Bismuth

 

Bismuth

Chemical formula	Bi
Atomic Number	83
OTP appearance	solid
Molar Mass(g/mol)	208.98
Density(g/cc)	9.8
Melting Point(°C)	271.5
Boiling Point(°C)	1564
NFPA 704	0 0 3

Uses

Other

• Feedstock for bismuth subsalicylate
• Feedstock for pewter
• Feedstock for low melting point alloys
• Feedstock for low thermal expantion alloys

Natural Occurrence

• Elemental bismuth does occur naturally
• Small (≤ 10%) amounts are present in lead ores such as galena
• Bismuth is the primary metal in the minerals bismite and bismuthinite

Production

Extraction

Bismuth (like silver) is found most often as a component of lead.

• The Betterton-Kroll process separates bismuth from lead as follows:
  1. Melt the bismuth-containing lead
  2. Repeat
     1. Add metallic calcium and magnesium to the ratio 1Ca:2Mg:2Bi
     2. Cool the mixture to just above the melting point of lead
     3. Retain the floating slag, which contains lead and CaMg₂Bi₂
     4. Remove the lead
  3. Until as much bismuth as possible is removed
  4. Melt the slag in a chlorine atmosphere

     Pb + Ca + Mg + Bi + xCl2  → PbCl₂ + CaCl₂ + MgCl₂ + Bi

  5. Skim the lead, calcium and magnesium chlorides from the bismuth

Also:

The ore containing Bi, Pb, and Zn is first treated with molten caustic soda to remove traces of arsenic and tellurium. This is followed by the Parkes process to remove any silver and gold present. The ore now contains Bi, Pb, and Zn. It is treated with Cl2 gas at 500 °C. ZnCl2 forms first and is removed. Then PbCl2 forms and is removed leaving pure Bi. BiCl3 would form last.