115Beneficiation Practice
minor amounts of insulated wire and denser nonmetallic material (stones, glass). It
is marketed using the ISRI specication Twitch (see Figure 4.1). The heavy fraction
from the second HMS stage contains higher-density metals such as copper, zinc, and
stainless steel and is known by the ISRI specication Zebra.
The Twitch recovered from the second HMS can be further upgraded by process-
ing in an eddy current separator (Gesing et al., 2010; Manouchehri, 2007). This
separates the aluminum from the wire and nonmetallics. The Zeppelin recovered
from the rst separator can also be upgraded using ECS, but will have to be further
processed to separate the aluminum from the magnesium, using either hand picking
or a sensor-based ...