Contributions of Non-ferrous Smelters to Metal Resource …
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containing the active metals by pretreatment of E-scrap such as printed circuit boards,
particularly by physical separation techniques. In copper smelters in particular, the
influence of increased charging of secondary raw materials such as printed circuit
boards has been highlighted, and there is an urgent need to appropriately cope with
an excess increase in impurities.
Due to a limitation of the removal of impurities in the smelting process constructed for the concentrates, the physical selection techniques of E-scrap such as
printed circuit boards should be focused and developed with the aim of removing
impurities that impede the smelting processes. In addition, for improving the process
to withstand impurities in main smelting processes, for example, it is necessary to
consider introducing a new smelting process such as the TSL (top submerged lance),
a furnace specialized in treatments of secondary raw materials.
Features and Technologies of Non-ferrous Smelters in Japan
Usually, printed circuit boards are incinerated, roasted [2, 3], or melted [4, 5] prior
to being charged into copper smelting furnaces in the form of metal-containing ash,
or slag and metal, along with concentrates. In copper smelters, Se, Te, and precious
metals are recovered from the anode slime; however, the excess increase in other
impurities such as Ni, Sb, Sn, and Bi derived from secondary raw materials such as
printed circuit boards is a serious problem.
Ni is originally recovered as crude nickel sulfate from copper electrolyte; however, Sn, Sb, and Bi should essentially be recovered in lead smelting processes as
they are impurities that copper smelters find difficult to treat properly. Although
the technology for removing Sb in copper electrolyte with a chelate resin has been
used in copper smelters [6], it is also important to appropriately treat the residue
accumulated with these impurities in lead smelters. It is also important to separate
beforehand various mounting components and solder containing impurities from the
printed circuit board by physical separation techniques. Generally, when components
are separated from the printed circuit board, precious metals tend to be distributed
there, but by introducing these separated components into the lead smelting process,
precious metals could be recovered along with other minor metals such as Sb, Sn,
and Bi.
In the general copper smelting process consisting of flash smelting furnace and
converter, the limit of the secondary raw material ratio to concentrate is expected to
be about 20% due to impurities and heat balance. In order to increase the charging
amount of secondary raw materials, it is necessary to fundamentally change the main
smelting processes. In Japan, a copper smelter that treats only secondary raw materials, mainly printed circuit boards, is already in operation based on a TSL furnace
[7]. In addition, the treatment of shredder residues using a copper smelting facility
[8] and also sulfurization process [2] for converting copper-containing secondary
materials into copper matte are also operated in Japan. They are very interesting
287
containing the active metals by pretreatment of E-scrap such as printed circuit boards,
particularly by physical separation techniques. In copper smelters in particular, the
influence of increased charging of secondary raw materials such as printed circuit
boards has been highlighted, and there is an urgent need to appropriately cope with
an excess increase in impurities.
Due to a limitation of the removal of impurities in the smelting process constructed for the concentrates, the physical selection techniques of E-scrap such as
printed circuit boards should be focused and developed with the aim of removing
impurities that impede the smelting processes. In addition, for improving the process
to withstand impurities in main smelting processes, for example, it is necessary to
consider introducing a new smelting process such as the TSL (top submerged lance),
a furnace specialized in treatments of secondary raw materials.
Features and Technologies of Non-ferrous Smelters in Japan
Usually, printed circuit boards are incinerated, roasted [2, 3], or melted [4, 5] prior
to being charged into copper smelting furnaces in the form of metal-containing ash,
or slag and metal, along with concentrates. In copper smelters, Se, Te, and precious
metals are recovered from the anode slime; however, the excess increase in other
impurities such as Ni, Sb, Sn, and Bi derived from secondary raw materials such as
printed circuit boards is a serious problem.
Ni is originally recovered as crude nickel sulfate from copper electrolyte; however, Sn, Sb, and Bi should essentially be recovered in lead smelting processes as
they are impurities that copper smelters find difficult to treat properly. Although
the technology for removing Sb in copper electrolyte with a chelate resin has been
used in copper smelters [6], it is also important to appropriately treat the residue
accumulated with these impurities in lead smelters. It is also important to separate
beforehand various mounting components and solder containing impurities from the
printed circuit board by physical separation techniques. Generally, when components
are separated from the printed circuit board, precious metals tend to be distributed
there, but by introducing these separated components into the lead smelting process,
precious metals could be recovered along with other minor metals such as Sb, Sn,
and Bi.
In the general copper smelting process consisting of flash smelting furnace and
converter, the limit of the secondary raw material ratio to concentrate is expected to
be about 20% due to impurities and heat balance. In order to increase the charging
amount of secondary raw materials, it is necessary to fundamentally change the main
smelting processes. In Japan, a copper smelter that treats only secondary raw materials, mainly printed circuit boards, is already in operation based on a TSL furnace
[7]. In addition, the treatment of shredder residues using a copper smelting facility
[8] and also sulfurization process [2] for converting copper-containing secondary
materials into copper matte are also operated in Japan. They are very interesting