Speisses are alloys of heavy metals like iron, cobalt, nickel and copper
[ White, L.A. "The development of the lead blast furnace at Port Pirie, South Australia", ''Transactions AIME, Vol 188, October 1950, Journal of Metals'', pages 1221–1228.] with arsenic, antimony and, occasionally, tin.
The latter elements lower the melting point to around 1000 °C.
Speisses commonly occur in
lead
Lead is a chemical element with the symbol Pb (from the Latin ) and atomic number 82. It is a heavy metal that is denser than most common materials. Lead is soft and malleable, and also has a relatively low melting point. When freshly cu ...
smelting
Smelting is a process of applying heat to ore, to extract a base metal. It is a form of extractive metallurgy. It is used to extract many metals from their ores, including silver, iron, copper, and other base metals. Smelting uses heat and a ch ...
operations
[Samans, Carl H. ''Engineering Metals and their Alloys'', 1949 MacMillan] and
copper
Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkis ...
smelting
Smelting is a process of applying heat to ore, to extract a base metal. It is a form of extractive metallurgy. It is used to extract many metals from their ores, including silver, iron, copper, and other base metals. Smelting uses heat and a ch ...
operations.
Speisses are only partially miscible with
mattes, and if there is enough arsenic or antimony in the copper feed to a matte smelting furnace, a separate speiss melt can form.
Speisses show high affinities for
platinum group
The platinum-group metals (abbreviated as the PGMs; alternatively, the platinoids, platinides, platidises, platinum group, platinum metals, platinum family or platinum-group elements (PGEs)) are six noble, precious metallic elements clustered to ...
metals and
gold
Gold is a chemical element with the symbol Au (from la, aurum) and atomic number 79. This makes it one of the higher atomic number elements that occur naturally. It is a bright, slightly orange-yellow, dense, soft, malleable, and ductile met ...
.
The mass concentration of platinum group metals in the speiss phase is about 1000 times that of the concentration in the matte phase, while the ratio for gold is about 100 times.
Speisses are also immiscible in liquid lead and flow out of lead blast furnaces as a separate phase.
References
Metallurgical processes
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