Abstract

The element bismuth, Bi, found in Group 15 (VA) of the Periodic Table, has at no. 83, at wt 208.98. Its valences are +5 and +3. Bismuth is a silvery metal having a high metallic luster and exhibiting a slightly pink tinge on a cleanly broken surface. The metal itself is brittle in nature and easily broken. Bismuth is referred to as a minor metal. Bismuth occurs in the earth's crust in a concentration of approximately 0.1 ppm on the average. The physical properties of bismuth are characterized by a low melting point, a high density, and expansion on solidification. The thermal conductivity of bismuth is lower than that of any other metal except mercury. Bismuth is mined primarily as a by-product of the processing of ores of other metals, mostly copper and lead. The principal portion of the bismuth in copper ores follows the copper into the matte. During the conversion of the matte to blister copper most of the bismuth fumes off. The fumes are caught in the baghouse or Cottrell system. The portion of the bismuth remaining with the blister copper is separated during the electrolytic refining in the slimes. The bismuth found in the lead ore accompanies the lead through the smelting operation right up to the last refining steps. Bismuth is leached from roasted tin concentrates and other bismuth-bearing materials by means of hydrochloric acid. There are four basic forms of bismuth that are readily available commercially: ingot, needle, pellet, and powder. The three primary categories of uses of bismuth in industry are chemical, metallurgical additive, and fusible alloy. The Chemical category can be broken down into pharmaceuticals, cosmetics, catalysts, industrial pigments, and electronics, and the metallurgical additive category into steel, aluminum, and cast-iron additives. The fusible alloy category is divisible into more than a dozen subcategories dependent on a specific application. Because bismuth alloys with certain other metals to give low melting point alloys, bismuth is particularly well-suited for a number of uses. No industrial poisoning from bismuth has been reported. Ingestion and inhalation of dusts and fumes should be avoided.