New approach for rapid preparation of block caving mines

Abstract

Block and panel caving is one of the most suitable methods for exploitation of large massive ore bodies where a high rate of extraction is required. However, many authors have studied the rate of extraction and concluded that it may be limited by the ability to prepare mines at high rates. Different approaches, to increasing the rate of extraction, tend towards the introduction of some kind of continuous drawing and materials handling on production levels, which apparently are close to reaching a practical solution. However, corresponding studies to match the rate of mine preparation to high extraction rate operations have not been discussed or published to any great depth. This paper describes some layouts and constructive techniques compatible with rapid mine preparation demand. A significant reduction of time in mine preparation, in both underground drifting and construction, is expected as a consequence of the introduction of non-blasting excavation methods and using precast concrete modules to build up underground mine construction. The main advantage of non-blasting drifting is the predictability of finishing underground drifts, such that it is possible to standardise all the components of single underground mine constructions (i.e. drawpoint and dump points). The solution requires adapting and developing both new equipment and new layouts, because neither standard full face boring machines nor current layouts for conventional block/panel caving are suitable to high speed development of caving levels. The layouts discussed focus on conventional load–haul–dump units and on mechanised continuous drawing system arrangements. In each case, the general arrangement presented has been developed by JRI Ingeniería S.A. as part of its technological innovation policy. Finally, an evaluation of the impact upon scheduling and costs is presented in comparison with conventional methods. New approaches are also mentioned about other issues such as logistics and commissioning, with new actors in the business, which may produce additional benefits for project and operation management.