The Palabora Underground Mine Project

Palabora Mining Company operates an integrated open pit mine, concentrator, smelter and refinery complex located in the Northern Province of South Africa. The Palabora open pit went into production in 1966, mining 30 000 t/d to produce some 62 000 tpa of copper. With continuous modification and improvement, a mining rate of 82 000 t/d, producing up to 135 000 tpa of refined copper, has been achieved. While these improvements have also enabled the mine life to be nearly doubled, the open pit will reach the end of its economic life by 2003. The Palabora orebody is vertical and the reserve extends to a depth of 1800 m over an area of 700 m by 200 m. Studies to assess the economics of mining the orebody by underground means began in the mid-1980s. These studies indicated that block caving is the lowest cost underground mining method that would generate a suitable return. In March 1996, a decision was made to develop a 30 000 t/d block cave mine that will extend the life of the Palabora Mining Company by a further 20 years. In terms of the relatively high rock strength and the resultant coarse fragmentation that is expected at the drawpoint, the Palabora cave can be considered rather unique when compared to other block cave operations. This paper describes the project in broad terms and details the mining method, particularly with respect to the cavability of the orebody and the design features to deal with the coarse fragmentation. The project commenced in July 1996 and final development of the undercut and drawbells is scheduled for completion in November 2003. This paper describes the status of the project and planning as of April 2000.