. In addition, it can also contain manganese, scandium, titanium, zirconium, tungsten, and dispersed elements such as iridium and gallium.
The presence of Fe3+ often affects the magnetism, color and specific gravity of cassiterite. Cassiterite is the main raw material source of tin.
(2) Kesterite: also known as tetrahedronite, its chemical composition is Cu2FeSnS4, Cu 29.58, Fe 12.99, Sn 21.61, S 29.82. Tetragonal crystal system. The crystals are rare, in the form of pseudo tetrahedrons, pseudo octahedrons, plates, etc. Yellow tin deposits are more common in Guangxi tin-bearing sulfide metasomatic deposits and filling-type tungsten-tin deposits, and Hunan high- and medium-temperature hydrothermal lead-zinc deposits.
(3) Antimony tin-lead ore: The chemical composition is Pb5Sb2Sn3S14, Pb 49.71, Sb 11.64, Sn 17.04, S 21.51, and iron, zinc, etc. are mixed in the composition. The crystal is thin, often curved, and the twin crystals are complex. The aggregates are massive, radial or spherical. It is produced together with stibnite and kesterite, and is also produced in tin ore veins.
(4) Sulfur tin lead ore: chemical composition is PbSnS2, Pb 53.05, Sn 30.51, S 16.44. Orthogonal crystal system. The crystals are plate-shaped and nearly square in shape. Usually a massive aggregate. It is often produced in tin ore veins together with cassiterite, galena, sphalerite, and pyrite.
(5) Cylindrical tin ore: The chemical composition is Pb3Sb2Sn4S14. Orthogonal crystal system. Into a cylindrical or massive and spherical aggregate. Together with stibnite, sphalerite and pyrite, it is produced in tin ore veins.
Usages of tin
Tin is mainly used in the metallurgical industry to produce tinplate (tinplate) and various alloys. Tin plate is the main consumption area of tin, accounting for about 40% of tin consumption. It can be used as food and beverage containers, various packaging materials, household appliances, and dry battery shells.
The low melting point alloy composed of tin-lead and a small amount of antimony is solder, which accounts for about 20% of the amount of tin. The bearing alloy is an alloy of tin, lead, antimony, and copper. Tin-containing bronze is widely used in ships, chemicals, construction, currency and many other aspects. Tin can also be combined with other metals to make Babbitt alloys, movable type alloys, titanium-based alloys, niobium-tin alloys, etc., and are used in the atomic energy industry, aviation industry and other fields.
In the chemical industry, Tin is mainly used to produce tin compounds and chemical reagents. The organic compounds of tin are mainly used as wood preservatives and pesticides, and the inorganic compounds of tin are mainly used as catalysts, stabilizers, additives and emulsifiers in the ceramic industry. Tin concentrate is the main raw material for tin smelting.