Mine Call Factor issues at Iduapriem Mine: Working towards a Mineral and Metal accounting protocol Monica Naa Morkor Tetteh A research report submitted to the faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in partial fulfilment of the requirements for the degree of Master of Science in Engineering. Johannesburg 2014 DECLARATION I declare that this report is my own, unaided work. I have read the University Policy on Plagiarism and hereby confirm that no Plagiarism exists in this report. I also confirm that there is no copying nor is there any copyright infringement. I willingly submit to any investigation in this regard by the School of Mining Engineering and I undertake to abide by the decision of any such investigation. __________________ ________ Signature Date ii ABSTRACT The theory of Mine Call Factor (MCF) compares the sum of metal produced in recovery plus residue to the metal called for by the mines evaluation method expressed as a percentage. This MCF concept is well known in underground scenarios and therefore this report highlights the MCF issues and the variable components affecting it from a surface mine perspective. The MCF investigation established the relationship between actual measurements and reporting against measurement protocols. Such measurements include “tonnage, volume, relative density, reconciliation strategy, and truck tonnage determination, sampling and assay standards. This study investigated how these measurements are conducted on Iduapriem Mine according to the mine’s standard operating procedures (SOP). An improvement of documents towards a metal accounting protocol based on the AMIRA protocol is recommended. The mine’s current quality control protocol was further expanded to reflect current practices. The mine to mill reconciliation compared production estimates from various sources (resource model, grade control model, pit design, plant and stockpile, truck tally, stockpile and plant feed, plant feed and plant received) in the period 2009 and 2010. Reconciliation factors expressed as a percentage were statistically analysed for discrepancies for tonnages and grades. It was realised that there is more confidence in mass (tonnage) measurement compared to grade. A generic mine to mill reconciliation path was suggested to be used by the mine. iii DEDICATION I DEDICATE THIS REPORT TO ALL THE ANGELS WHO’S NAMES THE REPORT WIL NOT BE ABLE TO CONTAIN. I AM FULL OF GRATITUDE FOR THE SUPPORT, ENCOURAGEMENT AND GUIDANCE THROUGH OUT THIS JOURNEY OF BEGINNING AND COMPLETING. iv ACKNOWLEDGEMENT This research report has been made possible by the assistance of the following persons: 1. Mr Asante Yamoah the Chief mining engineer, Mr Eric Heloo a senior mine surveyor, Mr Frederick kyeremateng a senior planning engineer and all the management team of AngloGold Ashanti Iduapriem mine for assistance received during my visit to the mine and for allowing me to use their data. 2. Mr Dave Borman, a senior lecturer of the University of the Witwatersrand, for his readiness to listen, discuss and share experiences whilst working on the mine (both in Ghana and South Africa) as well as suggestions. 3. Mr Eric Engman the Chief geologist at Newmont Ghana gold limited for all the inputs and suggestive ways forward. 4. Big thanks to my parents Mr Robert Tetteh and Mrs Theresa Tetteh, my siblings (Anthony, Hilda, Robert and Albert) who have always encouraged me to do more. 5. My friend Paskalia Neingo for being a selfless friend. 6. My heartfelt gratitude to all the administration staff of the school of mining engineering. 7. A faithful friend, teacher and husband Mr Senyo Dedzo dzokoto, I say thank you for your deep understanding, encouragement and passion for education. 8. To my supervisor Professor Frederick Cawood. I simply don’t have words to describe my deepest appreciation for your mentorship over the years. You are simply the best. Thank you v Table of Contents DECLARATION ......................................................................................................................................................... ii ABSTRACT .............................................................................................................................................................. iii DEDICATION ........................................................................................................................................................... iv ACKNOWLEDGEMENT ............................................................................................................................................ v TABLE OF FIGURES ................................................................................................................................................. ix LIST OFACRONYMS ................................................................................................................................................. x LIST OF DEFINITIONS ............................................................................................................................................... x 1 INTRODUCTION .............................................................................................................................................. 1 1.1 Problem Definition ................................................................................................................................ 1 1.2 Relevance of the research ..................................................................................................................... 2 1.3 Objectives .............................................................................................................................................. 2 1.4 Expected outcome ................................................................................................................................ 3 1.5 The methodology employed ................................................................................................................. 3 1.6 Overview of Iduapriem mine ................................................................................................................ 4 1.7 Geology and Mineralisation .................................................................................................................. 5 1.8 Processing Plant .................................................................................................................................... 6 1.9 Sampling and assaying procedure after mill fence ............................................................................... 7 1.10 Mining and operation............................................................................................................................ 8 1.11 Iduapriem production reports and MCF issues ................................................................................... 12 1.12 Mine call factor and its significance .................................................................................................... 14 1.13 Apparent and real losses ..................................................................................................................... 15 1.14 Summary of MCF issues at Iduapriem ................................................................................................. 19 1.15 Conclusion ........................................................................................................................................... 19 CHAPTER 2 ............................................................................................................................................................ 21 2 Theory of Metal accounting ......................................................................................................................... 21 2.1 Ore flow balance sheet ....................................................................................................................... 23 2.2 AMIRA P754 code ................................................................................................................................ 30 2.3 Mass measurements ........................................................................................................................... 33 2.4 Accuracy and precision of mass measurement ................................................................................... 34 2.5 Measurement of density and moisture .............................................................................................. 36 2.6 Sampling and analyses ........................................................................................................................ 39 2.7 Storage of samples and labelling ........................................................................................................ 40 2.8 Sample preparation and analyses ....................................................................................................... 40 2.9 Spangenbergs sampling checklist ........................................................................................................ 40 2.10 Survey compliance code...................................................................................................................... 40 2.11 Reconciliation between planned and actual in the coal industry ....................................................... 41 2.12 Mine planning and reconciliation process .......................................................................................... 42 2.13 Statistical