MIL-HDBK-1003/7
of a belt conveyor. The tramp iron clings to the belt as it goes around the pulley drum
and falls off into a collection hopper or trough after the point at which coal is
discharged from the belt. The other type consists of permanent or electromagnets
incorporated into a belt conveyor that is suspended above a belt conveyor carrying coal.
The tramp iron is pulled from the moving coal to the face of the separating conveyor,
which in turn holds and carries the tramp iron to a collection hopper or trough.
Magnetic separators shall be used just ahead of the coal crusher, if any, and/or just
prior to coal discharge to the in-plant bunker or silo fill system.
Coal Sampling. Coal sampling is done when there is a need to determine or
9.9
verify the analysis or content of some constituent in the coal either on an as-received
or as-fired basis. Sampling of coal may be done either manually or automatically. In
either case, the method of sampling must provide a representative sample of a relatively
large amount of coal without bias. If moisture content determinations are to be made,
the sample must be collected in a container which can be immediately sealed following
the sample collection. The major components of automatic sampling systems are as
follows:
a) In-line, spoon-type primary and secondary sample cutters with
electric or hydraulic drive assemblies.
b)
Motor-driven, rotary tertiary sample cutters.
c)
Flanged belt sample feeders with rubber-lagged head pulleys and
variable speed drives.
d) Sample crushers with adjustable breaker plates or screen bars to
permit control of product size and compensate for wear.
128
Previous Page
