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 - 07/4/2017)
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With the start of this decade, there was great interest in IPCC systems, particularly in Australia. Innovative mining companies are focusing on high angle conveyors as the vital link to any IPCC system. This has led to some significant mine planning studies that are on track for future implementation. The interest has not focused on the traditional IPCC systems, viewing them as old, rigid technology that does not fit their operations; rather they are developing their own IPCC systems with the Sandwich Belt high-angle conveyor as the vital link between their multi-level operations; from the pit to the surface, between benches, to spoil dumps, both on the surface and in back fill of mined out pits. Linked by the most direct path of the high angle conveyor, the system is compact and versatile.

It is worth noting that since the 1970s, very little progress has occurred in the second C of the IPCC systems. Aside from high angle conveyors, which have been largely ignored by the prominent IPCC manufacturers, the conveying highlights have included; conventional troughed conveyors that strain, at great risk of slide back, to achieve 18° of incline angle; high powered conveyors with gearless drives; low angle bench conveyors. These are hardly earth shattering innovations.

Sandwich Belt High Angle Conveyor Development

Fig. 2 traces the Sandwich Belt high angle conveyor development time line from the first introduction of “Conveyor with Cover Belt” in 1951, through the USA Bureau of Mines Study in 1979, the first J.A. Dos Santos involvement, through the present. Along the way citing some notable, historical milestones provides some perspective.

Fig. 2: Sandwich belt high angle conveyor development timeline (Click image for larger version).

Cover Belts of the 1950s

The first introduction of the sandwich belt concept was in 1951, in Germany, in the form of “Conveyor with Cover Belt”. A cover belt was installed at the boom belt of a bucket wheel excavator in order to increase the conveying angle without the occurrence of material slide-back. This was to increase the cutting height of the excavator without increasing the boom length. This first sandwich belt is shown in Fig. 3. Rubber tired wheels pressed onto the cover belt, imparting a hugging pressure onto the material, to develop the material’s internal friction facilitating high angle conveying.

Fig. 3: Conveyor with cover belt pressed onto material by rubber tyres.

A sandwich belt model, shown in Fig. 4, was developed in order to calculate the hugging pressure required to develop the friction that would resist the gravitational slide back forces. Clearly this system was not well executed. The widely spaced pressing tires did not impart a continuous pressure without lapse over the material. The analysis model would be a reasonable basis for calculation if it were accurate. The model depicts a material load that fills to the edges having no allowance for belt misalignment. Sadly, Fig. 4 indicates that the designer believed that such an ambitious material load was possible. Fig. 3 clearly shows that it was not.

Fig. 4: Sandwich belt model #1 - 1951.

Throughout the 1950s, many variations of cover belts were developed and many of these were awarded patents. None of these inventions were a lasting success and by the end of that decade all were abandoned.

Loop Belts of the 1970s

The next development, arguably the most significant, was the Loop Belt of the 1970s. The “Loop Belt” system was developed by Stephens Adamson of Canada as the vital elevating component of a complete conveyor based self unloading ship system. Since the 1970s, these have been used extensively on the Great Lakes of North America. In the 1980s and 1990s, they found world wide use including long haul shipments between North America and Europe and between North and South America.

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