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High-angle conveying;

The vital (missing) link to IPCC - 2018

by Joseph A. Dos Santos

Dramatic reduction in energy use and                                and to use a sandwich belt high-angle conveying
      environmental impact can be achieved                          system to elevate the ore continuously, directly
with sandwich belt high-angle conveyors that                        out of the pit, along the high wall to the pit
                                                                    perimeter where it then transferred to a
serve as the vital link in any in-pit crushing and                  conventional conveyor for the remaining haul
                                                                    to the plant. The system had significant features
conveying (IPCC) system. These high-angle                           including 2,000-mm (78-in.) wide belts that
                                                                    elevated 250 mm (10 in.) coarse ore, at 4 kt/h
conveyors are not new, but have not found wide                      (4,400 stph), over six 15-m (50-ft) high benches
                                                                    for a total 90 m (295-ft) of net lift. The system
use in IPCC systems where they can realize the                      was able to reduce the truck haulage fleet by
                                                                    10, 200 t (220 st) trucks realizing great cost
greatest advantage.                                                 savings, zero emissions to the air and greatly
                                                                    reduced traffic congestion in the pit. The system
                         Reduced energy consumption and             operated successfully until 2002 when the mine
                                                                    shut down. Many successful sandwich belt high-
environmental impact, with IPCC systems,                            angle conveyors followed with the current count
                                                                    of commercial installations at more than 150.
was first realized in the 1970s. With the bulk                      Despite the great success with this system, its
                                                                    use has not been repeated as part of an IPCC
material haulage limited to conventional open                       system.

trough conveyors the most direct path out of                            The high-angle conveyor offers the link
                                                                    to optimization of any IPCC system, yet the
the openpit was precluded, requiring low-angle                      industry continues to struggle with the use of
                                                                    conventional conveyors and haul trucks to
spiral ramps and/or deep slots and/or tunnels                       achieve the high-angle function. The results are
                                                                    sluggish, low-angle conveyor systems of limited
through the high wall of the openpit. These                         flexibility requiring excessive maneuvering
                                                                    time, excessive excavation, fill and rehandling in
excavations, to accommodate the low-angle                           order to accommodate the low-angle limitations.
                                                                    The current alternative to conveyors is the fall
limitations, represented undesirable impact                         back position of using 300 t (330 st) haul trucks
                                                                    at great operating, environmental and safety
on cost and on the environment. Against                             cost. Recent IPCC studies have represented
                                                                    resurgence in interest in high-angle conveying
this backdrop, a major study in 1979 sought                         and have demonstrated the technical and
                                                                    economical advantages along with the reduced
to develop high-angle conveying systems                             environmental footprint.

that could continuously haul the mined bulk                         Sandwich belt high-angle conveyors
                                                                        This article deals predominantly with
material directly out of the pit, along the high
                                                                    the Dos Santos Sandwich Belt High-Angle
wall, which is the shortest distance between                        Conveyors, a technology that is more than 40
                                                                    years old. To clarify; by Dos Santos Sandwich
the two end points. Between 1979 and 1982,                          Belt High-Angle Conveyors, the author is
                                                                    referring to the work of J.A. Dos Santos
that study developed sandwich belt high-angle                       since 1979 while the employee of the various
                                                                    companies:
conveying systems that utilized all conventional
                                                                        While at Dravo Corp., Pittsburgh, PA:
conveyor equipment including smooth surfaced
                                                                        •	 Development work of 1979-1981, under
rubber belts that could be continuously                                       a U.S. Bureau of Mines study. It was
                                                                              here that the author developed the
scraped clean. These systems had all of the                                   sandwich belt high- angle conveyor,

positive features of conventional conveyors                                                            www.miningengineeringmagazine.com

but overcame the angle limitation. By hugging

the bulk material between two belts, the

material’s internal friction could be developed

to facilitate conveying at any high-angle up to

90 degrees (vertical). After an intense testing

period (about one year) on the first large scale

prototype system, commercialization began in

1983 with the installation of a 60 degree incline

system at a western United States coal mine,

elevating 2 kt/h (2,200 stph) of coal to a train

load out system. It did not take a long period

of scrutiny and acceptance before this high-

angle conveyor found use in the most rugged

requirements of an IPCC system. This was only

the second commercial sale, and after more

than 150 commercial installations, it remains

arguably the most significant high-angle

                                       conveying system. In 1984,

Joseph A. Dos Santos, member           a copper mine in Serbia,
SME, is president - Dos Santos In-     already using pit perimeter
ternational, Marietta, GA email jds@   crushing and conveying,
dossantosintl.com.                     decided to move its primary
                                       crusher deep into the pit

2 August 2018     Mınıng engıneerıng