Tin is one of ten commonly used non-ferrous metals. At present, tin is mainly used in electronic solder, tinplate, tin chemical industry, tin alloy, float glass, tin handicraft and other industries. Tin applications in the electronics industry is mainly tin solder, used in electronic welding, the field currently accounts for 70 percent of China’s tin downstream application, in addition to tinplate and tin chemical products accounted for 8 percent and 12 percent of the downstream application.
Tin is closely related to people’s life, such as used to make wood alloy, used as a safety valve for fuses and cauldrons, made tin bronze and tin-containing brass; Tin-based bearing alloy is an excellent wear-resistant material with low friction coefficient and good toughness, thermal conductivity and corrosion resistance. Tin can also be configured into fusible alloy, solder, printing alloy, tin bronze and tin containing brass; Zirconium base alloy containing tin is used as nuclear fuel packaging material in atomic energy industry. Tin-containing titanium alloy for aviation, shipbuilding, atomic energy, chemical nuclear medical equipment and other industrial sectors; Tin niobium intermetallic compound can be used as superconductor. Tin’s traditional Chinese medicine compounds tin dioxide, tin tetrachloride and tin’s organic compounds are respectively used as raw materials for ceramic glazes, coal dyes for printing and dyeing silk fabrics, as well as insecticides, antifouling agents, wood preservatives and flame suppressants.
The world’s proven tin base reserves are about 4.8 million tons, mainly distributed in China, Indonesia, Peru, Brazil, Bolivia, Malaysia and other places. China is the world’s largest producer and consumer of tin, but also the world’s largest tin resources. At present, the proven tin base reserves are 1.38 million tons, accounting for 29% of the world’s total reserves, mainly distributed in yunnan, guangxi, Inner Mongolia, hunan, jiangxi, guangdong and other places. The recoverable reserves are less than 1.4 million tons, mainly in yunnan, guangxi, jiangxi and hunan. The tin resources in Inner Mongolia are mainly in the form of companion.
According to the analysis, the market demand for tin is expected to grow by 2% annually in the future, which is mainly due to the growth of downstream industry and tin application in new fields. Since the second half of 2012, the global printed circuit board mounting field obvious recovery, driving the tin price up gently, tin industry demand recovery is expected to continue, and is expected to strengthen, the scope is expected to expand. In addition, the replacement of tin for anode carbon in the field of lithium battery, for chromium nickel in the field of stainless steel, and for lead in the field of polyvinyl chloride is also gradually promoted, which is expected to contribute to the growth of tin demand.
At present, the recycling of secondary tin resources in China has begun to take shape. Under the dual incentives of the market and the government, the recycling of secondary tin resources has taken up a considerable share of the market supply. Although there is no complete and systematic statistics of tin industrial solid waste in China, according to the distribution of tin mines and industrial characteristics in China, a large number of tin industrial solid waste heaps exist in gejiu, yunnan and hechi, guangxi. Gejiu and hechi are also the pilot areas for the establishment of large-scale industrial solid waste base by the Ministry of Industry and Information Technology. In addition to gejiu, tin tailings are mainly distributed in guangxi, hunan, jiangxi, sichuan, Inner Mongolia and other mining areas. It is known that the tailings in these areas are basically unused and are a large number of potential resources.
Recovery of tin sheet waste is also the focus of recycling tin production. Tin recovery from tin-containing alloy wastes should be directed towards the production of new alloys. Hot tin plating is gradually replaced by electroplating tin, and the amount of hot tin residue decreases.
In addition to the above sources, enterprises are also constantly digging tin secondary resources. As far as I know, there are some copper smelters around chifeng, Inner Mongolia. Some people collect the chimney ash that the copper smelter prepares for landfill, namely smelting dust, and sell it to yunnan for profit. The reason is that the chimney ash contains valuable metal tin, which can be smelted and extracted by the enterprise. Recycled tin has become a necessary supplement of resources in China
The tin produced by separation and smelting from the recovered waste containing tin is called recycled tin, which is different from the original tin produced directly from the tin concentrate. Tin is a rare and expensive heavy metal. The recycled tin produced from the waste tin can not only save a lot of energy, but also protect the environment from pollution and supplement the shortage of tin mineral resources. The production cost of recycled tin is generally lower than that of original tin, and the waste tin-containing sundries used to produce recycled tin are increasing with the development of economy. Therefore, all countries in the world attach great importance to the recycling of tin. The amount of recycled tin in developed industrial countries is equivalent to more than 60% of the original tin output. At present, China has reached the level of about 40%.
According to incomplete statistics, the annual output of recycled tin in China has reached 35,000 ~ 37,000 tons. Mainly distributed in guangdong qingyuan, shantou, chaozhou and zhejiang taizhou, hebei baoding, hunan yongxing, yunnan gejiu and other areas.
Recycled tin refers to the recovery from the tin waste, smelting into metal tin. Tin waste includes tin plate waste, tin alloy waste, hot tin residue and tin foil ash. Tin plate scrap tin containing low generally in 0.35% ~ 2%, but the number of large, the world’s annual consumption of tin plate amount to 18 million tons. There are various kinds of tin alloy waste, there are various kinds of babbitt bearing alloy, fusible alloy, solder, these collectively referred to as lead-tin alloy, as well as tin-green brass waste, generally containing tin 2% ~ 5% or higher, but also containing lead, copper, antimony, zinc and other components of recycling value. Hot – dip tin slag contains the highest amount of tin, less. Generally, tin is recovered from tin plate, lead-tin alloy, tin-green brass and hot tin residue. Tin foil ash is mainly composed of tin oxide, melting point of 1630℃, using 1:2 hydrochloric acid and sodium chloride mixture, fully stirred electrolysis, is a common industrial method. Add a mixture of hydrochloric acid and sodium chloride to the tin foil and electrolyze it, which can also be obtained at the cathode of the carbon rod.
From the background of supply and demand of Sikkim industry, the total demand of China’s tin market will continue to grow, and the supply of tin resources is unlikely to increase significantly in the short term. Due to the scarcity of tin resources, it is inevitable to promote the development and utilization of tin resources technology level.
Full utilization and deep excavation of tin secondary resources will become the norm and gradually develop and perfect. Although after years of large-scale mining and production in China, the scarcity of highly concentrated high-quality tin resources has become increasingly prominent, the comprehensive utilization of tin tailings has been continuously strengthened. Through the recycling of tin waste, tin tailings, tin plate waste, tin foil ash and smelting dust, it has become a necessary supplement to our country’s tin mineral resources, but also to implement the development of circular economy, energy-saving emission reduction concrete action. In order to ensure the healthy and rapid development of tin industry, we must in all aspects of tin industry of continuous exploration and innovation, expand the scope and depth of the secondary tin resources, improve the level of secondary tin resources recycling, tin mining and use of limited and precious resources fully, continuously develop new application areas, let the metal tin better benefit, benefit the human world.