Assessment of Ore Dilution and Quality Control Practices in Open-Pit Mining Operations

Abstract

Ore dilution and quality control represent two of the most critical challenges facing modern open
pit mining operations, directly impacting economic viability, operational efficiency, and resource
recovery. This capstone research examines the causes, measurement, and control of ore dilution at
Frontier Copper Mine, an open-cast operation located in the Haut-Katanga Province of the
Democratic Republic of the Congo, near the Zambian border. Frontier Mine, operated by Eurasian
Resources Group (ERG), processes over 10 million tonnes of copper sulphide ore annually to
produce approximately 100,000 tonnes of high-quality copper concentrate. The mine's distinct
geological setting—a structurally-controlled, vein-hosted copper deposit within the Katangan
Supergroup—presents unique challenges for grade control and dilution management.
This research employs a mixed-methods approach combining quantitative analysis of production
data with qualitative assessment of operational practices. Primary data were collected through
structured questionnaires administered to 45 respondents across geology, mine planning,
production, and quality control departments, semi-structured interviews with 8 key informants
including department heads and senior engineers, and direct observation of grade control and
mining activities. Secondary data included production records, geological reports, blast movement
data, and reconciliation reports from 2020 to 2024.
The study identifies primary dilution sources including blast-induced rock movement (accounting
for approximately 42% of total dilution), geological complexity (28%), operational
miscategorization (18%), and equipment selectivity limitations (12%). Analysis of production data
reveals dilution rates ranging from 8.5% to 16.2% across different ore zones, with an average of
12.3% over the study period. Reconciliation analysis shows a systematic negative variance
between planned and actual grades averaging 6.8%, indicating significant grade control
challenges. The economic impact is substantial, with estimated revenue losses of approximately
US$ 8.2 million annually due to dilution-related grade reductions.
Key findings reveal that dilution at Frontier Mine is exacerbated by the complex vein-hosted
mineralization geometry, where copper occurs predominantly as coarse-grained chalcopyrite in
quartz-carbonate veins, making ore-waste discrimination particularly challenging. The research
proposes an integrated quality control framework encompassing advanced geological modelling,
blast movement monitoring, real-time grade control, and multi-disciplinary dilution control
forums. The findings contribute to the broader understanding of dilution management in
structurally complex copper deposits and offer practical recommendations for improving ore
recovery and economic performance at Frontier Mine and similar operations.

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