Synthetic ropes

Calculations and optimization for a friction hoist rely on the friction over the drum, the counterbalance mass, and the strength of the hoist motor. Replacement of steel wire with synthetic rope results in a dramatic reduction in hanging mass, which in turn affects each of these design parameters and their interactions. A system model was developed to determine the hmitations and adjustments to design factors for a range of hoist depths. 

All calculations are compared to the reference case with steel ropes. Strength and mass values for synthetic ropes are taken as an average representation of the technology while steel rope data is referenced from those ropes which are currently in use at LKAB. 

Table 1 provides the basic data used to describe the materials, ropes, and machine characteristics in the model. The values in Table 1 are based on existing steel ropes and an equivalent synthetic rope as well as the existing hoists at LKAB. Future bend-over-sheave testing of ropes will determine whether or not an increased diameter is feasible. Maximum friction coefficient used in all cases is the maximum value allowed by the Swedish standards for mining hoists (BRAGS). While the friction values can be considered high, it is assumed that apphcation specific drum hning materials can be developed to be used with synthetic ropes. 

Figure 2. Safety factor vs. depth and skip load for double skip hoist with synthetic ropes...

Figure 6. Required friction coefficient vs. ore mass and depth for doubie skip hoist synthetic ropes...

Figure 9. Skip mass required for acceptable friction with synthetic ropes for skip-counterbalance hoist...

Application of synthetic rope technology to Iriction hoists in deep underground mines has the potential to allow for effective production from significantly greater depths than currently possible with steel wire ropes. The primary difference between the application of steel and synthetic ropes to friction hoists at today s and future depths is that steel rope is limited by the strength per mass properties of the rope while synthetic rope is limited by the friction over the drum generated by the coimterbalance mass and system design. 

In the case of skip-counterbalance hoists synthetic ropes can be applied to current systems at current depths without major equipment modifications. For skip-skip systems, significant modifications would be necessary for apphcation of synthetic ropes at current depths. Application of synthetic ropes for skip-skip systems becomes reasonable at depths greater than approximately 1000 m. 

W.E. Brown. Friction coefficients of synthetic ropes . Ocean Technology Department, Naval Undersea Center, San Diego, USA. February 1977. 

C. Hunter. Synthetic Rope for Mine Hoisting . Natural Resources Canada. May 2013. Learning the ropes . Lloyds list, p. 10, May 15, 2009. 

Leonard, J. Applications for Synthetic Rope in Logging . Thesis, Master of Forestry. Oregon State University. September 2003. 

High-Performance Synthetic Ropes for Mine Hoisting... 

HIGH-PERFORMANCE SYNTHETIC ROPES FOR MINE HOISTING... 

Use of synthetic ropes on a Koepe hoist should be more predictable compared with drum hoists, as the external rope-to-rope contact and resulting wear/damage mechanisms do not... 

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