High-purity bismuth is mainly used in the nuclear industry, aerospace industry, electronics industry and other sectors. Because bismuth has semiconductor characteristics, its resistance decreases with increasing temperature at low temperatures. In terms of thermoelectric cooling and thermoelectric power generation, Bi2Te3 and Bi2Se3 alloys and Bi-Sb-Te ternary alloys attract the most attention. In-Bi alloy and Pb-Bi alloy are superconducting materials. Bismuth has a low melting point and high density, low vapor pressure, and small neutron absorption cross section. It can be used in high-temperature atomic reactors.
Guixi Sanyuan Company has an annual output of 4,000 tons of bismuth ingots and a trade volume of 2,000 tons. It is the largest bismuth ingot producer in China with a domestic market share of about 25%. The "Hongxia" bismuth ingot produced by Guixi Sanyuan Company is a well-known domestic trademark. Guixi Sanyuan Company has a long history of smelting and producing bismuth ingots. The product quality is very stable, especially the content of lead and silver elements are controlled within 5ppm. Unanimous praise from customers at home and abroad. The income exceeds 3.5 billion, and the profits and taxes exceed 320 million. It has successively won the honorary titles of "Jiangxi Province Top 100 Enterprises", "Provincial Excellent Private Enterprises", and "Jiangxi Province High-tech Enterprises".
At present, the most industrially valuable methods for purifying 5N bismuth are vacuum distillation and zone melting purification.
The trace impurities contained in refined bismuth can be divided into two types: easily volatile impurities and difficult to volatile impurities. Easily volatile impurities can be removed by vacuum heating, and difficultly volatile impurities can be removed by vacuum distillation.
●Zone melting purification:
When molten bismuth is cooled and crystallized, impurities are condensed earlier than bismuth and precipitated on the edge of the container. Therefore, the impurities in the center of the bismuth ingot are less than those on the edge of the bismuth ingot. Regional purification is based on this principle. The bismuth rod is heated and melted in a region, and the bismuth rod is slowly moved through the melting zone and repeated multiple times to enrich the impurities at the ends of the head and tail of the bismuth rod to achieve the purpose of purification.
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