Improved grade control

Collaboration between Maptek™ and Cerro Negro Norte to control ore grade resulted in better decision-making and improved site practice.

The Cerro Negro Norte mine, owned and operated by Minera del Pacífico S.A., is located in the Copiapó valley in Chile, 1100 to 1500 m above sea level.

The mine is on a 600 km iron-rich belt, where the orebodies are mostly massive magnetite lenses. Cerro Negro Norte is an irregular deposit hosted by volcanic or metavolcanic rocks in the vicinity of intrusive bodies.

The mine required a grade control system to manage allocation of materials to be extracted from blasting. The scope included grade evaluation and quantities to extract per block, automatic and manual assignment of blocks to different destinations using assignment rules, evaluation using blast holes and block model grade estimations, report generation and plotting.

The objective was to reduce the runtimes in the daily update of blasting zones and conform to the short term schedule. The existing blast management database was in spreadsheet format, and there was no short term block model.

When Vulcan Grade Control was implemented, an historical blast database and a short term block model were created. Grade control scripts were configured to classify the material type and destination based on zones generated by the production geologist.

Subsequently, using Vulcan tools, procedures were established to perform statistical analysis of long term data (grade estimated from the drilling data) and short term data (grade estimated from blast hole data). Boolean tools were used to update the topography daily, to provide better control of production.

    Advantages of the new grade control process:
  • Hours are saved in the blast zoning process, improving quality and productivity, allowing closer attention to operational requirements.
  • Fully integrated system for grade estimation parameters and product classification.
    All information - drillholes, solids, blocks and reports - is stored in an accessible centralised grade control database.
  • Faster generation of more effective reports (monitoring, tracking, audits).
  • Comparison between long and short term information.
  • Quick recall of blasting already done for reconciliation.
  • Automation and connection with other systems to integrate all processes of the grade control cycle (e.g. dynamic equipment allocation).

Better management of the blast information in turn leads to better decisions, incorporating technological development and best practice on ore control at Cerro Negro Norte.

Thanks to Cristián Astudillo
Chief Geologist, Cerro Negro Norte
Compañía Minera del Pacífico
Presented at 2012 South America Users Conference