Minera San Cristobal Grade Engineering production trial

A new production trial study has been flagged for Minera San Cristobal (MSC). The focus of the study is to upgrade ~400kt of marginal grade Zn, Pb and Ag ore via Grade Engineering screening and then campaign the upgraded product through the concentrator over several days to quantify concentrator impacts due to Grade Engineering.

This article was published in CRC ORE News - March 2018

By Luke Keeney, General Manager - Implementation

Over the last 12 months, CRC ORE in partnership with MSC have conducted a Phase 1 Grade Engineering study investigating the opportunity for exploiting natural and induced Grade Engineering strategies. A detailed work program was carried out to identified rock types with a high propensity for metal to deport into the fine size fractions. A significant bulk and variability testing program was conducted with results interpolated into the resource block model.

MSC Trial Resource Block Model

Based on the results of the Grade Engineering test work and in collaboration with MSC, it has been identified that if Grade Engineering responses as identified in the Phase 1 study exist at production scale, there is a sizable proportion of low grade waste halo material that may be economic. Site estimates that if this ore can be upgraded, then the opportunity for MSC is ~$1B in value. MSC have requested CRC ORE to develop and manage a Grade Engineering production trial as the next phase of study.

The objectives of the study are:

  • Validate Grade Engineering benefits at MSC through a production trial.
  • Measure the impacts of processing grade engineered material on downstream processes (i.e. concentrator).
  • Quantify the economic benefit to MSC through the application of Grade Engineering to run-of-mine (ROM) ore and mineralised stockpiles.
  • Understand operational requirements to progress Grade Engineering to full scale implementation.
  • Provide technical justification for MSC to implement Grade Engineering into the operation.

CRC ORE in collaboration with METSO conducted a 1-week planning study at MSC to define the scope of the Grade Engineering production trial project. Two opportunities for assessing the Grade Engineering amenability were identified, namely:

  • Test ex-pit ores within the appropriate grade range and rock type
  • Test mineralised stockpile that is currently sub-economic

The following diagrams provide the conceptual work program to be conducted for each trial option.

MSC Conceptual 1

MSC Conceptual 2

To conduct the screening campaign of the ex-pit and mineralised stockpile material, METSO will deploy a Lokotrack ST2.8 unit to MSC (see following image). The unit will operate ~450tph and will operate for ~2-3months on the ex-pit and stockpile material respectively. The Lokotrack is a commercial product supplied by Metso and will be customised to the MSC trial specifications and fitted with Metso flow up system and conveyor scales. The undersize product generated from the screening trial will be campaigned through the concentrator over a 3-5 day period blended with direct ROM ore in a ratio of approximately 25% GE feed and 75% direct ROM.

MSC Metso Lokotrack

Key outcomes from this project will be:

  • Quantification of natural deportment response of marginal ores at production scale.
  • Quantification of natural deportment response of mineralised stockpile at production scale.
  • Quantification of Grade Engineering impacts on Concentrator operation due to Grade Engineering feed being processed.
  • Implementation Plan for MSC to incorporate Grade Engineering into the operation.

For more information about Grade Engineering, please click here.


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