trodes
(120° angle between electrodes projected on
horizontal plane) are immersed in a batch pile contained
in a ceramic container. Nozzles in the electrodes
supply ionized argon gas. Due to an alternating
current between the electrodes, the plasma travels
between these electrodes. The plasma transfers within
the batch pile the heat to the material, forming a silicate
melt that becomes electrically conductive. The
electric current will partly pass through the melt and
will heat the melt by the Joule principle. The melt
flows from an orifice in the bottom of the ceramic
container to a next process step. The quality of the
melt depends on the residence time. The molten glass
is covered by cold batch preventing volatilization
losses. A special starting-up procedure is required.
Often extra fining after this kind of melting processes
is required to produce glass products, such as tableware
or container glass. Total energy (mainly electricity)
costs (plus argon) can be rather high but the
melter is very compact and flexible.