The design of open stope rib pillars has been done using many empirical methods, but none of the methods has been verified with a design survey. This thesis uses data collected in the "Integrated Mine Design Study" to develop an empirical rib pillar design method for open, stope mining. The method is called the "pillar stability graph".

The design variables in the method are:​ the compressive strength of the intact pillar material, the average pillar load determined by numerical modelling, the pillar width and the pillar height. The graph has been refined with the use of more than 80 literature case histories of hard rock pillars in room and pillar mining.

The pillar stability graph and the pillar data base are used to examine the applicability of empirical methods commonly used in open stope rib pillar design. The investigation found the pillar strength curves developed by Hoek and Brown (1980) may be useful under some conditions for the design of open stope rib pillars but formulas by Hedley (1972), Obert and Duvall (1967) and Bieniawski (1983) are not applicable.

Guidelines, using the pillar stability graph method, are proposed for the design of permanent open stope rib pillars, stable temporary open stope rib pillars, and failing temporary open stope rib pillars.