Development status of recycled Tin Industry
Tin is a metal element, belongs to the IVA family, atomic number is 50, the relative atomic mass of 118.71, it is IVA metal, melting point is 231.89 C, boiling point is 2260 C, density is 7.28g/cm³. Tin is a silvery white metallic luster of low melting point metal, pure tin soft, good exhibition, stable chemical properties, not easy to be oxidized, often keep silver shining luster. The content of tin in the crust is 0.004%, almost exists in cassiterite (SnO2) form, in addition to a very small amount of tin sulfide ore. As one of "hardware" (gold, silver, copper, iron, tin), tin has been used by humans as early as 2000 BC. At present, it mainly used in the manufacture of tin solder, tin plate, alloy, chemical products, which are widely used in electronics, electrical appliances, information, chemical industry, metallurgy, building materials, food packaging, machinery, atomic energy and aerospace industry and other industries.
As the heavy metal, tin is scarce and expensive, with the continuous development of economy and the construction industry, its consumption also increased year by year, tin waste is also increasing in the process of industrial production or life, and the reserves is decreasing, so in order to meet the rapid development of tin industry, recycling tin industry has become an important direction of the development of tin industry.
The development of the recycled tin industry not only uses the two resources of tin to supplement the deficiency of the world's original tin mineral resources, but also can save energy and protect the environment from pollution, reduce the industrial production costs at the same time. With the development of economy, the development of recycled tin has attracted worldwide attention. The amount of recycled tin is more than 60% of the original tin output in developed countries. The world's higher level production of recycling tin is mainly in industrial developed countries, such as the United States, Britain, Germany, Japan and so on.
Sources and recycling methods of tin
Tin is produced directly from concentrates, it is called primary tin, tin is obtained from metallurgy of tin containing waste, which is called recycled tin. The comprehensive exploitation and utilization of recycled tin resources include tin associated ore, paragenetic ore, tailings produced during ore dressing, slag and soot produced in smelting process, and utilization of other wastes.
Tin slag, gray tin, tin wire, solder paste, tin wire, silver tin are tin waste in the comprehensive development and utilization of renewable resources.
As time goes by, tin ore resources are depleted, the grade is getting lower and lower, and some are close to or even lower than that of early tailings. Whether the early tailings can be used as a replacement resource and the exploitation of tin mine tailings as renewable resources must be paid more attention to. However, with the development of modern beneficiation technology, especially the rapid development of fine ore dressing and low tin smelting technology, the recycling process of tin mine tailings has been accelerated. At present, the tin tailings re-election early has a lot of experience, the tin tailings in the comprehensive recovery of valuable metals has become a hot research topic. Undoubtedly, tin tailings will be of great importance to our recycling tin resources.
Tin waste is the third important source of recycled tin resources. Tinplate is commonly known as tin plated thin steel plate. It is a cold-rolled low carbon steel sheet or strip coated with commercially pure tin on both sides. Recycling waste tin plate is mainly recycled tin production, the waste contained low tin (0.5% ~ 2%), tin scrap mainly includes tinplate production plant waste cans, beverage cans. The number of tinplate in the world consumption amounted to 18 million tons every year. The waste materials are prepared first by classification, shearing, deoiling, washing and drying, and then tin removal and tin recovery are carried out.