Environmental Engineering Reference
In-Depth Information
ing products and other technical or environmental specifications. Depending on the
process principle and flow sheet, the occurrence of accompanying elements is either
beneficial—since their separation is easy and their contribution to turnover substan-
tial - or pernicious, where the opposite is the case. This leads to highly diversified
flow sheets and operating conditions, in which some plants recover a wide range of
additional elements, separating these one by one, and other plants merely removing
these as undesirable impurities, e.g. in the slag. Such choices are made on the basis
of economic, logistic, as well as technical reasons.
Copper is a valuable element, and silver even more so. Yet, during electrolysis
silver is precipitated willfully with the slimes, since it is separated easily, sold prof-
itably, and moreover its continued presence lowers the quality of electrolytic cop-
per. Nickel similarly is highly valuable and yet its presence in a copper smelter may
become a real nuisance: when it appears, it cannot be separated so easily and still
has to be sluiced out, together with a considerable amount of copper co-entrained
in the bleed stream in order to safeguard copper specification standards. Of course,
some dedicated smelters operate schemes that allow separation of these two valu-
able metals, but these smelters may be situated far away and not too much interested
in custom co-treating such an occasional mixed copper/nickel stream. Extracting
value for less usual or more complex flows is not so evident and the picture of sup-
ply and demand for such services is often unfavorable and continuously evolving.
13.5
In Conclusion
We have considered the impacts on the environment of base metals from a resource
perspective. Environmental problems will continue to be important, but so will
natural resource security. Creating a zero-waste society will help to combat both
these issues and promote sustainable development. Natural resources depend on the
land in which they are found, and can therefore become easily involved in politics.
Environmental sustainability is next to impossible without bold political leadership.
Thus, we need to consider both the environment and natural resource security when
formulating national strategy. Especially in countries like Japan where advanced
technology is everywhere but there are few resources, there is a need to thoroughly
debate the use of technology to create a zero-waste society and then to create such
a society.
Non-ferrous metals recycling is vital to maintaining a supply chain for minor
rare metals in Japan. Non-ferrous smelters are important to advance recycling of
basic and minor rare metals. A new system is necessary for this and greater develop-
ment of recycling technologies for non-ferrous metals and minor rare metals. This
would have considerable impacts on the environment from a resource perspective.
Environmental problems will continue to be important but natural resource security
will also become as important. Creating a zero-waste society aims to combat both
of these issues and promotes sustainable development.
