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E. Shibata
wastes, etc.). Pyro-treatments enable separation and concentration of various elements by controlling multiple phases such as molten metal, slag, matte, speiss, and
gas phases. By combining pyro-treatments with various hydro-treatments (leaching,
precipitation, solvent extraction, ion exchange, electrolytic refining, etc.), various
metals are separated and recovered. Environmental load elements are also controlled
in smelters.
However, the continuous development of smelting and refining technologies is
indispensable due to social constraints such as strengthening of environmental regulations and increases in impurities derived from secondary raw materials. In addition,
by treating the concentrate and secondary raw materials, environmental load elements
such as arsenic (As), mercury (Hg), and cadmium (Cd) are inevitably introduced and
concentrated in the smelting processes. In this way, the non-ferrous smelting industry is responsible for the recovery of valuable metals, as well as the concentration
and stabilization of environmental load elements. The non-ferrous smelting industry
is socially indispensable for the recycling of metal resources and the controlling of
environmental load elements. It has the potential to turn into a growth industry by
extending this advantage in the future.
In this review, the present status and contributions of Japanese non-ferrous smelting industry for metal resource circulation are introduced with a summary of the
technologies, features, and problems in smelters [1].
Treatments of Secondary Raw Materials and Associated
Problems in Non-ferrous Smelters
The non-ferrous smelting industry in Japan has been reorganized and each company
is generally focusing on copper, lead, or zinc smelting. However, to recover various
metals from each smelting residue, such as dust, sludge, and dross, it is necessary to
recharge them into a proper smelting process or individually treat them by considering
the chemical components of each residue. In addition, regarding the treatments of
secondary raw materials such as industrial wastes, it is also indispensable to charge
them into a proper smelting process according to their form and contents. Under the
situation where the ratio of secondary raw materials has been increasing, it should
be emphasized that valuable metals such as precious metals (Au, Ag, Pt, Pd, Rh),
selenium (Se), tellurium (Te), nickel (Ni), cobalt (Co), antimony (Sb), bismuth (Bi),
tin (Sn), cadmium (Cd), gallium (Ga), and indium (In) can be recovered by efficiently
using an organic linkage among copper, lead, and zinc smelters related to exchanges
of various smelting residues.
However, the metals that can be recovered through the organic linkage among
smelters are limited to the above, and the so-called active metals, such as rare earth
elements (Nd, Dy, etc.), tantalum (Ta), and tungsten (W), cannot be recovered in the
non-ferrous smelting process because they become diluted in the slag as their oxides.
Therefore, to recover these active metals, it is necessary to separate components
E. Shibata
wastes, etc.). Pyro-treatments enable separation and concentration of various elements by controlling multiple phases such as molten metal, slag, matte, speiss, and
gas phases. By combining pyro-treatments with various hydro-treatments (leaching,
precipitation, solvent extraction, ion exchange, electrolytic refining, etc.), various
metals are separated and recovered. Environmental load elements are also controlled
in smelters.
However, the continuous development of smelting and refining technologies is
indispensable due to social constraints such as strengthening of environmental regulations and increases in impurities derived from secondary raw materials. In addition,
by treating the concentrate and secondary raw materials, environmental load elements
such as arsenic (As), mercury (Hg), and cadmium (Cd) are inevitably introduced and
concentrated in the smelting processes. In this way, the non-ferrous smelting industry is responsible for the recovery of valuable metals, as well as the concentration
and stabilization of environmental load elements. The non-ferrous smelting industry
is socially indispensable for the recycling of metal resources and the controlling of
environmental load elements. It has the potential to turn into a growth industry by
extending this advantage in the future.
In this review, the present status and contributions of Japanese non-ferrous smelting industry for metal resource circulation are introduced with a summary of the
technologies, features, and problems in smelters [1].
Treatments of Secondary Raw Materials and Associated
Problems in Non-ferrous Smelters
The non-ferrous smelting industry in Japan has been reorganized and each company
is generally focusing on copper, lead, or zinc smelting. However, to recover various
metals from each smelting residue, such as dust, sludge, and dross, it is necessary to
recharge them into a proper smelting process or individually treat them by considering
the chemical components of each residue. In addition, regarding the treatments of
secondary raw materials such as industrial wastes, it is also indispensable to charge
them into a proper smelting process according to their form and contents. Under the
situation where the ratio of secondary raw materials has been increasing, it should
be emphasized that valuable metals such as precious metals (Au, Ag, Pt, Pd, Rh),
selenium (Se), tellurium (Te), nickel (Ni), cobalt (Co), antimony (Sb), bismuth (Bi),
tin (Sn), cadmium (Cd), gallium (Ga), and indium (In) can be recovered by efficiently
using an organic linkage among copper, lead, and zinc smelters related to exchanges
of various smelting residues.
However, the metals that can be recovered through the organic linkage among
smelters are limited to the above, and the so-called active metals, such as rare earth
elements (Nd, Dy, etc.), tantalum (Ta), and tungsten (W), cannot be recovered in the
non-ferrous smelting process because they become diluted in the slag as their oxides.
Therefore, to recover these active metals, it is necessary to separate components