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镉是比较稀有的元素,在地球岩石中的平均含量为1.5克/吨。自然界中的镉以硫镉矿(CdS)存在,主要存在于锌、铜和铅矿内,以锌矿内的含量较高。存在于锌矿和多金属矿中的镉为锌量的0.1～5％。 工业性生产镉是冶炼锌时的副产品。由于挥发的原因,电镀、轧制锌熔化、压铸(2500大气压)、银焊料、废物燃烧、锌矿焙烧、黄铜铸锭、铅渣烟雾、锌矿熔炼、铅鼓风炉、铜吹炼和废钢熔炼等作业均可造成镉逸散到环境中去成为环境污染的因素。目前镉和镉化合物在工业上的用途广泛,因而镉对环境的污染越来越受到人们的重视。
Cadmium is a relatively rare element, with an average content of 1.5 g / t in earth rocks. Cadmium in nature exists as cadmium sulfide (CdS), mainly in zinc, copper and lead mines, with a high zinc content. The cadmium present in zinc and polymetallic ores is 0.1 to 5% of the amount of zinc. Industrial production of cadmium is a by-product of smelting of zinc. Electroplating, rolling zinc melting, die casting (2500 atmospheres), silver solder, waste burning, zinc ore roasting, brass ingots, lead slag fumes, zinc smelting, lead blast furnace, copper blowing and scrap smelting due to volatilization Such operations can cause cadmium escape into the environment to become a factor in environmental pollution. At present, cadmium and cadmium compounds are widely used in industry. Therefore, the pollution of cadmium to the environment has drawn more and more attention.