Advanced Grade Control with Multivariate Geostatistics, Blast Movement Modeling, and Optimized Dig Limits

• Author / Creator

  Vasylchuk, Yaroslav Valentynovych

• Grade control in open pit mines establishes the final destination for mined material (e.g., plant, leach pad, stockpile, waste dump, etc.). In contrast to long- and medium-term mine planning, errors at this stage of a mine operation cannot be changed in the future; correct decisions bring a certain amount of profit, while wrong decisions incur a certain amount of loss. In the simplest grade control case, there is only ore and waste. Ore is more profitable to process in the plant than send to the waste dump. More complex cases may involve multiple grades, multiple destinations, locally varying geology, and complex profit calculations. Any flaw in the grade control procedure can lead to significant losses.

  This thesis formulates and develops improved theory and practice for grade control procedures in open pit mines. An integrated grade control system called the Advanced Grade Control (AGC) is developed that considers all the relevant data and encodes rules and algorithms to make important decisions automatically. The developed system is a nearly automatic algorithm that seamlessly links all the grade control processes. The main components of the system are: i) spatial prediction of grades or profit, ii) modeling the blast-induced displacement of pre-blast spatial predictions, and iii) optimization of mineable dig limits.

  AGC uses the maximum expected profit approach for making grade control decisions. High resolution expected profit is automatically calculated using a new local multivariate simulation algorithm called the Advanced Grade Control-Expected Profit (AGC-EP). The algorithm utilizes a k-fold cross-validation procedure to optimize input parameters. Two case studies based on real data demonstrate that AGC-EP outperforms carefully applied kriging estimation in terms of total profit from a mine bench.

  An optimization-based algorithm called the Advanced Grade Control-Blast Movement (AGC-BM) has been developed to model blast-induced displacement of rock in 3-D using gridded pre- and post-blast topography and direct blast movement measurements. The blast movement of rock is considered an optimization assignment problem approximately solved by a heuristic algorithm. The objective function and optimization details are explained and examples are provided. A method is proposed to calibrate limited blast movement measurements using firing pattern information. Blast movement modeling with approximate topography is considered.

  An algorithm for optimizing the classification of surface mine material subject to excavating constraints called the Advanced Grade Control-Dig Limits (AGC-DL) is developed. High resolution expected profit models are input and optimized to classification maps subject to site specific rectangular or non-rectangular excavating constraints. The algorithm is fast and produces classification maps that allow selecting up to 98-99 \% of the total maximum expected profit obtained with free selection.

  A grade control system should work nearly automatically and be integrated within a mine’s short-term planning and processing workflows. It should work in unison with precise location tracking and measuring equipment providing constantly updated information on the position of excavating equipment and ore grade. The Advanced Grade Control system is a step towards intelligent grade control utilizing all available information in real time for maximizing profit from mining operations.

• Subjects / Keywords

  • Blast movement modeling
  • Mining engineering
  • Grade control
  • Short-term mine planning
  • Dig limits optimization
  • Multivariate geostatistics

• Graduation date

  Fall 2019

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/r3-5qkm-r822

• License

  Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.