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High Angle Conveying, the Vital (missing) Link to IPCC Systems – 2017

Belt Conveyor Technology

High Angle Conveying, the Vital (missing) Link to IPCC Systems – 2017

Installations and recent studies have demonstrated the technical and economical advantages of high angle conveying for optimization of any IPCC system, yet that industry continues to struggle with the use of conventional solutions to achieve the high angle function.
(ed. WoMaMarcel - 07/4/2016)
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Fig. 1: The high angle conveyor offers the link to optimization of any IPCC system, yet that industry continues to struggle with the use of conventional conveyors and haul trucks to achieve the high angle function (DSI Snake Sandwich Conveyor for Continental CN at Red Chris Project, British Columbia, Canada).

Dramatic reduction in energy use and environmental impact can be achieved with sandwich belt high angle conveyors that serve as the vital link in any In-Pit Crushing and Conveying system (IPCC). These high angle conveyors are not new at all, but have not found wide use in IPCC systems where they can realize the greatest advantage.

Reduced energy consumption and environmental impact with IPCC systems was already realized in the 1970s. With the bulk material haulage limited to conventional open trough conveyors, the most direct path out of the open pit was not possible, requiring low angle spiral ramps and/or deep slots and/or tunnels through the high wall of the open pit. These excavations, to accommodate the low angle limitations, represented undesirable impact on cost and on the environment.

Against this backdrop, a major study in 1979 sought to develop high angle conveying systems that could continuously haul the mined bulk material directly out of the pit, along the high wall – the shortest distance between the two end points. Between 1979 and 1982, that study developed sandwich belt high angle conveying systems that utilized all conventional conveyor equipment, including smooth surfaced rubber belts that could be continuously scraped clean. These systems had all of the positive features of conventional conveyors 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° (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° incline system at a western USA coal mine, elevating 2000 t/h 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, the Majdanpek copper mine in Serbia, already using pit perimeter crushing and conveying, decided to move their primary crusher deep into the pit and to use a sandwich belt high angle conveying system to elevate the ore continuously, directly out of the pit, along the high wall to the pit perimeter where it then transferred to a conventional conveyor for the remaining haul to the plant.

The system had significant features, including 2000 mm wide belts that elevated 250 mm coarse ore, at 4000 t/h, over six 15 m high benches for a total 90 m of net lift. The system was able to reduce the truck haulage fleet by ten 200 t trucks realizing great cost savings, zero emissions to the air, and greatly reduced traffic congestion in the pit. The system operated successfully until 2002 when the mine shut down. Many successful sandwich belt high angle conveyors followed with the current count of commercial installations at more than 150. Despite the great success in the Majdanpek system, its use has not been repeated as part of an IPCC system.

The high angle conveyor offers the link to optimization of any IPCC system, yet that industry continues to struggle with the use of conventional conveyors and haul trucks to achieve the high angle function (Fig. 1). The results are sluggish low angle conveyor systems of limited flexibility requiring excessive maneuvering time, excessive excavation and fill, re-handling and grading in order to accommodate the low angle limitations. The current alternative to conveyors is the fall back position of using ever larger (+300 t) haul trucks at great operating and environmental costs. Recent studies have represented resurgence in interest in high angle conveying and have demonstrated the technical and economical advantages along with the reduced environmental footprint.

Though the primary purpose is to demonstrate suitability for open pit mining applications, this article will first recap the early development of the latest sandwich belt high angle conveyors and their commercialization over the last 30 years. Particular emphasis will be paid to who did what, and when, giving due credit. This will show that since 1979, the constant of the development is the invention and the work of the writer. The article will highlight the features that make Dos Santos sandwich belt high angle conveyors particularly energy efficient and suitable for use in the harsh requirements of the IPCC systems, highlighting the success in Serbia (former Yugoslavia) and in the latest studies. We make a brief comparison with pipe conveyor systems. Finally we ask the question, why is this gift so often treated with such suspicion and then declined?

Introduction

This article deals predominantly with the Dos Santos Sandwich Belt High Angle Conveyors, a technology that is more than 30 years old. To clarify; by Dos Santos Sandwich Belt High Angle Conveyors this article is referring to the work of J.A. Dos Santos since 1979 while in the employ of the various companies:

  • While at Dravo Corporation, Pittsburgh (PA), USA:Development work of 1979 to 1981, under a US Bureau of Mines study; it was here that this author developed the sandwich belt high angle conveyor technology, rationalized in the conventional conveyor technology. This also produced the landmark publication “Evolution of Sandwich Belt High Angle Conveyors”, a writing that is complete in defining the theory and design rules and in the conceptualization of the designs that went on to commercialization.
  • While at Continental Conveyor and Equipment Company, Winfield (AL), USA: The HAC Systems from 1982 to 1997
  • Since the founding of Dos Santos International: The DSI Snake Sandwich and GPS (Gently Pressed Sandwich) High Angle Conveyors from 1997 until the present.
     

The study and research work began in 1979. Commercialization began with the first sale in 1983. The first sale as part of an IPCC (In-Pit Crushing and Conveying) system occurred in 1984, only the second commercial sale. That system began operation in 1991 and operated successfully until the mine shut down in 2002. Arguably the most significant Sandwich Belt high angle conveyor to date, it is the only IPCC application thus far.

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