Ulrich, BF 2008, 'Geotechnical Aspects of the Hydro-Jex Operation', in AB Fourie (ed.), Rock Dumps 2008: Proceedings of the First International Seminar on the Management of Rock Dumps, Stockpiles and Heap Leach Pads, Australian Centre for Geomechanics, Perth, pp. 47-55, https://doi.org/10.36487/ACG_repo/802_4
(https://papers.acg.uwa.edu.au/p/802_4_Ulrich/)
Abstract: Many heap leach operations are very large, covering many hectares and containing millions of tonnes of 
low-grade ore.  Operators estimate recovery from laboratory column tests on ore samples that typically 
produce metal values somewhat lower than the column leach tests with the resultant metal inventory 
remaining in the heaps.  After the ore material is placed and ripped, the only operational technique to 
improve recovery revolves around solution and reagent management.  The key to reducing metal values in 
the heap inventory is to promote the contact of the leaching lixiviant to the valuable mineral and then to 
rinse the dissolved metal from the ore.   This is normally accomplished by applying additional solution to the 
surface of the leach pads in a two dimensional fashion via emitters and sprinklers.   
Hydro Jex, a proprietary metallurgical technique, was developed to take heap leaching into three 
dimensions, a new concept for the metals extractive industry.  This technology has been used by Newmont 
Mining Corporation on gold heap leach pads on the Carlin Trend in Nevada for the last three years to 
recover the inventory gold remaining in heaps after traditional solution application. It is the nature of 
Hydro-Jex to deliver significant amounts of solution, in a controlled manner, to discrete areas within a heap.  
As a consequence, the resulting pore pressures an elevated phreatic surface could have a considerable and 
adverse influence on the slope stability of a heap.  It is therefore vital that the possible effects of the Hydro-
Jex operation on slope stability be thoughtfully investigated prior to its implementation. Such investigation 
and analytical processes are presented herein and preliminary advice pertaining to slope stability is 
provided.