10-04-2017, 09:04 PM
Development of a laboratory scale air plasma torch and its application
to electronic waste treatment
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INTRODUCTION
The production of electrical and electronic
equipment is one of the fastest growing businesses in
the world. The useful life of consumer electronic
products is relatively short and decreasing as a result
of rapid changes in equipment features and
capabilities. Technological innovation and market
expansion are accelerating the replacement of outdated
equipment, leading to a significant increase in waste
that induces a new environmental challenge. Concerns
over environmental issues arising from these electrical
and electronic products have led to a number of
environmental regulations such as the waste electrical
and electronic equipment (WEE) and restrictions on
hazardous substances (RoHS) directives. These
directives directly affect the electrical and electronic
industries throughout the world (Hsu and Hu, 2008).
Electronic waste is considered to be one of the priority
streams in waste management.
MATERIALS AND METHODS
Fig. 1 shows schematically design of a DC plasma
torch, consisting of a steel rod cathode and an air
cooled anode, shaped in the form of nozzle. The two
electrodes are separated by an insulator which has
an inlet for plasma gas. When compressed air is
introduced thru the electrode gap and a DC arc is
established between the electrodes, the plasma arc is
emerged from the nozzle resulting in a high
temperatur e, high velocity plasma flame.
Electromagnetic forces from magnetic coil and gas
flow act to constrict the arc column.
RESULTS AND DISCUSSION
Plasma torch performance
From simple visual observation, a pure air plasma
flame showed milky white lights with blush-like,
turbulent flame tip at normal operation. This was the
expected character of high ionized plasma density in
air discharge. Plasmas flame exhibited marginal
fluctuation in length with an observed average length
of about 100 mm. The radius of the plasma was
observed to be about 3 mm.