15 February 2017: Summit Mining International, a wholly owned subsidiary of Sumitomo Corporation, has kick-started a Grade Engineering® Study on its Minera San Cristobal mine in Bolivia. An intensive regime of test work and trials has provided valuable data to make a rapid assessment of Grade Engineering® Screening opportunities.

  CRC ORE has been working with the local Minera San Cristobal (MSC) team on their newly commenced Grade Engineering® study.

This article was published in CRC ORE News - February 2017

Grade Engineering at Minera San Cristobal, Bolivia

By Jon Rutter, Senior Mine Geologist

CRC ORE technical staff have recently returned from Bolivia where they spent close to two weeks on site at Minera San Cristobal (MSC), working with the local team to establish sound foundations for their newly commenced Grade Engineering® study. The Minera San Cristobal mine is located between 4000 and 4500m above sea level in the Bolivian High Plateau, and is operated by Summit Mining International, a wholly owned subsidiary of Sumitomo Corporation.

During the 12 days on site, CRC ORE technical specialists Michael Scott and David La Rosa worked closely with site personnel to rapidly define suitable Grade Engineering® target zones and kick off the site test work in earnest.

An integrated test work plan was finalised for the mine, with specific site requirements and constraints incorporated before site personnel hit the go button. During the visit, drill core samples, blast hole samples and bulk samples from the pit were collected and a Grade Engineering® analysis commenced.

Whilst on site, Michael and David worked closely with Senior Metallurgist Silvia Vidal and Senior Geologist Miguel Romano and were pleased that the first round of results were returned within just a few days. Initial bulk samples from the pit were also transported to a selected processing area and were crushed, split and sub sampled, ready for screening.
Due to a great effort by the MSC team, the first samples had been completely processed before the CRC ORE team left the site, and knowledge transfer of the process and methodology was left with operational personnel who are continuing the work.

MSC is planning to complete a program of around 150 preliminary lab scale tests, and 5 bulk sample tests within 4-6 weeks from commencement, with 95% of the work completed on site by current operational personnel.

This will provide valuable data to make a rapid assessment of Grade Engineering® Screening opportunities, when the results are incorporated into the mining schedule and business case analysis completed. The outcome will provide management the necessary information to assess the merits of proceeding to a concept study, or to conclude the current program.

The level of commitment displayed by MSC staff has been impressive and will facilitate the rapid turnaround of the project. In particular, CRC ORE recognises the commitment of David King and Mike Bunch from Summit Mining in getting the Grade Engineering® study off the ground, right through to MSC site personnel for their rapid uptake and assistance in completing the field test work and trials.
This will enable the value adding technology and decision making capability, to be evaluated by site, within a very short time frame.


The analysis to date has showed that differential blasting could be an important driver of Grade Engineering value for Escondida. The resultant induced and natural grade by size deportment demonstrated a positive NPV, with a payback period of six years. The differential blasting will now be ranked against other Grade Engineering opportunities.


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