Nonferrous Slags

In addition, molybdenum has high resistance to a number of alloys of these metals and also to copper, gold, and silver. Among the molten metals that severely attack molybdenum are tin (at 1000°C), aluminum, nickel, iron, and cobalt. Molybdenum has moderately good resistance to molten zinc, but a molybdenum—30% tungsten alloy is practically completely resistant to molten zinc at temperatures up to 800°C. Molybdenum metal is substantially resistant to many types of molten glass and to most nonferrous slags. It is also resistant to hquid sulfur up to 440°C. 

Iron slag Steel slag Nonferrous slag... 

Table 4.10 lists some typical physical properties for nonferrous slags. Because they have similar properties, lead, lead-zinc, and zinc slags are grouped together. 

Nonferrous slags (NFS) are produced diuing the recovery and processing of nonferrous metal from natural ores. The slags are molten by-products of high temperature processes that are primarily used to separate the metal and non-metal constituents contained in the bulk ore. When cooled, the molten slag converts to a rocklike or granular material [129-135]. 

There are various NFS, which include copper, nickel,phosphorus,lead,lead-zinc, and zinc. Approximately 3.6 million metric tons (4 million tons) each of copper and phosphorus slag are produced each year in the United States, while the annual production of nickel, lead and zinc slags is estimated to be in the range of 0.45-0.9 million metric tons (0.5-1.0 million tons) [143]. A summary of the different types of nonferrous slags is represented in Table 7. 

Hydratable oxides may also be present in NFS from some sources, which could potentially contribute to volumetric instability. Depending on the ore and metallurgical process, nonferrous slags produced from sulfide ores can contain leachable elemental sulfur and heavy metals, which should be investigated prior to use. Sulfurous leachate is primarily of aesthetic concern, resulting in sulfur odor and possible discoloration of water in poor drainage conditions. In addition, phosphate rocks can contain between 30-200 ppm uranium. Most of this uranium is incorporated in the phosphorus slag and results in the release of some radiation (in the form of radon gas). 

Table 14 Typical chemical compositions of nonferrous slag ...

Granular base Blast furnace slag Coal boiler slag Mineral processing wastes Municipal solid waste combustor ash Nonferrous slags Reclaimed asphalt pavement Contaminated soils Reclaimed concrete Steel slag Waste glass... 

Nonetheless, there have been reported uses of nonferrous slag as an aggregate... 

Nonferrous slags are produced in a few locations, often remote from potential markets. As a result, nonferrous slags are not well utilized and most of the nonferrous slag produced is disposed of in slag dumps or stockpiles... 

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