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TIN – A GREEN METAL Tin is everywhere in nature. Small amounts are found in rocks and soil, in plants and water, and in our bodies. Tin and tin alloys are excellent candidates as replacement for environmentally undesirable metals, especially lead and cadmium. Legislation from some of the world’s foremost regulatory bodies supports the safety of tin. | WORLD HEALTH ORGANISATION | | Guidelines for Drinking Water Quality 1993 | These do not list tin among the inorganic chemical restricted for health reasons. (In contrast, lead, mercury and cadmium are listed.) | EUROPEAN UNION | | Directive on Drinking Water | Tin is not on the list of substances of concern. Metals for which maximum concentrations are set on health Grounds are antimony, cadmium, copper, lead, mercury and nickel. | Directive on Packaging & Packaging Waste 1994 | Tin is not one of the metals whose concentration is restricted in packaging | Directive on Hazardous Substances | Tin powder is so harmless, it does not require to be labelled as ‘harmful if swallowed’. |
UK GOVERNMENT | | The Natural Mineral Waters Regulations 1985 | Tin is not included in the list of toxic substances whose concentration is restricted in UK mineral waters. | Tin Food Regulations | The legal general maximum limit in the UK for tin in food is 200mg/kg. This is many times higher than the limit on lead, cadmium and mercury. Unlike those metals, tin is not cumulative, and does not build up in the body to any serious extent, or have long term effects. |
US ENVIRONMENTAL PROTECTION AGENCY | | Primary Drinking Water Standards 1987 | Tin is not on the list of inorganic primary contaminants. |
TIN METAL PRODUCTS Pure tin is a silvery white metal which is soft, ductile and malleable. Tin is valued for its non-toxicity, resistance to corrosion and attractive appearance. A high proportion (about a third) of all the tin produced today goes to make tinplated steel (tinplate) for food and beverage cans. Recyclability is one of tinplate’s great merits. Tin readily forms alloys with other metals. In recent years tin in solder has emerged as a major use. Other new uses, such as tin shot gun pellets and tin sheet cork covers for wine bottles, are adding to overall in consumption. Tin in Solder The boom in consumer electronics goods is particularly strong and at the heart of every camera, portable phone, computer, TV and radio is a circuit board using tin solder. Environmental and safety concerns have led many manufacturers to switch from lead to 90% tin solders. Tin in Tinplate The use of tin plate in canned foods and beverages is a long established safe and dependable means of packaging and storing. while demand for tin-plated cans in the US and Europe has stabilised, the growth changing from lead to tin shot. The substitution of tin potential for Asia is still large. In parts of Asia today, per capita consumption of tin cans is at a level equivalent to one per cent of the tin can consumption in the West. Tin cans are than aluminium cans in the manufacture. Tin in Chemicals The chemical industry is the fastest growing consumer of tin. Demand is strong for household and industrial paints, in plastics and in non-ferrous alloys for use in engineering industries. | New Uses of Tin New uses of tin are being discovered, particularly as a result of the ongoing research at the International Tin Research Institute Ltd. A number of major beverage manufacturers in western markets are increasing their use of ultra-thin plated steel cans. The new energy efficient and easily to respond to environmental concerns in Europe. In sport, golf club manufacturers are turning to tin coatings for golf club shafts and an increasing number of suppliers of ammunition for sports guns are changing from lead to tin shot. The substitution of tin for lead in wine-bottle capsules is a typical example of a growing health consciousness. Tin alloys are also being developed to replace mercury dental amalgams used for fillings. Studies are showing that tin-based activities, stannates, can be highly effective as fire retardants in polymers for use in making PVC cable coverings, plastics and polyester fabrics. There are also positive results for tin in the development of fire retardants for use in paper manufacture. |
TIN METAL TRADING
Tin was one of the original four (copper, lead, zinc, tin) metal traded on the LME in the late 19th century. The LME provides the principal pricing mechanism for the tin industry, an international exchange where the sales and purchases can be hedged. Trading is in 5 tonne lots and the US dollar is the major currency in use. Traded option contracts for tin are also offered. The LME is a 24-hour market and not restricted to the periods of floor trading. Tin sale agreements can be negotiated whereby the mining company is paid 80% of the value of the concentrates against assay documents prior to export. The 20% balance is payable on smelter out turn.
Summary - TIN THE ENVIRONMENT FRIENDLY METAL
Tin is valued for its non toxicity, resistance to corrosion, its low melting point and alloying capacity. It is increasing seen as a green metal.
Tinplate is a long term and well established, safe and dependable material used in the food packaging industry. A thin coating of tin metal on the steel cans used by the food industry provides the non corrosive layer that allows long term, and robust storage of food products from production, through transport to warehouses and supermarkets, to the home shelves. The tin metal is recovered in the recycling of the cans for ongoing use.
Tin in solder is essential in the electronics industry. Solder, to date, is an alloy of tin and lead. Solder is the low temperature material that allows the joining of all the components on the circuit board on every electronics instrument made. Every computer, mobile phone, camera has a solder join. The lead component in solder has come under increasing environmental concern as the amount of electronic equipment makes its way into rubbish fill and the toxic nature of lead is seen to be draining away from these fill areas . There are now mandated requirements for the increasing tin component in solder, such that 90% tin component solders are now the main solder type used in the electronics industry. Lead has had major use as pellets in sporting shooting clubs. Lead has had major use as weights in the sporting fishing clubs. There has been increasing environmental concern of lead in the marine and freshwater settings. Tin metal has the high density and ability to mould and shape at low temperature, with the non toxicity in the marine and freshwater environments. Tin metal is a green metal. *Tin – Mineral Facts Courtesy of the Australian Government Geosciences website
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Tin Information