Scalping
Carrying out scalping with roller
screens before sending the material to
a crusher is a proven technology in
coal processing. Some of the main
advantages of using roller screens
before crushers are: lower wear,
reduced energy consumption,
reduced risk of clogging in the
crusher itself and – at best – in using a
smaller crusher. Hence, in general,
roller screens lead to reduced energy
and operational costs and/or
increased operational safety.
Typical cut size is between 150 mm
down to 15 mm.
At a PT Indonesia plant, a
Hazemag HRS 2242 roller screen has
been in operation since August 2014
ahead of a Hazemag HFB 0714 feeder
breaker. The length and width of the
roller screen is 2.2 m by 4.2 m. It is
equipped with 16 shafts and two
22 kW drives each, with cut size of
65 mm. It is designed with a
guaranteed feed rate of 1000 tph coal.
Typical feed is 98% -600 mm with 50%
-65 mm and moisture of up to 25%.
The roller screen takes out nearly
100% of the -65 mm fines at 1200 tph
feed and more than 95% of the fines
at 1500 tph. As a result, the
downstream feeder breaker is
relieved of about 600 – 700 tph of fine
product -65 mm, which leads to a
reduced crusher size.
Crushing
Depending on the detailed
requirements of the project, Hazemag
& EPR selects the appropriate type
and size of the crusher from its wide
portfolio of machinery for coal,
ranging from horizontal impact
crushers for coarse crushing to
hammer mills for a product particle
size of less than 1 mm.
Hazemag feeder breakers
and horizontal impact
crushers
The Hazemag feeder breakers (HFB)
and horizontal impact crushers
(HHI), together with HCF reclaim
feeders, are of particular interest to
both the underground and opencast
coal mining industry.
The following describes recently
installed HFB in Indonesia and
South Africa and presents their uses.
In South Africa’s Witbank
coalfield, a HFB for the primary
crushing station helped to simplify
the project installation and operation.
The HFB is used to crush ROM coal
at an average rate of 600 tph. Few to
no civil structures are required. The
design employs low truck ramps and
the trucks tip directly onto the
crusher’s chain feeder (Figure 1).
There is no need for expensive feed
hoppers or complex concrete or steel
structures as the tipping action
creates a natural bunker.
The HFB, which accepts feed sizes
of up to 2000 mm in edge length and
crushes the material down to 95% of
150 mm, was custom-scoped for the
project by Hazemag’s South African
subsidiary, IMS, and manufactured at
Hazemag & EPR’s facilities in
Dülmen, Germany.
Meanwhile, the Hazemag HHI (a
heavy-duty type of feeder breaker) is
able to handle a much harder type of
rock. It is ideal for ROM hard coal,
Figure 2. Hazemag horizontal impact crusher (HHI).
Figure 1. Hazemag feeder breakers (HFB).
50
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World Coal
|
January 2016
