Gangue rejection in practice -the implementation of Grade Engineering® at the Minera San Cristóbal Site

B. Adair, L. Kenney, D. King, M. Scott


There are a number of potential technology opportunities to effect up-front gangue rejection in the minerals sector. CRC ORE has been working with several of its mining participants to assess the efficacy of a range of such technologies, assessed across a variety of operations and commodities. Our “Grade Engineering®” approach references a suite of integrated technologies to effect gangue rejection across several separation “levers” – dependant on the textural amenability of the ore domains concerned. This paper details recent implementation trials of Grade Engineering® at the Sumitomo-owned Minera San Cristóbal operation in Bolivia.

This Pb/Zn/Ag mine operates with some of the lowest head grades in the Industry – yet ranks as one of the most profitable. The implementation strategies at the site trails are presented and the upgrading of “mineralised waste halos” to ores is detailed. Preliminary results indicate a significant financial opportunity exists in converting these low-grade marginal and mineralised wastes to ore feed. Some two thirds of the total metal value of this material reports to 25% of the “Grade Engineered” mass - contained in the -19mm fraction.

An upgrade factor of 2.7 readily converts these mineralised wastes to high grade ore feed-stock. Exploitation of this material will result in a predicted minimum value uplift at the operation of some+450M$ in profit or +257M$ in NPV from the existing mine plan. This success has implications for unlocking “hidden value” across the sector


Grade Engineering®, Gangue Rejection


B. Adair (a), L. Keeney (a). D. King (b), M. Scott (a)

a CRCORE, 1Technology Court, Pullenvale, QLD 4069 Australia.

b Minera San Cristóbal, Calacoto calle 15, Torre Ketal Floor 5, La Paz, Bolivia.

Principal author email - This email address is being protected from spambots. You need JavaScript enabled to view it.


Special thanks are due to the Minera San Cristóbalsite staff who conducted the sampling and analysis of the various evaluation regimes. This work was conducted under the auspices of the Australian Government Cooperative Research (CRC) Program.

CRC ORE is part of this Program, which is made possible through the investment and ongoing support of the Australian Government.The CRC Program supports industry-led collaborations between industry, researchers and the community.Sumitomo (and its Minera San Cristóbaloperation) is one of seven mining companies that are “Essential Participants” of CRC ORE